Abstract: Objective Reverse transcription polymerase chain reaction(RT-PCR)was used for inflammatory factor expression in experimental rat temporomandibular joint cartilage by the occlusal interference. Methods The six week old female SD 9 rats were randomly divided into occlusal disorder group,removed occlusal disorder group and normal control group,3 rats in each group. The occlusal interference animal model was established. After six weeks,occlusal disorder group did not receive any treatment,removed occlusal disorder group was rid of occlusal interference,normal control group served as normal control. After eight weeks,the rats were sacrificed,the right side of the temporomandibular joint was cut out. RT-PCR was used to detect interleukin-1(IL-1),interleukin-6(IL-6),tumor necrosis factorα(TNF-α),and interferon -γ(IFN-γ)expression in the temporomandibular joint cartilage. Results In occlusal interference condition,RT-PCR results showed inflammatory cytokines IL-1,IL-6 and TNF-α in rats of different groups were expressed. However,the inflammatory cytokines expression of the experimental group were higher than those of control group. IL-6 and TNF-α expression in occlusal disorder group were higher than those of removed occlusal disorder group. IFN-γ expression in three groups was not detected. Conclusion Under the occlusal interference condition,the expression of the inflammatory cytokines IL-1,IL-6 and TNF-α in the temporomandibular joint cartilage got enhancement. These results suggested that inflammatory cytokines and temporomandibular joint condylar remodeling in rats activity correlated.

Key words: malocclusion, temporomandibular joint disorders, gene expression