Induction of traumatic temporomandibular joint ankylosis in growing rats: a preliminary experimental study.

There are many reports on the management of pediatric temporomandibular joint (TMJ) ankylosis. However, few authors have investigated the etiology of this disease in children. The purpose of this study was to determine the role of damage to both the condylar cartilage and disk in the induction of traumatic TMJ ankylosis during the growth period. The study was performed in growing rats by a common condyle fracture model. Intentional damage was performed to both the disk and condylar cartilage in the experimental group (n = 12), while the disk and condylar cartilage in the control group was left untouched (n = 12). Sham-operated growing rats were deemed the blank group (n = 10). Two rats from the experimental group and two from the control group were killed 24 h after the operation, and the result following surgical intervention was observed. Each rat's body weight in the three groups was monitored and recorded at 1, 2, 4, 6, 8, 10, and 12 weeks after surgery. Twelve weeks after the operation, all animals were killed. The prognosis was compared by mandible deviation measure, body weight evaluation, and histological observation. Animals from the experimental group presented a slow body weight increase and obvious mandible deviation while all involved TMJs showed fibrous ankylosis in various degrees. The damage to both the condylar cartilage and disk in the condylar fracture might play a vital role in traumatic TMJ ankylosis development during the growth period. The results of this study suggest that more attention should be paid to condylar fractures in children that are accompanied with severe cartilage and disk damage, which is a matter of significance for pediatric TMJ ankylosis prevention.