Accuracy Of Clinical Application Of Invisalign Progress Assessment With Clear Aligners Treatment: A Retrospective Study

Since the advent of clear aligners in 1997,it is more and more popular among clinical orthodontists and patients,because of its better appearance,comfort and other characteristics different from the traditional fixed appliance.However,due to material deficiency,there are still some shortcomings of clear aligners.So,early,clear aligners were mainly used in the treatment of mild and moderate malocclusion,such as mild and moderate crowding of anterior teeth,closing teeth loose gap,etc.With the development of materials science and computer science,the research progress of clear aligners technology has gradually broadened the treatment range of clear aligners treatment,that is,from the early treatment of mild and moderate crowding cases to the treatment of complex tooth extraction cases,orthodontic-orthognathic combined treatment cases.Different from the traditional fixed orthodontic technique,clear aligners treatment requires the orthodontist to have sufficient experience,including the judgment of indications,the design of 3D tooth movement plan before treatment and the monitoring of the effect during clear aligners treatment.As a product that entered the market at an early stage,the Align Technology Company’s " Invisalign " clear aligners has a wide range of clinical applications.In order to assist orthodontists to more accurately and conveniently monitor the effect of clear aligners treatment,its iTero workflow provides the function of Invisalign Progress Assessment.This function mainly evaluates tooth movement through automatic model superimposition function and automatic model analysis,so it is welcomed and relied on by orthodontists.But few studies have reported its accuracy.In this study,the manually 3D digital model superimposition technology was used to overlap the maxillary models before and after treatment,measure the actual movement data of maxillary teeth and the analysis data of models,and compare the movement of maxillary teeth and the model analysis data shown by the automatic model superimposition of Invisalign Progress Assessment,in order to study the accuracy of the clinical application of Invisalign Progress Assessment.To provide reference for clinical orthodontists to apply the function reasonably.Objective1.To investigate the accuracy of automatic model superimposition of Invisalign Progress Assessment by manually model superimposition.2.To investigate the accuracy of automatic model analysis of Invisalign Progress Assessment by manually model analysis.Methods1.Part 1: Nineteen cases were included in this retrospective case control study.Pretreatment dental cast(T0)and post treatment dental cast after staged treatment(T1)were available for three-dimensional(3D)model superimposition.The movements of maxillary teeth in the horizontal plane(cross section)after staged treatment were measured by 3D model superimposition in real world and Invisalign Progress Assessment.The data collected from the two methods were compared.2.Part 2: The same nineteen cases were included,and the widths of upper and lower dentitions,overbite and overjet were measured by 3D model superimposition in real world.Then collecting the Invisalign Progress Assessment automatic model measurement data.The data collected from the two methods were compared.Results1.Part 1: The movements of maxillary teeth in the horizontal plane after staged treatment were 2.31(1.59,3.22)and 1.79(1.21,3.03)mm in Invisalign Progress Assessment and 3D model analysis,respectively.Significant difference was observed between the two groups(P<0.05).2.Part 2: In the measurement of upper and lower dentition width,four indicators were measured,including Intercanine width upper,intermolar width upper,intercanine width lower,and intermolar width lower.Before treatment,the measurement of Invisalign Progress Assessment were(35.78±2.49),(56.21±2.51),(27.43±1.38),(52.26±2.91)mm,respectively,and actual measurement were(35.77±2.53),(56.17±2.47),(27.40±1.41),(52.30±2.86)mm,respectively,without significant difference(P>0.05).After stage treatment,the measurement of Invisalign Progress Assessment were(37.37±2.86),(57.76±2.56),(28.89±2.00),(54.16±2.19)mm,respectively,and actual measurement were(37.29±2.94),(57.71±2.63),(28.88±2.05),(54.01±2.15)mm,respectively,and there was no significant difference(P>0.05).In the measurement of overbite and overjet,Before treatment,the measurement of Invisalign Progress Assessment were 3.23±1.50 mm,2.85±1.87 mm,respectively,and actual measurement were2.77±1.31mm、4.06±1.51 mm,respectively,there was statistical difference(P < 0.05).After stage treatment,the measurement of Invisalign Progress Assessment were 2.87±0.97 mm,2.64±0.77 mm respectively,and actual measurement were 3.81±0.92mm、3.32±0.92 mm,respectively,and there also was significant difference(P<0.05).Conclusion1.Part 1: The data from Invisalign Progress Assessment did not coincide with the data form manually model superimposition with palate as reference.The accuracy of automatic model superimposition of Invisalign Progress Assessment needs further investigation.2.Part 2: The arch width analysis of Invisalign Progress Assessment is accurate.While its accuracy in measuring overbite and overjet need further verification.