Abstract
he present study was conducted to evaluate the effect of unilateral mandibular lengthening on TMJs. We studied the histological and radiological changes in the right ipsilateral and left contralateral TMJs after unilateral mandibular distraction osteogenesis in goats. Eighteen adult female goats of comparable age and weight were included in this study. They were divided into three groups. Group I: consists of six animals served as control group n=12 condyles), sacrificed without being subjected to any procedure. Group Il and group III consist of twelve experimental animals had the right side of the mandible distracted after a five days latency period postoperatively at a rate of 2 mm / day (n=24 condyles) producing 14 mm gap, distraction was performed twice daily every 12 hours for each animal. In experimental group II (n= 12 condyles), the animals were sacrificed one month after the consolidation period. While in experimental group III, the animals were sacrificed 6 months after the consolidation period. After animal sacrificed, the heads of the animals with the mandible were dissected and cut into two halves at the symphysis. ipsilateral and left contralateral IMJs using enclosed X-ray unit. X-ray films were scanned and qualitative and geometrical interpretations were made following standardized parameters. TMJs from both sides were harvested and prepared for histological examination under light microscope using haematoxylin and eosin stain. Histological findings revealed that there were no degenerative or inflammatory changes in either IMJ in any of the groups after unilateral distraction osteogenesis. Radiographic examination showed no gross changes in the general morphology and architecture of the condyle and the glenoid fossa, no erosions, or abnormal deformity of the joints and no any signs of luxation of the condyle. Statistical analysis showed that there was no significant difference in anterior, posterior and superior joint spaces between the right and left joint in all groups. From these results we concluded that: - Lengthening of the mandible by gradual distraction produces changes in the condylar processes of both operated and contralateral sides in the form of adaptive process. - The major changes occur between the cartilaginous layers and the bone as well as in the condylar bone structure