Scanning accuracy of nondental structured light extraoral scanners compared with that of a dental-specific scanner

Abstract

Statement of problem

Diagnostic stone casts can be digitized by using dental optical scanners based on structured light scanning technology. Nondental structured light scanning scanners could also be used; however, the accuracy of these nondental scanners remains unclear.

Purpose

The purpose of this in vitro study was to measure the scanning accuracy (trueness and precision) of 3 nondental extraoral structured light scanners.

Material and methods

A representative maxillary diagnostic cast was obtained and digitized by using an extraoral dental scanner (Advaa Lab Scan; GC Europe), and a reference or control standard tessellation language file was obtained. Three nondental extraoral scanners were evaluated: groups ND-1 (Space Spider; Artec), ND-2 (Capture Mini; Geomagic), and ND-3 (DAVID SLS3; David). Ten digital scans per group were recorded at a constant room temperature (23 °C) by an experienced geodetic engineer following the manufacturer's recommendations. The control or reference file was used as a reference to measure the discrepancy between the digitized diagnostic cast and 3 different nondental scans by using an open-source software (CloudCompare v.2.6.1; CloudCompare) and the iterative closest point technique. The Shapiro-Wilk test revealed that the data were normally distributed. The data were analyzed by using 1-way ANOVA, followed by post hoc Bonferroni tests (α=.05).

Results

Significant differences between the 3 experimental nondental scanners and the control or reference scan (P<.001) were found. The ND-2 group had the lowest absolute mean error (trueness) and standard deviation (precision) (39 ±139 μm), followed by the ND-3 group (125 ±113 μm) and the ND1 group (-397 ±25 μm). No statistically significant differences were found in the mean error between the ND-2 and ND-3 groups (P=.228).

Conclusions

Only 1 nondental extraoral scanner tested obtained trueness mean values similar to those of the reference dental scanner. In all groups, the precision mean values were higher than their trueness values, indicating low relative precision.