Purpose: The fit alteration after ceramic layering of soft Cobalt-Chromium (Co-Cr) and zirconia is poorly documented. This study compared the marginal and internal fit of presintered Co-Cr and zirconia three-unit fixed dental prostheses before and after ceramic veneering.
Materials And Methods: Co-Cr master model was prepared and duplicated 60 times to receive three-unit fixed dental prostheses (FDPs). Sixty dies were prepared, scanned and assigned to 3 groups (n = 20/group), to receive the FDPs made of presintered Co-Cr (CS), presintered zirconia (CZ) and cast Ni-Cr (Wi). Each framework was seated on its specific cast. A replica technique was used for marginal and internal discrepancy measurements in mesiodistal and buccolingual planes. Frameworks were ceramic veneered. Results were compared before and after ceramic layering within each group. Data were analyzed using the Levene, t test, and ANOVA (α = 0.05).
Results: Significant difference was found when gaps were compared within groups for CS and CZ but not for Wi. At the abutments level, significant difference was found for both premolars and molars in the buccolingual planes (p < 0.001). A multiple comparison between materials tested showed significant differences between presintered and cast Ni-Cr. No significant difference was detected between CS and CZ (p = 1.000).
Conclusions: Although ceramic layering increased the discrepancy for presintered Co-Cr and zirconia, the marginal adaptation remained clinically acceptable.
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http://dx.doi.org/10.1111/jopr.13336 | DOI Listing |
J Biomed Mater Res B Appl Biomater
January 2025
Dental Materials Unit, Center for Dental Medicine, Clinic for Masticatory Disorders and Dental Biomaterials, University of Zurich, Zurich, Switzerland.
The purpose of this study was to evaluate the characteristics of the ceramic bonding to cobalt-chromium (Co-Cr) alloys fabricated by casting, milling, and additive manufacturing, compared with zirconia and nickel-chromium. One hundred specimens (N = 100), prepared with the dimensions of 25 × 3 × 0.5 mm, were assigned to five groups (n = 20): presintered milled Co-Cr (Group M), additively manufactured Co-Cr (Group SLM), cast Co-Cr (Group C), presintered zirconia (Group Zi), and cast Ni-Cr (Group Ni).
View Article and Find Full Text PDFJ Indian Prosthodont Soc
April 2024
Department of Public Health, Faculty of Medical Sciences, Lebanese University, Beirut, Lebanon.
J Prosthet Dent
August 2023
Lecturer, Department of Prosthodontics/Dental Materials Science, Institute of Odontology, The Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden; Researcher, Centre for Clinical Research Sörmland, Uppsala University, Eskilstuna, Sweden.
Statement Of Problem: Cobalt chromium (Co-Cr) alloys possess beneficial mechanical properties because alloys, even in thin sections, can resist high mastication forces and exhibit an acceptable bond to the surface porcelain layer. Traditional manufacturing techniques of Co-Cr alloys such as casting have been replaced with newer fabrication techniques, such as milling, laser melting, and presintered milling. Despite scarce documentation, these new manufacturing techniques are being used to fabricate dental and implant constructions.
View Article and Find Full Text PDFInt J Oral Maxillofac Implants
April 2023
To evaluate the marginal accuracy of soft-milled cobalt-chromium (Co-Cr) compared to other construction methods/restorative materials in tooth/implant-supported restorations. PICO questions were defined, and a systematic search was conducted in six electronic databases. Titles and abstracts were collected and screened by two independent reviewers.
View Article and Find Full Text PDFPurpose: Internal and marginal fit accuracy of an implant-supported fixed partial denture (I-FPD) along with passive fit are required for long-term clinical success. This study compared the fit accuracy of three-unit CAD/CAM-fabricated cementretained I-FPDs milled from pre-sintered cobalt-chromium (Co-Cr) and zirconia (Zr) and evaluated the effect of applying porcelain.
Materials And Methods: Two implant analogs were positioned parallel at first premolar and first molar sites in an acrylic model.
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