Comparison of the fit of cast gold crowns fabricated from the digital and the conventional impression techniques

Abstract

Purpose: The purpose of this study was to compare the fit of cast gold crowns fabricated from the conventional and the digital impression technique.

Materials and methods: Artificial tooth in a master model and abutment teeth in ten patients were restored with cast gold crowns fabricated from the digital and the conventional impression technique. The forty silicone replicas were cut in three sections; each section was evaluated in nine points. The measurement was carried out by using a measuring microscope and I-Soultion. Data from the silicone replica were analyzed and all tests were performed with α-level of 0.05.

Results: 1. The average gaps of cast gold crowns fabricated from the digital impression technique were larger than those of the conventional impression technique significantly. 2. In marginal and internal axial gap of cast gold crowns, no statistical differences were found between the two impression techniques. 3. The internal occlusal gaps of cast gold crowns fabricated from the digital impression technique were larger than those of the conventional impression technique significantly.

Conclusion: Both prostheses presented clinically acceptable results with comparing the fit. The prostheses fabricated from the digital impression technique showed more gaps, in respect of occlusal surface.

Keywords: Conventional; Crown; Digital; Fit; Impression.

Fig. 1. Artificial tooth preparation and master model fabrication.

Fig. 2. Using (A) the conventional impression technique (B and C) gypsum models fabricated in a master model.

Fig. 3. Using (A) the conventional impression technique (B) gypsum model fabricated in a patient.

Fig. 4. Using (A) the digital impression technique (B and C) polyurethane models fabricated in a master model.

Fig. 5. Using (A) the digital impression technique (B) polyurethane model fabricated in a patient.

Fig. 6. Cast gold crowns fabricated from the conventional (left) and digital (right) impression techniques: (A) in a master model and (B) in a patient.

Fig. 7. Cut silicone replicas of the cast gold crown: (A) in the buccolingual direction and (B) in the mesiodistal direction.

Fig. 8. Measurement points of the thickness of the silicone replica: (A) in the buccolingual direction (capital letter: mesial, and lowercase letter: distal) and (B) in the mesiodistal direction.; absolute marginal discrepancy (A, I, a, i, 1, and 9), the distance between the restoration margin and the abutment margin: internal marginal gap (B, H, b, h, 2, and 8), the perpendicular distance between the restoration and the tooth surface in the marginal-axial plane transition area: internal axial gap (C, G, c, g, 3, and 7), the perpendicular distance between the inner wall of the restoration and the tooth in center of the axial plane: occlusal gap (D, E, F, d, e, f, 4, 5, and 6), the perpendicular distance between the inner wall of the restoration and the tooth in occlusal surface quadrisection points.

Fig. 9. Captured figures after sectioning in the buccolingual direction using a digital microscope camera: (A) the margin, (B) the axial surface, and (C) the occlusal surface. (Magnification: ×100)