[Establishment of rat models with altered anterior guidance and observation of histological changes in temporomandibular joint synovium].

OBJECTIVE: This study aims to establish a stable animal model with altered anterior guidance and investigate histological changes on temporomandibular joint (TMJ) synovium in rats.

METHODS: Thirty-two rats were divided into four groups, namely, control group, anterior-guidance-deficient group (T1), and anterior guidance inclined up to 15 degree (T2) and 30 degree (T3) groups. Metal crowns that add 15 and 30 degrees to the palatal side were cemented to the incisors of maxilla to increase the inclination of anterior guidance. The low-speed diamond wheel shorts for both upper and lower incisors of rats were applied to avoid contact between anterior teeth in all direction, thus establishing an anterior guidance deletion model. TMJ joints on one side of two animals in each group were harvested after 3, 7, 14, and 28 days. Pathological changes were investigated in the TMJ synovium using hematoxylin-eosin (HE) staining.

RESULTS: The weight of T1 decreased briefly at first, and then increased slightly (P<0.05). The weight of T3 obviously reduced and then slowly increased, but remained below the initial weight (P<0.05). T3 manifested obvious synovial lining proliferation and vascular dilation (P<0.05).

CONCLUSIONS: The rat model of anterior guidance inclined up to 30 degree could imitate the pathological features of TMJ synovium with excessive increase in anterior guidance. A higher inclination of anterior guidance might cause more damage of TMJ synovium. The effect of anterior guidance deletion on TMJ synovium is yet to be determined.
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