Rin-vitro evaluation of fatigue strength of resin matrix ceramics

Koseoglu Sahin M. In-vitro Evaluation of Fatigue Strength of Resin Matrix Ceramics, Hacettepe University Institute of Health Sciences, PhD Thesis in Prosthodontics, Ankara, 2018. Resin matrix ceramics are newly developed ceramic material alternatives that collect the positive properties of all ceramics and composite systems in their structure, have an elastic modulus close to dentin, do not require additional heat treatment, can be easily milled and provide time saving in parallel. However, information on the mechanical properties of these newly developed materials is limited. The purpose of this in-vitro study is; the comparative evaluation of flexural strengths and fatigue strengths of three different resin matrix ceramic materials. To accomplish this study, a total of 105 beams were produced in the form of 2x2x12 mm rectangular prisms from three different ceramic blocks. After error scanning with the optical magnifier, n = 10 samples from each group were subjected to a quasi-static test. On the basis of the findings obtained here, dynamic fatigue tests were performed with n = 25 samples of each group using the "stair-case" method. The fatigue limits of the materials were determined. Scanning electron microscopy was used to examine the structure of the materials and the effect of the dynamic fatigue test on the materials. Normal distributions of data were examined by Shapiro Wilk test. Normal distribution data were compared using one-way ANOVA. Tukey HSD and Tamhane's T2 were used when testing differences among the groups. The causality relationship between stress and cycle was determined using non-linear regression model. Analyzes were conducted at a confidence interval of 0.05. While no statistically significant difference was found between the Lava Ultimate and GC Cerasmart samples in the flexural strength comparison of the materials, the flexural strength of Enamic samples was found to be statistically lower than the other two materials. The fatigue strengths of the materials after dynamic fatigue test were determined as Lava Ultimate, GC Cerasmart and Enamic in descending order. The differences among groups were statistically significant (p<0.05). Keywords: All ceramic, CAD/CAM, hybrid ceramic, polymer infiltrated ceramic, single-tooth restoration, fatigue test, four point bending test