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

STATEMENT OF PROBLEM: 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. PURPOSE: 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. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSION: 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. CLINICAL SIGNIFICANCE: 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.

Comparison of the Accuracy and Reliability of Instrumental Shade Selection Devices and Visual Shade Selection: An in Vitro Study.

OBJECTIVE: New shade-matching devices are available for clinical use, but their accuracy and reliability have not been investigated. This in vitro study compared the accuracy and reliability of a shade-matching colorimeter (Optishade), a spectrophotometer (VITA Easyshade V), and visual shade matching in simulated clinical conditions. MATERIAL AND METHODS: Shade matching was conducted with two digital devices; (Optishade and Vita Easyshade) and the visual shade selection method, with a new 16-tab Vita Classical shade guide. Shade tabs were placed within a gingival matrix and measurements were taken from the central area of each shade tab enclosed in a black box to simulate the oral cavity. Visual assessments were conducted independently by two examiners. For the reliability assessment, each shade tab was measured 20 times by each examiner. Accuracy was calculated as a percentage of the matching readings with the actual shade per each tab. Data were analyzed with the one-way ANOVA test (α = 0.05) and Pairwise Comparison (Bonferroni Post hoc Test) to assess accuracy. The reliability evaluation was conducted by comparison between both examiners using mean and standard deviation; by a two-tailed t-test for the independent samples for all the three groups included in the study. RESULT: The shade matching accuracy of Optishade was 97.50%, Vita Easyshade 89.38%, and visual method 62.19%. Statistically, high significant difference in accuracy (p < 0.001) was found when comparing both Optishade and VITA Easyshade with the visual method. Additionally, there was statistically significant difference in accuracy (p < 0.05) when Optishade was compared to Vita Easyshade. The reliability of the Optishade was 99.6% and Vita Easy shade was 99.38%. Statistically, showed no statistically significant difference in the reliability of shade match obtained within the same group when comparing the readings of Examiner 1 and Examiner 2 (p > 0.05). CONCLUSION: The colorimeter demonstrated the highest accuracy, followed by the spectrophotometer, and the visual shade selection method. Both digital methods investigated in this study showed comparable reliability. CLINICAL IMPLICATION: The results of this study emphasize the clinical advantage of digital shade-matching devices over visual shade-matching. The colorimeter offers high accuracy for shade matching and should be considered to use for shade matching especially with restorations in the esthetic zone.