Comparison of the acquisition accuracy and digitizing noise of 9 intraoral and extraoral scanners: An objective method

The quality of the digital cast obtained from an intraoral scanner is an important comparison parameter for computer-aided design and computer-aided manufacturing (CAD-CAM) restorations. However, data on cast quality are typically provided by manufacturers, and objective evaluation of these devices is lacking.The purpose of this in vitro study was to build an evaluation protocol of 8 intraoral scanners by using an objective method for a small-scale model equivalent in size to a 4-tooth wide cast. In addition, a laboratory scanner was included to compare the performance of intraoral and extraoral devices.An 8-mm-thick zirconia gauge block was scanned 10 times with a laboratory scanner (Iscan D104) and 8 intraoral scanners (Omnicam, Primescan, Itero element 5D, CS 3600, TRIOS 3, Emerald, Planscan, and Medit i500). The obtained digital casts were extracted as standard tessellation language (STL) files and analyzed to evaluate the digitizing noise, dimensional trueness, and dimensional precision of each scanner. After validation of the normal distribution of the digitizing noise, dimensional trueness, and precision test results for each scanner with the Shapiro-Wilk test (α=.05), differences were determined with a 1-way ANOVA test.Statistical differences were found between scanners (P<.05). The digitizing noise ranged from 3.2 ±0.6 μm with the Primescan to 15.5 ±2.5 μm with the Planscan. The dimensional trueness ranged from 19.1 ±11.5 μm for the CS3600 to 243.8 ±33.6 μm for the Planscan. The dimensional precision ranged from 7.7 ±2.4 μm for the Primescan to 53.7 ±3.4 μm for the Emerald. The group Iscan D104, Primescan, Itero 5D, CS3600, and TRIOS 3 showed minimally significant differences.Significant differences were found among the intraoral scanners for small-scale scans. The objective methodology of using a gauge block provided coherent and repeatable results.