| Abstract: | Objective To establish TMJ-OA rat models by occlusal disorder and forced open mouth, compare two TMJ-OA induction methods and assess their applicability by pathological changes in the cartilage, subchondral bone. Methods Twenty-one 8-week-old Sprague-Dawley （SD） male rats were divided into four groups, namely control group, and three rats were conventional feeding. eighteen SD rats were randomly allocated to three groups using the randomization table; each group had the same number of SD rats. The Forced open mouth （OP） , steady mouth opening was imposed to 20 mm daily （1 minute/day for 16 days）. the occlusal disorder group （OD）, an orthodontic ligation silk （0.25 mm diameter） revolved around the first molar, and a ligation knot was created on the first molar of the maxillary. The control group of occlusal disorder （ODS） use the same method, a ligation knot in the mesial of the first molar. Rat models were employed and followed for 4 weeks after experimental procedures, and TMJ joints in each group were harvested. The TMJ changes were evaluated by micro-CT, HE staining, and Safranin-O/Fast green staining. Results We found apparent histological phenotypes of TMJ-OA in the OP and OD groups, and observed a pronounced drop in bone volume fraction , BV/TV and Tb.Th between OD and OP groups had no significant difference （P > 0.05）, and a substantial increase in the modified Mankin score was found, there was no significant difference in the two groups （P > 0.05）, but two samples of OP group didn’t present apparent histological phenotypes of TMJ-OA. Conclusions Osteoarthritis-like pathological changes in the cartilage and subchondral bone can be observed in both of the two methods. The occlusal disorder is a stable TMJ-OA model, forced open mouth caused osteoarthritis-like changes, but it’s unstable and inefficient. |
