Influence of different inlay configurations and distance from the adjacent tooth on the accuracy of an intraoral scan

Abstract

Statement of problem: Clinical guidelines for obtaining accurate scan data during the intraoral scanning of inlay cavities with various configurations and interproximal distances are lacking.

Purpose: The purpose of this in vitro study was to evaluate the effect of interproximal distance and cavity type on the accuracy of digital scans for inlay cavities, including proximal cavities.

Material and methods: Four artificial teeth with 4 types of inlay cavities designed based on the buccolingual width and gingival level of the proximal box were installed in a mannequin at distances of 0.6, 0.8, and 1.0 mm from the adjacent teeth. Reference scans of the 4 artificial teeth were obtained by using a laboratory scanner. The CEREC Primescan AC was used to acquire digital scan data (each n=10). Standard tessellation language (STL) files were analyzed with a 3-dimensional analysis software program. The mean deviation values were measured with a 3-dimensional best-fit alignment method to evaluate the accuracy of the digital scan data. Statistical analyses were performed by using 2-way ANOVA and the Bonferroni multiple comparison test (α=.05).

Results: As per the interproximal distance, the 1.0-mm group showed significantly higher trueness than the 0.6-mm group (P<.05). As the interproximal distance increased, the maximum positive deviation significantly decreased (P<.05). Maximum negative deviation and precision of the scan data were not significantly different among the distance groups (P>.05). Cavity type had a significant influence on the trueness and precision of the scan data (P<.05). In particular, the narrow long cavity type had an adverse effect on the precision and maximum positive deviation of scan data.

Conclusions: During the intraoral scanning of class II inlay restoration, interproximal distance and cavity type affected the accuracy of an intraoral scan. As the interproximal distance increased, the trueness of the acquired digital images increased and the maximum positive deviation significantly decreased. The narrow long cavity type negatively affected the mean maximum positive deviation and precision of scan data.