| Background and Object:Through the application of orthodontic tooth,orthodontic force and certain stress transfer to the periodontal tissue,so the alveolar bone undergoes constant bone remodeling that the pressure side of alveolar bone tissue in the mechanical pressure and bloodstream changes caused by hypoxia stimulation occurred bone resorption,then the tooth movement and finally to be corrected.The third national oral health in 2005 had showed that 70%～90%of adult population had different degrees of periodontitis.With the increasing awareness of oral health care,orthodontic-periodontal treatment has become a routine way for malocclusion patients with periodontitis.However,the tooth movement with periodontitis is more likely to the loss of periodontal tissue.For the patients who need orthodontic treatment after periodontal sequence,it is a question whether the orthodontic force is beneficial to the alveolar bone modeling or not?Also,at present,the lack of assessment indexes built in periodontal tissue during orthodontic tooth movement in patients with periodontitis in the clinic,which greatly constrained orthodontists.The coordination of osteoclast mediated bone resorption and osteoblast mediated bone formation determines the balance of bone metabolism.Especially the formation and the activity of osteoclast play a vital role in the process and the final result of bone modeling.The RNAKL/RANK/OPG system is an important signal transduction pathway for the regulation of osteoclast differentiation and bone resorption activity in recent years.The receptor activator of nuclear factor-κB ligand(RNAKL)and the osteoclasts(OC)surface receptor activator of nuclear factor-κB(RNAK),promote the formation of OC and activate the maturion of OC,which leads to bone resorption.Osteoprotegerin(OPG)is a decoy receptor RANK,through competitive binding with RANKL protection from excessive bone absorption,therefore,the relative concentration of RANKL and OPG in the bone is a major determinant of bone mass and strength factor.Orthodontic tooth movement is a periodic process of the absorbing and modeling of periodontal ligament and bone tissue,and a process of non infectious and minimally invasive inflammatory reactions.At present,it is believed that the immune response determines the final direction of the development of inflammation.Recently,some researchers had discovered a specific IL-17 secreted by Th 17 cells,with strong mediated inflammation and bone destruction are widely involved in the occurrence and development of a variety of inflammatory diseases including periodontitis.However,there are few reports about the expression and function of tooth movement with periodontitis.Based on the important role in bone metabolism of IL-17 on the orthodontic tooth movement,we use the model of orthodontic teeth movement in rats,rats with experimental periodontitis and periodontitis after removal of orthodontic stimulation,to evaluate the expression of alveolar bone in the pressure side of IL-17 in different periodontal and orthodontic force,and to evaluate the molecular mechanism of IL-17 in bone modeling under orthodontic force inflammatory on the pressure side of alveolar bone.The purpose is to understand the orthodontic force and the reaction pressure side of alveolar bone of adult patients with periodontitis after periodontal treatment,and to explore the characteristics of the tooth movement during the orthodontic treatment of adult periodontitis patients and provide theoretical basis for the prediction and prognosis after orthodontic-periodontal.Methods:64 8-week-old male Wistar rats were randomly divided into 4 groups:blank control group(A group)and experimental group(B group),inflammation group(C group)and inflammatory loading group(D group).In group B,the right maxillary first molar was moved to the right side by nickel titanium with 50g force.The periodontitis model was established by gingival dissection + silk ligature + high glucose feeding.After C group was set up,the above factors were removed and cleaned.In group D,the right maxillary first molar was moved to the right side by nickel titanium with 50g force.They were executed at 0,3,7,and 14 days,respectively.16 of them was used for histological observation,24 of them for the expression of IL-17 mRNA and RANKL and OPG mRNA in D group was detected by qRT-PCR method,24 were used to detect the expression of the IL-17 protein and RANK and OPG protein in D group..Results:1.In normal rats,the gums were pink,shiny,a blade edge,tough texture,depth of about 1mm,and no bleeding.After the ligation of 4W,there are large amounts of food residue and soft dirt adhered to the silk thread surrounding the gums.After removal the ligation,the gingival of maxillary first molar shows edema,dark red,soft texture,probing depth is about 3mm,and bleeding on probing,which lead to a clinical diagnosis of periodontitis.After 3 days,the gap between the maxillary first molar and the second molar was presented,and the maxillary first molar move mesially.After 14 days,the distances move to the maximum.The above symptoms shows that the successful establishment of rat model of orthodontic tooth movement,model of periodontitis and periodontitis rat model of orthodontic force.2.HE staining shows:the periodontal membrane fiber arrangement rules,alveolar bone surface is smooth,in group A.After 3,7 days in group B,the pressure area of the periodontal space narrowing,periodontal fibers were disordered and the tension zone of periodontal space became wider.After 14 days,the number of osteoclasts reduced in the pressure zone and the tension side increased new bone deposition.The junctional-epithelium proliferate to the root side ditch in 0 day in group C and there were infiltration of lymphocytes and neutrophils and the alveolar crest height was reducing.With the 3,7,14 days,the inflammation was subsiding.The group D and group B are basically the same,but the number of osteoclasts increased obviously.3.The results of qRT-CR and Western Blot:Compared with A group,the expression of IL-17mRNA in alveolar bone of C group was higher,and decreased with the prolongation of time,and reached a normal level at fourteenth days.In normal and inflammatory state,the expression of IL-17 induced by orthodontic force in alveolar bone on the pressure side with afterburner prolonged changes increased first and then decreased,seventh days reached peak,but in the inflammatory state of higher expression.The expression of IL-17 protein in each experimental group was similar to that of IL-17 mRNA.The trend of RANKL mRNA and RANKL/OPG ratio of alveolar bone in the pressure side of the D group was consistent with the trend of IL-17mRNA expression with the extension of time.The changes of RANKL and OPG protein expression were consistent with the expression of RANKL and OPG mRNA.Discussion:1.IL-17 was present in the alveolar bone under normal and inflammatory conditions,and was involved in alveolar bone remodeling during orthodontic tooth movement.2.Upon the condition of inflammation,the orthodontic force can induce the increase of IL-17 mRNA release,and the synergistic effect of inflammatory chemical signal and mechanical force can cause the inflammatory effect to overlap,which affect the alveolar bone remodeling.3.IL-17 may be involved in the process of alveolar bone remodeling by the RANKL/RANK/OPG signaling pathway. |
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