Effect of functional lateral shift of the mandible on hyaluronic acid metabolism related to lubrication of temporomandibular joint in growing rats.

Abstract

Hyaluronic acid (HA) is a major molecular component of the articular cartilage of the temporomandibular joint (TMJ) influencing joint lubrication. Functional lateral shift of the mandible (FLSM) can lead to malocclusion. This study investigated the effects of FLSM on HA metabolism and lubrication of the TMJ in growing rats. Thirty 5-week-old male Wistar rats were divided into shift, recovery, and control groups. Rats in the shift and recovery groups were fitted with guiding plates to produce a 2-mm FLSM which were removed from the rats in the recovery group 14 days later. Animals were sacrificed at 14 and 28 days after the appliances were attached. Immunohistochemistry of HA-binding protein (HABP), hyaluronan synthase (HAS), and hyaluronoglucosaminidases (HYALs) was examined. The thickness of HABP-positively stained areas in the lateral regions in the bilateral condyle was reduced during the experimental period in the shift group compared with that in the control group. The proportion of HAS2-stained areas was bilaterally decreased in different regions of condylar cartilage during the experimental period in the shift group. The reduction of the HYAL2-stained area proportion in the condylar cartilage was more significant than that of HYAL1 at 14 days after appliance attachment in the shift group. HAS2 staining was not recovered in the recovery group. This research was based on animal experiments with a limited experimental period. FLSM altered lubrication related HA metabolism in the articular cartilage of the TMJ in growing rats.