Evaluation of Marginal and Internal Fit of Presintered Co‐Cr and Zirconia Three‐Unit Fixed Dental Prosthesis Compared to Cast Co‐Cr

Abstract

Purpose: The precision of soft metal processing technologies is poorly documented. This study compared marginal and internal fit of presintered cobalt-chromium (Co-Cr) and zirconia three-unit fixed dental prostheses (FDPs) to cast Co-Cr. Materials and Methods: Three-unit FDPs were prepared on metal dies (N = 60) from typodont preparations of the maxillary right first premolar and molar. A standardized preparation of a metal-ceramic restoration was done on abutment teeth. The dies (N = 60) were scanned and divided into three groups (n = 20/group) to receive the FDP made of presintered Co-Cr (Ceramill Si), presintered zirconia (Ceramill Zi), and cast Co-Cr (Girobond NB). Each framework was seated on its specific cast. A replica technique was used for marginal and internal discrepancies measurements in mesiodistal and buccolingual planes. Data were analyzed using the Levene test, t-test, and analysis of variance (α = 0.05). Results: When the overall mean discrepancy values were compared in the mesiodistal plane, a significant difference was found between Ceramill Sintron and Ceramill Zi groups (p = 0.026). No significant difference was detected between Girobond NB and Ceramill Sintron groups and between Girobond NB and Ceramill Zi groups (p = 0.537 and p = 0.569, respectively). In the buccolingual plane, there was no significant difference in the overall mean discrepancy between the three groups: CS/CZ (p = 1.000), GI/CS (p = 0.51), and GI/CZ (p = 0.87). Significant differences at several measurement points were found at the inter or intramaterial level. The increase in discrepancy values between marginal and occlusal measurements was evident for the three groups. Conclusions: Presintered three-unit FDPs fabricated from zirconia and Co-Cr exhibited internal and marginal discrepancy values similar to cast Co-Cr. A significant difference was reported between CS and CZ in mesiodistal planes. The axial and marginal differences in values for the three tested groups were below or around the 120 µm clinically acceptable threshold except for the occlusal area. When comparing first premolar to first molar, the internal and marginal discrepancies were similar with no apparent distortion of the framework after the sintering process.

The affects of cement space thickness and material type with application of micro-CT scanner on marginal discrepancy of restoration

“…In other words, the least marginal discrepancy was related to the monolithic zirconia group with 50-micron cement space and the most marginal discrepancy was seen in the Cr-Co alloy group with 30-micron cement space. This results are compatible with Elie E. Daou study that compares marginal discrepancy in zirconia and sintron framework and shows both are clinical acceptance but zirconia has less marginal discrepancy [31]. In the present study, the cement space was determined digitally for the restorations during computerized design.…”

Comparison of marginal and internal adaptation of three‐unit fixed dental prostheses made using CAD/CAM metal‐free materials

“…One hundred stainless-steel dies were used for the master model in this study. Stainless-steel dies prepared with a configuration of 5 mm for abutment height, 1 mm for 120c hamfer, and 6˚angle of convergence in total with 3˚on each wall were designed on a computer numerical control machine to simulate the left lower first premolar and the left lower first molar teeth and the pontic area [32,33] (Figure 1).…”

New generation CAD-CAM materials for implant-supported definitive frameworks fabricated by using subtractive technologies

“…However, the results of studies should be carefully interpreted considering the differences between single crown and complete-arch fabrication methods, and the size of the restoration [ 26 , 27 ]. Daou et al [ 28 ] investigated the marginal accuracy of 3-unit FDPs fabricated with soft-milled alloy, casting Co-Cr alloy, or presintered zirconia. The marginal discrepancy of restorations in all groups was similar and within the clinically acceptable range (<120 μ m).…”