微种植体辅助无托槽隐形矫治器压低上颌前牙的三维有限元分析

Three-dimensional finite element analysis of maxillary anterior teeth intrusionby clear aligner assisted with micro-implant

目的 利用三维有限元分析法探究无托槽隐形矫治器治疗拔牙病例时,不同部位植入微种植体辅助上颌前牙压低的牙齿移动特点,以指导临床实践。方法 构建无托槽隐形矫治器治疗拔除上颌第一前磨牙的三维有限元模型,根据微种植体植入部位分为4组,包括工况1(无微种植体对照组),工况2(上颌中切牙间植入微种植体),工况3(上颌两侧中切牙与侧切牙间植入微种植体)和工况4(上颌两侧侧切牙与尖牙间植入微种植体)。施加自微种植体至矫治器舌侧边缘切割口的牵引力,分析不同工况下的牙齿移动特点。结果 工况1中,中切牙与侧切牙表现为牙冠向舌侧、牙根向唇侧的倾斜移动,第二前磨牙至第二磨牙表现为牙冠向近中少量移动,牙根向远中微量移动。工况2至工况4中,前牙区均表现为压低的同时伴有唇倾移动,后牙区均表现为牙冠近中倾斜的同时伴有少量压低移动。中切牙压低量为工况2>工况3>工况4,侧切牙压低量为工况3>工况4>工况2,尖牙及后牙区压低量为工况4>工况3>工况2。结论 当前牙区植入微种植体进行弹性牵引时,可有效增加前牙压低量。植入部位后移,尖牙压低量显著增加,后牙牙根远中移动量增加,对前牙唇倾作用减小。

Objective To investigate tooth movement characteristics of maxillary anterior teeth intrusion by three-dimensional finite element analysis with micro-implants implanted in different parts during the treatment of tooth extraction with clear aligners,so as to guide clinical practice.Methods A three-dimensional finite element model was established for the treatment of maxillary first premolar extraction with the clear aligner,and divided into four groups according to the implantation site of the micro-implant including working condition 1(control group without micro-implant),working condition 2(micro-implants implanted between maxillary central incisors),working condition 3(micro-implants implanted between maxillary central incisors and lateral incisors)and working condition 4(micro-implants implanted between maxillary lateral incisors and fangs).The traction force from the micro-implant to the cutting edge of the tongue side of the appliance was applied to analyze the tooth movement characteristics under different working conditions.Results In the first condition,the central incisor and lateral incisor showed oblique movement of the crown to the lingual side and the root to the lip side,while the second premolars to the second molars showed a small movement of the crown to the mesial root,and a small movement of the root to the distal root.In working condition 2 to working condition 4,the anterior tooth area showed depression accompanied by lip tilt movement,while the posterior tooth area showed midpoint crown inclination accompanied by a small amount of depression movement.The pressure of central incisor was in the order of working condition 2>working condition 3>working condition 4;the pressure of lateral incisor was in the order of working condition 3>working condition 4>working condition 2;the pressure of fangs and posterior teeth was in the order of working condition 4>working condition 3>working condition 2.Conclusion Elastic traction with micro-implants in the anterior tooth area can effectively increase the anterior tooth pressure.When the implant site moves back,the molar pressure increases significantly;the distal root movement of the posterior tooth increases,and the effect on anterior tooth lip inclination decreases.