Influence of conventional and digital intraoral impressions on the fit of CAD/CAM-fabricated all-ceramic crowns

Abstract

Objectives: To compare the fit of all-ceramic crowns fabricated from conventional silicone impressions with the fit of all-ceramic crowns fabricated from intraoral digital impressions.

Methods: Thirty patients with 30 posterior teeth with a prosthetic demand were selected. Zirconia-based ceramic crowns were made using an intraoral digital impression system (Ultrafast Optical Sectioning technology) (digital group, D) and 2-step silicone impression technique (conventional group, C). To replicate the interface between the crown and the preparation, each crown was cemented on its corresponding clinical preparation using ultra-flow silicone. Each crown was embedded in resin to stabilize the registered interface. Specimens were sectioned in buccolingual orientation, and internal misfit was measured at different areas using stereomicroscopy (×40). Data was analysed using Student's t test and Mann-Whitney test (α = 0.05).

Results: No statistically significant differences were found (P > 0.05) between two groups. The mean internal misfit and mean marginal misfit were 170.9 μm (SD = 119.4)/106.6 μm (SD = 69.6) for group D and 185.4 μm (SD = 112.1)/119.9 μm (SD = 59.9) for group C.

Conclusion: Ceramic crowns fabricated using an intraoral scanner are comparable to elastomer conventional impressions in terms of their marginal and internal fits. The mean marginal fit in both groups was within the limits of clinical acceptability.

Clinical significance: Impressions based on Ultrafast Optical Sectioning technology can be used for manufacturing ceramic crowns in a normal workflow, with the same results as silicone conventional impressions.

Keywords: All-ceramic crowns; CAD/CAM; Digital impression; Intraoral scanner; Marginal fit; Replica technique; Trios scanner.