Comparison of digital intraoral scanner reproducibility and image trueness considering repetitive experience

Statement of problem: Because the digital workflow can begin directly in the oral cavity, intraoral scanners are being adopted in dental treatments. However, studies of the relationship between the experience of the practitioner and the accuracy of impression data are needed. Purpose: The purpose of this clinical study was to investigate the effect of the experience curve on changes in trueness when a patient's complete dental arch is scanned. Material and methods: Twenty dental hygienists with more than 3 years of experience in dental clinical practice (group 1 had 3 to 5 years; group 2 had >6 years) were recruited to learn to operate 2 intraoral scanner systems. All learners scanned the assigned patient's oral cavity 10 times during the experience sessions. Precision was calculated as the mean deviation among all superimposition combinations from the 10 scanned data sets of each learner [n=₁₀C₂=45]. Trueness was evaluated by superimposing the 10 consecutive intraoral scan data onto the impression scan data from each patient's rubber impression body (n=10). The acquired images were processed and analyzed using a 3-dimensional analysis software. For statistical analysis, the independent 2-sample t test and repeated measures ANOVA were performed (α=.05). Results: The mean precision of the Trios scanner was greater than that of the iTero (Trios, 52.30 μm; iTero, 60.46 μm; P<.01). The iTero group showed an improvement in trueness upon repeated experience (P<.05), whereas the Trios group did not (P>.05). In the iTero group but not in the Trios group, the length of clinical experience influenced the change of trueness as a result of repeated experience (P<.05). In terms of the scanned region, the results for trueness were better for the maxillary arch than the mandibular arch with repeated scanning in the iTero group (P<.05). Conclusions: The single-image based system required repeated learning sessions for effective clinical application. The newer system offered better trueness and precision and was less likely to be influenced by the length of clinical career or the region being scanned.