The role of biology in the orthodontic practice

The purpose of this article is to emphasize the fact that orthodontics is a field of endeavour where mechanics and biology are integrated, and to stress the reality that tooth movement is conducted in individual human beings, each composed of a unique and intricate physiological system. Biological variations may be the foundation of the differences that are frequently observed in the outcomes of orthodontic treatment between patients with similar malocclusions, treated identically.

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 mobilize their teeth. These movements result from the development of strains in dental and paradental 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 staunchly entrenched in biology, all the way to the molecular level. As a clinical profession, it must be based on a commanding knowledge of mechanics, biology, physiology, and pathology. The goal of this article is to enhance the biological awareness of the orthodontic practitioner, in order to minimize or avoid tissue damage during orthodontic treatment. It will demonstrate that this objective may be achieved by closely focusing on the nature of root movements, and avoiding dogmatic following of “prescription” methods that promise “automatic” correction of all malocclusions.

Page 1     Introduction

Page 2     Tissue remodelling and orthodontic tooth movement

Page 3     The age factor

Page 4     The effects of pre-existing medical conditions and the development of complications

Page 5     The etiology of tooth resorption

Page 6     The biological nature of an optimal orthodontic force

Page 7     How to move teeth without resorbing their roots

Page 8     Summary