In growing patients with a retrusive mandible, growth modification is the main goal of orthodontic treatment. Orthopaedic forces to the TMJ used in functional appliances might influence the interaction between the mandibular condyle and the glenoid fossa. Histological and biochemical research in this field mainly aims to provide basic information about the nature of the skeletal growth modification in response to functional appliance therapy. The aim of this study was to develop a simple, convenient, and functional animal model to reproduce the orthodontic effects of functional appliances. The appliance was mounted onto upper jaw of 5 week-old Sprague-Dawley rats and 3, 7, 14, 21, and 28 days onward, animals were sacrificed for the analysis. Metric analysis was carried out by measurements from micro-CT taken from sacrificed animals. Condyle width was increased initially after mounting of functional appliance but was not changed afterwards. Condyle was observed to position more to the anterior than control 3 days after functional appliance application, but relocated to the similar position as control with time. Mandibular length was increased by 7 days after functional appliance application than control, but the difference was gradually diminished with time. Mandibular height was steadily increased after functional appliance application than control. Based on these results, comparison between effects of animal model and clinical cases were carried out and showed that prognosis of experimental functional appliances were similar to that of previous clinical studies. These results suggested that this experimental animal model could provide a reliable and testable way to elucidate the important histological and biochemical changes induced by clinical functional appliance.
Disclosure: The authors declared no competing interests.