Evaulation of the fracture strength and fit of laser sintering, casting and zirconia frameworks

ABSTRACT Kavvas Çelik, E. (2021). Evaluation of Fit and Fracture Strength of Casting, Laser Sintering and Zirconia Frameworks. İstanbul University, Institute of Health Science, Department of Prosthodontics. PhD Thesis. Istanbul. Marginal and internal fit is one of the most important factors in the long term success of fixed dental prostheses (FDP). Poor marginal and internal fit of restorations can cause many biological and mechanical complications. It is known that the presence of curvature in restorations and veneering to frameworks have an effect on the fit of the restorations. In this study, we aimed to evaulation of the effect of curvature and veneering on fit in FDPs obtained with different production methods and framework's materials; investigation of the effect of curvature on fracture strength; examine the correlation between fit and fracture strength. Two different master models were designed in the 4-unit linear bridge restoration in the posterior region and in the 6-unit curved bridge restoration in the anterior region. Frameworks were produced from Co-Cr metal alloy by casting and laser sintering methods and from zirconia material by milling method. The fit of the frameworks before and after veneering was evaluated using the three dimensional optical scanning method. Then, four point bending test was applied and fracture strength was evaluated. According to the results, significant differences were found in terms of the fit between linear/curved configuration and before/after veneering. According to different manufacturing techniques and framework material, it has been determined that the curved configuration has different effects on the fracture strength. Key Words: casting, laser sintering, zirconia, fit, fracture strength The present work was supported by the Research Fund of Istanbul University. Project No. 34441