| Results of preliminary studies by our group showed that rats gradually induced occlusal disorders can lead to significant condylar cartilage pathological alterations.Endochondral bone is cartilage important physiological activities of the reconstruction, during which experienced a proliferation of cartilage cells, mature stage of hypertrophy and, ultimately, apoptosis. PTHrP and its receptor PTH1R, and Sox9 is involved in cartilage growth and development of important growth regulatory factors. Thus PTHrP and receptor PTH1R involved in cartilage growth and remodeling. The Sox9 in cartilage play a crucial role in early development, if the aggregation of mesenchymal cells prior to deactivation will result in developmental disorders of cartilage. This study was built by the our research group of gradually induced occlusal disorders in rats condylar cartilage to Sox9, PTHrP receptor PTH1R other substances testing of these macromolecules in the rat condylar reconstruction activities in the pathological expression of change and its significance.Choose 40 8 week old female SD rats weighing 180 ~ 200g, random, equally divided into experimental group and control group, experimental group 3 days after feeding adaptability to start the operation of experimental occlusal disorders. In the experimental group, the third molar of left maxilla and right mandible were moved distally . No treatment control, fed with the same environment, keeping up with the end of the experiment. Respectively, Experimental animals, together with their age-matched controls, were sacrificed at the end of 4th or 8th week after the start of experiment.The results are as follows:1. Control group, the surface smooth and continuous, condylar cartilage can be divided into fibrous layer, proliferative layer, hypertrophic and calcified cartilage layer and layer of cells in each layer arranged in neat, clear boundaries. Experimental group, experimental occlusal disorders can cause significant rat condylar cartilage degeneration (3/20 months condyle prominent changes are typical), and cartilage thickness of the corresponding changes in the experimental group on the rear of condylar cartilage thickness than the control group were significantly (P <0.05).2. Experimental condylar cartilage showed degenerative changes, coagulation necrosis of cartilage cells, cartilage cells significantly reduced and the number of nucleus shrinkage, chromatin condensation, partial region appears homogeneous staining.3. Immunohistochemistry Location: PTHrP was mainly expressed in hypertrophic layer of condylar cartilage , the cytoplasm was stained dark brown, its receptor PTH1R expressed mainly in hypertrophic layer of condylar cartilage, membrane was stained dark brown. Compared with the control group, experimental group cartilage degeneration region PTHrP and PTH1R positive cells were significantly reduced; sox9 mainly distributed in the hypertrophic layer of condylar cartilage, the nucleus was stained brown, experimental group cartilage degeneration region positive cells compared with the control group also decreased significantly.4. RT-PCR: the experimental group PTHrP, PTH1R, Sox9 significantly decreased compared with the control group.The following conclusions:1. Pushing the side of the maxillary, mandibular third molar to the distal occlusal disorders caused by progressive female rats may lead to condylar cartilage pathologic alterations2. The process of cartilage growth and development as an important regulatory factor, PTHrP and its receptor PTH1R and Sox9 are involved in the disorder caused by progressive occlusion of rat condylar cartilage reconstruction activities.
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