Objective: To observe the healing of sagittal fracture of the mandibular condyle (SFMC) and its effect on the temporomandibular joint in immature miniature pigs.
Methods: Twenty-seven immature miniature pigs were randomly chosen and divided into three groups. Twelve immature miniature pigs underwent sagittal fracture of the mandible condyle; 12 underwent transverse fracture, and 3 were maintained as a normal control. Three-phase scintigraphy, computed tomography (CT) imaging, and histological tests were conducted at 3 weeks, 6 weeks, 12 weeks, and 24 weeks.
Results: The data showed the value of the time-activity curve of blood-flow image increased and blood-flow arriving time was postponed after condylar fracture. The alpha/beta ratio was the highest at 2 weeks after SFMC. The count of blood-pool image and static image were higher than nonfractured sides. Peaks were seen at 2 weeks postfracture. Disc and condyle adhesion was found in all sagittal fractures of the mandibular condyle and bifid mandibular condyle was formed. Adhesive tissues between condyle and disc were fibro-connective tissues, which connected the disc directly to cartilage or bone tissue. A large number of fibroblasts and sparse chondrocytes were seen in the adhesive tissue. Blood vessels and adipose cells were seen in the disc, whereas there were no distinguishable changes in transverse fracture.
Conclusion: Bifid mandibular condyle was found in most SFMC in childhood. The mechanism of bifid condyle deformity is related to secondary injuries to the disc, adhesions between the condyle and disc, and displacement of the medial split fragment. The age when SFMC occurs is an important factor in bifid condyle formation.