Feasibility of using an intraoral scanner for a complete-arch digital scan

Statement of problem: The introduction of intraoral scanners has increased the use of digital technology in dental procedures. However, research on the extent of clinically recommended scans is lacking. Purpose: The purpose of this in vitro study was to compare 3D arch distortion according to the distance from the tooth at the beginning of a complete-arch scan made using an intraoral scanner. Material and methods: An industrial scanner was used to digitize a master model for a computer-aided design (CAD) reference model. In addition, the master model was digitized using 4 intraoral scanners (TRIOS2, TRIOS3, CS3500, and CS3600) and 1 dental laboratory scanner (FREEDOM HD) to make the CAD test model (N=20). The scanned teeth were divided using an inspection software program (Geomagic control X), and overlapping and 3D analyses of the CAD reference model and CAD test model were performed. The presence or absence of normal distribution in the root mean square (RMS) values of all divided teeth was assessed and evaluated with the Kruskal-Wallis test (α=.05), and post hoc comparison was performed using the Mann-Whitney U-test and Bonferroni correction method (α=.005). Results: The overall RMS value was significantly different for all scanners (P<.001). The dental laboratory scanner showed the lowest value (47.5 ±1.6 μm), whereas TRIOS2 showed the highest value (343.4 ±56.4 μm). TRIOS3 (9.6 ±1.2 μm) showed the best trueness in those teeth where the scan started. However, the larger the scan range, the lower the RMS value difference between TRIOS3 and CS3500. The RMS values of the dental laboratory scanners were higher than those of the intraoral scanners in the narrow scan range. CS3600 showed an RMS value less than or equal to that of the dental laboratory scanner at 5 teeth scan ranges. However, the wider the scan range, the lower the RMS values of all the intraoral scanners. Conclusions: Current complete-arch scanning is not sufficiently accurate for fabricating fixed prostheses. However, intraoral scanners are useful for short scans, such as those for single (TRIOS2, TRIOS3, and CS3500) or short-span prostheses (CS3600).