Affiliation: School of Dentistry, Department of Operative Dentistry
Objective: To compare the accuracy (trueness and precision) of optical and conventional impressions in-vivo. Materials and Methods: Five study participants were consented and enrolled. For each participant, optical (CEREC Omnicam; Dentsply Sirona, Charlotte, USA ) and conventional (vinylsiloxanether; Identium, Kettenbach, Huntington Beach, USA ) impressions of a custom-made intra-oral Co-Cr alloy reference appliance fitted to the mandibular arch were obtained. 3D digital models were created for stone models obtained from the conventional impression group and for the reference appliances using a validated high accuracy reference scanner (Infinite focus standard; Alicona Corporation, Bartlett, USA). For the optical impression group, 3D digital models were obtained directly from the intraoral scans. Total mean trueness of each impression system was calculated by superimposing the 3D models and averaging the mean absolute deviations of the impression replicates from their 3D reference model for each participant followed by averaging the obtained values across all participants. Total mean precision for each impression system was calculated by superimposing the 3D models and averaging the mean absolute deviations between all the impression replicates for each participant (10 pairs) followed by averaging the obtained values across all participants. Data were analyzed using repeated measures ANOVA at a 0.05 significance level. Results: Optical impressions had significantly lower mean trueness and precision (46.2 ± 11.4 µm and 61.1 ± 4.9 µm, respectively) than those for conventional impressions (17.0 ± 6.6 µm and 16.9 ± 5.8 µm, respectively), suggesting higher accuracy for conventional impressions. Conclusion: Within the limitations of this study, full-arch (first molar-first molar) optical impressions are less accurate than conventional impressions, but might exhibit enough accuracy for quadrant impressions.