Veterinary and radiological evaluations of open and closed treatment of type B diacapitular (intracapsular) fractures of the mandibular condyle in sheep.

The incidence of diacapitular (intracapsular) fractures of the mandibular condyle has increased in recent years, but their treatment remains inadequate, particularly of type B fractures. To evaluate and compare outcomes of open and closed treatments we created a sheep model of a type B fracture through an osteotomy. Eight sheep were randomly divided into two groups of four each to be given closed treatment or open reduction and internal fixation (ORIF) and were evaluated by veterinary and radiological examinations. Compared with before the osteotomy, there were significant reductions in maximum mouth opening (MMO) and left movement in the closed group, but no significant differences in the range of jaw movements in the ORIF group after 12 weeks of treatment. The two radiological scores that indicated the degree of osteoarthrotic changes and ankylosis of the temporomandibular joint (TMJ) in the ORIF group were significantly lower than those in the closed group. Anatomical observation confirmed the pathological changes in the right TMJ in the closed group and adaptive changes in the ORIF group. We conclude that ORIF is more efficient than closed treatment in restoring the function and shape of the TMJ to after a type B diacapitular condylar fracture.