| Background and Purposes:Periodontal disease is a chronic inflammatory and destructive disease which initiating by dental plaque and the main clinical manifestations are the gingival inflammation, the loss of periodontal attachment, different levels of alveolar bone absorption, the loosening of tooth, and eventually lead to the tooth lose. At present, Periodontal disease is one of the two common oral diseases, it’s has the higher incidence and widely population, can endanger oral health and even the whole body. Now, the clinical treatment of periodontal disease is mainly through periodontal non-surgical treatment, drug therapy, surgical treatment and supportive periodontal treatment to delay and control the continued development of periodontal disease, make periodontal destruction to maintain current levels or obtain a small amount of regeneration. In recent years how to make the destructed periodontal tissue regeneration and continue to exercise its physiological function is a hot research in periodontal field, but still has not gotten satisfactory results.So far, seed cells, biomaterial scaffold, and various of growth factors for tissue engineering is becoming more popular in the domestic and foreign study of periodontal tissue regeneration, while the results do not reach our pursuit of periodontal tissue regeneration targets. The most main reason may be due to the study of tissue engineering techniques only consider the more important factors associated with tissue repair and regeneration, cannot reach the accuracy and systemic of the body’s own repair regulation, particularly the importance of the body innervations. Science magazine reported in 2007[1], in the lizard limb regeneration experiment, if the lizard was amputated the limb and extracted the corresponding innervations, the limb cannot regeneration; artificial add a kind of protein which are from newt anterior gradient protein in nerve cells, the lizard can get the limb regeneration without innervate. This study confirmed that the nerve and the related factors may have the decisive role to the tissue regeneration, so the importance role of the nerve system to regulate the tissue regeneration cannot be ignored.The main pathological change characteristics of periodontal disease is alveolar bone absorption, in the destruction of periodontal tissue the structure and function of nervous vascular system exist different degree damage. Neurovascular system as a widespread conditioning system, through a variety ways of systemic and local to adjust bone growth and maturity[2]. In the process of alveolar bone to obtain the regenerative repair, the mercy of the angiogenesis and regeneration of nerve may play an important role. Alveolar bone is the most active bone in the whole body, the role of in the process of alveolar bone reconstruction the role of neurovascular system should not be ignored. Most of the existing researches focus on how to get more tissue regeneration, while the study of the function of innervations and the regeneration of vascular system in bone regeneration are relatively less. At the same time the regenerated periodontal tissue compared with the natural physiological periodontal tissue, there are big disparities in terms of morphological structure, bone density and stress of alveolar bone. Obviously this "simple reduction replication" compared with the organization "naturally formed", the "simple reduction replication" ignores the complexity and accuracy of body’s biological phenomena. Therefore, it is necessary to explore the tendency and the function of the nerve and its related factors in periodontal tissue regeneration.Based on the above research background, the present study was designed to cut off the inferior alveolar nerve in rats then to observe the nerve regeneration, and retain or cut off rat’s inferior alveolar nerve with periodontal defect then to observe the periodontal tissue repair and regeneration and the nerve regeneration in the repaired tissue, in hopes to provide theoretical instruction for the periodontal regeneration research.Method:1、The expression changes of ruffini ending in periodontal tissue following inferior alveolar nerve transection in rats.Establishment animal models with cutting off rat inferior alveolar nerve, rats were divided into blank control group and experimental group, the blank control group were received no treatment, the experimental group of rats were cut off the left inferior alveolar nerve. At postoperative 3,7,14,21,28 days the left mandible specimens were removed, then the specimens were embedded in paraffin and stained with protein gene product 9.5(PGP9.5), and then observed the change of nerve endings in the periodontal membrane after inferior alveolar nerve resection in rats.2、Observation on healing of rat periodontal tissue defects after losing of the inferior alveolar nerve.The left periodontal defects model was established, the inferior alveolar nerve transaction accompanied with the same side periodontal defects as the experimental group, the nerve-sparing only do periodontal defect in rat as the control group, and then the alveolar was obtained from animals of each group at 1,2,4,6 and 8 weeks after operation, respectively, H&E staining, scanning electron microscopy(SEM) observation were performed to observe the effect of nerve to restore and repair periodontal tissues.3、Observation on the regeneration of nerve fibers in the process of the periodontal defect repairmen.Unilateral periodontal defects model was established, and then the alveolar was obtained from animals of each group at 1,2,4,6 and 8 weeks after operation, respectively, then the specimens were embedded in paraffin. Protein gene product 9.5 and calcitonin generelated peptide (CGRP) immunohistochemical staining were performed to observe the status of nerve regeneration in the periodontal tissue.Result:1、The expression changes of ruffini ending in periodontal tissue following inferior alveolar nerve transection in rats.The control and the experimental group tissue specimens were taken to stain immunohistochemistry, the results showed that the number of nerve fibers in the periodontal ligament begin to reduce at 3th day; it was the lowest level at 7th day. Then the level begun to rise at 14th and 21th day, at 28th day the number of nerve fibers returned to normal level.2、Observation on healing of rat periodontal tissue defects after losing of the inferior alveolar nerve.H&E staining and scanning electron microscopy (SEM) observation results showed that the bone regeneration in defects of the control group is better than that of the experimental group, and the data had statistically significant.3、Observation on the regeneration of nerve fibers in the process of the periodontal defect repairmen.The results of immunohistochemical staining showed that the nerve tissue regeneration companied with the periodontal tissue regeneration in periodontal tissue defects area. PGP9.5 and CGRP had a higher level expression at the time of early tissue repairmen and bone maturity, and the results had statistically significant.Conclusion:1、After cut off the inferior alveolar nerve, peripheral nerve fibers in the periodontal membrane can regenerate, and the number of peripheral nerve fibers can reach to normal levels.2、After the inferior alveolar nerve resection, the new bone formation in periodontal tissue defect heals slowly.3、In periodontal tissue defects area nerve tissue regeneration companied with the periodontal tissue regeneration, and the neural factors have great significance to the early tissue regeneration and the bone’s maturity. |
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