无托槽隐形矫治器联合微种植钉对上前牙三维受力影响的体外研究

Effect of micro-implant combined with clear aligner on three-dimensional forces of upper anterior teeth:an in vitro study

目的体外研究无托槽隐形矫治中微种植钉植入位置及加力方式对上前牙三维受力的影响。方法研究于2021年5—8月在上海正雅齿科实验室进行。矫治器六轴测量平台代表上颌牙弓,定制微种植钉支抗附着装置。制作上颌牙列光固化树脂模型60个、无托槽隐形矫治器60副。根据微种植钉植入位置及加力方式,随机分为6组(中切牙唇侧组、中切牙舌侧组、中侧切牙唇侧组、中侧切牙舌侧组、侧尖牙唇侧组、侧尖牙舌侧组),每组各10个上颌模型和10副矫治器。测量分析微种植钉位于中切牙之间、双侧中切牙与侧切牙之间及双侧侧切牙与尖牙之间时分别在矫治器唇或舌侧施加0.98 N压入力的上前牙三维受力情况。结果中切牙唇侧组及中切牙舌侧组的中切牙与侧切牙受压低力,而对尖牙产生伸长力;两组上前牙受力比较,差异均具有统计学意义(均P<0.05)。中切牙所受压低力在中切牙唇侧组中最大,其次为中切牙舌侧组,差异均具有统计学意义(均P<0.05)。侧切牙在中切牙唇侧组所受压低力大于除侧尖牙舌侧组外的其他组,差异具有统计学意义(P<0.05)。尖牙在侧尖牙唇侧组所受压低力大于除侧尖牙舌侧组外的其他组,差异具有统计学意义(P<0.05)。除垂直向受力外,各组上前牙都受到了唇舌向力及近远中向力,且大多数呈现舌侧组受力小于唇侧组的趋势,其中右上中切牙和两侧侧切牙在各唇、舌侧组受力比较,差异均有统计学意义(均P<0.05)。结论微种植钉的位置及加力方式均对上前牙的三维受力有显著影响。从机械力学方面分析,仅需压低中切牙与侧切牙时,微种植钉植入中切牙之间是较优选择;若需同时压低切牙与尖牙时,微种植钉应植入中切牙与侧切牙之间或侧切牙与尖牙之间,并在矫治器舌侧加力较佳。所有位置下,与唇侧加力相比,舌侧加力更接近牙齿的整体移动。

Objective To investigate the three-dimensional forces exerted on the upper anterior teeth with different posi?tions and force application methods of micro-implant in clear aligners in vitro.Methods This study was conducted at the Zhengya Dental Laboratory in Shanghai from May to August 2021.The six-axis platform of the aligner represented the maxillary arch,and the corresponding device was customized to simulate the micro-implant anchorage.Totally 60maxillary light-curing resin models and 60 corresponding clear aligners were fabricated.According to the positions and force application methods of micro-implant,they were randomly divided into six groups(mesial incisor labial group,me?sial incisor lingual group,mesial lateral incisor labial group,mesial lateral incisor lingual group,lateral canine labial group,and lateral canine lingual group)with 10 maxillary models and 10 sets of aligners in each group.The three-dimen?sional forces on the upper anterior teeth were mea?sured and analyzed when the micro-implant was lo?cated between the central incisors,between the bi?lateral central incisors and lateral incisors,and be?tween the bilateral lateral incisors and canines,re?spectively,under the influence of a 0.98 N intrusion force applied to the labial and lingual sides of the aligner.Results In the mesial incisor labial and lingual groups,the intrusive forces were applied to the central and lateral incisors,while extrusion forces were produced on the canines,the forces on upper anterior teeth between the two groups being all statisti?cally significant(P<0.05).The intrusive forces on the central incisors was greatest in mesial incisor labial group,fol?lowed by the mesial incisor lingual group,with statistically significant differences(P<0.05).The intrusive forces on the lateral incisors were greater in the mesial incisor labial group than in other groups except the lateral canine lingual group,and the difference was statistically significant(P<0.05).The intrusive forces on the canines were greater in the lateral canine labial group than in other groups except the lateral canine lingual group,with statistically significant differences(P<0.05).The upper anterior teeth were subjected to labiolingual and mesiodistal forces in all cases except the vertical direction.In most cases,the labiolingual and mesiodistal forces in the lingual-side force group were less than those in the labial-side force group.The differences in the forces on the right upper central incisor and both lateral incisors in each labial and lingual group were statistically significant(P<0.05).Conclusion Both the micro-implant position and the force application method have a significant effect on the three-dimensional forces on the upper anterior teeth.From the mechanical point of view,micro-implants are optimal when only the central and lateral incisors need to be intruded,and they should be placed between the central and lateral incisors.When both incisors and canines need to be intruded,micro-implant should be placed between the central and lateral incisors or between the lateral incisors and canines,and with lingual force on the aligner.In all positions,the lingual-side force tends to move the tooth bodily more than labial force.