In vitro assessment of the accuracy of two intra-oral scanners for post space scanning in a fully digital workflow.

Abstract

Background: With the rapid advancements in computer-aided imaging, the potential for chairside fabrication of custom-made posts utilizing intraoral scanners may offer a reliable alternative to traditional physical impressions. Accordingly, this study aimed to evaluate the accuracy (trueness and precision) of two intra-oral scanners when different post space diameters were employed. Additionally, the scan depth of each intra-oral scanner (IOS) was assessed.

Methods: An endodontically treated mandibular canine was inserted in a printed typodont model and prepared with two post-space diameters; a small one (1.5 mm) and a large one (2 mm). Polyvinyl siloxane impressions for the two post-space diameters were taken and then scanned with an extra-oral scanner to serve as reference scans. Each post-space diameter was scanned using CEREC Primescan (n = 8) and Medit i700 (n = 8) intra-oral scanners. Standard tessellation language (STL) files of all intra-oral and extra-oral scans were uploaded to a 3D matching program to evaluate trueness, precision, and post-space length difference. Statistical analysis was performed using different tests for parametric and non-parametric data. The significance level was set at P < 0.05.

Results: Regarding the effect of the IOS and the effect of the post-space diameter, both Medit i700 and the small diameter groups using both scanners showed significantly higher root mean square (RMS) values when evaluating trueness. For precision, Medit i700 showed a significantly higher RMS value in the large diameter group. Medit i700 showed a significantly higher difference in post-space length than Primescan in both diameters. Primescan recorded a zero difference in the large diameter group compared to the reference scan.

Conclusions: The IOS type and the post-space diameter influenced the scan accuracy and the depth of the scan. Accuracy results were superior when Primescan was implemented for scanning the large diameter post-space subgroup.