Marginal and Internal Fit of Ceramic Restorations Fabricated Using Digital Scanning and Conventional Impressions: A Clinical Study.

Jeong-Hyeon Lee,Keunbada Son,Kyu-Bok Lee

doi:10.3390/jcm9124035

Abstract

This clinical study was designed with the aim of fabricating four ceramic crowns using the conventional method and digital methods with three different intraoral scanners and evaluate the marginal and internal fit as well as clinician satisfaction. We enrolled 20 subjects who required ceramic crowns in the upper or lower molar or the premolar. Impressions were obtained using digital scans, with conventional impressions (polyvinyl siloxane and desktop scanner) and three different intraoral scanners (EZIS PO, i500, and CS3600). Four lithium disilicate glass-ceramic crowns were fabricated for each patient. In the oral cavity, the proximal and occlusal adjustments were performed, and the marginal fit and internal fit were evaluated using the silicone replica technique. The clinician satisfaction score of the four crowns was evaluated as per the evaluations of the proximal and occlusal contacts made during the adjustment process and the marginal and internal fit. For statistical analysis, the differences among the groups were analyzed with one-way analysis of variance and Tukey HSD test as a post-test; Pearson correlation analysis was used for analyzing the correlations (α = 0.05). There was a significant difference in the marginal and internal fit of the ceramic crowns fabricated using three intraoral scanner types and one desktop scanner type (p < 0.001); there was a significant difference in the clinician satisfaction scores (p = 0.04). The clinician satisfaction score and marginal fit were significantly correlated (absolute marginal discrepancy and marginal gap) (p < 0.05). An impression technique should be considered for fabricating a ceramic crown with excellent goodness-of-fit. Further, higher clinician satisfaction could be obtained by reproducing the excellent goodness-of-fit using the intraoral scanning method as compared to the conventional method.

Highlights

In the processes of fabricating and restoring prostheses, it is crucial to take impressions accurately [1,2,3]
There was no significant difference in the marginal gap as per the three intraoral scanner types
The present results suggest that conventional impression and intraoral scanner type may affect the marginal and internal fit of the ceramic prostheses and the clinician’s satisfaction score; clinicians should consider the method for acquiring a virtual cast for the fabrication of an excellent ceramic crown

Summary

Introduction

In the processes of fabricating and restoring prostheses, it is crucial to take impressions accurately [1,2,3]. The use of an intraoral canner for taking a digital impression is a method that obtains impressions via direct scanning [5,6]. In the conventional method that uses impression material, dental stone, investing material, and alloy, etc., there are differences in the expansion and contraction rate of each material; the goodness-of-fit of the prostheses may differ, depending on the proficiency of the dental technician [8]. Digital impression taking is unlikely to cause the deformation of the impression material, and the additional scan and work are easy [9]. Compared to conventional impression taking, this method involves a lower cost and less time; this method tends to be used increasingly [10]

Methods

Results

Discussion

Conclusion