Comparative evaluation of low-level laser and systemic steroid therapy in adjuvant-enhanced arthritis of rat temporomandibular joint: A histological study

BACKGROUND: Low-level laser therapy (LLLT) has shown a promising effect in ameliorating symptoms of rheumatoid arthritis (RA). The aim of this investigation was to compare the early and late anti-inflammatory effects of LLLT and betamethasone in RA. MATERIALS AND METHODS: In this animal experimental study, after inducing a model of RA in temporomandibular joint (TMJ) of 37 Wistar rats using adjuvant injection, they were randomly distributed into three experimental groups of 12 animals each: (1) LLLT group; (2) steroid group which received a single dose of betamethasone systemically; and (3) positive control group, which did not receive any treatment. One rat served as the negative control. Half of the animals in all the experimental groups were sacrificed on the 21(st) day after RA induction (early phase), and the other half were sacrificed 2 weeks later (late phase). Then, the severity of TMJ inflammation was assessed histologically in each group on a semi-quantitative scale. Kruskal-Wallis and Mann-Whitney tests were used to compare differences (α = 0.05). RESULTS: The LLLT and steroid groups showed significantly (P < 0.05) lower inflammation mean scores in both early (5.66 [±1.86] and 1.66 [±1.21], respectively) and late phases of evaluation (1.16 [±1.47] and 6.50 [±1.04], respectively) compared to positive control group in early and late stages of assessment (11.66 [±3.50] and 8.66 [±1.36], respectively). However, the best results (P < 0.005) were achieved in early phase of the steroid group as well as late phase of the LLLT group. CONCLUSION: Within limitations of this study, it may be concluded that LLLT method has a long-term promising effect on reducing inflammation severity of TMJ similar to betamethasone in earlier stages.