Clinical evaluation comparing the fit of all-ceramic crowns obtained from silicone and digital intraoral impressions

Abstract

Objectives The aim of this study is 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 Twenty patients with 26 posterior teeth with a prosthetic demand were selected for the study. Two crowns (Straumann-Zerion) were made for each preparation. One crown was fabricated from an intraoral digital impression system (IDI group; Cadent-iTero), and the other crown was fabricated from a conventional one-step silicone impression (CI group; Express Penta Putty and Body Light). To replicate the interface between the crown and the preparation, each crown was cemented on its corresponding clinical preparation with ultra-flow silicone (Express Ultra Light Body). Each crown was embedded in resin to stabilize the registered interface, cut in 2-mm-thick slices in a buco-lingual orientation. Internal misfit was measured in microns using stereomicroscopy with a magnification of ×40. Measurements were taken at different landmarks: margin, chamfer angle, axial, crest, and occlusal fosse. After checking for normality, data was analyzed using paired Student’s t test (α = 0.05). Results Fit values were significantly affected by the impression technique (p = 0.000). Mean internal misfit and mean marginal misfit were 111.40 μm (SD = 54.04)/80.29 μm (SD = 26.24) for the crowns of the IDI group and 173.00 μm (SD = 92.65)/133.51 μm (SD = 48.78) for the CI group. Conclusion All-ceramic crowns fabricated from intraoral digital impressions with parallel confocal technology demonstrated a clinically acceptable internal and marginal fit as conventional impression. Clinical significance Intraoral digital impressions as initial step to the digital workflow could further improve the marginal adaptation of all ceramic single crowns