Dental disorders are associated with minimal synovial changes in the temporomandibular joint in horses

Introduction: Dental disorders have been proposed as factors contributing to temporomandibular joint (TMJ) discomfort in horses, but objective evidence linking these conditions to synovial fluid alterations remains limited. This study evaluated whether the severity of dental abnormalities influences the physicochemical and cytological characteristics of TMJ synovial fluid and whether occlusal adjustment induces measurable synovial changes over time. Methods: Thirty-three horses were assigned to mild, moderate, or severe dental abnormality groups. Synovial fluid was collected bilaterally from the discotemporal joint compartment before and 30, 60, and 90 days after dental treatment. Physicochemical and cytological variables were compared among severity groups and sampling times. Results: Synovial fluid characteristics remained stable across most variables, groups, and time points. A clearer synovial fluid appearance was observed in the contralateral TMJ of horses with severe dental abnormalities at 60 and 90 days, whereas an increased synovial fluid volume was detected in the ipsilateral joint of horses with moderate dental abnormalities at 90 days. No other variables differed significantly (p > 0.05). Discussion and conclusions: Dental disorders and their correction produced limited measurable effects on synovial fluid composition in the equine TMJ, indicating substantial biochemical stability. These findings suggest that, despite the proposed association between dental abnormalities and TMJ dysfunction, synovial fluid physicochemical and cytological characteristics remain largely unaffected by dental abnormality severity and occlusal adjustment.

Universidade do Estado de Santa Catarina
Universidade de São Paulo