The impact of different cavity design parameters on intraoral scanner accuracy in endocrown restorations.

PURPOSE: To evaluate the effects of different tooth structure thicknesses and cavity depths on the accuracy of intraoral scanners (IOS) in endocrown restorations. METHODS: A mandibular typodont model was used, with the left mandibular first molar replaced by an extracted real human tooth. Endocrown cavities with varying depths (3.5 mm and 5 mm) and remaining wall thicknesses (1.5 mm and 0.5 mm) were prepared. Master models were scanned using a high-precision extraoral scanner, and the data were exported in STL format. Ten intraoral scans were performed for each group using the TRIOS 3 IOS. Scanning accuracy was analyzed using the Root Mean Square (RMS) value for trueness and the Interquartile Range (IQR) for precision in Geomagic Design X software. The differences in RMS values among the groups were examined using Independent Samples T test and one-way ANOVA test. RESULTS: Significant differences in RMS and IQR values were observed between groups with different cavity depths and remaining tooth structure thicknesses (P< 0.001). Groups with thinner remaining tooth structures and deeper cavities exhibited greater deviations, indicating reduced scanning accuracy. CLINICAL SIGNIFICANCE: Cavity depth and tooth structure thickness significantly influenced the accuracy of intraoral scanners in endocrown restorations.