Neovascularization in the TMJ in response to mandibular protrusion

Abstract

Objective: To examine neovascularization in the TMJ in response to mandibular forward positioning. Material and Methods: One hundred female Sprague-Dawley rats, 5 weeks of age, were divided into 5 experimental groups and 5 control groups. Functional appliances were fitted to the upper incisors of animals in the experimental groups, causing a continuous mandibular protrusion. The animals in the experimental groups, together with their matched controls, were sacrificed 3, 7, 14, 21, and 30 days after mandibular protrusion. 7-痠 sections were cut through the TMJ and were processed for immunohistochemical analysis. Neovascularization was assessed by immunostaining for endothelial cells using the monoclonal antibody EN 7/44. Immunolocalization of neovascularization was quantified using Leica Qwin system. Results: In the fibrous tissue connecting the posterior aspects of both the condyle and the glenoid fossa, the amount of immunostaining for neovascularization in the experimental groups was on average 200% higher than in the controls (P < 0.001). In the condylar bondy tissue, as well as in the bony tissue of the fossa, the amount of immunostaining for neovascularization in the experimental groups was on average 103% and 163% higher than in the controls (P < 0.001). Conclusion: Neovascularization in the TMJ is increased in response to mandibular protrusion, which is a major contributory factor to increased new bone formation in the TMJ.