Invisalign ClinCheck Prescribed versus Performed Interproximal Reduction

Abstract

Objectives: Interproximal reduction is a technique used to reduce the mesiodistal dimension of teeth. Interproximal reduction is programmed into the Invisalign ClinCheck and should be reflected clinically. This study aimed to evaluate the initial, approved, and performed interproximal reduction to determine differences between what was planned and performed. Materials and Methods: 57 subjects had an initial and approved Invisalign ClinCheck over the study period. Patient number, dental arch, initial or approved Invisalign ClinCheck, interproximal location, and the amount of interproximal reduction were recorded. For 32 of 57 subjects with an additional intraoral scan prior to refinement, mesiodistal tooth width measurements were recorded using OrthoCAD software and digital caliper. Measurement difference between pre-treatment and refinement indicated the amount of interproximal reduction performed. Wilcoxon signed-rank tests were used to compare the initial, approved, and performed interproximal reduction. Results: There was a significant difference in interproximal reduction between the initial and approved Invisalign ClinCheck overall (p=0.00) and interproximal locations 6,15-19 (p<0.05), with an increased amount of interproximal reduction in the approved Invisalign ClinCheck according to median values. For those with an additional intraoral scan prior to refinement (n=32), there was a signficant difference in interproximal reduction between the initial and approved Invisalign ClinCheck for the maxillary arch (p=0.004). There was a signficant difference in interproximal reduction between the initial ClinCheck and measurement with a digital caliper for the maxillary and mandibular arches (p=0.02) with a median value of -0.1 mm. No other differences were found. The intra-examiner correlation was moderate (intraclass correlation = 0.589). Conclusions: There is significantly more interproximal reduction prescribed in the approved Invisalign ClinCheck than the initial ClinCheck, specifically between the maxillary central incisors and the mandibular incisors. However, there was no difference found between the initial ClinCheck interproximal reduction and performed interproximal reduction. This study found that significantly greater interproximal reduction is required than performed clinically.