Gosia Barley,* Gang Shen,† Mohammed Almuzian,*+ Alan Jones,‡ Rema Oliver,≠ Peter Petocz,§ William R. Walsh⊥ and M. Ali Darendeliler*Department of Orthodontics, Faculty of Dentistry, University of Sydney, Sydney, Australia,* College of Stomatology, Shanghai Jiao Tong University, Shanghai, China,† Department of Orthodontics, University of Edinburgh, Edinburgh, UK+ Electronic Microscopic Unit, University of Sydney, Sydney, Australia,‡ Surgical Orthopaedic Laboratories, University of NSW, Sydney, Australia,≠ Department of Statistics, Macquarie University, Sydney, Australia§ and Surgical and Orthopaedic Research Laboratories, University of New South Wales, Prince of Wales Hospital, Sydney, Australia⊥
Objectives: The purpose of this study was to qualitatively and quantitatively analyse the effect of glucosamine sulfate and chondroitin sulfate supplements on condylar remodelling in conjunction with bite-jumping functional appliance therapy in rats. Materials and methods: The study involved 140 three-week-old, female rats which were divided into a control group (CG), a supplementation group (SG), a functional appliance (bite-jumping) group (FG) and a bite-jumping appliance and supplement recipient group (FSG). The animals were sacrificed at Day 0, Day 7 and at Day 21 after appliance placement, as well as seven days following appliance removal. The condylar head from each animal was blindly scanned using micro-computed tomography (µCT). Qualitative evaluation and volumetric measurements of the condyles, including total condylar volume (TCoV), posterior condylar volume (PCoV), total cartilage volume (TCaV) and posterior cartilage volume (PCaV), were undertaken using VGStudioMax software.
Results: One hundred and thirty-five rats were analysed, some of which responded to the intervention with a protruded bite (Class III response) while others responded with a retruded bite (Class II response). The TCoV and PCoV of the CG decreased during the experimental period. The functional appliance alone and the combination of the functional appliance with the supplement had a significant effect on TCoV and PCoV over the intervention period (p < 0.01), peaking at Day 7. There was no statistically significant difference in TCaV between animals that experienced Class II and Class III bite responses at Days 21 and 28 (p > 0.05). However, at Day 21, the PCaV increased significantly in those animals which displayed a Class II bite response (p < 0.05). The shape of the condyles in FG and FSG varied significantly from that of the condyles in CG and SG.
Conclusion: Supplement therapy was found to enhance the normal biological response to functional appliance therapy in a rat model, particularly after the functional appliance was removed. Further research using an immuno-histochemical analysis of a modified bite-jumping appliance and improved food delivery is recommended.