INFLUENCE OF PORCELAIN FIRING AND CORE THICKNESS ON MARGINAL GAP OF CAD/CAM AND PRESSABLE ALL-CERAMIC CROWNS (IN-VITRO STUDY)

Document Type : Original Article

Authors

1 Associate Professor, Fixed Prosthodontics Department, Faculty of Dentistry, Cairo University, Giza, Egypt.

2 Associate Professor, Endodontic Department, Faculty of Dentistry, Cairo University, Giza, Egypt

Abstract

Statement of Problem: Marginal gap is important for the long-term success of all-ceramic restorations, the marginal accuracy of different manufacturing techniques and core thicknesses must be considered.
Purpose: This study compared marginal gap of CAD/CAM and heat-pressed ceramic cores with different thicknesses before and after veneering porcelain application.
Materials and Methods: A standard die was prepared. Sixty resin dies were duplicated. Samples were divided into two groups, Group I: samples were fabricated by CAD/CAM, Group II: samples were fabricated by heat pressing. Each group was divided into three subgroups: Subgroup 1: cores of 0.3 mm. thickness, Subgroup 2: cores of 0.5 mm. thickness, Subgroup 3: full contoured crowns were manufactured by characterization technique. marginal gap was measured at core stageand after veneering porcelain firings using a microscope .
Results: Marginal gaps of CAD/CAM samples in all subgroups were higher than pressable(P˂0.05), A significant increase in the marginal gap was observed after porcelain firing, Full contour crowns recorded the lowest marginal gap(58.54±9.1, 32.76±8.5) followed by 0.5mm.( 66.7±8.4, 40.06±4.1) while 0.3mm. thickness recorded the highest value (81.14±12.3, 47.96±7.15). Significant difference in pre-firing and post firing gap values in 0.3mm. thickness(P=0.001), while in 0.5mm. thickness and full contour there were no significant difference (P=0.657 and 0.88 respectively). no statistically significant difference in mean marginal gap between 0.5 mm. and 0.3mm. at both pre-firing and post-firing.
Conclusion: Marginal gap were all within the clinically acceptable range. Marginal gap increased after porcelain firing. for esthetic reasons, 0.3mm core thickness can be used instead of 0.5mm.

Keywords

Egyptian Dental Journal
Volume 67, Issue 3 - Serial Number 4
July (Fixed Prosthodontics, Removable Prosthodontics and Dental Materials)
July 2021
Pages 2377-2385

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