Accuracy of Invisalign Progress Assessment with Clear Aligners: A Retrospective Study

Abstract

Objective: The objective of this study was to detective the accuracy of model superimposition and automatic analysis for upper and lower dentition width in Invisalign Progress Assessment during the process of clear aligners. Methods 19 cases were included in this study. Pre-treatment dental cast(T0) and post-treatment dental cast after staged treatment(T1) were available for three-dimensional model superimposition. Subsequently, movements of maxillary teeth in horizontal plane (cross section) after staged treatment, width of upper and lower dentition were measured by three-dimensional model superimposition in real world and Invisalign Progress Assessment separately. Consequently, the data collected from these two methods was compared. Results In Invisalign Progress Assessment, movements of maxillary teeth in horizontal plane after staged treatment was 2.31（1.59,3.22 ） (median (upper quartile, lower quartile)) millimeter (mm), while in three-dimensional model superimposition, the result was 1.79（1.21,3.03）mm. The difference between two groups is significant(P＜0.05). Intercanine width upper, intermolar width upper, intercanine width lower, and intermolar width lower were 36.55±2.76mm, 56.98±2.62mm, 28.16±1.85mm, 53.21±2.72mm separately in Invisalign Progress Assessment and were 36.48±2.78mm, 56.89±2.58mm, 28.05±1.85mm, 53.16±2.64mm separately in three-dimensional model analysis, which were no significant difference among these groups (P＞0.05). Conclusions The data from Invisalign Progress Assessment was not in parallel with what achieved from model superimposition with palate as reference completely. The accuracy of model superimposition in Invisalign Progress Assessment needs further investigation, whereas the accuracy of model analysis in Invisalign Progress Assessment was accurate. Thereby, results from Invisalign Progress Assessment should be interpreted with caution by the orthodontist in clinic.