Abstract:

Objective  To study the effects of experimentally created unilateral anterior crossbite prosthesis on the expression of parathyroid hormone-related peptide(PTHrP) and parathyroid hormone receptor-1(PTH1R) in mandibular condylar cartilage of SD rat. Methods In experimental groups, the unilateral anterior crossbite metal prosthesis was cemented to the left incisors of the maxilla and mandible of 6-week-old SD rats, respectively. Animals were sacrificed at 2, 4, 8 weeks. Hematoxylin-eosin(HE) staining were carried out for studying the morphological changes of the condylar cartilage. Immunohistochemical staining and real-time polymerase chain reaction(PCR) analysis were performed to detect the levels of expression of PTHrP and PTH1R in the condylar cartilages. Results  The obvious degenerative changes were found in the condylar cartilages in experimental group at 8 weeks. Comparing to the control group, the expression of PTHrP mRNA(P<0.01) and protein (P<0.01) in the experimental group were increased， whereas PTH1R mRNA(P<0.01) and protein(P<0.01) levels were decreased. Conclusion  The expression of PTHrP was increased in the condylar cartilage of rat with unilateral anterior crossbite metal prosthesis but its effects might be limited because of decreased expression of PTH1R in the condylar cartilage. The low level expression of PTH1R should be a part of the constitution of the molecular pathomechanism of temporomandibular joint osteoarthritis(TMJOA)-like lesion.

Key words: occlusion, temporomandibular joint, osteoarthritis, cartilage, parathyroid hormone -related peptide, parathyroid hormone receptor-1