Preliminary Study On Rat Periodontal Tissue Defect Healing And Mechanism Following Nerve Transection

Background and Purposes:Periodontal disease is one of two major diseases of oral cavity, its incidence is high and difficult to control, and is also the main reason of losing teeth. There are four characteristic of this chronic progressive disease, inflammation of the gums, the formation of periodontal pocket, varies degrees of alveolar bone absorption, teeth loose even falling off. The ultimate goal of periodontal disease treatment is not only to remove the cause and prevent the progression of the disease, the most important thing is how to make the lesion and destruction periodontal tissue regenerate and have function. Although the research of periodontal tissue regeneration is more popular, but has not yet reached satisfactory results.In recent years, scaffolds, seed cells and growth factors for tissue engineering had becoming more popular in the study of periodontal tissue regeneration, while the combination of genetic engineering and tissue engineering was beginning to depth, but the results did not reach our pursuit of periodontal tissue regeneration targets. The growth factors of cells secreting is certainly important in periodontal tissue regeneration process for the surrounding matrix synthesis, but the tissue matrix’ nerving in the maintenance of its function is not to be ignored, the Nerve and regulatory role in periodontal tissue regeneration process had not been seriously. Nervous system has conduction of pain and feelings of pressure in the periodontal tissue, But apart from the basic nerve conduction, its secretion a variety of functional neural significance of the peptide on the maintenance of homeostasis in the periodontal tissue microenvironment can not be ignored. Vitro studies confirmed that nervous system may be mediated the activity of osteoblasts and osteoclasts, thus participated in the regulation of bone metabolism, played a crucial role in the repair of bone remodeling process. Nervous system can involve in the healing of bone trauma repair and remodeling on different levels, Sensory nerve can directly regulate the osteoblast’s biological activity and immune response through the neurotransmitter receptors on the cell membrane of the osteoblast, it can also be indirectly regulate the biological activity of the osteoblasts, thereby affecting the speed and quality of the bone wound healing. At the same time, some neuropeptides can promote Osteogenesis has been confirmed in the vitro studies. Calcitonin gene-related peptide widely distributed in bone tissue as a feeling functions neuropeptide, Hukkanen had first found it in the rat fracture model experiment, CGRP immunohistochemical staining positive fiber in growth of new bone callus[4]. Subsequently, the CGRP’s role and mechanisms became a hot spot in the research of fracture healing rebuilt, at the same time it became a hot research topic in the regulation of the digestive system, cardiovascular system, and the pain conduction mechanism.Studies had shown that CGRP-positive nerve fibers were distributed in the jaw and its periosteum, speculated that involved in the growth and development of jaw growth and post repair remodeling. Immunohistochemical staining revealed that CGRP distribute in the periodontal ligament fibroblasts, and perivascular alveolar bone, which illuminates CGRP has a certain significance in the process of periodontal tissue homeostasis and physiological functions, especially in the alveolar bone remodeling process. The present study indicated that CGRP can promote the healing of fractures of the mandible and can regulate remodeling of alveolar bone in the process of orthodontic. In view of the above experimental and theoretical basis, in order to investigate the role of CGRP in periodontal tissue regeneration process, the experimental design a cut or retained rat alveolar nerve with periodontal defect animal model, based on this model to study CGRP’s role in the regeneration process of the periodontal tissues.Method:1. The expression changes of CGRP in periodontal tissue following inferior alveolar nerve transection in ratsEstablish animal models with cutting off rat inferior alveolar nerve, the left transection nerve was experimental group, the opposite side nerve-sparing for the control group, divided into five groups of3days,7days,14days,21days,28days. Then detected the expression of CGRP and SP in rat periodontal tissue changes using immunohistochemistry method.2. Histological observation on healing of rat periodontal tissue defects after losing of the inferior alveolar nerve.Used the extraoral approach to establish the cut inferior alveolar nerve accompanied periodontal defect model in rats, the left cut the inferior alveolar nerve in rats accompanied periodontal defects as the experimental group, the opposite side nerve-sparing only do periodontal defect for the control group. Divided into five groups of1week,2weeks,4weeks,6weeks and8weeks. Observed the effect of the repair of periodontal tissue regeneration inferior alveolar nerve transection in rats by HE, Immunohistochemistry, Masson staining method.Result:1. The expression changes of CGRP in periodontal tissue following inferior alveolar nerve transection in ratsImmunohistochemical results showed that CGRP and SP in periodontal tissue rendered the trend of the first decreased and then increased to the normal level after losing IAN. Analysis using SPSS17.0statistical software, Displayed that a statistically significant between with3days,7days and14days group and the control group (P<0.05).2. Histological observation on healing of rat periodontal tissue defects after losing of the inferior alveolar nerve.Using the HE, Masson staining, immunohistochemical staining detection method and the SPSS17.0statistical software analysis, The results showed that the degree of mineralization of new bone in the experimental group have a statistically significant difference with the control group (P<0.05) in the process of periodontal tissue regeneration. CGRP expression in the new bone callus had a statistically significant difference between the experimental group and the control group.(P <0.05). OPG/RANKL expression was the same with CGRP change trend in the defect area.Conclusion:1. Neuropeptide CGRP and SP expression changed in periodontal tissues following inferior alveolar nerve transection in rats.2. The mineralization quality of the new bone reduced in healing of rat periodontal tissue defects after losing of the inferior alveolar nerve.