Dental News - A year in review (Part 3): Orthodontics

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A year in review (Part 3): Orthodontics

Dr Young Guk  Park, South Korea

Dr Young Guk Park, South Korea

Mon. 9. January 2012

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Clinical orthodontics must be viewed as a specialty cemented in biology, Dr Young-Guk Park from the Kyung Hee University in Seoul says. In this final part of our exclusive commentary series, he discusses the latest developments in the field in 2011.

The ultimate goal of any orthodontic treatment is to obtain better aesthetics of the dentition and the face, and the health of the periodontium, TMJ and longevity of the dentition throughout life by means of accurate diagnosis and mechanotherapy upon malocclusion and dento-facial disharmonies. Bringing all these propositions together requires discarding empirical and conceptual orthodontic planning by adopting 3-D movement algorithms for each tooth and, accordingly, design of corresponding biomechanics.

Orthodontic tooth movement results from forces that evoke cellular responses in the teeth and their surrounding tissues, including the periodontal ligament, alveolar bone and gingiva. It is advantageous for the orthodontist to control the details of the biological events that unfold during tooth movement, as some of these details may differ from one person to another owing to variables such as sex, age, psychological status, nutritional habits or drug consumption. Biological variations may be the foundation of the differences that are frequently observed in the outcomes of orthodontic treatment between patients with similar malocclusions but identical treatment.

Principles of orthodontic biomechanics are usually taught with the help of a typodont, consisting of artificial teeth embedded in wax. This set-up ignores entirely the biological aspect of tooth movement. However, in the clinical setting, living patients are encountered, and mechanical forces mobilise their teeth. These movements result from the development of strains in dental and para-dental tissues, followed by modelling and remodelling of these tissues.

In some patients, systemic conditions may exist, evoking complications such as root resorption, dehiscences and fenestrations of the alveolar bone. Hence, clinical orthodontics must be viewed as a specialty cemented in biology, all the way down to the molecular level. As a clinical profession, it must be based also on profound knowledge of mechanics, biology, physiology, and pathology.

The usual rate of tooth movement by conventional protocols of mechanotherapy is approximately 1 mm per month. The suggested minimal intervention, surgically assisted orthodontics is a minimally invasive peri-orthodontic procedure without flap elevation, which accelerates tooth movement with an enhanced turnover rate of surrounding structures. This milieu is clinically expedient with sound biological foundation, and makes the orthodontic outcome more stable and less prone to complications. It has elucidated the evidence that minor surgical procedures by orthodontists obtained accelerated rates of tooth movement with impunity, and enhanced the rate of bony and periodontal response, thereby shortening the duration of treatment.

Clinical orthodontics has seen innovative change with the rise of digital dentistry as these applications have brought cutting-edge technology to diagnosis and treatment. Laser scanning, structure photo-imaging, and surface image analysis have almost superseded the stone model in the clinical environment. In addition, these technologies enable clinicians to achieve an intended treatment result through individual custom appliances made possible by robotics that allow sophisticated individual tooth positioning, a procedure that was not possible with conventional preformed appliances.

These diverse technologies bring the prospective adjustment in fundamental framework of the conventional treatment, and consequently improve the accuracy of the orthodontic correction.

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