A histologic study of deformation of the mandibular condyle caused by distraction in a rat model.

OBJECTIVE: This study investigated the bone resorption process of the rat mandibular condyle after mandibular distraction. STUDY DESIGN: Male Wistar rats at 10 weeks of age underwent unilateral mandibular distraction at 0.175 mm per 12 hours for 10 days. Histologic and histochemical analyses were performed at postoperative day 1 and weeks 1 and 3. RESULTS: High-resolution computed tomography (micro-CT) observations showed that deformation of the condyle occurred in the anterior region, where a discontinuity of the condylar cartilage layer was found in histologic sections. This destroyed area gathered many osteoclasts. In the central region, disorganization with a thin hypertrophic cell layer was recognizable by day 1 but later thickened. Morphologic recovery of the mandibular condyle could be attained by week 3 in this animal model. CONCLUSIONS: These morphologic findings indicate that rapid deformation of the condyle, with destruction of the cartilage layer and bone resorption, was caused by artificial distraction.