EFFECT OF MANDIBULAR DISTRACTION ON THE TEMPOROMANDIBULAR-JOINT .1. CANINE STUDY

The effect of osteodistraction on the temporomandibular joint was eval uated in a canine model. Eleven mongrel dogs were used in the study. A n intraoral expansion device was placed after an osteotomy was made at the angle of the mandible via an intraoral approach. The mandibles we re expanded either fully to 20 mm or partially to 10 mm. After expansi on, nine animals were immediately killed; the remaining two were maint ained in fixation for an additional 10 weeks. Cephalometric radiograph s and computed tomographic scans obtained preoperatively and before ki lling were evaluated. No gross temporomandibular joint deformation or bodily movement was noted in the expanded or contralateral, unexpanded side. The temporomandibular joints were harvested en bloc for gross a nd microscopic evaluation. Flattening of the posterior aspect of the e xpanded condylar head was noted, with thinning of the condylar cartila ge. New bone deposition was noted, which was evident as anterior lippi ng. Condyles maintained in 10 weeks fixation showed reparative changes . No evidence of avascular necrosis, microfracture, or cystic degenera tion was noted. This study indicates that the force of distraction can induce bony changes in the temporomandibular joint and that these eff ects are minimal and reversible.