Influence of scan technology on the accuracy and speed of intraoral scanning systems for the edentulous maxilla: An in vitro study

Abstract

Purpose: To compare the accuracy of three intraoral scanners in terms of trueness and precision relative to the scanner acquisition technology and scan capture mode. Scan speed of each scanner was also evaluated.

Materials and methods: An edentulous maxillary arch was digitized (reference model) and 3D-printed using an SLA-based 3D-printer (XFAB; DWS, Italy) (n = 10). Each model was scanned using three intraoral scanners, each with different scan technologies: confocal (Trios 3; 3Shape, Copenhagen, Denmark), parallel confocal (iTero; Align Technology), and triangulation (Medit i700). Scan time and scanning accuracy (trueness and precision) were calculated using digital subtraction technique (Geomagic Control X v2020, 3DSystems, USA). One-way analysis of variance (ANOVA) test was used to detect differences in trueness, precision, and scanning time between the tested groups (p < 0.05).

Results: ANOVA results showed statistically significant differences in trueness, precision, and scan time among the tested groups. Confocal scanning technique (Trios 3) showed the highest trueness and precision (root mean square estimate [RMSE] 0.094 and 0.096, respectively) followed by iTero displaying parallel confocal technique (RMSE 0.113 and 0.133, respectively); the difference was not significant (p = 0.849, p = 0.488). Further, Trios showed the longest scanning time (100 s) compared to iTero and Medit i700 (p = 0.011 and 0.002, respectively). Medit i700 presenting triangulation scan technology revealed lowest trueness and precision (RMSE 0.268) (p = 0.000, p = 0.001) and fastest scan time (59 s) close to iTero (66 s) (p = 0.802).

Conclusions: Scanner technology had an influence on the accuracy and scan speed of the acquired intraoral scans. The Trios 3 scanner featuring the confocal acquisition technology displayed the highest trueness, precision, and longest scan time. Medit i700 IOS with triangulation acquisition concept featured the lowest trueness, precision, and fastest scan speed. There is no ideal scanner with the best combination of accuracy and scan speed.

Keywords: digital scan; edentulous maxilla; intraoral scanners; scanning technologies.