| Backgroud and Objectives:Occlusal trauma is that one teeth suffered occlusal force which exceeds the tolerance of its periodontal tissue induces to its periodontal trauma.It is very popular during the patients who come to department of stomatology.Studies prefer to alveolar when they want to analyze bone signaling pathways because its high plasticity. However, it is the first stage that establish an effective occlusal traumatic animal model if one want to know occlusal traumatic mechanism.Bonding square wire with composite resin on the molar occlusal surface is a low-damage and effective method.It was reported that MMP-9-a glycosylated protease-could be secreted by osteoclasts during bone resorption process and used to detect the process of bone resorption.Cell communication plays an important role in the process of bone remodeling.It transmits signals between cells in the bone accurately and efficiently including osteocytes,osteoblasts and osteoclasts.The signals interacted with receptors on effective cells.After that,a series of changes took place.There are three ways to carry on cell communication,such as direct adhesion,direct contact and indirect contact. Gene chip can detect and analyze hybridization signals accurately and sensitively.It is widely used in biomedicine fields,genomics researches,clinical diagnosis,and so on. The rats Roche-Nimble Gen genome-wide expression microarray used in this research is characterized by high-throughput and high-density.It can analyze the expression of26.419genes at the same time.At present,there is a few papers relating to the expression of cell communication in the early stage of occlusal trauma.It is also not clear that how the cell communication regulates bone remolding.In this study,we use composite resin bonding square wires on the occlusal surface of the right upper first molar in order to establish an occlusal traumatic animal model.Soon after, we detected the process of bone resorption in the alveolar by MMP-9.At last,we analyze the expression of cell communication in the rat alveolar after24hours’occlusal trauma by a whole genome microarray.It is hoped that the study can provide some experimental evidences to clarify the molecular mechanisms of bone remodeling and clinically prevent and treat bone diseases.Materials and Methods:1.Establishment of occlusal traumatic animal models in rats and expression of MMP-9in their alveolarsAt first,we bonded square wire on the rat right upper first molar with composite resin,raising1mm to bite,in order to form occlusal trauma on the rat right lower first molar. After feeding the prescribed time,we cut off the right mandibular molar alveolar bone,and then make decalcified bone tissue sections.We detect the expression of the MMP-9in the rat mandibular molar alveolar bone surrounded the root of first mandibular molar,when the rats subjected to occlusal trauma for1day,3days,7days and14days,respectively.2.Studies on changes of expression about cell communication in the rats alveolar during the early stage of occlusal traumaWhen the rats were subject to occlusal trauma for24hours,we cut off the right mandibular alveolar which was equal to the mesial-distal distance of the first mandibular molar.And then,total RNA in the alveolar was extracted using Trizol method.RNA has to be reverse transcribed to cDNA and labeled by probes at the same time.Following,the cDNA hybrid with gene chip.The results of hybridization was analyzed by Pathway and GO analysis method.In order to demonstrate the results were credible,we choose three factors whose changes were significant to do RT-PCR.Results:1.Establishment of occlusal traumatic animal models in rats and expression of MMP-9in their alveolarsMorphological observations show that there were apparent morphological changes in the rats which were subject to occlusal trauma for14days. The width of the periodontal ligament surrounding the apical of the first mandibular molar was apparently increased in the X ray graph. There were osteoclasts and bone lacuna in the slices with HE stain.Immunohistochemical staining results showed that positive staining cells of MMP-9were increased in the alveolar of rats which subjected to occlusal trauma for24hours compared with in control group.The difference was statistically significant(P<0.05).The number of positive staining cells of MMP-9was increased following the time of rats subjected to occlusal trauma.2.Studies on changes of expression about cell communication in the rats alveolar during the early stage of occlusal traumaThe gene chip hybridization results showed that there were586genes in the occlusal traumatic group which were significantly difference compared with the control group.The different genes were related to106different bone signaling pathways.In the106bone signaling pathways,some pathways were cell communication,such as Intercellular adhesion molecule,adhesion junction,gap junction,focal junction,tight junction,and so on.The main factors of these cell communication pathways were significantly down regulated.Therefore,cell communication was wide spread rejection.Conclusions:1.The method of established occlusal traumatic animal models in rats which bonded square wire on the rat right upper first molar with composite resin was effectively,raising1mm to bite.It can induce to bone resorption as occlusal trauma formed on the rat right lower first molar when bite raise1mm.It is feasible that study the mechanism of early stage of bone remodeling after24hours occlusal trauma in the rats.2.After occlusal trauma for24hours, the signaling pathways related to cell communication were wide spread rejected such as Intercellular adhesion molecule,adhesion junction,gap junction,focal junction,tight junction,and so on. |
