Effect of Experimental Traumatic Occlusion on Temporomandibular Joint

Comparison between Treated Side and Untreated Side of TMJ

Abstract

This study was designed to investigate the effects of experimental traumatic occlusion on the temporomandibular joint (TMJ) in rats. Composite resin 2mm thick was built up on the occlusal surface of the maxillary left first molar (experimental group) and then traumatic occlusion was induced in 7-weekold Wistar rats. Untreated rats were used as the control. Rats in each group were sacrificed at 3, 7, 14, 28, 42, and 56 days after the induction of traumatic occlusion. For the histopathological analysis the sections were stained with hematoxylin and eosin. The cell proliferative activity in the condylar cartilage was identified by immunohistochemistry after injection of 5-bromo-2′-deoxyuridines (BrdU) and examined histopathologically and histometrically. At both sides in the experiment group, the thickness of condylar cartilage and the number of labelled cells with BrdU in the cartilage decreased at 7 days, but increased at 14 days. At 28 days, the thickness of condylar cartilage and the number of labelled cells with BrdU in the cartilage in the experimental group decreased to the same level as that in the control group. Thus, the results indicate that the histological and cytological responses of both sides of TMJ are influenced by the induction of traumatic occlusion of only one tooth.