Quantitative evaluation of new bone formation in the posterior zone of the glenoid fossa in response to the mandibular advancement in rats

Abstract

OBJECTIVE: To quantify the new bone formation in the glenoid fossa of the temporal bone in response to the mandibular advancement. METHODS: A bitejumping appliance with guide slope was fit on the upper jaw of each rat in the experimental groups, resulting in a downward and forward displacement of condyle and continuous mandibular advancement. Sections were cut through the glenoid fossa at the sagittal plane and stained with PAS under the same condition. The new bone formation at the posterior zone of the glenoid fossa was detected by quantitative measurement through computer-assisted image analyzing system (Q550IW, Leica) with the advanced software (Leica Qwin Pro, Version 2.2). Statistical analysis was performed with GraphPad 3.0. RESULTS: 1. a comparison among experimental groups revealed a peak of new bone deposition at the 21-day group, significantly greater than other groups (P < 0.001); 2. a comparison among control groups showed a gradual decrease of new bone deposition characterized by a peak of at the 3-day group and a bottom at the 30-day group (P < 0.001); 3. a comparison between experimental and control groups showed no significant difference statistically at the 3-day groups (P > 0.05), whereas a significant difference of new bone deposition starting from 7-day groups, with a peak at 21-day groups and a decrease towards 30-day groups (P < 0.001). CONCLUSION: The advancement of mandible leads to the remodeling of the glenoid fossa indicated by the new bone deposition in growing rat.