Analysis of Flexural Strength and Monotonic Load to Failure Following Simulated Chairside Adjustments and Repair in a Lithium Disilicate Glass-Ceramic
Date of Award
Master of Science (MS)
Thompson, Geoffrey A.
Introduction: There are no studies regarding e.max Press that evaluate post-adjustment healing protocols and their effect on the load to failure in a clinically relevant test. It is essential to find the ultimate treatment protocol which will help clinicians preserve the physical properties of the ceramic restoration after adjustment. Material and Methods: The total number of samples used in this study was 440 IPS e.max press discs. The discs were 15 mm in diameter and 1 mm of thickness. The material was tested for flexural strength and monotonic load to failure. The test was done in two parts and with the same tests. The flexural strength contained 40 specimens per group while the load to failure group had 20 specimens per group. In the biaxial flexural test, the specimens were loaded at 0.5 mm/min until failure using a ring on ring arrangement and the biaxial strength was recorded. The monotonic load to failure specimens were cemented with a resin cement on epoxy resin blocks, and loaded with a 50-mm hemisphere at a cross head speed of 0.5 mm/min. The tests were performed on a universal testing machine (Instron). Weibull statistics determined intergroup differences. Results: In Part I: regarding the flexural strength tests, the Weibull plot and likelihood ratio contour plot revealed a significant difference between the control group and the other groups. Regarding the monotonic load to failure tests, the Weibull plot and likelihood ratio contour plot revealed no significant difference between the control and glazed groups. The diamond adjusted group was significantly different from the control group and the glazed group. In Part II: Regarding the monotonic load to failure, the Weibull plot and likelihood ratio contour plot revealed no significant difference between the tested groups. The strength of all the groups when subjected to glaze treatment after divesting increased in comparison with groups in Part I. Conclusions: Glazing treatment improved the physical properties of adjusted IPS e.max Press discs when subjected to biaxial flexural test and monotonic load to failure. When clinical adjustments are made on the IPS e.max Press intaglio surface, a subsequent glazing treatment is recommended.