Development of temporomandibular joint ankylosis in rats using stem cells and bone graft

64 male Wistar rats were used: 24 for the removal of stem cells, 4 as a control group, and 36 for the experiment, in which either stem cells or bone graft was used. The rats were divided into groups according to the type of procedure and time span (15, 30 or 60 days). The joints were submitted to histological study in order to score the ankylosis. The mean differences between initial and final maximal mouth opening (MMO) were gradually increased from 15 to 60 days, for all times of evaluation for both groups, being statistically significant at 15 days (p = 0.045) in the bone-graft group. When both groups were compared, the mean differences between initial and final MMO were statistically significant at 15 days (p = 0.018) and 30 days (p = 0.029). In relation to the histological scores, in the bone-graft group almost all animals had intra-articular fibrosis at all times of evaluation (n = 17). In the stem-cell group, there was new bone at 15 days (n = 4), 30 days (n = 3) and 60 days (n = 4). The study model permitted the development of fibrous ankylosis in the majority of animals for both groups and no bony bridge was observed.