| Objective: To study the changes of pathology and Insulin-like growthfactor (IGF-1) in periodontal tissue in occlusal trauma and periodontal localstimulus and the recovery process of them by establishing experimentaltraumatic occlusion associated with periodontitis in rats. To further explore theinfluence of occlusal trauma to periodontitis, as well as the clinical treatments.Methods:95male Wistar rats,3months old, weighing250-280g, wereincluded in this study. They were assigned randomly to one control group andthree experimental groups (A, B and C groups). The control group has5rats.One of the experimental group has6groups and each small group has5rats.The6small groups respectively observed3d,1w,2w,4w and6w, and2weeksafter traumatic occlusion removal for four weeks.After anesthesia and disinfection, the occlusal surface of the leftmaxillary first molar of Group A were raised0.5-0.8mm by sticking stainlesssteel wire of0.6mm diameter and1mm length. The cervical of the leftmandibular first molar of Group B were ligated with wire ligature of0.2mmdiameter, and make the wire in the gingival sulcus. The occlusal surface of theleft maxillary first molar of Group C were sticked stainless steel wire of0.6mm diameter and1mm length, and the cervical of the left mandibular firstmolar were ligated with wire ligature of0.2mm diameter at the same time.Make the wire in the gingival sulcus. Control group received no treatment.When each group arrived the observation time point, the rats wereanesthetized and the stainless steel wire, wire ligature and composite resinwere removed. After cardiac perfusion, the left maxillary and mandibularmolar area were separated and then fixed, decalcified, embedded, and sliced ina midsagittal direction, the slice thickness5μm. Strained with HE to observepathological changes of periodontal tissue. The other sections were strained with immunohistochemistry methods to IGF-1．Used Image Pro-Plus softwareand analysized the percentage of positive cells of IGF-1and the degree ofstraining. Used SPSS13.0statistical software for data analysis.Results:1Hematoxylin and Eosin StainingControl group: The periodontal ligament fibers arrange in neat rows, thesurfaces of cementum and alveolar bone are smooth, and the epithelialattachment to the cemento-enamel junction.Group A (occlusal trauma group): The injury including the slightlydisorder of periodontal ligament, vascular dilation and bleeding is firstobserved in1-week group animals. Bone resorption is visible in2-week group.The heavy trauma is observed in4-week group where the obvious resorptionof alveolar bone can be found. In6-week group and trauma removal group, theformation of bone and cementum is manifested. There is little difference intrauma removal group compared with the control group where valculardilation can be found.Group B (periodontitis): In1-week group, the inflammatory response ofgingiva begins to appear and increase gradually. The attachment loss ofjunction epithelium and the destruction of alveolar bone start to appear in4-week group. More osteoclasts are visible in the surface of alveolar bone.Inflammatory cells and osteoclasts are significantly reduced in ligationremoval group.Group C (periodontitis associated with occlusal trauma group): vasculardilatation can be found in several sections of3-day group. In1-week group,mild inflammation of gingiva, disorder of periodontal ligament and two orthree osteoclasts can be observed. The damage aggravate along with the timeprolonged. Many of osteoclasts in the surface of alveolar bone are found in the6-week group. In trauma and ligation removal group, inflammatory cells andosteoclasts reduce significantly, and the formation of bone and cementum canbe found in some sections. 2The experiment change of IGF-1Control group: The expressions of IGF-1are immunonegative in gingiva,and week immunopostive in periodontal ligament and alveolar bone.Group A (occlusal trauma group): The quantity and density of IGF-1inperiodontal tissue increase gradually. Durning the4-week group, most of theperiodontal ligament cells show changes. After the period, the changes beginto decrease, and give priority to osteoblasts expression. In trauma removalgroup, the main positive expressions lie in osteoblasts and cementoblasts.Group B (periodontitis): The expressions of IGF-1are weekimmunopostive in periodontal ligament in3-day and1-week groups. Whilethe expression of IGF-1are strong immunopostive in4-week group and6-week group. In ligation removal group, the immunoreactivities of IGF-1aredecreased.Group C (periodontitis associated with occlusal trauma group): Theexpression of IGF-1is no significant change in3-day group compared withthe control group. The expressions increase gradually in1-week group and2-week group. And the expression are strong immunopostive in4-week and6-week groups. In trauma and ligation removal group, the immunoreactivitiesof IGF-1are decreased.The results of the Kruskal-Wallis H test showed that there was asignificant defference among the control group and six groups of group A（3d,1w,2w,4w,6w, and removal）.Control group and group B, control groupand group C are also the same. Comparison between group B and group C, theresults of Wilcoxon test indicated that there were differences statistically inexpression level among1-week,2-week, and4-week groups. There were nosignificant differences among the other groups.Conclusion:1Traumatic occlusion can cause changes in rat periodontal tissue, whichreach the peak at4week, and then become weakening gradually.2Traumatic occlusion can accelerate the occurrence of periodontitis andaggravate the development of periodontitis 3Removol of occlusal trauma and local stimulus can be benefit to thehealing of periodontal tissue.4IGF-1may play a role in the rebuilding of periodontal tissue duringand after traumatic occlusion in rats．... |
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