Reconstitution of the human oxytalan system during orthodontic tooth movement.

Orthodontic tooth movement in man has revealed that the oxytalan fiber system possesses a high order of maintenance. Oxytalan fibers did not merely increase in number during orthodontic movement. On the contrary, the oxytalan fiber system underwent reconstruction and adaptation to extensive metabolic and anatomic changes within the periodontium. With the use of light orthodontic forces, the oxytalan fiber system was constantly remodeled on both the tension and compression sides and maintained a characteristic cementum-vascular relationship even when teeth were moved a significant distance through the alveolar bone. In contrast, heavier forces caused localized destruction of the oxytalan system in regions of excessive pressure and tension. Reconstitution of the oxytalan system provided evidence against the concept that oxytalan fibers are stretched by orthodontic movement and subsequently contribute to relapse by elastic rebound. In man the oxytalan fiber system of the periodontal ligament is arranged as a three-dimensional fiber meshwork and exhibits a complex geometry like other fiber systems in the connective tissues. Knowledge of the interaction between elastic and collagen fibrillar assemblies has been used to derive some speculative concepts of oxytalan-collagen interaction. These concepts have been put forward with the intention of stimulating further interest in the oxytalan fiber meshwork. The present investigation emphasizes that the use of the light microscope to examine and record static images of complex biologic changes can provide new knowledge of the structure and function of human connective tissues.