无托槽隐形矫治拔牙病例尖牙牙冠远移效率及支抗牙三维位移分析

Accuracy of canine crown distalization and 3D-displacement of anchorage teeth in extraction cases with clear aligners:a clinical study

目的研究无托槽隐形矫治在拔牙病例中远移尖牙的移动效率和未设计位移支抗牙的实际三维位移。方法收集无托槽隐形矫治第一前磨牙拔除的成人安氏Ⅰ类、分步法内收前牙患者17例,纳入研究牙齿共计170颗。通过三维扫描将患者治疗前模型和阶段研究模型数字化,利用数字化模型三维重叠技术收集中切牙、尖牙、前磨牙和磨牙的实际位移数据,计算尖牙的远中移动效率及未设计位移支抗牙的实际位移。结果尖牙平均远移效率为87.78%±9.3%。后牙备抗组尖牙平均远移效率为89.27%±10.2%,后牙非备抗组尖牙平均远移效率为86.27%±6.6%,结果无统计学差异(P=0.438),尖牙设计远中移动1~2 mm的移动效率为88.21%±15%,2~3 mm的移动效率为87.10%±4.4%,结果无统计学差异(P=0.762)。尖牙在矢状向设计位移量为-1.61±0.87mm,实际位移量为-1.47±0.77mm,差异意义有统计学(P<0.05),垂直向设计位移量为-0.07±0.35 mm,实际移动量为0.26±0.48 mm,差异意义有统计学(P<0.05)。后牙备抗组第二磨牙垂直向平均位移量-0.10±0.24 mm,后牙非备抗组第一磨牙垂直向平均位移量0.15±0.33 mm,,差异意义有统计学(P=0.037)。后牙备抗组第二磨牙垂直向位移量-0.08±0.30 mm,后牙非备抗组第二磨牙垂直向位移量0.18±0.32 mm,差异意义有统计学(P=0.023);在后牙备抗组和非备抗组中,磨牙的矢状向和颊舌向位移无统计学差异。结论后牙备抗对尖牙远移效率无显著影响,尖牙远中移动效率较高,但易发生伸长移动;未设计位移的支抗牙在尖牙远移阶段发生了三维位移变化。

Objective To study the accuracy of canine distalization in extraction patients with clear aligner and the actual three-dimensional displacement of anchorage teeth without planned movemnent.Methods Seven patients with Class Ⅰ malocclusion who underwent extraction of maxillary first premolar,were treated by frog pattern retraction with clear aligner.One hundred and seventy teeth were included in the study.Pre treatment and staged-treatment plaster models were digitized by laser-scanned,and the actual displacement of central incisors,canines,premolar and molars were obtained by digital model superimposition.The accuracy of canine distalization and the actual displacement of the non-predicted movements of anchorage teeth were calculated.Results The mean accuracy of canine distalization was(87.78±9.3)%.There was no statistically significant difference in the accuracy of canine distalization between the unpredicted posterior teeth anchorage group(UTA)(86.27±6.6)%,and in the predicted posterior teeth anchorage group(PTA)(89.27±10.2)%(P=0.438).The movement accuracy was(88.21±15)%when canine distalized by 1~2 mm,and(87.10±4.4)%when canine distalized by 2~3 mm,with no statistically significant(P=0.762).The predicted displacement in sagittal plan was(-1.61±0.87)mm,while the actual displacement was(-1.47±0.77)mm,showing significant statistical difference(P<<0.05).The predicted vertical displacement was(-0.07±0.35)mm,while the actual displacement was(0.26±0.48)mm,showing a statistically significance(P<0.05).The average vertical displacement of the first molars was(-0.10±0.24)mm in PTA and(0.15±0.33)mm in UTA,showing a statistically significant(P=0.037).The vertical displacement of the second molars was(-0.08±0.30)mm in PTA and(0.18±0.32)mm in UTA(P=0.023),showing a statistically significant.There was no statistically significant between PTA and UTA in the sagittal and transverse displacement of molars.Conclusions The posterior teeth anchorage has no significant effect on the accuracy of canine distalization.The movement efficiency of canine distalization is high,which was also accompanied by extrusion movement.The nonpredicted displacement anchorage teeth have 3D-displacement changes.