Efficiency Of Overcorrection Design On The Accuracy Of Clear Aligners In Controlling Orthodontic Tooth Movement:A Controlled Clinical Study

ObjectiveThe aim of this study was to investigate the efficiency of overcorrection design in clear aligners treatment. Besides, we analyzed the difference between overcorrection design and attachments including horizontal ellipsoid attachment and optimized attachment.MethodIn this study,12 patients with malocclusion were treated by Invisalign (Align technology). Four canines of each patient were divided into four groups and received different treatment design in ClinCheck respectively (Align technology). The initial and progress digital models were collected by laser scanner (Activity, Germany). Digital models were superimposed and measured using Geomagic software (Research Triangle Park, NC). A paired t-test (P<.05) was used to determine the significance of differences of tooth movement among groups. All statistical analyses were performed with SPSS statistical software (SPSS Inc, Chicago,Ill).Result1. The efficiency of teeth bodily movement(1) The difference between overcorrection and attachmentThere are significant differences in the changes of angulation (P<0.01), inclination (P<0.05) and rotation (P<0.01) between overcorrection group and No-treatment control group. In overcorrection group, the efficiency of bodily movement increased by 36% in angulation,39% in torque,40% in rotation.Compared with overcorrection group, the efficiency of bodily movement increased by 88% in angulation,66% in torque,43% in rotation. The significant in angulation, inclination and rotation are P<0.01, P<0.05, P<0.05 respectively.(2) The difference between rectangular attachment and optimized attachmentThe changes of angulation between rectangular attachment and optimized attachment has a significant difference(P<0.05). The rectangular attachment is about 1.5 times as effective as optimized attachment in the control of angulation. Highly difference (P<0.01) was found in terms of rotation as well. There is not any substantial difference in inclination control.2. The quantity of teeth movement(1) Mesiodistal movementThe most distal movement was found in control group (2.09 mm,8 Aligners). It is much more than the overcorrection group and attachment group (1.34mm,1.23mm, respectively). The Pearson’s correlation test demonstrated that there is an extremely significant correlation between the distal movement and angulation changes in control group(P<0.01).(2) Vertical movement (intrusion/extrusion)There is a significant intrusion in control group, about 0.4mm. it has a significant difference between control group and attachment group(P<0.05). No statistically substantial differences were observed between control group and overcorrection group.(3) Labiolingual movementNo substantial differences were observed in this aspect among four groups.ConclusionOvercorrection has the ability to increase the efficiency of BMT in clear aligner treatment. However, there is was a substantial gap with attachment in the efficiency of BMT with attachments. Conventional attachments are superior to optimized attachments in the control of angulation and rotation according to our study outcome. The staging process needs requires carefully design, and the choice of attachments choose should be take carefully consider of VTO carefully. Although no movement was designed for posteriors and incisors in ClinCheck, forward movement and intrusion in posteriors and extrusion in incisors were found when canines were retracted.