Animal Experimental Research On Surgery-First Approach In Accelerating Orthodontic Tooth Movement

Objective: In recent years,with the continuous improvement and development of combination of orthognathic surgery and orthodontics,the Surgery-First Approach(SFA)has been applied to clinical therapy.Compared with SFA,Conventional Orthognathic Surgery(COS)caused worse occlusion and profile at the beginning of the treatment,conversely,with SFA,these disadvantages could be resolved more rapidly.By the careful and collaborative planning between orthodontists and surgeons,the complex treatment procedures became simple.More importantly,SFA needed shorter treatment time,some investigators have found a phenomenon of accelerated tooth movement after surgery,however,much of the reports is based on case observation,experimental animal-based studies are lacking and starve for verify this acceleration effect.The purpose of this prospective experimental study was to identify whether orthognathic surgery increase tooth movement and the reconstruction of periodontal tissue.Methods: In the experiment,45 male Wistar rats had been adopted,all of them were 9 weeks of age,which were randomly divided into three groups: orthognathic surgery which operated on the same side(experimental group1),orthognathic surgery which operated on the opposite side(experimental group2)and only orthodontics(control group).In experimental group1and2,Le Fort I osteotomies were performed on the right and left maxillas,respectively,and the control group had no surgery.A force of 40 g was placed to move the right maxillary first molar mesially.Digital caliper was used to measure the first molar movement distances on days 7,14,and 28.All of the data were processed by SPSS22.0 software package,and the comparisons between groups were tested by One-Way ANOVA analysis and LSD test.Results: On days 7,the mean value of tooth movement in the experimental group1 、experimental group2 and control group were(0.174±0.036)mm、(0.158±0.019)mm and(0.146±0.011)mm,there was no statistical significance between groups(P>0.05).On days 14,the mean value of tooth movement in the experimental group1 and experimental group2 were greater than that in the control group:(0.310±0.029)mm、(0.280±0.026)mm and(0.206±0.020)mm,there was significant difference between experimental groups and control group(P<0.05).While between the experimental group1 and experimental group2,the mean value of tooth movement was no statistical significance(P>0.05).On days 28,the mean value of tooth movement in three groups were significance differences(P<0.05):(0.784±0.039)mm、(0.602±0.028)mm and(0.462±0.044)mm.Hyalinization on Pressure side was not obvious.Bone resorption occurred in the early stage of tooth.Active and extensive bone resoprtion was observed on the pressure side in the experimental group.Conclusion: Surgery-first approach significantly accelerated the rate of orthodontic tooth movement and alveolar bone remodeling.