The role of trauma on temporomandibular joint ankylosis and mandibular growth retardation: an experimental study.

The purpose of this pilot study was to analyze the role of different types of trauma in the formation of temporomandibular joint ankylosis. The specific aim was to explore the physical and histological effects of trauma on temporomandibular joint and mandibular growth. Fifty-five growing white male guinea pigs were used for the study. Initially, cadaveric studies were performed (n = 1) to assess the topographic anatomy of the temporomandibular joint region. Animals were then assigned to pilot (n = 4), experimental (n = 40), and control (n = 10) groups. The pilot group was used to assess the technical feasibility of creating various trauma types and endurance of the animals to the surgery. Four types of trauma were carried out in the experimental group: A) intra-articular hematoma (n = 10), B) mechanical damage to the articular surface (n = 10), C) fracture of the condyle neck (n = 10), and D) excision of the condyle head (n = 10). Each trauma group was further divided into two subgroups. Procedures were performed unilaterally or bilaterally in the subgroups. In the control group, no procedure was performed. Subjects were examined after a 2-month follow-up period. The development and anatomical structure of the mandible were evaluated, and histopathological assessment of the temporomandibular joint was carried out in each group. The results revealed that hyaline cartilage of the condylar head had an important role in the development of the mandible and traumas targeting this site may cause ankylosis, growth retardation, and resultant facial malformations. Hence, mechanical damage to the articular surface (B1, B2) and resection of the condylar head (D1, D2) almost always resulted in ankylosis. Intra-articular hematoma alone (A1, A2) was established not be a causative factor for ankylosis formation, however.