Clinical acceptability of the internal gap of CAD/CAM Pd-Ag crowns using intraoral digital impressions

Abstract

AbstractClinical acceptability of the internal gapof CAD/CAM Pd-Ag crownsusing intraoral digital impressionsTae-Gyung KimThe Graduate School, Department of Dental ScienceYonsei University(Directed by Professor Hong Seok Moon, DDS, MSD, PhD)Objectives The purpose of this study was to compare the internal gap between CAD/CAM Pd-Ag crowns and cast gold crowns generated from intraoral digital versus conventional impressions, and to determine the clinical acceptability of the internal gap of CAD/CAM Pd-Ag crowns using intraoral digital impressions. Materials and Methods A resin tooth model of a mandibular right first molar was prepared for a full veneer crown. Ni-Cr master dies were made from the prepared resin tooth with the conventional impression method (n=40). Master dies were divided into four groups. For group I, 10 intraoral digital impressions (i-Tero) were taken, and 10 CAD/CAM crowns of a Pd-Ag machinable alloy (Innovium) were generated. For group II, 10 gold crowns were cast from ten intraoral digital impressions. For group III, 10 CAD/CAM Pd-Ag crowns were made using the conventional impression method. For group IV, 10 gold crowns were fabricated from 10 conventional impressions. The space between the master die and the internal surface of the respective crown was filled with a low-viscosity addition silicone material. One hundred magnifications of the internal gaps of each crown were measured at 50 points with an optical microscope, and these values were statistically analyzed using a two-way analysis of variance (α= .05). Results The internal gap of the intraoral digital impression group was significantly larger than in the conventional impression group (P<0.05). No significant difference was observed between the CAD/CAM group and the cast group (P>0.05). Conclusion 1. crowns from intraoral digital impressions showed larger internal gap values than crowns from conventional impressions. 2. the internal gap of CAD/CAM Pd-Ag crowns was similar to that of cast gold crowns. 3. all crowns showed clinically acceptable internal gap, regardless of the impression and fabrication methods.