The Clinical Study Of Cortical Incision Assisted Orthodontic Correction Of Skeletal Class ?

[Objective]The aim of this study was to investigate the effect of corticotomy-facilitated orthodontic on the treatment time and final outcome of skeletal class ? malocclusion,and analyze the effect of corticotomy on root length and alveolar bone thickness in the operative area with CBCT.[Methods]Twenty patients who need to extract two maxillary first premolars because of skeletal class ? malocclusion were included and assigned to the corticotomy group and the control group evenly.In the corticotomy group,maxillary anterior teeth were retracted by miniscrew anchorage,apart from conventional treatment,a corticotomy in anterior maxillary region was peformed.Then treatment time were recorded and compared.All CBCT pretreatment(T1),after closure of maxillary space(T3)and posttreatment(T4)were taken and three-dimensional reconstructed by Dolphin imaging 11.9 software,then the change of soft and hard tissue at T1 and T3 were compared,and the root length of maxillary anterior teeth and alveolar bone thickness of upper incisor region at T1 and T3 were measured and compared.[Results]1.There was no significant difference of the alignment time between two groups,while the time of maxillary space closure and the total treatment course in corticotomy group[(5.79±1.27)months and(24.9±5.13)months,respectively]were shorter than that of control group[(9.94±1.09)months and(30.8±4.6)months,respectively],and the differences were siginificant(P<0.01).2.In the corticotomy group,the retraction amount of the upper central incisal margin,apical tip,superior prosthion,upper lip and the increase of nasolabial angle were higher than those in the control group(P<0.05),the mesial movement distance and angle of maxillary first molar in the corticotomy group were both smaller than those in the control group,and there were statistically significant(P<0.05).3.Compared with the control group,the root resorption in the corticotomy group was significantly reduced(P<0.01),and a significant difference was observed in alveolar bone thickness at S2 level for upper incisor region and S1 level for upper central incisors(P<0.05).[Conclusions]For patients with mild to moderate skeletal class II division 1 malocclusion,corticotomy-facilitated orthodontic can not only shorten the treatment time,but is more conductive to the retraction of upper anterior teeth,profile improvement and anchorage protection,and the alveolar corticotomy can reduce the amount of root resorption,provide the advantage of increased alveolar bone at the surgical site.