Accuracy of Intraoral Scanners for Simulated Tooth Wear Using RMS Surface Deviation Analysis

Objectives. This study evaluated the performance of three intraoral scanners with different acquisition technologies in detecting early signs of tooth wear, using micro-computed tomography (micro-CT) as the reference standard. Methods and Materials. Three IOS were examined, including an active triangulation scanner, a structured-light triangulation scanner, and a parallel confocal technology scanner. Ten extracted unrestored and caries-free premolars were placed in the maxillary left second premolar position of a dental mannequin and scanned at baseline, generating quadrant digital models. Micro-CT scans were also obtained at baseline. Wear was simulated by immersion in a 1% citric acid solution followed by brushing of the buccal surfaces. All specimens were rescanned with IOS and micro-CT. Micro-CT datasets were reconstructed into stereolithography models and compared with IOS models using mesh analysis software. Statistical analysis was performed in R using linear mixed-effects models to account for repeated measurements across teeth. RMS values and absolute errors relative to the micro-CT reference were analysed with device as a fixed effect and tooth as a random effect, with Tukey-adjusted pairwise comparisons. Repeatability was additionally assessed from the repeated scans using within-tooth variability. Results. Significant differences were observed among the evaluated systems in the detection of changes related to tooth wear (p < 0.001). The micro-CT reference showed the lowest RMS value, followed by Trios 3, Primescan, and Omnicam. Model-based analyses confirmed significant differences among the evaluated systems, while the magnitude and statistical support of pairwise contrasts depended on the specific outcome considered. Repeatability analysis showed that Trios 3 had the lowest within-tooth standard deviation and repeatability coefficient (0.0215 mm and 0.0595 mm, respectively), followed by Primescan (0.0290 mm and 0.0802 mm), whereas Omnicam showed the highest within-tooth variability and repeatability coefficient (0.0624 mm and 0.173 mm). Conclusions. The parallel confocal and structured-light triangulation intraoral scanners produced RMS values numerically closer to the micro-CT reference than the active triangulation scanner. However, none of the evaluated intraoral scanners demonstrated quantitative agreement sufficient to be considered interchangeable with the reference standard.