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Association between Ectopic Eruption of Maxillary Canines and First Molars Becktor KB, Steiniche
K, Kj r I March 3,
2006 |
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[Ãʹú¿ø°í] As you¡¯re reviewing a panoramic x-ray taken on your patient Samantha, you note a very disturbing finding, an ectopic maxillary canine on the right side has caused resorption of almost half of the adjacent lateral incisor root. As you look back at your notes, you see that you treated Samantha several years earlier for bilateral ectopic eruption of the maxillary first molars, but nothing else significant. You question whether you should have taken a x-ray sooner. But there was no clinical indication to do so. All was there. An interesting article appeared in the April 2005 issue of the European Journal of Orthodontics called ¡°Association between Ectopic Eruption of Maxillary Canines and First Molars.¡± The purpose of this investigation was to look specifically at an ectopic first molars and later incisor resorption caused by ectopic canines. This is not a study looking for a cause and effect, but simply for an association. |
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The authors identified a group of 30 patients, about two thirds female, who exhibited maxillary incisor root resorption due to ectopic canine eruption. With these thirty patients, they look back at the dental histories to see whether there was an indication of earlier ectopic molar eruption resulting in significant second primary molar root resorption. Most investigations have ectopic molar eruption indicate a prevalence of about five percent. What the investigators found were they look the group of 30 patients with incisor resorption, which at the prevalence of ectopic molar eruption was not the expected 5 percent, but more like 25 percent. This is almost five times expected rate. |
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The authors theorize that the association was not a chance happening, but likely the result of some genetic PDLs weakness or susceptibility the resorption. They believe that the same factors that allowed the erupting first molars, the prematurely reserve the primary molars could be responsible for allowing the ectopic canines to reserve the permanent incisors later. We must recognize that the level of evidence provided by this study for the association between ectopic molar eruption and incisor resorption is relatively low. The sample size is small. And the increased prevalence of ectopic molar eruption could be due to the chance alone. However, until we get more definitive information, it may be wise to watch more closely the canine eruption in those patients who demonstrate ectopic molar eruption. If you had this informations before, you may handle your patient, Samantha that I described at the beginning of this review, a bit differently. Since she had a history of ectopic molar eruption, you may have a like to take a panoramic X-ray earlier. And the end of the X-ray demonstrated possible ectopic canine eruption, you may have a like to recommend earlier intervention, because of the possible link to incisor resorption. Again, this information is relatively weak, but you may want to keep a little close your eye on those patient with history of ectopic molar eruption. For more information, see the April 2005 issue of the European Journal of Orthodontics. |
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Leadereship and Team Building Levin R. March 10,
2006 |
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[Ãʹú¿ø°í] I think it is fair to say that a great majority of most orthodontic education is focused primarily on gaining a good understanding of basic principles of orthodontic diagnosis and treatment, and as well as an understanding of the basic research that supports these principles. When most orthodontists complete their orthodontic education, they enter some form of private practice, either a solo private practice or group practice. In either case, like it or not, this new environment forces them to become leaders and team builders for which all too often they have received very little education. In article titled¡°Leadership and Team Building¡±by Roger Levin, which appeared in the May 2005 issue of the Journal of the American Dental Association, discusses leadership and team building for dentist. |
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Doctor Levin emphasizes that at a time of increased complexity in managing professional practices, the dentist or orthodontist must become more of an effective leader. He further suggests that leadership qualities rarely are genetic and becoming an excellent leader has a great deal to do with having the right desire, skills and behavior. He notes that while desire alone does not create an excellent leader, it is an important ingredient in the essential step from moving in that direction. Dentists who develop a desire to be excellent leaders for their teams are more open-minded to leadership training and skills enhancement. Leadership is more than simply having a vision or mission, and communicating them to your team. It also involves a number of major and minor factors such as good hiring, proper training, compensation plans that motivate employees and a host of other factors. To become excellent leaders, all orthodontist would be well served to read at least one leadership book a year and concentrate on books that enable them to acquire additional skills, and enhance motivation for the practice team. To be a good leader, you not only need to have the appropriate desire and leadership skills but also exhibit appropriate behavior. |
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In this article, Doctor Levin notes that most studies indicate that money is number 6 or 7 concerning what is important to employees. These studies note that if employees are underpaid, other factors do not matter. However if they are compensated at a reasonable level, then money is not the main motivating factor. Factors that rank higher on the scale include recognition, appreciation, respect, enjoyable work environment and the opportunity for professional development. |
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To be a good leader, you should develop a system to accomplish certain things on a regular basis. Included on this list should be daily compliments to team members, annual evaluation of skills for team members with specific continuing education suggestions, appreciations demonstrated through bonuses, time off and special items that are relevant to individual team members. |
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The bottom line is that orthodontists, who are willing to spend a small amount of time focused on leadership, inevitably will build better teams with lower turnover and higher efficiency. You can find this very practical article in the May 2005 issue of the Journal of the American Dental Associations. |
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The Nuts and Bolts of Hemisection Treatment: Managing Congenitally Missing Mandibular Second Premolars Northway WM. March 17,
2006 |
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[Ãʹú¿ø°í] How do you treat patients with congenitally missing mandibular 2nd premolars? If these patient have significant crowding in the mandibular arch or protrusion of the mandibular incisors, extraction of the primary mandibular 2nd molars is a logical choice. However, more often, patients with congenitally missing mandibular 2nd premolars have a well-aligned mandibular arch and mandibular incisors that are not protrusive. If you decide to extract, the primary mandibular 2nd molars in patients like this, it is necessary to totally protract the mandibular 1st molars to the large space created by the extraction of the primary mandibular 2nd molars. This requires excellent reverse anchorage and if this anchorage is not satisfactory, an undesirable retraction of the mandibular incisors and flattening of the facial profile can occur. In an article titled¡°The Nuts and Bolts of Hemisection Treatment, Managing Congenitally Missing Mandibular 2nd Premolars¡±by William Northway which appeared in the May 2005 issue of the American Journal of Orthodontics and Dentofacial Orthopedics, described the technique to support mesial movement of the mandibular 1st molars. |
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This technique involves hemisecting the mandibular primary 2nd molar and extracting the distal half. It is suggested that this allows immediate mesial drift of the mandibular 1st molar, and that the maintained mesial half of the primary molar acts to prevent distal drift of the anterior teeth. After the mandibular 1st molar has drifted into contact with the mesial half of the hemisected primary molar, the mesial half is extracted. At this point, it is necessary to cooperate appropriate mechanics to close the remainder of the extraction space from the distal. To do this, Dr. Northway suggested using a functional appliance such as an activator to hold the mandibular teeth in position using class 1 elastics to complete the protraction of the mandibular 1st molar. He further suggests that more recently he has been implementing more of a called a cuttomy approach when he moving the mesial half of a deciduous molar with a hope of reducing the edentulous side left by the congenitally missing mandibular 2nd premolars even more rapidly. |
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Total protraction of the mandibular 1st molars to a space of approximately 11mm is a very difficult challenge and the hemisection technique described in this article appears make sense to me. Much of its success depends on the maintain mesial half of the primary molar defectively preventing distal drift of the anterior teeth. Dr. Northway suggests that this does happen. |
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If you have a patient with congenitally missing mandibular 2nd premolars for whom total mesial movement of the 1st molars is required, I would suggest that you read this article which contains excellent photographs demonstrating the technique that appears in the May 2005 issue of the American Journal of Orthodontics and Dentofacial Orthopedics. |
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Evidence-based Orthodontics: What Do We Want to Know? Huang GJ. March 24,
2006 |
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[Ãʹú¿ø°í] In the dental and orthodontic literature, more and more attention is being paid to evidence-based practice or our task, evidence-based orthodontics. As I mentioned in previous preview concept on evidence-based practice is gaining momentum or more surely having influence on the way to orthodontic practice in the future. |
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What is evidence-based orthodontics? Evidence-based medicine, dentistry or orthodontics is simply making treatment decisions based on the result or conducted research studies. On each phase value is a hard bear pose such a concept. However, some dentists or orthodontists are concerned about evidence-based practice because they feel it might limit treatment options or be used by insurance companies to limit coverage. |
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A recent article which appeared June 2005 issue of the American Journal of Orthodontic Dentofacial Orthopedics by Greg Huang discussed some reason advanced to coverage related with evidence-based practice. American Dental Association released its 2005 research agenda, which encouraged this association to take the leading role in promoting, conducting, and critically reviewing research on topics related to dentistry and its relationship to the overall health of the individual. |
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Also recently the National Institutes of Health funded 3 centers to develop practice-based research network in general dentistry. Acknowledging many private practitioners are skeptical of university research, under the new concept of the evidence-based practice practicing dentists will be recruited to develop questions of the greatest importance to dentistry that need to be the focus on the future research. Also the same practitioners will receive training on research methods and then participate research network to answer the question that they have developed. |
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In this article, Dr. Huang suggests that the AAO should survey its members and answer them to identify the important questions that need to be answered the Orthodontics. Next step, it will do conduct well-designed size studies possibly with the practice network model and then systematically review the result to obtain evidence-based answers. I should know that the AAO council on scientific affairs is already taking the leadership position in this area. This article which appeared June 2005 issue of the American Journal of Orthodontic Dentofacial Orthopedics contains some interesting well proud outcome on the potential for evidence-based orthodontics. |
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Long-Term Follow-Up of Severely Resorbed Maxillary Incisors after Resolution of an Etiologically Associated Impacted Canine Becker A, Chaushu S. March 31,
2006 |
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[Ãʹú¿ø°í] If you have been practicing orthodontics for reasonable amount of time, I assume you have experienced the patient who had impacted maxillary canine that caused significant resorption of either the maxillary lateral incisor or maxillary central incisor roots. How do you treat the patient like this? If root resoption of maxillary lateral incisor is significant, do you attempt canine substitution, or do you prophylactically extract lateral incisors in preparation for implant or some other form of prosthetic restoration. A recent study titled ¡°Long-Term Follow-Up of Severely Resorbed Maxillary Incisors after Resolution of an Etiologically Associated Impacted Canine¡± by Adrian Becker and Stella Chaushu, which appeared in June 2005 issue of American Journal of Orthodontics and Dentofacial Orthopedics evaluated 11 patients with 20 severly resorbed maxillary incisors. Assessments of root resorption were made prior to treatment after resolution of impacted canine after overall orthodontic treatment of completed and at a minimum of 1-year follow-up. The average treatment time of resolution of impacted canine was approximately 10 months, the mean overall orthodontic treatment was approximately 23 months and the mean follow-up period was approximately five and half years. |
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I found the results of study to be fascinating. The survival rate of the severly resorbed incisors was 100% with none of the teeth involved in lost, and root cannal therapy was not required in any patients. During the period between the initiation of orthodontic treatment and resolution of impacted canine root resorption was aggressive and rapid, resulting in a 17% increase in the crown /root ratio of the affected incisors. However, once the impacted canine was distant from the root area, resorption almost always ceases. and resorbed incisor can subsequently be moved orthodontically with minimum risk of further resorption. Not only were none of resorbed incisors lost in this study and none of teeth show discoloration, not required root canal therapy and no patient was found it necessary to stop treatment because of the resorption. |
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This findings are particularly impressive, in light of fact many of incisors underwent significant orthodontic treatment after canine impaction was result. The bottom line of this study is that it is critical to identify patients who have impacted maxillary canine that may be causing incisor root resorption and initiate treatment to redirect eruption of impacted canine as soon as possible. After this has been done, the prognosis for the incisors is good and there is no need to consider canine substitution or extraction of the incisors. This is good news for both patients and orthodontists because it justifies more conservative approach to this patient. You can find the article in June 2005 issue of American Journal of Orthodontics and Dentofacial Orthopedics. |
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Effect of Antimicrobial Monomer-Containing Adhesive on Shear Bond Strength of Orthodontic Brackets. Bishara S, Soliman M,
et al. April 7,
2006 |
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[Ãʹú¿ø°í] Do you still have problems with decalcification around orthodontic brackets in some of your adolescent patients? I think all orthodontists would have to answer yes to that question. Although most of our patients have adequate oral hygiene to prevent decalcification around brackets, there are some patients who simply do not clean adequately. And we all know the scars that decalcification leaves on the teeth, but there may be new hope. There¡¯s a new product on the market that combines an anti-microbial agent in the monomer of the bonding material and fluoride in the adhesive portion of the bonding material. Together perhaps, these could have an influence on potential decalcification in patients who don¡¯t clean adequately. But does the addition of an anti-microbial agent and fluoride affect the shear bond strength of the bonding composite. That issue was addressed in an article that was published in the May 2005 Angle Orthodontist. |
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The title of the article is "Effect of Anti-microbial Monomer Containing Adhesive on Shear Bond Strength of Orthodontic Brackets". The study was co-authored by Sarmir Bishara and three other associates from the department of orthodontics at the University of Iowa. The purpose of their study was to determine the effect of using this new adhesive system on the shear bond strength of orthodontic brackets. Now this was a laboratory or in vitro study. The authors collected 40 freshly extracted human molars. The teeth were cleansed, and the enamel surface was polished. The 40 teeth were randomly divided into two groups. In the control group, Transbond XT adhesive system was used to bond the brackets to the teeth. Now the teeth were prepared in the typical manner using 35% phosphoric acid to etch the teeth followed by washing with water spray. Then the brackets were placed on the teeth and light-cured. The experimental group of 20 teeth were prepared in the same manner, however, after etching, a primer containing an anti-microbial monomer was applied to the etched surface and left for 20 seconds. Then, this was sprayed with a mild air stream to evaporate the solvent. Next, a material called Clearfil protect bond which contains fluoride was then applied to the tooth and the bracket was light-cured. After half an hour of setting time, each of the teeth was subjected to a testing machine which tested the shear bond strength of each of the brackets. Okay, so much for methodology. |
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What have these researchers find? The answer is straight forward. Based upon careful analysis of the control and experimental groups, the authors found no significant difference between the shear bond strength of the anti-bacterial fluoride releasing adhesive and the control adhesive. In fact, the shear bond strength of the anti-bacterial fluoride releasing adhesive was slightly higher than the control adhesive. So it appears that this new agent which has both anti-bacterial and fluoride releasing properties does not result in decreased bond strength but only time will tell if these additive agents really have an effect on decalcification around orthodontic brackets. The next test that should be carried out by these researchers is an in vivo evaluation of subjects who perhaps have less than adequate oral hygiene in order to determine if the anti-bacterial and fluoride properties really have an effect clinically. In the mean time, if you would like to review this laboratory study on this new product, you can find it in the May 2005 issue of the Angle Orthodontist. |
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Skeletal Class III Oligodontia Patient Treated with Titanium Screw Anchorage and Orthognathic Surgery Kuroda S, Sugawara Y,
et al. April 14,
2006 |
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[Ãʹú¿ø°í] Traditionally I have not reviewed many case report articles for practical reviews. However in the June 2005 issue of the American Journal of Orthodontics and Dental Facial Orthopedics, I read a case report article titled ¡°Skeletal Class III Oligodontia Patient Treated with Titanium Screw Anchorage and Orthognathic Surgery¡± by Shingo Kuroda et al. It attracted my attention because from my experience I have found that patients with mutilated dentitions are some of the most difficult patients to treat. I was anxious to see how this patient was treated because I knew if it was presented as a case report in the AJODO it would be a well treated case. What I found was interesting. The patient was a 15 year old 8 month Japanese female who was missing seven premolars and one mandibular lateral incisor. Additionally she had one over retained maxillary primary molar and two over retained mandibular primary molars. She had a mild to moderate Class III skeletal dental malocclusion with an ANB of -2 degrees and an edge to edge incisor relationship as a result of retro-inclined mandibular incisors. |
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The authors decided on a surgical orthodontic treatment plan that involved surgical mandibular reduction for the prognathic mandible but also included maxillary impaction. Because they also wanted to close as many of the edentulous spaces as possible they had to develop a treatment plan that would allow them to close the mandibular spaces from the posterior and not retract the mandibular incisors so that they could maintain the class III malocclusion to accomodate the mandibular reduction surgery. They chose to provide this anchorage by placing two titanium screws in the retromolar area about 5mm distal to the mandibular second molar. Two large 19 by 25 arch wires were then placed between the vertical slots on the brackets on the mandibular right lateral incisor and the left canine and the titanium screws. Basically these heavy arch wires acted as an anchorage to prevent the anterior teeth from moving distally during mandibular space closure. This is the same type of anchorage system previously reported by Jim Roberts at the University of Indiana. And in this case the system was effective in maintaining mandibular incisor position while achieving significant mesial movement of the mandibular molars. Up until this point everything that I have described seems logical. As I read further through the case report however there were aspects of the treatment that I found particularly interesting. |
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First, when I reviewed the initial records I saw nothing that indicated the need for maxillary impaction surgery because the patient did not have an excessive labial gap and had a rather low smile line. The authors noted that they did the LeFort I osteotomy to avoide clockwise rotation of the mandible. I thought this was unusual because mandibular reduction surgery should not necessarily cause a clockwise rotation of the mandible. Also they noted that the titanium screws were placed during the mandibular reduction surgery to avoid the pain of placing the screws. I would have thought that placing the screws initially to help set up the teeth for surgery would have been preferable to placing them at the time of surgery. The post treatment radiographs showed the placement of rigid fixation in the maxilla but no wiring or screws in the mandible to support the vertical ramus osteotomy. I previously mentioned that I was surprised that impaction surgery was done in a patient with no evidence of vertical access. And I wondered how a good result could be achieved doing this. When I reviewed the pre treatment and post treatment composite tracings they indicated that in fact the maxillary molars were not impacted as a result of the surgery. The bottom line of this case is that I believed the authors achieved a good result and clearly demonstrated that the titanium screws were effective in providing anchorage to move the mandibular posterior teeth anteriorly without retracting the incisors. However, I questioned whether maxillary surgery was needed for this patient. I encourage you to look at this case report, review the initial records and decide what you would have done to treat this patient. You can find this article in the June 2005 issue of the "American Journal of Orthodontics and Dental Facial Orthopedics" |
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A Prospective Long-Term Study of Signs and Symptoms of Temporomandibular Disorders in Patients Who Received Orthodontic Treatment in Childhood Edermark I, Carlsson G,
Magnusson T. April 21,
2006 |
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[Ãʹú¿ø°í] Dose previous orthodontic treatment have any correlation with occurrence of temporomandibular disorders? In the eyes of some general dentist, there is an association between orthodontics and the development of TMD in later life. What dose the science say? Let me give an excellent study that was recently performed which evaluated the incidence of TMD after orthodontic therapy and a carefully controlled study. The title of the article is ¡°A Prospective Long-Term Study of Signs and Symptoms of Temporomandibular Disorders in Patients Who Received Orthodontic Treatment in Childhood.¡± The study was co-authored by Inger Edermark and Gunnar Carlsson from the University of Goteborg in Sweden. The purpose of their study was to evaluate a group of orthodontically treated patients long-term after treatment in order to assess the development of signs and symptoms of TMJ disorders. |
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The sample for the study consisted of 50 consecutively treated patients who underwent orthodontic treatment between 1981 and 1983. Their mean age at start of treatment was 13 years. After an average time of 17 years, an attempt was made to locate these patients and determine whether or not temporomandibular disorders had occurred long-term after their orthodontic treatments. 90 percent of subjects was traced and sent the questionnaire. Out of the original 50, 40 subjects returned the questionnaire and 30 appeared for a clinical examination. Now, in the questionnaire issues such as headache, pain, limited opening and the other factors that was suggested temporomandibular disorders were asked. During the examination, the occlusion and muscles were examined to determine any return of malocclusion or direct symptom of temporomandibular disorder. |
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So, what are these researchers find? Is orthodontics in childhood related to the development of TMD at a later time? Absolutely not. The authors found the incidence of manifesting TMD that require treatment in the sample of subjects over this time interval was about 1%. This is probably no different than of none orthodontically treated populations of individuals. Furthermore, the authors found that the prevalence of signs and symptoms of TMD was low both before and after the active phase of orthodontic treatment as well as 17 years post-treatment. The vast majority of subjects were pleased with orthodontic result and were symptom free. |
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In conclusion, the authors believe that the vast majority of subjects who have undergone orthodontic treatment during childhood have a low incidence rate of manifesting TMD. Therefore, this suggests that there is no elevated risk for developing TMD after orthodontic treatment. |
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If you'd like to review this study which assess the incidence of TMD in an orthodontically treated populations, you can find it in the July 2005 issue of the Angle Orthodontist. |
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Digital Design and Manufacturing of the Lingualcare Bracket System Mujagic M, Fauquet C,
et al. April 28,
2006 |
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[Ãʹú¿ø°í] When was the last time you treated a case with lingual appliances? I have to admit, I gave up about ten years ago because it was hard on the patient, hard on my back, and I had a difficult time getting the results that I was accustomed to with labial appliances. Recently I reviewed an article with you that described the SureSmile system which uses advanced 3D technology to provide robot bent archwires to help with finishing. In the June 2005 issue of the Journal of Clinical Orthodontics, there is an article called "Digital Design and Manufacturing of the Lingualcare Bracket System". |
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The Lingualcare system uses similar technologies of 3 dimensional treatment simulation along with custom bracket manufacturing to provide a lingual bracket system that reportedly is more comfortable for the patient and easier for the orthodontist to get the nicely finished result that we all desire. The Lingualcare procedure starts with making polyvinyl siloxane impressions of the patient's teeth, much like is done for invisalign. Two sets of dental casts are poured from these impressions. The first set of casts is sectioned and reset in the ideal finished position like a lab would do to make a tooth positioner. After the set -up is done, it is scanned 3 dimensionally into the computer. A technician then uses these virtual models to design custom bracket bases that covered the majority of the lingual surface of each tooth. |
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After the bases are all aligned, virtual brackets are added to the bases with digital tools, so that the bracket slots are perfectly aligned. Once the base and bracket design is complete, wax prototypes are produced using a 3D digital wax printer and these prototypes are cast in gold. After polishing, the brackets are placed back on the second set of casts which still represent the original malocclusion. Placing the brackets into the correct position is easy because the large lingual base indexes into the right location. Indirect bonding trays are then constructed and used to transfer the brackets into the patient's teeth. The Lingualcare system also includes robot bent archwires to provide correct alignment and archform. The technology used with the Lingualcare system is fascinating. As things progress, I am sure they will do virtual set-ups instead of the plaster set-ups and the process will be come more automated. |
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I believe the ultimate success will depend on two things. First, will it truly make it easy for the orthodontist to get consistently good results and similar treatment time with good patient comfort? And secondly, can the process be made efficient enough to be cost effective? If you're interested in learning more about the Lingualcare system of lingual orthodontics, you can find a description and many helpful pictures in the June 2005 issue of the Journal of Clinical Orthodontics. |
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Histomorphometric and Mechanical Analyses of the Drill-Free Screws as Orthodontic Anchorage Kim J-W, Ahn S-J, Chang
Y-I. May 12,
2006 |
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[Ãʹú¿ø°í] Achieving adequate anchorage is a challenge in many orthodontic patients. This challenge increases significantly for patients who have numerous missing teeth or severe skeletal relationships. This need for adequate anchorage led to use of implants and onplants as a source of anchorage. However, because implants and onplants have significant disadvantages in that they can only be used in limited locations such as the palate and edentulous areas, require delayed loading and often need surgery for removal, the use of screws for orthodontic anchorage became popular. |
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Initially, the use of screws for anchorage required pre-drilling before placement. However, a more recent development has been the emergence of drill-free screws which have a tip like a corkscrew and a specially formed cutting flute that enables them to be inserted without drilling. Drill-free screws can provide excellent screw to bone contact and inserting them produces little bone debris and less thermal damage than screws that require pre-drilling. This raises the question that given the easier use of drill-free screws, are they better, equal to or worse than pre-drill screws as a source of orthodontic anchorage? This question was addressed in an article titled ¡°Histomorphometric and Mechanical Analyses of the Drill-Free Screw as Orthodontic Anchorage¡± by Jong-Wan Kim et al, which appeared in the August 2005 issue of the American Journal of Orthodontics and Dentofacial Orthopedics. |
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In this study, the authors used 2 male beagles (dog) as experimental subjects and placed 32 screws measuring 1.6 mm in diameter into the buccal and palatal regions of the maxilla and the buccal region of the mandible. The screws were divided into 2 groups; one utilizing drill-free screws and the other screws that required pre-drilling. In both groups, a force of 200 to 300 g was applied to screws using a nickel-titanium coil spring. The Force was placed 1 week after insertion for a period of 11 weeks. At this point, the screws were tested for mobility after which the dogs were sacrificed and the screws with the surrounding bone were prepared for histomorphometric evaluation. |
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How did the two different types of screws compare as sources of orthodontic anchorage. The bottom line is that screws in the drill-free group showed less mobility, had more bone-to-metal contact and more bone area when compared with the drilling group. In the drill-free group, one screw in the maxilla was lost and in the drilling group, one in the maxilla and one in the mandible was lost. the authors suggest that the difference in the performance of the screws may be due to the damage caused by surgical drilling, specifically overheating during drilling and local disturbances that can inhibit normal healing. The bottom line of this study is that if you are contemplating using screws for orthodontic anchorage it is easier and advantageous to use a drill-free screw. You can find this article in the August 2005 issue of the American Journal of Orthodontics and Dentofacial Orthopedics. |
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The Influence of Lower Face Vertical Proportion on Facial Attractiveness Johnston DJ, Hunt O, et
al. May 19,
2006 |
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[Ãʹú¿ø°í] We all realize it is hard to define how facial proportions influence the perception of attractiveness or beauty. Our profession tends to focus on anteroposterior problems more than vertical ones. But previous research has indicated that vertical proportions are actually more important than horizontal features in determining attractiveness. Researchers from Queen's University in Belfast were interested in further investigating the influence of vertical proportions on facial attractiveness and they published the results of their investigation in the August 2005 issue of the European Journal of Orthodontics. |
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The purpose of their study was to determine how increasing or decreasing the lower face height affects the perception of attractiveness by a group of lay judges. In order to complete this study two things were needed-a series of profiles with a variety of lower face height proportions and a group to act as the lay judges. The profiles were generated by first obtaining a cephalogram of a male with ideal facial proportions. This tracing had the ideal lower anterior face height ratio of 55%. This ideal tracing was then modified to provide 8 additional tracings that had a face height ratio of 1, 2, 3, and 4 standard deviations greater and 1, 2, 3, and 4 standard deviations less than the ideal. These nine tracings were then converted to profile silhouettes to be shown to the judging panel. The judging panel, the second thing needed for this study, was 92 social science students that ended up being mostly female. Although the authors suggested that previous studies did not indicate differences between male and female judges for such ratings, it would have been nice to have a bit more balanced group. The judges were given the silhouettes in various orders and asked to rate them from one to ten with ten being the most attractive. In addition, the judges were asked for each profile if it were them, would they seek treatment based on the profile appearance. |
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The results reinforce the ideal 55% lower face height ratio. This profile was rated the most attractive by the panel. The attractiveness ratings decreased faster for the increases in face height compared to the reduction face height. In other words, a two standard deviation increase in face height was judged less attractive than a two standard deviation reduction in face height. This also translated to the question of whether they would seek treatment for the profile. 25% of the judges indicated they would seek treatment for the extreme reduction in face height and twice that many indicated they would seek treatment for the extreme increase in face height. |
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The take home message is that variation in lower face height proportions does affect the perceived facial attractiveness and increase in lower face height was more detrimental to attractiveness than a similar decrease. As orthodontists we should be sensitive to assessment of vertical proportions as well as horizontal proportions to maximize the facial esthetic outcome of our patients. Based on these results, we may have more ability to treat skeletal deep bite patients non-surgically with an acceptable esthetic result than we could with a similar degree skeletal open bite patient. |
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For more details about the effect of lower face height on facial attractiveness, read the article by Johnston et al called, "The influence of lower face height vertical proportions on facial attractiveness" that can be found in the August 2005 European Journal of Orthodontics. |
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Labially Displaced Ectopically Erupting Maxillary Permanent Canine: Interceptive Treatment and Long-Term Results Leite HR, Oliveira GS,Brito
HHA. June 16,
2006 |
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[Ãʹú¿ø°í] If you have been subscribing to practical reviews in orthodontics for any length of time, you are aware that I do not usually review case report articles. However periodically a case report article appears in the American Journal of Orthodontics and Dentofacial Orthopedics that is particularly interesting and worthy of review. Such as the case this month, the article is titled ¡°Labially Displaced Ectopically Erupting Maxillary Permanent Canine: Interceptive Treatment and Long-Term Results¡± by Helo sio de Rezende Leite et al. which appears in the August 2005 issue of the American Journal of Orthodontics and Dentofacial Orthopedics. |
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In this article, the authors present a case report of a Brazilian girl aged 10-years, 10-months who had a Class II division 1 deep bite malocclusion with a buccally and mesially angulated, impacted maxillary left canine. The canine overlapped the adjacent lateral incisor root and there was mild to moderate crowding of the mandibular anterior teeth. It was the author s decision to treat this young lady non extraction with a cervical pull face bow headgear which is not an unusual treatment plan and which was effective in taking advantage of the patient's growth. |
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The interesting part about this case however was that the treatment was initiated by placing a cervical pull face bow headgear, a mandibular lingual holding arch and extracting the primary maxillary left canine. For slightly over a year this was the only treatment provided. At the 1 year mark, the cervical pull face bow headgear was effective in achieving a Class I molar relationship and was just continued and the lower lingual holding arch successfully maintained enough arch length to allow the mandibular arch to be treated non-extraction. The most impressive part of this treatment however was the spontaneous alignment of the buccally and mesially inclined impacted maxillary left permanent canine. The spontaneous alignment of the impacted canine was dramatic. |
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I decided to review this article because I believe the potential to significantly improved the position of impacted maxillary canines by the early extraction of a primary canine is frequently overlooked. I often have cases referred to me that have impacted canines and when I go back and look at earlier records, it was obvious at a much earlier age that the canine was erupting ectopically and yet the primary canine was maintained in place. This case report would be a good article to share with your referring general dentists to make them aware of the potential benefit of early extraction of primary canines as a preventive and interceptive orthodontic procedure. It appears in the August 2005 issue of the American Journal of Orthodontics and Dentofacial Orthopedics. |
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Outcome Assessment of Invisalign and Traditional Orthodontic Treatment Compared with the American Board of Orthodontics Objective Grading System Djeu G, Shelton C, Maganzini
A. June 23,
2006 |
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[Ãʹú¿ø°í] Because they offer esthetic advantages, many patients find Invisalign appliances an attractive alternative to full-bonded orthodontics. For this reason, many orthodontics offer this option of treatment to their patients if they feel the patient's specific malocclusion has a reasonable prognosis for success using Invisalign. However, because the few articles in the literature related to Invisalign have mainly been case reports and technique descriptions, it is difficult to determine exactly what type of cases are appropriate for use of Invisalign and more importantly to answer the question about how Invisalign compares with traditional full-bonded orthodontic treatment when the quality of treatment is evaluated. An article in the September 2005 issue of the American Journal of Orthodontics and Dentofacial Orthopedics address this question. It is titled ¡°Outcome Assessment of Invisalign and Traditional Orthodontic Treatment Compared with the American Board of Orthodontics Objective Grading System.¡± by Garret Djeu et al. |
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In this study the authors used the American Board of Orthodontics objective grading system to evaluate the treatment results of two groups of patients. Each group consisted of 48 patients. One group comprised of all the completed patients treated by a single orthodontist using only removable Invisalign appliances. The second group consisted of an equal number of randomly selected patients treated by the same orthodontist using a traditional full-bonded technique. The American Board of Orthodontics discrepancy index was used to compare the initial treatment difficulty of the two groups of the patients and statistical analysis showed that there was no significant difference in the difficulty of the initial malocclusions between the two groups. The post-treatment records for each group were then graded using the ABO objective grading system and the total scores, and the scores for each of the 8 categories was statistically analyzed. Using the ABO¡¡objective grading system, the Invisalign cases lost an average of 13 more points than the braces groups. When the individual grading categories were evaluated, the results indicated that the Invisalign scores were consistently poorer than the braces group for bucco-lingual inclination, occlusal contacts, A-P occlusal relationships and overjet. When the two groups were compared using the score of 30 points or less as the criteria for passing. In the Invisalign group, 10 cases received passing grades, and 38 received failing grades. In the braces group, 23 received passing grades, and 25 received failing grades. There was a statistically significant difference between the 20.8% passing rate for the Invisalign group and the 47.9% passing rate for the braces group. However, when the duration of treatment for the two groups was evaluated, the treatment time for the braces group which was 1.7 years was significantly longer than that for the Invisalign group which was 1.4 years. |
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In evaluating the results of this study, it is important to understand that all of the cases in each group were treated non extraction, thus avoiding extraction treatment which would obviously be more difficult to accomplish with the Invisalign appliances. The bottom line of this study is that when compared with traditional braces Invisalign produces poor treatment results particularly in the area of bucco-lingual inclination, occlusal contacts, A-P occlusal relationships and overjet which evaluate how well anterior and posterior discrepancies are corrected. In fairness I should note that the Invisalign cases that were evaluated for the orthodontist's first 48 cases, and with greater experience, the quality of the Invisalign results might have improved. You can find this article in the September 2005 issue of the American Journal of Orthodontics and Dentofacial Orthopedics. |
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Apical Root Resorption of Maxillary First Molars after Intrusion with Zygomatic Skeletal Anchorage Arzu A, Mazin A, Nejat
E. June 30,
2006 |
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[Ãʹú¿ø°í] You can't open up an orthodontic journal today without seeing an article about the use of mini-implants, micro-implants, mini-implant anchorage, or palatal implant anchorage. The use of implants to enhance orthodontic anchorage has truly revolutionized some of our treatment plans, and our treatment concepts for certain patients. But when implants are used to move teeth, there can also be a downside risk. One of those concerns could be an increased risk of root resorption especially if implants are being used to intrude teeth with a significant force. Now in the past, research on animals has shown that intrusive mechanics especially in the maxillary posterior region will produce accelerated root resorption. Does this happen with implant anchorage? That question was answered in a study that was published in the September 2005 issue of the Angle Orthodontist. The title of this article is "Apical Root Resorption of Maxillary First Molars after Intrusion With Zygomatic Skeletal Anchorage". This study was co-authored by Dr. Demirkaya and two other research colleagues from Marmara University in Istanbul, Turkey. |
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The purpose of this article was to evaluate radiographically the apical root resorption of the maxillary first molars after intrusion was accomplished using zygomatic mini-plates as skeletal anchorage in open bite cases. The sample for this study consisted of 16 consecutively treated open bite patients. 13 of these subjects were females and the other 3 were males. Prior to orthodontic treatment, panoramic radiographs were available in all of these subjects. In addition, panoramic radiographs were also taken after the intrusion had occurred. In each of these subjects, mini plates were placed in the zygomatic buttress and then the maxillary posterior segment including first molars were intruded using Ni-Ti coil springs. The average age of these patients was about 20 years. The authors scanned the pre- and posttreatment radiographs and transferred them to a computer. They were corrected for magnification and then the image was enhanced on the computer so that the actual tooth and its apex could be visualized. The distance from the most occlusal point on the crowns of the first molars to the most apical point on the roots were measured. The amount of shortening of the roots was compared between those subjects who had the molars intruded compared with the similar group of control subjects who had orthodontic treatment but no intrusive mechanics. |
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What did these authors find? Is there a difference in the amount of root resorption seen on first molars when teeth are actively intruded to correct open bites using mini-plate anchorage? The answer to that question is "No". Now the authors did find root resorption, varying between 0 and 2.5mm for the subjects who had implant anchorage compared to 0 to about 1.5mm for subjects who had routine orthodontic treatment. When the differences between these groups were compared, the difference was only about half a millimeter. This difference was not statistically significant and was beyond the range of measurement error using the measurement device depicted in this study. So the bottom line of this study is that when maxillary molars were intruded using skeletal anchorage although there was some root resorption, it was not statistically significant. My only problem with this study is the use of panoramic radiographs to assess the result. This is not ideal. Scanning of the radiographs and enhancement using the computer did help in these situations but I think the use of vertical bite-wing radiographs would of perhaps been a better way to assess the true root length in these individuals. On the other hand, I believe the data in this study. I think it points out that some patients are susceptible to root resorption with intrusive forces and others are not. It really depends upon the patient's genetic makeup and not the intrusive force that causes the root to resorb. |
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If you're interested in reviewing this study on the use of mini-implants to intrude teeth, you can find it in the September 2005 issue of the Angle Orthodontist. |
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Effect of Saliva Contamination on the Shear Bond Strength of Orthodontic Brackets Bonded with a Self Etching Primer Campoy MD, Vincente A,
Bravo LA. July 7,
2006 |
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[Ãʹú¿ø°í] Do you use self-etching primer to bond brackets to teeth? I think many orthodontists have made the switch to this approach. It does avoid the use of separate etching procedure and there is not much of significant difference in the shear bond strength. Anyway, here is my question. If you do use a self-etching primer what happens? If the tooth surface becomes contaminated with saliva during the process, do you start over? Will it affect shear bonding strength? Does it make any difference if saliva contamination occurs before or after placement of the self-etching primer? Those questions were addressed in the study that was published in the September 2005 issue of the Angle Orthodontist. The title of the article is "Effect of Saliva Contamination on Shear Bonding Strength of Orthodontic Brackets Bonded with a Self-Etching Primer." This study was co-authored by Dolores Campoy and Ascension Vicente from the Orthodontic Department at the University of Murcia in Spain. The purpose of this study was to evaluate the effect of saliva contamination at different stages of the bonding procedure using a self-etching primer. |
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The sample for this study consisted of 70 human premolars that had been extracted. These teeth were free of any caries or restorations. The teeth were washed in water and then stored in distilled water. 70 metal premolar brackets were used. The sample of 70 was divided into 4 subgroups. The first subgroup was the uncontaminated control. In other words, no saliva contaminated the surface. In this sample a self-etching primer was placed on the tooth and then light cured. Then Trandbond XT was used to bond the bracket to the primer. In the second subgroup, prior to placement of the self etching primer, saliva was brushed onto the tooth. Then the self-etching primer was applied, light cured and the bracket was bonded. In the third subgroup, saliva contamination occurred after placement and light curing of self-etching primer. The saliva was painted on just before the Transbond XT was applied. Finally, in the fourth group saliva contamination occurred before and after application of the self-etching primer. Then the brackets and teeth were stored for 24 hours. At that time the brackets were debonded using a universal testing machine and the shear bond strength was measured. |
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What are these authors find? Does saliva contamination at a specific time interval affect shear bonding strength? The answer is "Yes, absolutely." What happened? Let me explain. In the uncontaminated group where saliva did not contaminate the surface the shear bonding strength was consistently around 12 MPa. This is clinically acceptable. When the saliva contamination occurred after application and light curing of the self-etching primer, there was no significant difference. Even though saliva contaminated the self-etching primer after it was light cured, placing the Transbond XT and bonding the bracket did not cause any reduction in shear bonding strength. Here's where the problem occurred. If the saliva contamination occurred before placement of the self-etching primer and that is in group 2 and 4, then there was reduction in shear bond strength. But why did that occur? It's because the saliva dose not allow the self-etching primer to penetrate the enamel surface because the saliva was coating the tooth. The shear bond strength that are used in those groups was reduced to around 9 MPa. |
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So, what dose this study mean to you? Well, if you use a self-etching primer and you experience saliva contamination before you place the self-etching primer, you'd better start over. Clean the tooth, dry it and then apply the self-etching primer. However, if the contamination of saliva occurs after you've light cured the self-etching primer, then don't worry. It won't affect the shear bonding strength. |
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If you'd like to review this study for yourself, you'll find it in the September 2005 issue of the Angle Orthodontist. |
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The Influence of Force Magnitude on Intrusion of the Maxillary Segment van Steenbergen E, Burstone
CJ, et al. July 14,
2006 |
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[Ãʹú¿ø°í] How much force does it take to intrude maxillary anterior teeth? Suppose you're planning treatment for an adolescent female. She's 12 years of age and has a Class I malocculsion. Her main problem is that she has a deep anterior overbite. The overbite is caused by over-eruption of the maxillary incisors and when she smiles she shows excess gingiva. Your treatment plan involves intruding her maxillary incisors as part of the orthodontic treatment. Here's my question. How much force is necessary to intrude these maxillary incisors? Should you use 20 g of force, 50 g, 100 g or does it make any difference? These questions were addressed in a study that was published in the September 2005 issue of the Angle Orthodontists. The title of the article is "The Influence of Force Magnitude on Intrusion of the Maxillary Anterior Segment". The study was co-authored by Dr. van Steenbergen and three other research colleagues form the Academic Center for Dentistry in Amsterdam. The purpose of this study was to determine whether the magnitude of intrusive force influences the rate of intrusion and the amount of intrusion of maxillary anterior teeth. |
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In order to accomplish this objective, these authors gathered a sample of twenty subjects. This was in-vivo study. All subjects were patients who required orthodontic treatment and as a part of the treatment, they required at least 2 mm of intrusion of the maxillary central and lateral incisors. This sample ranged from about 10 to 15 years of age. Now a segmental approach was used to intrude the teeth. The maxillary premolars, molars, and canines were bracketed and they were placed in the segment on each side. Then an intrusion arch was attached to the maxillary molars and to the maxillary incisors. An intrusive force was applied to the maxillary incisors making the appropriate bends in the maxillary archwire at the molars. But the sample was divided into two groups. In one group, the intrusive force was 40 g and in the other group, the intrusive force was 80 g. Lateral cephalometric radiographs were used to determine the amount of intrusion and measurements were made over the treatment interval to determine the rate of intrusion. In addition, the authors also gathered information about the amount of extrusion of the molars and posterior teeth as well as axial changes in the maxillary anteriors. |
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Okay, what do you think these authors found? Does the amount of force influence the amount of intrusion of maxillary anterior teeth? The answer to that question is NO. With both the 40 and 80 g forces, although there were minor differences in the rate of intrusion, even the rate difference was not statistically significant. Both the 40 and 80 g forces intruded the teeth about the same amount. What about the axial inclination changes? Still no difference. Both the 40 and 80 g forces produced about the same axial inclination changes in the anterior teeth. Question number 3, how about extrusion of the molars? Was there a difference between the 40 and 80 g forces? Again the answer was NO. There was statistically no difference between these two groups. |
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So there you have it. There's a reasonably well done clinical study that shows that there's really no difference in rate or amount of maxillary incisor intrusion, when you're using a 40 g or an 80 g force. If you like to review this study that compares different forces to intrude anterior teeth, you'll find it in the September 2005 issue of the Angle Orthodontists. |
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Microscrew Implant Anchorage Sliding Mechanics Park H-S, Kwon O-W, Sung
J-H. July 21,
2006 |
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[Ãʹú¿ø°í] Let me describe a patient who could very well walk in to your office next week. The patient is a 22-year-old female with a Class I occlusion, minimal crowding and protrusive incisors with very protrusive lips. A main concern is the fullness of her lips and like many adult females, she's not willing to wear extraoral appliances. Your goal for this patient is to maximally retract both the maxillary and mandibular anterior teeth in order to, as much as possible, reduce the fullness of her lips. Extracting four first premolars would obviously be an appropriate way to provide space to retract the maxillary and mandibular anterior teeth. The problem is, after having done this, how are you going to prevent posterior anchorage loss so that can you retract the anterior teeth as much as possible to improve the profile? |
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A technique and case report article titled "Microscrew Implant Anchorage Sliding Mechanics" by Hyo-Sang Park et al which appeared in the volume 6 No. 3, 2005 issue of the World Journal of Orthodontics described a technique for using microscrews along with sliding mechanics and presented a case report of the 22-year-old female that I described. In this case report, microscrews were placed between the maxillary second premolars and the first molars, approximately 8 to 10 mm gingival to the archwire. In the mandibular arch, microscrews were placed between the mandibular first and second molars. In the maxilla, .016 .022 archwire was placed which had vertical arms soldered between the lateral incisors and the canines. These arms extended gingivally approximately 8 to 10 mm, making the end of the wire at the same level vertically as the microscrews. Nickel titanium closed coil springs were then attached between the microscrew implant and the soldered hooks, distal to the lateral incisors to retract the maxillary 6 anterior teeth en masse. By having the horizontal pull of the closed coils located significantly apical to the archwire, the retraction force was closer to the center of resistance and there was less likelihood of tipping the maxillary anterior teeth distally. In the mandibular arch, the vertical elastic was placed between the microscrew and the archwire mesial to the second molar. This provides an intrusive force on the mandibular molars and eliminated the likelihood of molar extrusion if Cl II mechanics were later used. |
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The patient described in this case report was treated in 18 months and the records indicated that significant retraction of both the maxillary and mandibular anterior teeth and the lips was achieved greatly improving her profile. Basically, the microscrews provided almost perfect anchorage for the retraction of the anterior teeth and by retracting the anterior teeth en masse, treatment time was reduced. |
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If you're interesting in learning more about the use of microscrew anchorage combined with sliding mechanics, I would suggest that you read this article which has excellent photographs of both the microscrew implants and the sliding mechanic technique that was used. The article appears in volume 6 No. 3, 2005 issue of the World Journal of Orthodontics. |
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Does Antibacterial Self-Etch
Adhesive Affect Eminkahyagil N, Korkmaz
Y et al. August 17,
2006 |
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[Ãʹú¿ø°í] How do you prevent decalcification around brackets during orthodontic treatment. Although most of our orthodontic patients have good oral hygiene, there are some patients who simply do not clean their teeth well during orthodontic therapy. These patients could experience significant decalcification. So how do you prevent that? You know today new materials are being developed to counteract the effects of the bacteria. In fact, a new experimental fluoride-releasing and antibacterial bonding agent has been developed by combining the physical advantages of dental adhesive technology with an antibacterial effect. But will the shear bond strength of this type of bonding material be adequate for orthodontic purposes. That question was addressed in the studied that was published in the September 2005 issue of the Angle Orthodontist. The title of article is¡°Shear Bond Strength of Orthodontic Brackets with Newly Developed Antibacterial Self-Etch Adhesive¡±. |
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This study was co-authored by Neslihan Eminkahyagil and 3 other colleague from the department of conservative dentistry at Baskent University in Turkey. The purpose of this study was to determine the shear bond strength of brackets bonded with a fluoride-releasing, self-etch adhesive system and an experimental antibacterial self-etching adhesive system. In order to accomplish this in vitro study, the authors gathered 24 human premolars that had been extracted for orthodontic purposes. These were divided into 2 groups. After cleaning the teeth adequately, in group 1, a fluoride-releasing, self-etching adhesive system was used to etch the enamel. Then Transbond XT was used as the adhesive system to bond metal bracket to the teeth. In group 2, an experimental fluoride-releasing, antibacterial self-etching adhesive system was used to etch the tooth first and then Transbond XT was used to bond the brackets. The entire sample was stored in water for 48 hours, then a testing machine was used to debracket the teeth to determine the shear bond strength. |
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OK. I think you get the idea. This is a typical methodology for testing shear bond strength. What did these researchers find? If you use an antibacterial agent as the self-etching primer will this decrease the shear bond strength? The clear answer in this study was No. The mean shear bond strength between the 2 groups was not statistically significantly different. So, these authors have shown that at least in terms of bond strength this experimental material which has a fluoride releasing self-etch primer does not negatively effect the retention of bracket to the tooth. |
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But there is one other problem. This was an in vitro study. What really needs to be studied at this point is whether this antibacterial self-etching primer actually does have antibacterial effects in the mouths of adolescent subjects who don t clean their teeth adequately during orthodontics. Even the authors agreed that this is the next step. But at least in the mean time you know that this material does have similar shear bond strength. If you'd like to review this study, you can find it in the September 2005 issue of the Angle Orthodontist. |
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Longitudinal Measurement of Tooth Mobility during Orthodontic Treatment Using a Periotest Tanaka E, Ueki K, et al.
September
1, 2006 |
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[Ãʹú¿ø°í] Does tooth mobility among patients differ during and after orthodontic treatment? As orthodontists, we know that teeth become mobile during the active stage of the treatment. But is the degree of mobility different between males and females? Between younger and older individuals? Or between extraction and nonextraction cases? Is it possible to accurately measure tooth mobility longitudinally in a sample of subjects. All of those questions were addressed in the study that was published in the January 2005 issue of the Angle Orthodontist. I thought that it would be an interesting study for us to review on this month's tape. The title of the article is "Longitudinal Measurement of Tooth Mobility during Orthodontic Treatment Using a Periotest". |
[¼öÁ¤¿ø°í] Does tooth mobility among patients differ during and after orthodontic treatment? As orthodontists, we know that teeth become mobile during the active stage of treatment. But is the degree of mobility different between males and females? Between younger and older individuals? Or between extraction and nonextraction cases? Is it possible to accurately measure tooth mobility longitudinally in a sample of subjects. All of those questions were addressed in a study that was published in the January 2005 issue of the Angle Orthodontist. I thought that this would be an interesting study for us to review on this month's tape. The title of the article is "Longitudinal Measurements of Tooth Mobility during Orthodontic Treatment Using a Periotest". |
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The study is co-authored by Eiji Tanaka and six other researchers from the department of orthodontics at Hiroshima university in Japan. The purpose of this article was to examine the alterations of tooth mobility through orthodontic treatment and to evaluate the influence of age, gender, treatment method and retention duration on tooth mobility. In order to accomplish these subjective, the authors began with the sample of eighty subjects with crowded dentitions. Twenty five percent of the sample was male and seventy five percent was female. The eighty ranges about ten to sixteen years. Eighty percent of the sample had first premolar extracted and twenty percent were treated nonextraction. |
This study is co-authored by Eiji Tanaka and six other researchers from the Department of Orthodontics at Hiroshima University in Japan. The purpose of this article was to examine the alterations of tooth mobility through orthodontic treatment, and to evaluate the influence of age, gender, treatment method and retention duration on tooth mobility. In order to accomplish these subjectives, the authors began with a sample of eighty subjects with crowded dentitions. Twenty five percent of the sample was male and seventy five percent was female. The age range about ten to sixteen years. Eighty percent of the sample had first premolars extracted and twenty percent were treated nonextraction. |
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Now, prior to any orthodontic treatment a Periotest was used to measure the maxillary and mandibular incisor tooth mobility. The Periotest is an electronic device that measures damping characteristics of the periodontium. It calculates tooth mobility precisely by tapping on the surface of the tooth. It's actually and excellent means of accurately accessing tooth mobility over time. At the end of orthodontic treatment, all of these subjects had tooth mobility evaluated a second time using the Periotset. |
Now, prior to any orthodontic treatment, a Periotest was used to measure the maxillary and mandibular incisor tooth mobility. The Periotest is an electronic device that measures damping characteristics of the periodontium. It calculates tooth mobility precisely by tapping on the surface of the tooth. It's actually an excellent means of accurately accessing tooth mobility over time. At the end of orthodontic treatment, all of these subjects had tooth mobility evaluated a second time using the Periotest. |
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The average length of treatment was about twenty months. Then after two years of retention, the tooth mobility was measured for the third time. The retention was fixed using a lingual braided wire on both maxillary and mandibular anterior teeth. The wire was bonded to each tooth. Then the Periotest measurements were compared before orthodontic treatment, at the end of the orthodontic treatment, and then after two years of retention. What do you think the authors found? Let's take these questions one another time. First of all, Did tooth mobility increase after orthodontic treatment? And the answer to the question is obviously "yes". But, did the tooth mobility return to normal after retention? The answer to that question is "yes" and a little bit more. The authors found that in nearly all cases, at the end of retention the tooth mobility was less than they were at the beginning of orthodontics. How about gender? Do males or females show any differences in tooth mobility during treatment? Actually, after treatment and after retention the mean mobility values of all teeth tend to be higher in females than in male patients. How about comparing extraction and nonextraction treatments? Actually, there were no statistically significant differences between the two subgroups at all the stages. How about associations with age? Actually these authors found that all of the correlations for the teeth were negative. What that means is that the Periotest values decreased with age, or in another words mobility decreased with age. But, remember the age ranges only ten to sixteen years. How about length of the treatment? Is the treatment lasting longer, did these patients have more mobility? The answer to that question is "No". So, we can conclusion these authors have perception what you might expect. Tooth mobility increases at the end of the orthodontic treatment, but, decreases after retention. What you might not have known, is that the mobility after retention was actually less than was at the beginning of the treatment. |
The average length of treatment was about twenty months. Then after two years of retention, the tooth mobility was measured for the third time. The retention was fixed using a lingual braided wire on both maxillary and mandibular anterior teeth. The wire was bonded to each tooth. Then the Periotest measurements were compared before orthodontic treatment, at the end of orthodontic treatment, and then after two years of retention. What do you think the authors found? Let's take these questions one at a time. First of all, did tooth mobility increase after orthodontic treatment? And the answer to that question is obviously "yes". But, did the tooth mobility return to normal after retention? The answer to that question is "yes" and a little bit more. The authors found that in nearly all cases, at the end of retention, the tooth mobilities were less than they were at the beginning of orthodontics. How about gender? Do males or females show any differences in tooth mobility during treatment? Actually, after treatment and after retention, the mean mobility values of all teeth tend to be higher in females than in male patients. How about comparing extraction and nonextraction treatment? Actually, there were no statistically significant differences between the two subgroups at all the stages. How about associations with age? Actually, these authors found that all of the correlations for the teeth were negative. What that means is that the Periotest values decreased with age, or in another words, mobility decreased with age. But, remember the age range was only ten to sixteen years. How about length of treatment? If the treatment lasts longer, did these patients have more mobility? The answer to that question is "No". So, in conclusion, these authors have shown what you might expect. Tooth mobility increases at the end of the orthodontic treatment, but, decreases after retention. What you might not have known, is that the mobility after retention was actually less than it was at the beginning of treatment. |
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If you're interested in reviewing this study on tooth mobility during at and after orthodontics, you can find it, in the January 2005 issue of the Angle Orthodontis. |
If you're interested in reviewing this study on tooth mobility during, and after orthodontics, you can find it, in the January 2005 issue of the Angle Orthodontist. |
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Foming an Interdisciplinary
Team Spear FM September
8, 2006 |
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[Ãʹú¿ø°í] If you have a successful orthodontic practice, I'm sure you interact with many general practitioners. When you interact with them, are you providing multidisciplinary care or interdisciplinary care? Let me explain the difference. In the multidisciplinary care model, the general dentist sends the patient to the specialist, who then performs an examination, makes a diagnosis, and develops a treatment plan. The specialist treats the patient, and then sendsthe patient back to the referring dentist, for the next phase of treatment. On the other hand, in the interdisciplinary care model, the patient is seen by all the practitioners who may be involved, and a treatment plan is created through the interaction of these clinicians. This interaction can be accomplished face to face, through conference calls, electronically, or through a combination of these methods. These two models of specialty treatment where described in an article entitled "Forming an Interdisciplinary Team; A Key Element in Practicing in Confidence and Efficiency" by Frank Spear, which appeared in the October 2005 issue of the Journal of the American Dental Association. |
[¼öÁ¤¿ø°í] If you have a successful orthodontic practice, I'm sure you interact with many general practitioners. When you interact with them, are you providing multidisciplinary care or interdisciplinary care? Let me explain the difference. In the multidisciplinary care model, the general dentist sends the patient to the specialist, who then performs an examination, makes a diagnosis, and develops a treatment plan. The specialist treats the patient and then sends the patient back to the referring dentist for the next phase of treatment. On the other hand, in the interdisciplinary care model, the patient is seen by all the practitioners who may be involved, and a treatment plan is created through the interaction of these clinicians. This interaction can be accomplished face to face, through conference calls, electronically, or through a combination of these methods. These two models of specialty treatment were described in an article titled "Forming an Interdisciplinary Team: A Key Element in Practicing with Confidence and Efficiency" by Frank Spear, which appeared in the October 2005 issue of the Journal of the American Dental Association. |
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In this article, Dr. Spear describes the benefits and characteristics of an interdisciplinary care model of treatment. I should note, that Dr. Spear is a Prosthodontist who participates in an interdisciplinary care team with Vincent Kokich and has given numerous presentations with Vincent on this topic. One of the points that Dr. Spear emphasizes in his article, is that in the classic model of multidisciplinary care, there is often little, or no interaction between the treating clinicians. The reason that the classic multidisciplinary model for patient care no longer works, is that the practice of general dentistry has evolved from simply satisfying the treatment of dental carries and most of all amalgam restorations, to the treatment of more challenging problems. In order to treat these challenging problems, and achieve the best results, it is necessary to take advantage of the knowledge and expertise of a number of specialists. |
In this article, Dr. Spear describes the benefits and characteristics of an interdisciplinary care model of treatment. I should note, that Dr. Spear is a Prosthodontist who participates in an interdisciplinary care team with Vince Kokich and has given numerous presentations with Vince on this topic. One of the points that Dr. Spear emphasizes in his article, is that in the classic model of multidisciplinary care, there is often little, or no interaction between the treating clinicians. The reason that the classic multidisciplinary model of patient care no longer works, is that the practice of general dentistry has evolved from simply satisfying the treatment of dental carries and multiple amount of amalgam restorations, to the treatment of more challenging problems. In order to treat these challenging problems, and achieve the best results, it is necessary to take advantage of the knowledge and expertise of a number of specialists. |
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In the interdisciplinary model for patient care, the general practitioner usually assumes the roll of team leader, monitoring progress with normal recall visits. However, each practitioner on the team is responsible for presenting his or her phase of treatment, and the fees associated with it. Once a Treatment plan is agreed upon by the interdisciplinary care team, it is written down, step by step, so that each member of the team understands the treatment sequence, the anticipated time frame and, which member of the team will be performing which phase of care. |
In the interdisciplinary model of patient care, the general practitioner usually assumes the roll of team leader monitoring progress at normal recall visits. However, each practitioner on the team is responsible for presenting his or her phase of treatment and the fees associated with it. Once a Treatment plan is agreed upon by the interdisciplinary care team, it is written down, step by step, so that each member of the treatment team understands the treatment sequence, the anticipated time frame, and which member of the team will be performing each phase of care. |
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Dr. Spear suggests that the key, to the interdisciplinary model is to form the correct team of individuals. Characteristics that great team member share include, commitment to function as a member of an interdisiplinary care team, self confidence, that is, having team members who are able to voice their opinions and discuss options without becoming defensive, and, finally, confidence. |
Dr. Spear suggests that the key to the interdisciplinary model is to form the correct team of individuals. Characteristics that great team members share include commitment to function as a member of an interdisiplinary care team, self confidence, that is, having team members who are able to voice their opinions and discuss options without becoming defensive, and finally competence. |
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Dr. Spear further suggests, that a key requirement in forming an interdisciplinary care team, is that someone, likely a general practitioner must decide, that the frustration of practicing without the support of a group of specialists is affecting the quality of care provided and distracting from the enjoyment of dental practice. Being a member of an interdisciplinary care team is exciting, educational and is very satisfying, because it allows you to provide a level of patient care that would not otherwise, be possible. If you are interested in forming an interdisciplinary care team, I would suggest, you read this article, and share it with a general practitioner and other specialists, with whom you work. You can find it in the October 2005 issue of the Journal of the American Dental Association. |
Dr. Spear further suggests, that a key requirement in forming an interdisciplinary care team, is that someone, likely a general practitioner, must decide that the frustration of practicing without the support of a group of specialists is affecting the quality of care provided and distracting from the enjoyment of dental practice. Being a member of an interdisciplinary care team is exciting, educational and is very satisfying, because it allows you to provide a level of patient care that would not otherwise be possible. If you are interested in forming an interdisciplinary care team, I would suggest that you read this article, and share it with the general practitioners and other specialists, with whom you work. You can find it in the October 2005 issue of the Journal of the American Dental Association. |
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Retrospective Analysis of Long-Term Stable and Unstable Orthodontic Treatment Outcomes Ormiston JP, Huang GJ,
et al. September
15, 2006 |
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[Ãʹú¿ø°í] What do you think you'll find if you took long term post treatment record on the large sample of your patients, and then divide them into two groups. Group 1 would be patients demonstrated excellent stability, and group 2 would be patients demonstrated very poor stability. Specifically, what difference you think you would find between the two groups of patients? Well, this is exactly was done in a study title "Retrospective Analysis of Long Term Stable and Unstable Orthodontic Treatment Outcomes" by Jonathan Ormiston et al which appeared in November 2005 issue of the American Journal of Orthodontics and Dentofacial Orthopedics. In this study the authors were from the University of Washington in Seattle uses a sample of 86 patients from the postretention archives from the University of Washington. |
[¼öÁ¤¿ø°í] What do you think you would find if you took long-term posttreatment records on a large sample of your patients, and then divided them into two groups. Group 1 would be patients who demonstrated excellent stability, and Group 2 would be patients who demonstrated very poor stability. Specifically, what difference do you think you would find between these two groups of patients? Well, this is exactly was done in a study titled "Retrospective Analysis of Long-Term Stable and Unstable Orthodontic Treatment Outcomes", by Jonathan Ormiston et al., which appeared in the November 2005 issue of the American Journal of Orthodontics and Dentofacial Orthopedics. In this study, the authors were from the University of Washington in Seattle, used a sample of 86 patients from the postretention archives at the University of Washington. |
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Model and radiographic measurements were made before treatment, after treatment, and after retention which average over 14 years. Unweighted PAR score was taken at the time of postretention were used to divide the sample into two groups. One of which had excellent stability, and the second which demonstrated unstable treatment results. I should know that the sample included both Class I and Class II patients but Class III patients were excluded. This might be expected results indicated that they were significantly more Class II patients in the unstable group than in the stable group. |
Model and radiographic measurements were made before treatment, after treatment, and after retention, which averaged over 14 years. Unweighted PAR scores taken at the time of postretention were used to divide the sample into two groups. One of which had excellence of stability, and the second which demonstrated unstable treatment results. I should note that the sample included both Class I and Class II patients, but Class III patients were excluded. This might be expected. Results indicated that there were significantly more Class II patients in the unstable group than in the stable group. |
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Male sex and a sustained period of growth were both associated with increased instability. From posttreatment to postretention, both groups had decreases in intercanine width to distances below those at the initiation of treatment. However the unstable group had significantly larger decrease during retention than the stable group. I was somewhat surprised to find that there was no significant differences between stable and unstable group in mandibular plane angle or SNA measurement. I would have thought that patient have higher mandibular plane angle and larger anteroposterior skeletal discrepancy would be more unstable. From posttreatment postretention the unstable group also experienced significantly more maxillary growth than stable group. The bottom line of this study is that male are more than four times as like as female do have a unstable condition and growth is a major factor in stability. Interestingly, it is apparent that growth can correct poor occlusal relationships and cause good relationships to deteriorate. Whether growth will help or hurt patients depends primarily on the initial malocclusion, the posttreatment occlusion, and the amount and direction of subsequent growth. Pretreatment arch length, and severity, pretreatment malocclusion were also related to relapse. I thought of interesting to know that there was not large differences when the posttreatment scored or evaluated for the groups suggesting that patients was from both groups was finished with comparable levels and there for the posttreatment finishing results was not the most influential factor in long term instability. It's might be surprise a lot of people. |
Male sex and a sustained period of growth were both associated with increased instability. From posttreatment to postretention, both groups had decreases in intercanine width, to distances below those at the initiation of treatment. However, the unstable group had a significantly larger decrease during retention than the stable group. I was somewhat surprised to find that there were no significant differences between the stable and unstable groups in mandibular plane angle or SNA measurements. I would have thought that patients with higher mandibular plane angles, and larger anteroposterior skeletal discrepancies, would have been more unstable. From posttreatment to postretention, the unstable group also experienced significantly more maxillary growth than the stable group. The bottom line of this study is that males are more than four times as likely as females to have unstable conditions and growth is a major factor in stability. Interestingly, it is appears that growth can correct poor occlusal relationships and cause good relationships to deteriorate. Whether growth will help or hurt patient, depends primarily on the initial malocclusion, the posttreatment occlusion, and the amount and direction of subsequent growth. Pretreatment arch length, and severity of the pretreatment malocclusion were also related to relapse. I thought it was interesting to note that there was not a large difference when the posttreatment scores were evaluated for the groups, suggesting that patients from both groups were finished to comparable levels, and therefore the posttreatment finishing result was not the most influential factor in long term stability. This might be surprise a lot of people. |
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Also, an ABO model scores for use to evaluate occlusion that indicate patient with excellent scores tends to get worse and those with poor scores tends to be improve. Considering that excellent cases can do anything really get worse, in poor cases likely only to get better, it should not be surprising. Once again sample of postretention cases at university washington has proved to be excellence resource for valuating posttreatment instability. you can find this article in November 2005 issue of the American Journal of Orthodontic Dentofacial Orthopedics. |
Also, when the ABO model scores were used to evaluate occlusion, they indicated that patients with excellent scores tended to get worse, and those with poor scores tended to improve. Considering that excellent cases can't do anything to really get worse, and poor cases likely to only get better, this should not be surprising. Once again, the sample of postretention cases at the University of Washington has proved to be an excellent resource for valuating posttreatment instability. you can find this article in the November 2005 issue of the American Journal of Orthodontics and Dentofacial Orthopedics. |
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Root Resorption After Orthodontic Intrusion and Extrusion : An Intraindividual Study. Han G, Huang S, et al.
September
22, 2006 |
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[Ãʹú¿ø°í] Do you worry about root resorption in your orthodontic patients? I think most orthodontist would answer "yes" to that question. Based upon recent research we know that nearly every tooth suffers from some root resorption during any type of orthodontic movement. But in most individuals, the resorptive areas are small and after treatment, the cementum usually repairs it self. But there are some patients who are susceptible to more severe root resorption. These are the ones we really worry about. So here is my question. If your orthodontic treatment requires tooth intrusion or the patient experienced more root resorption then if you extruded the teeth . That question was addressed in the study that was published in the November 2005 issue of the Angle Orthodontist. Since intrusion and extrusion of teeth are a common types of tooth movement, especially now with the addition of miniplates and micro-implants to our argument for anchorage, I thought that this study would be a good one to review on this month's tape. |
[¼öÁ¤¿ø°í] Do you worry about root resorption in your orthodontic patients? I think most orthodontist would answer "yes" to that question. Based upon recent research, we know that nearly every tooth suffers from some root resorption during any type of orthodontic movement. But in most individuals, the resorptive areas are small, and after treatment the cementum usually repairs itself. But there are some patients who are susceptible to more severe root resorption. These are the ones we really worry about. So here is my question. If your orthodontic treatment requires tooth intrusion, will the patient experience more root resorption than if you extruded the teeth? That question was addressed in the study that was published in the November 2005 issue of the Angle Orthodontist. Since intrusion and extrusion of teeth are common types of tooth movement, especially now with the addition of miniplates and micro-implants to our armamentarium for anchorage, I thought this study would be a good one to review on this month's tape. |
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The type of the article is root resorption after orthodontic intrusion and extrusion. The study was co-authored by Guangli Han and for other research colleagues from the departments of the orthodontics of Wuhan university in china and the department of the orthodontics at the university of Nijmegen in the Netherlands. Now the purpose of this study was to compare root resorption after the application of intrusive and extrusive forces on premolars in the same patient. In order to achieve the subjective, the authors gathered the sample of 9 adolescent patients who are going to have orthodontic treatment. Their average age was 15 years. In each of this subjects, maxillary first premolars were to be extracted, but prior to extraction appliances were placed on the maxillary teeth. Then, either the right or left maxillary first premolar in the experimental group was randomly assigned to either the intrusive or extrusive groups. Utility arch was designed to apply an extrusive or intrusive force using elastics. The force of the elastics was about 100cN and it was applied for 8 weeks. Immediately, after the 8 week time interval had expired, the experimental teeth were extracted. Each of these teeth were then subjected to scanning electron microscopy and also visual observation. The scans were photographed and the percentage of root surface that had experienced resorption was calculated for both the intrusive and the extrusive groups. In addition, a sample of comparable number of control subjects who also required premolars extraction was included. The control teeth that did not receive any force, also had scanning electron microscopy in order to observe their root surfaces. OK, I think you get the idea of the methodology. What had these researchers find? Remember the primary question :
"Does intrusion cause more or less root resorption than extrusion of teeth?" and the answer is "more" Based upon careful and precise analysis of the scanning electron micro-radiographs, the authors found that in the same individual, tooth intrusion produced about 4 times as much of root resorption as extrusion. So what are we talking about in terms of the percentage of root surface that had resorption? In teeth that were intruded? About 5%. That is correct, about 5% of the surface of the apex showed resorption. In the extrusive sample, only 1% of the root surface showed resorptive defects. Now, on the other hand, we know that some patients are more susceptible to root resorption than others. |
The type of the article is root resorption after orthodontic intrusion and extrusion. This study was co-authored by Guangli Han, and four other research colleagues from the Departments of Orthodontics at Wuhan University in China and the Department of Orthodontics at the University of Nijmegen in the Netherlands. Now the purpose of this study was to compare root resorption after the application of intrusive and extrusive forces on premolars in the same patient. In order to achieve this objective, the authors gathered a sample of 9 adolescent patients who are going to have orthodontic treatment. Their average age was 15 years. In each of these subjects, maxillary first premolars were to be extracted, but prior to extraction, appliances were placed on the maxillary teeth. Then, either the right or left maxillary first premolar in the experimental group was randomly assigned to either the intrusive or extrusive groups. A utility arch was designed to apply an extrusive or intrusive force using elastics. The force of the elastics was about 100 cN, and it was applied for 8 weeks. Immediately after the 8 week time interval had expired, the experimental teeth were extracted. Each of these teeth were then subjected to scanning electron microscopy and also visual observation. The scans were photographed and the percentage of root surface that had experienced resorption was calculated for both the intrusive and the extrusive groups. In addition, a sample of comparable number of control subjects who also required premolar extraction was included. The control teeth that did not receive any force, also had scanning electron microscopy in order to observe their root surfaces. OK, I think you get the idea of the methodology. What did these researchers find? Remember the primary question,
"Does intrusion cause more or less root resorption than extrusion of teeth?" and the answer is "more". Based upon careful and precise analysis of the scanning electron micro-radiographs, the authors found that in the same individual, tooth intrusion produced about 4 times as much root resorption as extrusion. So what are we talking about in terms of the percentage of root surface that had resorption? In teeth that were intruded? About 5%. That's correct, about 5% of the surface of the apex showed resorption. In the extrusive sample, only 1% of the root surface showed resorptive defects. Now, on the other hand, we know that some patients are more susceptible to root resorption than others. |
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so when the authors quoted percentages, really, it's a relative thing. In the susceptible patients, the percentage of root resorption would be much greater, but the authors pointed out that extrusive forces in the susceptible patient will also produce a significant amount of root resorption. But intrusive forces will produce 4 times that amount in the susceptible subject. |
So when the authors quoted percentages, really, it's a relative thing. In a susceptible patient, the percentage of root resorption would be much greater, but the authors pointed out that extrusive forces in a susceptible patient will also produce a significant amount of root resorption. But intrusive forces will produce 4 times that amount in a susceptible subject. |
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This was a very interesting and informative study. If you'd like to review this study, you will find it in the November 2005 issue of the Angle Orthodontist. |
This was a very interesting and informative study. If you'd like to review this study, you will find it in the November 2005 issue of the Angle Orthodontist. |
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The influence of Accelerating the Setting Rate by Ultresound or Heat on the Bond Strength of Glass Ionomers used as Orthodontic Bracket Cements Algera TG, Kleverlaan
CJ, et al. September
29, 2006 |
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[Ãʹú¿ø°í] The use of glass ionomer cements or resin-modified glass ionomers for bonding orthodontic brackets has always been appealing. This is because they require limited or no acid conditioning and because they can act as a flouride reservoir to help battle decalcification. Unfortunately, these benefits have been offset by a big drawback: the lack of sufficient bond strength especially immediately after bonding. Researchers in the Netherland have been investigating ways to improve the early bond strength of these cements and have reported the results of their research in the October 2005 issue of the European Journal of Orthdontics. The title of their paper is "The influence of accelerating the setting rate by ultrasound or heat on the bond strength of glass ionomers used as orthodontic bracket cements." |
[¼öÁ¤¿ø°í] The use of glass ionomer cements, or resin-modified glass ionomers, for bonding orthodontic brackets has always been appealing. This is because they require limited or no acid conditioning and because they can act as a fluoride reservoir to help battle decalcification. Unfortunately, these benefits have been offset by a big drawback: the lack of sufficient bond strength, especially immediately after bonding. Researchers in the Netherlands have been investigating ways to improve the early bond strength of these cements, and have reported the results of their research in the October 2005 issue of the European Journal of Orthdontics. The title of their paper is "The influence of accelerating the setting rate by ultrasound or heat on the bond strength of glass ionomers used as orthodontic bracket cements." |
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The purpose of their research was to see if the application heat or ultrasound during setting could accelerate the setting reaction and therefore increase early bond strength. This study was a laboratory study done on extracted bovine teeth. Several authors have verified the use of bovine enamel to simulate human enamel for these sorts of experiments. Three cements were tested; one conventional glass ionomer and two resin modified glass ionomers. Each of the three cements was tested under three setting conditions for a total of nine experimental groups. The three testing conditions were: one, a conventional cure as for manufacturer's instructions, two, the addition of 60 seconds of heat using a modified soldering iron like device and three, the addition of 60 seconds of ultrasound. One of the resin-modified glass ionomer cements fusi orthowell see had enamel conditioning with polyacrylic acid prior to bonding as recommended by the manufacturer. The other two groups had no enamel conditioning. Because the intent was to investigate an increase in early bond strength, all tensile bond strength testing was done 15 minutes after bonding. The tensile testing was done until failure and the distribution of the cement after failure was scored with the standard adhesive remnant index where higher score indicates more adhesive black on the enamel. |
The purpose of their research was to see if the application of heat or ultrasound during setting could accelerate the setting reaction, and therefore increase early bond strength. This study was a laboratory study done on extracted bovine teeth. Several authors have verified the use of bovine enamel to simulate human enamel for these sorts of experiments. Three cements were tested; one conventional glass ionomer, and two resin modified glass ionomers. Each of the three cements was tested under three setting conditions for a total of nine experimental groups. The three testing conditions were: 1) a conventional cure as per manufacturer's instructions; 2) the addition of 60 seconds of heat using a modified soldering iron-like device; and 3) the addition of 60 seconds of ultrasound. One of the resin-modified glass ionomer cements Fusi Oortho LC had enamel conditioning with polyacrylic acid prior to bonding, as recommended by the manufacturer. The other two groups had no enamel conditioning. Because the intent was to investigate an increase in early bond strength, all tensile bond strength testing was done 15 minutes after bonding. The tensile testing was done until failure, and the distribution of the cement after failure was scored with the standard adhesive remnant index, where a higher score indicates more adhesive left on the enamel. |
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Do you think that heat or ultrasound was effective in increasing the early bond strength of glass ionomer cement? The answer is "yes". Both heat and ultrasound caused a significant increase in the bond strength of glass ionomers cements at the fifteen minute time when a orthodontist may want to tie in the initial arch wire. The heat and ultrasound treatment also increased the adhesive remnant index scores indicating that there was better adhesion to the enamel surface. Although I don't recommend you clean off the old soldering iron in the basement and bring it to the office quite yet, it is interesting to know that there is continued investigation into how the shortcomings the glass ionomer cements can be overcome so that we may benefit from their considerable advantages as a bracket bonding adhesive. To find out more about this research from amsterdam, look in the October 2005 issue of the European Journal of Orthodontics. |
Do you think that heat or ultrasound was effective in increasing the early bond strength of glass ionomer cements? The answer is "yes". Both heat and ultrasound caused a significant increase in the bond strength of glass ionomers cements at the fifteen minute time, when an orthodontist may want to tie in the initial arch wire. The heat and ultrasound treatment also increased the adhesive remnant index scores, indicating that there was better adhesion to the enamel surface. Although I don't recommend you clean off the old soldering iron in the basement and bring it to the office quite yet, it is interesting to know that there is continued investigation into how the shortcomings of glass ionomer cements can be overcome, so that we may benefit from their considerable advantages as a bracket bonding adhesive. To find out more about this research from Amsterdam, look in the October 2005 issue of the European Journal of Orthodontics. |
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Osteonecrosis of the Jaws in Patients with a History of Receiving Bisphosphonate Therapy Melo MD, Obeid G. October
13, 2006 |
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[Ãʹú¿ø°í] The December 2005 issue of the journal of the American Dental Association contains 3 separate articles related to the use of bisphosphanate drugs. Bisphosphonates inhibit osteoclast production and are commonly used to treat bone lesions of multiple myeloma, metastatic bone lesions in patients with breast and prostate cancer, osteolytic lesions from any solid tumor, and osteoporosis. One of the 3 articles in the December 2005 issue of the journal of the American Dental Association was titled ¡°Osteonecrosis of the Jaws in Patients with a History of Receiving Bisphosphonate Therapy¡± by Micho Mello and George Obeid, and reviewed the side effects of bisphosphonate therapy. |
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In this article, the authors note that extensive data demonstrate the beneficial effects of bisphosphonates in the treatment of osteolytic lesions. However, these drugs, particularly the more potent nitrogen containing bisphosphonate pamidronate and zoledronic are capable of causing osteonecrosis of the jaws. In this article, the authors reviewed 11 patients with osteonecrosis of the jaws, and the history of bisphosphonate therapy. None of these patients had a history of head and neck irradiation. This is important, because the bone lesions associated with bisphosphonate therapy, outwardly resemble bone lesions that are a result of osteonecrosis. Although similar in appearance, these two bone lesions are very different. It is interesting to know also that a majority of the patients studied had a history of recent dental surgery that corresponded to the site of osteonecrosis. Unlike osteoradionecrosis, bisphosphonate related osteonecrosis does not appear to be amenable to hyperveric oxygen therapy. Another differentiating characteristic is at the maxilla commonly is involved in bisphosphonate related osteonecrosis, whereas this is observed rarely in cases of oseteoradionecrosis. Also, in osteoradionecrosis, the risk of the irradiation induced injury may be minimized by an inherently rich vascular supply, whereas in bisphosphonate related osteonecrosis, a rich vascular supply paradoxically may be responsible for the condition because bisphosphonates reach the bone near the blood stream. Another major difference is that the authors recommend limiting surgery to patients for symptomatic and have lesions that are refractory to conservative antibiotic therapy. |
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They suggest that in these cases surgery to be conservative and limited to debridement of necrotic bone with no attempt made to extend the debridement to margins of viable healthy bone as contrasted with the treatment for osteoradionecrosis. Because the bone lesions associated with bisphosphonate therapy are often related to a previous history of surgery, the extraction of teeth, placement of dental implants and orthognatic surgical procedures are contraindicated. As important to orthodontists, is the fact that bisphosphonate inhibits osteoclast formation and therefore prevent effective orthodontic tooth movement. I believe you'll be reading more and more about the side effects of bisphosphonates and until then, I strongly encourage you to screen your patients with the use of these drugs. You can find this article in the December 2005 issue of the journal of the Americal Dental Association. |
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Smile esthetics: Perception and comparison of treated and untreated smiles Isiksal E, Hazar S, et
al. October
20, 2006 |
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[Ãʹú¿ø°í] One of the major goals of orthodontic treatment is achieving optimal facial esthetics. And a major part of achieving optimal facial esthetics is achieving a beautiful or attractive smile. Because a beautiful smile can be very subjective it is possible that diverse groups of people might evaluate smiles very differently. Additionally, the attractiveness of smiles might be significantly affected by orthodontic treatment and further by the specific type of orthodontic treatment that a patient received namely non-extraction vs extraction treatment. In this respect, some people have suggested that extraction treatment results in a narrower arch and larger buccal corridors and a less attractive smile. An article titled "Smile Esthetics: Perception and Comparison of Treated and Untreated Smiles" by Erdal Isiksal et al. which appeared in the January 2006 issue of the American Journal of Orthodontics and Dentofacial Orthopedics addressed these questions. |
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In this study frontal and 3 quarter view smiling photographs direct by a metric measurements and cephalometric data were collected from 25 extraction patients, 25 non-extraction patients, and 25 untreated participants with well balanced faces and good occlusion. In the extraction group 4 first premolars were extracted. All the subjects had excellent occlusions with Angle class I molar and canine relationships and well balanced faces. The frontal and 3 quarter photographs for each subject were cropped so that only the lower face was shown and the crop images were converted to black and white to minimize any extraneous variables that might affect the perception of each patient's smile. These photographs were then rated on a scale from 1 to 5 from excellent to poor by six different groups namely 10 orthodontists, 10 plastic surgeons, 10 dental specialists, 10 general dentists, 10 artists, and 10 parents. When the results of these ratings were statistically analyzed what do you think they showed? Were there differences in ratings between the six groups and were there differences in ratings of the patients treated with 4 first premolar extraction, those treated non-extraction, and the control group of untreated subjects. The answer is that the 3 groups did not differ statistically in mean esthetic score as evaluated by the six panels. When the individual groups were evaluated there were no differences between the orthodontists and artists, and between plastic surgeons and general dentists. |
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However parents on average rated the smiling photographs significantly more attractive than the other 5 panels. I found this encouraging in that parents who are a primary group that we need to satisfy were more lenient in their evaluation of the smiles. Because extraction treatment does not narrow arches but simply move teeth into different positions in the patient's established arch form it did not surprise me that there were no differences between the extraction and non-extraction groups. Two things however did surprise me. The first is that the authors found the extraction group to have slightly wider dental arches relative to the soft tissues than the non-extraction group. And while I would not expect extraction groups to have narrower arches, I would also not expect them to have wider arches. Additionally, the authors concluded that transverse characteristics of a smile appear to be of little significance to an attractive smile. Again this surprised me because recent research have shown that the larger the buccal corridor, the less attractive the smile. Finally, the authors concluded that the greater the maxillary gingival display on smile, the lower the esthetic score. The bottom line of this study is that there is no difference in smile attractiveness between orthodontic patients treated non-extraction, orthodontic patients treated with 4 first premolar extractions, or untreated subjects with good occlusions and that parents tend to rate smiles more attractive than other professional groups. You can find this study in the January 2006 issue of the American Journal of Orthodontics and Dentofacial Orthopedics. |
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A Comparative Study of Dental Arch Width: Extraction and Non-Extraction Isik F, Sayinsu K, et
al. October
27, 2006 |
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[Ãʹú¿ø°í] We continue to hear individuals advocate non-extraction treatment for all to prevent narrowing the arches and producing dark corridors upon smiling. To make the best individual decisions for our patients, we must have as much information as possible about the effects of our treatment on arch width of our patients. I would like to review an article with you from the December 2005 issue of the European Journal of Orthodontics that edges to a knowledge base in this area. The article is called to ¡°A Comparative Study of Dental Arch Widths: Extraction and Non-Extraction Treatment¡±. The purpose of this study was to compare the before and after treatment arch width dimensions in patients undergoing orthodontic treatment with and without extraction of premolars. |
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This was retrospective study of completed orthodontic cases. There were 84 cases included consisting of 42 that had non-extraction fixed orthodontic treatment. There were 15 that also had non-extraction treatment, but also had rapid maxillary expansions before braces. And then, there were 27 patients that had four first premolars removed as part of their comprehensive orthodontic plan. The before and after study casts were measured for all 84 cases. The measurements included the width between the cusp tips of canines, premolars and molars for both the upper and lower arches. The average age at the start of treatment was about 14 years and did not differ among the three groups. |
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The results showed that the pre-treatment width of the upper premolars and molars was about 2 mm less in the extraction and RME groups compared to the non-extraction without expansion group. The upper inter-canine width after treatment was the same for all three groups whether extractions were done or not and whether RME was done or not. The lower inter-canine width was actually greatest for the extraction group, perhaps due to larger tooth size. The post-treatment width of the arche at the second premolars and first molars was less in the extraction group than the non-extraction groups. But, this may have been due to being in a more forward position in the arch. |
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There are some limitations to this study. Most significantly, it is retrospective. And so the patients were treated as extraction or non-extraction for some reason. There were not randomly assigned. But we can"t say that extraction of premolars dose not necessarily result in narrower inter-canine width. In this study, the extraction group had upper inter-canine width equal to the non-extraction groups and actually had the widest lower inter-canine dimension. This study also did not take into account more forward position that the second premolars and molars may have in the arch after extraction treatment. If I look at the data tables, the width of the second premolars after treatment in the extraction group was almost identical to the first premolars in the non-extraction groups. So the actual arch form may have been very similar. |
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If you like to read more about the specifics of this clinical study on arch width changes during orthodontic treatment, check out the December 2005 issue of European Orthodontics. |
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Cephalometric Predictors of Long-Term Stability in the Early Treatment of Class III Malocclusion Moon Y-M, Ahn S-J, Chang
Y-I. November
17, 2006 |
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[Ãʹú¿ø°í] In recent years, there has been considerable discussion about the efficacy of early orthodontic treatment. The unanimous conclusion of several large randomized clinical trials shows that early treatment of Class II malocclusion does not result in easier, faster or more reliable treatment of the malocclusion. But what about early treatment of Class III malocclusion? How do you manage the 6 or perhaps 7 years old child who has an anterior crossbite? Do you simply wait? Do you treat early? Can you predict which patients maybe stable or lack stability before you even attempt to correct a Class II malocclusion in the young child. Those are questions that run through the minds of orthodontics who treat children and adolescence. Those specific questions were addressed in the study that was published in the September 2005 issue of the Angle Orthodontist. The title of the article is "Cephalometric predictors of long-term stability in the early treatment of Class III malocclusion". |
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This study comes out of Korea. And we know that in the Asian population, Class III malocclusion is predominant and this study was completed at Seoul National University in the Department of Orthodontics. The senior author on this study is doctor Young-Min Moon. And the purpose of this study was to identify simple cephalometric key determinants that could explain the differences in early craniofacial morphology of Class III malocclusion among patients with good, fair or poor prognosis to successful treatment. You see, we all know that sometimes treatment of Class III malocclusion works. Well, othertimes it doesn't. So the goal of these researchers was to determine if they could review a sample of subjects who had early treatment of Class III malocculsion, to determine if certain cephalometric variables could help to predict whether or not treatment would be successful. |
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So this was a retrospective study. The authors gathered a sample of 45 subjects who had had Class III malocclusions that were treated during primary or mixed dentitions. Most of these subjects treated with a chin cap. All were successfully treated during this first phase of treatment. Then the subjects were allowed a mean follow-up period five and an half years or they were re-evaluated and then devided into three groups according to their final occlusal status: either good, fair or poor occlusal stability. Then these authors traced the cephalometric head films taken on each of these subjects and compared various cephalometric landmarks. Their goal was to determine if there were specific cephalometric relationships that could help to predict whether early treatment would be successful or not. Anyway I think you get the idea. This was basically a retrospective analysis of successful and non-successful treatment. And which the authors were trying to determine if they could find landmarks that would help them to predict the successful outcomes. What did they find? Well if you want to read the study you'll find an exhaustive analysis of many different cephalomatric variables. But I'll try to give you the bottom line. |
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Basically there were two specific cepholometric relationships that helped to predict whether or not treatment would be successful. The first was the gonial angle. Generally, subjects with a smaller gonial angle and more hypodivergent skeletal pattern had a good prognosis after early treatment of Class III malocclusion. Conversely those subjects with a greater gonial angle and more hyperdivergent skeletal pattern had a poor prognosis. The second cephalometric relationship that helped to discriminate between good and poor result was the relationship between the AB plane and the mandibular plane, simply stated it's the AB to mandibular plane angle. In fact, this was the most significant variable in terms of the discrimination. The authors found that as the AB to mandibular plane angle became more acute, the outcome of Class III treatment became less successful or stated slightly differently the higher the angle between the AB and mandibular plane, the greater the stability of Class III treatment. In fact when the authors used this variable in the discriminant analysis of these subjects, it showed the highest accuracy in predicting a poor prognosis. This accuracy was at the level of over 90%. So if you do provide early treatment for Class III malocclusion in your orthodontic patients, you might find this article interesting. It may help you to determine whether or not to become involved in treating subjects by evaluating the gonial plane angle and the AB to mandibular plane angle in these specific patients. Again if you like to read this article for yourself, you will find it in the September 2005 issue of the Angle Orthodontist. |
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Self-Reinforced Biodegradable Screw Fixation Compared With Titanium Screw Fixation in Mandibular Advancement Turvey TA, Bell RB, et
al. November
24, 2006 |
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[Ãʹú¿ø°í] Have you ever had a patient like this? You're planning orthodontic and orthognathic treatment for a female with a Class II, division 1 malocclusion. She has had no crowding of the teeth, but a 7 mm overjet. So, your orthodontic plan is non-extraction. To correct the overjet she'll receive a mandibular advancement surgical procedure as a sagittal osteotomy. The patient is almost ready for the surgery. But, here is the problem. She doesn't want to have any metal screws left in her jaw after the surgical procedure. So what do you do? Today most surgeons use rigid fixation after orthognathic surgery. If patients don't want titanium screws left in the mandible, then a second surgical procedure would be required to remove these screws after the bony fragments had healed. But, another option is to have the surgeon use biodegradable screws. These have been around now for a few years. But, are they as effective? Are they strong enough? What's the data on these screws? An excellent study was published in the January 2006 issue of the Journal of Oral and Maxillofacial Surgery that evaluates these questions. I thought this would be an interesting story to review on this month's tape. |
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The title of this article is ¡°Self-Reinforced Biodegradable Screw Fixation Compared With Titanium Screw Fixation in Mandibular Advancement¡±. This study is co-authored by Tim Turvey and several well-known researchers and faculty members from the orthodontic and surgical departments at the University of North Carolina. The purpose of their study was to compare the skeletal stability and treatment outcome of two groups of patients undergoing bilateral sagittal split osteotomies for advancement using either biodegradable or titanium screw fixation. The sample for this study consisted of 70 patients who had undergone bilateral sagittal split ramus osteotomies of the mandible using an identical surgical technique. In half of the subjects, biodegradable screws were used. These were 2-mm self-reinforced polylactate biodegradable screws. In the other half of the sample, 2-mm titanium screws were used to fix the surgical site. Cephalometric radiographs were made on each patient preoperatively, immediately postoperatively, and 1 year postoperatively to evaluate and compare the changes. |
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What did these researchers find? Are these biodegradable screws less effective than titanium screws? The answer is ¡°No¡±. First of all, the authors found no clinical failures in the group with titanium screws. There was one single failure in the group with the biodegradable screws. But this surgical failure was not necessarily due to the biodegradable screw. The authors found that when they compare these two methods of fixation, there were differences in the vertical position of gonion and the mandibular plane angle with greater upward remodelling at gonion in the group with the titanium screws. But, there was no difference in the antero-posterior position of the mandible indicating that the biodegradable screws were just as effective. These authors conclude that self-reinforced polylactate 2-mm biodegradable screws can be used to stabilize sagittal split ramus osteotomy of the mandible for advancement with outcomes that are similar to those from stabilization with titanium screws. So, there's your answer. In patients today who would rather not have metal left in their jaws after orthognathic surgery, biodegradable screws are now an excellent means of rigidly fixing the mandible after surgery with the system that will gradually be resorbed over time. |
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If you'd like to review this study on biodegradable screw fixation after sagittal split ramus osteotomy, you can find it in the January 2006 issue of the Journal of Oral and Maxillofacial Surgery. |
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Tooth wear in maxillary anterior teeth from 14 to 23 years of age Kononen M, Klemetti E,
et al. December
1, 2006 |
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[Ãʹú¿ø°í] Suppose your about to begin orthodontic treatment on a 14 years old boy who has a mildly crowded class I malocclusion. At the consultation appointment when you the parent and the child are discussing the proposed treatment. The parent informs you that this boy tends to grind teeth at night. When you look at the dental cast you know that the maxillary central incisors and canines already show occlusal wear at 14 years of age. Then the parent asks you the big question. "Will this wear tend to increase over time?" How would you answer that question? Do children at adolescence with history of bruxism tend to show increased wear of the teeth up and to adulthood? That question was analyzed in the study was published in the February 2006 issue of Acta Odontologica Scandinavica. |
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The title of that study is "Tooth wear in maxillary anterior teeth from 14 to 23 years of age". This study was coauthored by Mauno Kononen and several other researcher associated from the University of Helsinki in Finland. That a purpose of this study was to monitor the development of horizontal wear in a permanent anterior teeth of subjects from 14 to 23 years of age. The sample was divided into male and female groups. Dental casts had been made of the subjects 14, 18 and 23 years of age. All of these subjects had class I occlusions with average overbite and overjet relationships. None of the sample had ever had orthodontic treatment. On a dental cast the authors traced the borders of the incisal edges of the canines and central incisors at the three time periods. These were then photographed and a method were developed to enlarge these photographs accurately so that they could be compared. Then these enlarged photographs were overlaid so that the area of wear could be accurately compared and measured. |
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What did these researchers find? Does wear during this time period differ from adolescence to early adulthood and does it increase in a sample of subject with normal occlusion? The answer of the question is "Yes". These authors showd that the wear of the maxillary central incisors and canines from 14 to 23 years of age increased significantly. In fact, the total wear area increased from 14 to 18 years of age as well as from 18 to 23 was no differences between these two time period. At 23 years of age the maxillary canine showd the strongest wear well the central incisors had the largest wear facets. By the way no significant differences was found between males and females. So based upon their data these authors conclude that horizontal wear of the maxillary anterior teeth is continuous phenomenon in adolescence and into young adulthood. So there we have it. If we go back to the hypothetical patient that you are about to begin orthodontic treatment whose 14 years of age. Now we have an answer for that parent. This study has shown that patient with bruxing habit tend to produce increased wear even during adolescence and early adulthood on their anterior teeth. Perhaps this type of patient should receive protection for those teeth after orthodontic treatment. This protection could come in the form of nightguard or maxillary occlusal splint which could help to protect this surfaces from continue to wear in attrition with time. |
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If you would like to review this study that evaluate the amount of wear and a non orthodontic sample with normal occlusion, you are find it in the February 2006 issue of Acta Odontologica Scandinavica. |
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Factors Influencing Treatment Time in Orthodontic Patients Skidmore KJ, Brook KJ,
et al. December
8, 2006 |
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[Ãʹú¿ø°í] Two of the questions that I get asked most commonly by parents and patients are¡°How long will I need to wear braces?¡±and¡°When do I get my braces off?¡±. How do you predict treatment time in your practice? Obviously there are likely some variables that you can measure at the start of treatment, that will be helpful in predicting over all treatment time and there are others related to patients' cooperation that are not known until treatment is initiated. What are these variables that can help you predict overall treatment time for your patients. This question was addressed in an article titled ¡°Factors influencing treatment time in orthodontic patients¡±by Kirsty Skidmore et al which appeared in the February 2006 issue of the American Journal of Orthodontics and Dentofacial Orthopedics. |
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In this study, 366 consecutively treated orthodontic patients who completed treatment in a single stage with fixed appliances were evaluated. I should note that all of these patients were treated by a single practitioner which significantly eliminated the presence of extraneous variables. Participants' records were kept for the treatment each patient and were used to retrospectively identify individual variables that were related to the length of treatment. When these records were statistically analysed the authors found that 38% of variance in treatment time, could be explained by 9 variables of which 5 could be identified prior to treatment another 3 related to the patient cooperation and 1 variable was related to clinical judgement. What do you think these variables were? For the 5 variables that could be identified at the start of treatment that increased treatment time were male sex, maxillary crowding of 3 mm or more, Class II molar relationship, at proposed treatment plan involving extractions and delayed extractions. I should note before going further that the mean treatment time was 23 and a half months with a range of 12 to 37 months. It is interesting to note that on average extractions resulted in an increase of approximately 3 and a half month of treatment whereas extractions midway through treatment resulted in additional 6 months of treatment. The increase of 6 months due to delayed extractions was obviously result of patients who started with an initial nonextraction treatment plan that later had to be converted to an extraction treatment plan. |
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The authors also noted that banding maxillary second molar within the first 12 months of treatment decreased treatment time by at least 2 months when compared with banding the same teeth after that time. What were the patients cooperation factor that result in an increased treatment time? As you might expect, there were poor oral hygiene, poor elastic wear and bracket breakages. The last of the nine factors identified was brackets rebonded for repositioning. What if the advantages of this study, was that the authors separated brackets that were rebonded due to loss versus stoles that were rebonded to improve the proper positioning of the bracket. The authors note that other although bracket cooperation variables can not be encounted for before treatment, treatment time could possibly be reduced, if they were used as motivators to encourage cooperation. Also, knowing that rebonding brackets, repositioning increases treatment time would encourage commissions to develop better technique to place brackets initially with maximum accuracy. I thought this was an excellent study on a large sample by one orthodontist who kept excellent records. If you would like to find more detailed information about this specific increases in treatment time related to different variables, you can find that information in this article which appeared in the February 2006 issue of the American Journal of Orthodontics and Dentofacial Orthopedics. |
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An Investigation into the Bonding of Orthodontic Attachment to Porcelain. Larmour CJ, Bateman G,
Stirrups DR. December
15, 2006 |
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[Ãʹú¿ø°í] Bonding to porcelain restorations can be a challenge when treating adult patients. With the use of silane coupling agents, we now can usually get adequate bond strength for clinical use when bonding with conventional light cure resin adhesives. But what if you are using a resin modified glass ionomer adhesive for routine clinical bonding. Can these adhesives be used with a silane coupling agent to achieve adequate bond strength? To provide some initial answers to these questions, researchers from the UK conducted a study that is published in the February 2006 issue of the European Journal of Orthodontics. The article is titled "An investigation into the bonding of orthodontic attachments to porcelain". |
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This was a laboratory study done using porcelain denture teeth. Previous studies have used this type of teeth to stimulate bonding to porcelain restorations. Although I have some questions whether this truly represents the type of porcelain we normally bond to. The researchers mounted 80 porcelain teeth and divided them into 4 groups of 20. Group 1 represented the typical way of bonding to porcelain using a phosphoric acid etch, a silane coupling agent and then a light cured composite adhesive, in this case, TransbondTM. Group 2 was identical except that it used hydrofluoric acid instead of phosphoric acid since it has been suggested that this may improve bond strength Group 3 used hydrofluoric acid etch, a silane coupling agent and Fuji Ortho L.C.TM a resin modified glass ionomer adhesive. Group 4 was like group 3 except for the use of phosphoric acid instead of hydrofluoric acid . All teeth were allowed to cure for 24 hours and then were subjected to bond strength testing. |
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The result showed that the highest bond strength was groups 1 and 2 which used the transbond adhesive. Although there was a tendency for the hydrofluoric acid to be slightly stronger than the phosphoric, it was not significant different when using the light cured composite resin. The Fuji Ortho L.C.TM group that used the phosphoric acid had the lowest bond strengths, probably inadequate for clinical use. The Fuji group that used hydrofluoric acid conditioning had better bond strength values that tended to be less than the transbond groups, but not statistically different. So the change to hydrofluoric acid conditioning did not make a significant difference for the transbond adhesive but did make a big difference for the Fuji Ortho L.C.TM . |
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Based on the results of this study, and we must remember this is an initial laboratory study only. I would conclude that if you are bonding routinely with a resin modified glass ionomer adhesive like Fuji Ortho L.C.TM, you have two choices when bonding to porcelain. First, you could use a conventional light cured adhesive for these specific teeth, or second, you could use hydrofluoric acid conditioning prior to silane coupling. For those of us using composite resins, there does not seem to be any great advantage to using hydrofluoric acid rather than phosphoric acid in terms of bond strength. For more information about Orthodontic bonding to porcelain, take a look at this article by Dr. Larmour and colleagues in the February 2006 issue of the European Journal of Orthodontics. |
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Effects of a Segmented Removable Appliance in Molar Distalization Akin E, Gurton AU, Sagdic
D. December
22, 2006 |
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[Ãʹú¿ø°í] Various types of upper molar distalizers have become a popular treatment option for class 2 patients. The upper class 2 correction with the promise of less patient cooperation. They can however be a hygiene challenge and they can irritate the parallelal tissue that is often used as anchorage. Reserchers from Turkey were interested to see if a removable molar distalizer could offer similar treatment results but without the hygiene problems or tissue irritation. The results of their study are published in the Feburary 2006 issue of the European journal of orthodontics in an article titled ¡°Effects of a Segmented Removable Appliance in Molar Distalization¡±. |
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This was a perspective clinical trial with 31 subjects originally recruited, 28 subjects completed the distalization treatment. These subjects were selected to have a class 2 dental relationship but a class 1 skeletal pattern. In addition, they had normal vertical proportions and a clinical crown height that was judged to be adequate to retain the appliance. The appliance consisted of an acrylic palate with heavy palatal wires which supported independent molar segments that were free to slide posteriorly. The activation was done with nickel-titanium coils which were initially adjusted to give 225 grams of force. Adams clasps retain the appliance on the first molars and on the first premolars. Measurments of treatment effects were done from lateral chephalometric films and study models. The result showed that a class 1 molar relationship was achieved in an average of 4.5 months. The average molar change was about 4mm of distal movement including 5 degrees of tipping. During the same time, the incisors moved forward a little more than a millimeter and also tipped slightly. Molar extrusion of about 1mm was measured and the inter-molar width increased about 2 mm. Based on these results I would say that the treatment effects of this appliance are much like one would expect from a fixed distalizer like a pendulum or a distal jet. The class 1 molar relationship was achieved but part of the correction was due to molar tipping which maybe hard to retain. In addition there was a reciprocal effect on the incisors and although mild, would require some anchorage to correct. The authors noted that hygiene and tissue condition were very good with this appliance. |
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I think it is important to note that this study was conducted on a selected group of mild class 2 patients. Its use in more severe skeletal class 2 patients may not lead to similar results especially if the absorbed molar extrusion would be undesirable. If you're interested in more details about this appliance the article gives more specifics about appliance construction and has many photographs of the various steps in fabrication. You can find the article in the Feburary 2006 issue of the European journal of orthodontics. |
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Clinical Comparison of Bond Failures Using Different Enamel Preparations of Severely Fluorotic Teeth Duan Y, Chen X, Wu J. December
29, 2006 |
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[Ãʹú¿ø°í] Orthodontic alignment of severely fluorotic teeth can be a challenge because of difficulty in keeping brackets attached to enamel. Many times have resorted to banding these teeth to allow efficient treatment but that option is definitely esthetic compromise. An article that appears in the March 2006 issue of JCO written by clinicians from China tested 3 different bonding approaches for these severely fluorotic teeth and compared the results in an article called "Clinical Comparison of Bond Failures Using Different Enamel Preparations of Severely Fluorotic Teeth". |
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This was a small prospective trial of 17 consecutive patients that presented with severely fluorotic enamel. A total of 324 teeth were bonded using the three different enamel preparations. The patients were randomly assigned to the treatment groups. Group 1 had conventional polishing with pumice and thorough rinse. Group 2 had small amount of outer enamel removed with a carbide bur following the pumice treatment. Group 3 had the same treatment as group 2 with the addition of a thin composite veneer over the whole facial surface. All groups then had brackets bonded with composite resin and self-etching primer. The bracket failures were recorded for the first twelve weeks and the three groups were compared. |
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The results may surprise you. Group 1 that had only pumice polishing prior to bonding had 74 percent failure rate. This is where we may be reaching for advance. Group 2 reduced the failure rate to about 25 percent, a significant reduction by just removing a small amount of outer enamel with the carbide bur. The best results by far came with group 3 where the brackets were bonded to a thin composite veneer. This group had a failure rate of only 2 percent comparable to bonding to normal enamel. |
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These results suggest to me that it may be beneficial to have the general dentist place thin composite veneers prior to orthodontic treatment on this type of severely fluorotic enamel. These thin veneers were provided in immediately esthetic improvement for the patient but most importantly it appears to be significantly improved the brackets retention during orthodontic treatment. The authors attribute the improved bracket retention when using the veneer to the increase in enamel bonding surface area. |
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To read the details of this useful clinical article, look in the March 2006 issue of the Journal of Clinical Orthodontics. |
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Masticatory Performance in Children and Adolescents With Class I and II Malocclusions Toro A, Buschang PH, et
al. January
5, 2007 |
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[Ãʹú¿ø°í] Consider a situation in which you are speaking to the parent of a 12-year-old girl with a mild Class II malocclusion. You discuss with her mother the many health and esthetic advantages of correcting her problem during the early permanent dentition. Mother says that the family is not concerned with the appearance but what she wants to know is if her daughter's chewing function is reduced due to the Class II malocclusion. What good research dated we have to answer this question? If you read the April 2006 issue of the European Journal of Orthodontics, you will find some new informations to help answer this particular question from your patient's mother. The paper is called "Masticatory performance in children and adolescence with Class I and II malocclusions". |
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The purpose of this research was to test how well children of different ages and with different malocclusions could chew. The subjects for this study were recruited from 2 private schools in Cloumbia. These were not people seeking orthodontic care. Over 2000 children were screened and 335 were selected. There were children selected at four ages; 6, 9, 12 and 15 years. In addition, these children either had a normal occlusion, a Class I malocclusion or Class II malocclusion. The chewing efficiency was tested by seeing how well the subjects could break apart a food bolus in 20 chewing strokes. To standardize the testing, the food bolus was actually a piece of CutterSil, a silicone impression material. After chewing, the pieces were spit out and collected. 5 chewing samples were combined for each subject and then run through various sills to be able to calculate the average particle size that was produced. |
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The results showed that children got better in chewing as they got older. Mostly due to the overall body size but also due to the development of the dentition. The surprising result was that those children with normal occlusion had better chewing efficiency than the Class I malocclusion group but there was no difference between the normal occlusion group and the Class II group. In other words, the children that had Class II malocclusions did not have more difficulty breaking apart food when chewing. |
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The authors had a couple of explanations why no difference was found with Class II malocclusions. First, the Class II group were generally mild malocclusions. The requirement was only one half cusp Class II. They thought the result may have been different with more severe Class II subjects. Also the Class II group was the smallest group in the study which makes it more difficult statistically to demonstrate a difference. But if we were to answer the mother of the Class II patient that we were discussing at the start of this review, we would have to tell her that at this point time there is no evidence to demonstrate that a mild Class II malocclusion would significantly hamper individuals chewing ability. For more information on the relationship between malocclusion and chewing efficiency, look at this article by Toro A et al in the April 2006 issue of the European Journal of Orthodontics. |
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Biomechanics of Skeletal Anchorage Part 1 Class II Extraction Treatment Cornelis MA, De Clerck
HJ January
12, 2007 |
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[Ãʹú¿ø°í] The use of mini-screws or plates for skeletal anchorage is rapidly increasing in orthodontics. One specific situation whether the use is suggested is when a full class II cases treated with upper premolar extraction and no posterior anchorage loss can be tolerated. If you choose to use skeletal anchorage in this situation, other some changes in mechanics would be needed as compared to the conventional treatment? According to Dr.'s Cornelis and De Clerk at the answers to that question is yes. They are some mechanics changes that can improve efficiency. They published the paper on the mechanics of Class II correction in extraction cases in the April 2006 issue of the Journal of Clinical Orthodontics called ¡°Biomechanics of Skeletal Anchorage Part 1 Class II Extraction Treatment.¡± |
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This paper is based on the experience of using skeletal anchorage in 137 patients over the last 5 years. The purpose is to report their experience and to help those of us with less experience benefit from their expertise. Their version of skeletal anchorage is a miniplate held by two screws with a special connector for orthodontic attachments. They have had very good results with this anchorage system, but the mechanic's suggestion would apply to the use of many screws as well. When treating a Class II patient with upper premolar extractions, the author suggested first retracting the upper canine using the elastics from the canine to the skeletal anchors. Unlike conventional mechanics, incisor alignment and overbite correction are not needed prior to this step. They find that during canine retraction, the incisors also retract significantly as well due to the lack of molar rotation and binding that normally occurs when using the molars for anchorage. After the canine is retracted, then the incisors are aligned if needed and a T loop closing wire is used to complete incisor retraction and overbite correction. During this time, an elastic chain is placed from the canine to the skeletal anchor to provide vertical and horizontal support. Another difference that the authors have noticed compared to conventional treatment is that during canine retraction again since there is no reactive force in rotation of the molars. The upper molars maintain in narrow. This tendency for molar narrowing may require the placement of a transpalatal arch to prevent posterior cross bite from developing. Overall, the authors have discovered skeletal anchorage to be very useful in the treatment Class II extraction patients. They have found that discomfort and cost of anchorage placement is more than offset by the reduced treatment time and the lack of needed for auxillaries such as headgear, enhanced appliances, or class II elastics. |
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For more information and many excellent color photographs describing the use of skeletal anchorage in class II extraction cases. Look for this articles in the April 2006 issue of the Journal of Clinical Orthodontics. |
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Image Artifact in Dental Cone-Beam CT Katsumata A, Hirukawa
A January
19, 2007 |
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[Ãʹú¿ø°í] Conebeam imaging is making rapid inroads into dentistry and orthodontics. The ability to image in 3D is a huge advantage for diagnosis and treatment planning. But, what are the limitations of this technology? Is it susceptible to image artifacts, or image distortions? Radiologists from Japan noticed an artifact and solid objects placed near the edge of the field of view in conebeam images and decided to investigate. The results of their investigation are published in the May 2006 issue of the journal Oral Surgery Oral Medicine Oral Pathology Oral Radiology and Endodontology in an article called "Image artifact in dental conebeam CT". |
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This was a laboratory investigation using a phantom model. Various rectangular solid test objects were manufactured out of material representing different levels of density from soft bone to metal. The test objects were placed in a water filled phantom that represented the human head. The machine used for imaging was a limited-volume conebeam unit called the 3DX Accuitomo. This is one of units that are a modified panoramic unit with a small field of view. The test objects were positioned in a variety of locations in the phantom and imaged in each of the locations. The required images were reconstructed and the image slices were viewed looking for distortion or artifact. The authors were able to reproduce the artifact that they had observed clinically. This was an arch shaped defect in the test objects that occurred on the side towards the edge of the phantom. The artifact appeared only on those images taken with the test object near the edge or outside of the phantom. Based on their findings, the authors suggest that the artifact is due to halation of the image intensifier. This occurs when some part of the X-ray beam reaches the image intensifier without passing through the phantom, a sort of overload of the image intensifier. The authors state that this type of defect will not likely occur in a larger field of view machine using image intensifiers like the "NewTom" or the "Hitachi Mercuray". Some machines like the "i-CAT" do not use an image intensifier at all. And so I would assume not be affected by this type of artifact. |
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The conclusion for me is that we need to learn about the limitations as well as the tremendous advantages of conebeam technology. This report indicates that these imaging systems are not immune from problems of image artifacts or distortions. Fortunately, the larger field of view machines that are more likely to be used in orthodontics do not appear to be susceptible to this particular artifact. But smaller field of view machines that may be suitable for looking at impacted canines or for planning implant locations could be affected. This is quite a technical article but if you are so inclined you can find further details about this project and its finding in the May 2006 Triple O. |
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