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Ortho Tribune Middle East & Africa No.3, 2017

Dental Tribune Middle East & Africa Edition | 3/2017 ORTHO TRIBUNE E7 ◊Page E6 Discussion The case reports presented dem- onstrate examples of the change in the size and shape of the maxil- lary and mandibular alveolar bone observed in adolescent, adult and children treated with a passive self- ligating, continuousarch appliance and Damon low-friction/low-force treatment protocols. Specifically, the increase in the transverse di- mension of the alveolus appears to be the result of lateral translation of the buccal and lingual cortical plates induced by the biomechanical load applied to the teeth and transmitted to the alveolar bone. These cases pro- vide additional clinical evidence for the ability of the alveolar bone to un- dergo biomechanical loadinduced modeling. As Frankel had done previously with his Function Regulator appliance, Damon has proposed a mechanism of action for the dentoalveolar re- sponse to his treatment regimen. Based on clinical observations and analysis of photographs, plaster study model measurements and medical CT surveys36 of treated cases, he suggests that the light, continu- ous force delivered by his treatment approach disrupts the equilibrium of the tooth positions maintained by the inner and outer oral musculature acting on the alveolus and dentition. When the anterior component of the force acting along the continuous archwire is kept low, it is mitigated by the resting pressure of the lip38 in patients with adequate circumoral muscle tonus. The posterior compo- nent of force is likewise resisted by multi-rooted molars along with the ascending ramus in the mandible and the tuberosity in the maxilla. A resultant lateral component of force is expressed and transmitted from the teeth to the alveolar bone, induc- ing bone modeling or posterior arch adaptation as he describes it. The OSIM findings of Badawi sup- port Damon’s proposed mechanism of action, specifically the assertion of a lower anterior vector of force delivered with a passive self-ligating appliance compared with an elasto- meric-ligated appliance applied to the same simulated malocclusion. In addition, there is a cellular mecha- nism of action that supports alveolar bone modeling induced by tooth dis- placement. Figure 8 from Graber de- scribes bone modeling occurring in the periodontal ligament and on the periosteal surfaces resulting from net apposition of bone in the direc- tion of the line of applied force and net resorption of bone away from the direction of force. Furthermore, this ability to move bone with a light, continuous load applied to the teeth has been corroborated in the sagittal dimension by Melsen39,40 and Allais.41 Despite the evidence presented in this article, there remains consider- able debate regarding the immuta- bility of the alveolar bone and the treatment response to low-friction/ low-force passive self-ligating appli- ances. Rigorous investigation should be undertaken to validate and un- derstand these clinical observations. Future clinical investigations should incorporate case selection criteria that include subjects with adequate circumoral muscle tonus as well as close adherence to the established treatment protocols as described in the case reports above. In addition, future CBCT analysis should consider the voxel size and resolution of the machines used in making alveolar bone determina- tions as well as the time period in which the posttreatment assess- ments are undertaken to allow ad- equate time for completion of sec- ondary mineralization. Conclusions This article presents case reports demonstrating a change in the size and shape of the alveolar bone in child, adolescent and adult patients treated by a continuous-arch, self- ligating appliance. These cases, along with a growing body of evidence, challenge the immutability of the alveolar bone and the axiom of treat- ing to the existing arch form. It is the authors’ considered opinion that Melvin Moss’s Functional Matrix Theory is correct and the change in alveolar form induced by this low- friction, low-force treatment ap- proach provides an opportunity to recapture the full genetic potential of the patient’s alveolus. Furthermore, alveolar bone mode- ling is a practical treatment objective that can decrease the need for more invasive approaches in appropriate- ly selected and appropriately treated patients. Acknowledgment The authors wish to acknowledge Dr. Rob Laraway, resident at the Uni- versity of Maryland, Department of Orthodontics, for his assistance with the literature review for this article. Editorial notes: References are available from the publisher. Featured Article from Clinical Impres- sions Journal, Volume 20, Number 01, April 2017. Visit ormco.com/ci for more information Thomas W. Barron, D.M.D., M.S. Timonium, MD, USA In the private prac- tice of orthodontics, Dr. Barron is also a member of the Dean’s Faculty and an assistant clinical professor in the Department of Orthodontics at the University of Maryland School of Dental Medicine. He is a member of the Ormco speakers’ bureau. Frank Bogdan, D.M.D. Bayonne, NJ, USA In the private prac- tice of orthodontics with his son Dr. Mark Bogdan, Dr. Bogdan is also an assistant clini- cal professor in the Department of Ortho- dontics at Rutgers University. He is also a member of the Ormco speaker’s bureau. Figure 8. Orthodontic bone modeling, or sitespecific formation and resorption, oc- curs along the periodontal ligament and periosteal surfaces. Illustration from Orthodontics: Current Principals and Techniques, Graber, Va- narsdall & Vig, 4th edition. Reprinted by permission. International Magazines ortho international magazine of orthodontics www. dental-tribune.com issn 1868-3207 Vol. 1 • Issue 1/2016 EUR 22 per year (2 issues per year; incl. shipping and VAT for customers in Germany) and EUR 23 per year (2 issues per year; incl. shipping for customers outside Germany). ORTHO international magazine of orthodontics 12016 Your subscription will be renewed automatically every year until a written cancellation is sent to Dental Tribune International GmbH, Holbeinstr. 29, 04229 Leipzig, Germany, six weeks prior to the renewal date. Shipping Address Name Address Zip Code, City Country E-mail Date, Signature practice management Short-term gains… long-term problems? trends & applications Vibration therapy in orthodontics: Realising the benefits industry report From straightforward to complex cases PayPal Credit Card Credit Card Number Expiration Date Security Code SUBSCRIBE NOW! F +49 341 48474 173 subscriptions@dental-tribune.com

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