Evaluation of the accuracy of direct intraoral scanner impressions for digital post and core in various post lengths: An in-vitro study.

Abstract

Despite the growing utilization of direct intraoral scanners (IOSs) in dentistry, there is a scarcity of research investigating their accuracy, specifically in post and core. Few studies have conducted comprehensive three-dimensional assessments and comparisons of IOSs with the conventional impression technique, particularly in different post space lengths. The purpose of this in vitro study was to digitally assess the accuracy of direct intraoral scanner (IOS) impressions for different post space lengths, specifically 6, 8, and 10 mm. A total of 45 typodont teeth (maxillary central incisors) were selected for this study. The teeth underwent endodontic treatment and were divided into three subgroups, each with 15 teeth, based on the desired post space lengths: 6, 8, and 10 mm. Intraoral scans of all specimens were acquired directly using the CEREC Primescan intraoral scanners by two trained examiners. The obtained scan data were compared with conventional impressions obtained using light and heavy bodies of polyvinyl siloxane (PVS). As a control, the conventional impressions were subsequently scanned using an inEos X5a lab scanner. The accuracy of the digital scans was evaluated in the coronal, middle, and apical thirds using the Geomagic Control X software. Statistical analysis was performed using Bonferroni Post-hoc and One-way ANOVA tests to analyze the data. The overall mean root mean square (RMS) deviations for the different post lengths across the three thirds groups were 58, 81, and 101 μm for the 6, 8, and 10 mm subgroups, respectively. There were no statistically significant differences in the accuracy of the coronal and middle thirds among all subgroups (p > 0.5). However, in the apical third, the 10 mm subgroup exhibited a significantly lower accuracy (163 μm) compared to the 6 mm (96 μm) and 8 mm (131 μm) subgroups (p < 0.05). These results suggest that while the accuracy of intraoral scans using direct IOS impressions was consistent in the coronal and middle thirds regardless of the post length, there was a noticeable decrease in accuracy in the apical third, particularly with longer post lengths. Considering the limitations of this in vitro study, chairside direct IOS impressions offer a viable and clinically acceptable alternative to the conventional impression technique for post space lengths of 6 and 8 mm. However, as the post space length preparation increases, the accuracy of IOS decreases. The Chairside direct IOS enables expedited and efficient digital impression capture within the root canal, ensuring acceptable accuracy for intracanal post length preparation of up to 8 mm.