Histological evaluation of intraperitoneal injection of dexamethazone and hydrocortisone on the temporomandibular joint inflammation in rats

Introduction: Temporomandibular joint (TMJ) dysfunction is one of the most common jaw disorders. Corticosteroids are indicated for severe pain in the TMJ, related to inflammatory conditions. The aim of this study was to compare histological effects of intraperitoneal injection of dexamethasone and hydrocortisone on TMJ inflammation in rats.Materials and Methods: In this experimental study twenty-seven rats weighing 200-250 g were used. Inflammation was induced by opening the rats’ mouth 20 mm manually once a day for 10 consecutive days. The rats were randomly divided into three groups. Group I rats (n = 3) were left without any treatment; the rats in group II (n = 12) were injected with a single intraperitoneal dose of 1.2 mg/kg of dexamethasone; the rats in group III (n = 12) were injected 32 mg/kg of hydrocortisone after 11 days. The control rats were sacrificed at 6 weeks, while the rats in groups II and III were sacrificed at weeks 1 and 6 after injection. The groups received scores of 1-11 according to four factors of synovial hyperpelasia, vascularity, fibrin deposits and synovial adhesion. Data were analyzed with Mann-Whitney and Kruskal-Wallis tests (α = 0.05).Results: The results of this study indicated statistically significant differences in inflammation severity between the experimental groups of II and III and the control group (p value = 0.006). There was a significant difference in inflammation severity in group II between week 2 and week 6 (p value = 0.026).Conclusion: Intraperitoneal injection of dexamethasone and hydrocortisone was seen to reduce rat TMJ inflammation in the histological evaluation. The greatest inflammatory response was seen in group II six weeks after injection of medicine. Key words:Corticosteroids, Inflammation, Injection, Temporomandibular joint