The Study Of Bone Turnover Markers During Tooth Movement Assisted By Corticotomy

Object: To analyze the effects of the corticotomy on tooth movement andprovide experimental evidence for clinical application by observing the rate changesof tooth movement after establishing rapid tooth movement model of rats assisted bycorticotomy, and evaluating the bone turnover markers alkaline phosphatase(ALP)and osteocalcin (OC)expression during experimental tooth movement．Methods:52eight-week male SD rats, were usd in this study,and the52SDrats were randomly divided into5groups:G1group(10rats served ascorticotomy-assisted tooth movement),G2group(10rats served as standard toothmovement),G3group(14rats served as corticotomy-assisted tooth movement),G4group(14rats served as standard tooth movement),G5group(another4rats served asbaseline control group).G1and G3groups were operated the corticotomies, a weeklater,the either side of the upper molars of the rats in G1，G2，G3，G4groups wereligated with the NiTi closed-coil spring to the upper incisors which were used asanchorage teeth, the NiTi closed-coil spring was activated with30g force to move thethe upper first molar mesially. The distance in G1and G2groups were measured fromthe mesial of the experimental side molars to the distal of the incisors at different time(t=0,1,3,5,7,14,21,28days) after first loading, the difference in the distance of theadjacent timing was recorded as molar movement. The rats in G3and G4weresacrificed at times (t=1,3,5,7,14,21,28days),and were divided into7subgroupsrandomly.After the rats killed,HE staining was carried out to observe the periodontaltissues,special staining was carried out to examine the ALP and immunohistochemicalstaining was carried out to examine the OC.Results:1.There was statistical difference of the distance of experiment upper first molarmesial movement between the G1and G2groups from t＝3day（P<0.05）.2. The expression of the ALP in G3group increased to a higher level comparedwirh G4group at day3,7,14,28points(P<0.05),and at day5,the statistical difference was significant（P<0.01）. The peak of ALP expression in G3group ocurred at day5,then kept at a high level though it decreased as the time went by, while in G4group,it ocurred at day14.The expression of the ALP at day28in G3group still stayat the high level than pre-operation,but in G4group,it recovered basically to the levelof pre-operation (P<0.05).3. The expression of the OC in G3group increased to a higher level whencompared to G4group, it was significantly higher at day5(P<0.01).In G3group,theexpression of the OC increased in early period,peaked at day7,and still stayed at thehigh level than pre-operation though weaking gradually from the peak, while in G4group,the peak ocurred at day14and it basically recovered to the level ofpre-operation at day28(P<0.01).Conclusion:1.Corticotomy can increase the rate of experimental tooth movement.2.Corticotomy can change the periodontal bone metabolism of the rats in theearly stage,increase bone formation,and lead to regional acceleratory phenomenon(RAP) which will last for at least4weeks after the operation.