Accuracy of complete arch nonsplinting and noncalibrated splinting implant scanning techniques recorded by using five intraoral scanners.

Abstract

Statement of problem: Splinting implant scan bodies (ISBs) has been reported to improve the accuracy of intraoral scanners (IOSs) compared with nonsplinting methods. However, the accuracy of commercially available horizontal noncalibrated ISBs remains unknown.

Purpose: The purpose of this in vitro study was to compare the accuracy of complete arch scans obtained using horizontal noncalibrated or standard ISBs recorded by using 5 different IOSs.

Material and methods: An edentulous maxillary stone cast with 6 implant abutment analogs (MultiUnit Abutment Plus Replica) was used. The reference scan was obtained by digitizing the reference cast with a calibrated laboratory scanner (T710). Five groups were created based on the IOS tested: TRIOS 5, i700, Primescan, Aoralscan 3, and iTero. Two subgroups were defined based on the ISBs selected to record complete arch implant scans: standard ISBs (Stand subgroup) or horizontal noncalibrated ISBs (Apollo subgroup) (n=10). In the Stand subgroup, a standard ISB (Accurate Implant Body MUA) was positioned on each implant abutment, and experimental scans were captured. In the Apollo subgroup, a horizontal ISB (Apollo) was positioned on each implant abutment, connecting the implants horizontally following the arch shape. The standard tessellation language (STL) files of all the experimental scans were exported. A program (DentalCAD) was used to design a complete arch implant-supported bar from the control and each experimental scan. Then, another program (Geomagic) was used to perform linear and angular measurements of the implant interfaces of each bar. The measurements obtained in the control scan were used as a reference to measure the scanning distortion of each specimen. The 2-way ANOVA Welch and pairwise multiple comparison Tukey tests were used to analyze trueness (α=.05). The Levene and pairwise multiple comparison Wilcoxon rank tests were applied to analyze precision (α=.05).

Results: Significant linear trueness differences were found between the subgroups (P<.001) with a significant interaction group×subgroup (P<.05). The iTero system demonstrated a significantly worse linear trueness compared with the other IOSs (P<.001). The TRIOS 5 obtained the worst linear precision. Significant angular trueness discrepancies were found between the groups (P<.001) and subgroups (P=.048) with a significant interaction group×subgroup (P=.041). The Apollo group obtained better angular trueness (P<.001) and precision (P<.001) compared with the Stand ISBs group.

Conclusions: Both the implant scanning technique and choice of IOS impacted the accuracy of complete arch implant scans.