Aim: The aim of this study is to evaluate the proliferative and hypertrophic activities in the Mandibular Condylar Cartilage and the Glenoid Fossa during mandibular advancement in Sprague Dawley Rat’s Temporomandibular Joint , evidenced by Fibroblas Growth Factor 8 (FGF8)and Proliferative Cell Nuclear Antigen (PCNA).
Materials and Methods: Fifty five female 24-day old Sprague-Dawley rats where randomly divided into four experimental and control groups, with mandibular advancement appliance on the experimentals’ lower jaw. The rats were euthanized on day 3, 14, 21 and 30 of the study and their TMJ was prepared for immunohistochemical staining procedure to detect FGF8 and PCNA.
Results: FGF8 expression was significantly higher in the experimentals (p=0.002), while PCNA expression was not significantly increased in the experimental samples (p=0.327). The pattern of raise and decline of FGF8 and PCNA expression was similar in experimentals and controls. However, it was different between the condyle and the glenoid fossa. The results overall show an enhanced osteogenic transition occurring in both condyle and glenoid fossa in experimentals in comparison with controls. The level of cellular changes in the condyle is remarkably higher than glenoid fossa.
Conclusion: In the condyle and the glenoid fossa hypertrophic differentiations are significantly increased during mandibular advancement, while the cellular proliferation is not significantly increased. It could be concluded that the endochondral ossification in the condyle and more likely intramembranous ossification in the glenoid fossa occurs during adaptive remodeling.