Distortion Assessment of Different Materials in Full-Arch Dentate Impressions in Relation to Operator Experience: A Comparative In Vivo Study

Purpose: To evaluate the distortion probability in impressions of completely dentate arches when different impression materials are used in relation to operator experience. Materials and Methods: A total of 28 students (Group A) and 7 dentists (Group B) performed three maxillary impressions on 28 participants, each using vinyl siloxane ether (VSE), polyether (PE), and irreversible hydrocolloid (IHC). Gypsum master casts were fabricated and subsequently digitized. Intraoral scans were taken as a control. Differences between master casts and intraoral scans were visualized with heatmaps, and planar deviations were investigated. If planar deviations > 120 µm were found, the impression was rated as “distorted.” An additional superimposition using the casts from VSE or PE was performed to confirm the presence of distortions. The relative number of surfaces with distortions in each impression was calculated. The procedure was repeated for a distortion threshold of 500 µm. The statistical analyses included repeated measures ANOVA (RMA) and post hoc tests (α < .05). Results: When 120 µm was considered as the threshold for distortions, IHC impressions showed higher distortion probability than PE impressions in Group A (P = .003) and Group B (P < .0001). In Group B, PE showed a lower distortion probability than VSE (P = .02). There was no significant difference between the study groups (P = .42). Considering 500 µm as a threshold for distortions, there was no difference between impression materials (P = .17) or study groups (P = .53). Conclusions: There were no statistically significant differences in relation to operator experience. Different impression materials had a significant impact on distortion probability. PE impressions showed the lowest distortion probability.