Flexural properties and fatigue resistance of resin-infused feldspathic porcelain

PLEASE NOTE: This work is protected by copyright. Downloading is restricted to the BU community: please click Download and log in with a valid BU account to access. If you are the author of this work and would like to make it publicly available, please contact open-help@bu.edu.Unorthodox numbering: xviii leaves of preliminary pages; main text continues this count, begins with "Introduction" on leaf 19 rather than on leaf 1 as is usual.Thesis (DScD) --Boston University, Henry M. Goldman School of Dental Medicine, 2011 (Department of Restorative Sciences and Biomaterials).Includes bibliographic references: leaves 186-193.Objective: The objective of this study were to investigate the characteristics and density of porous ceramic and resin-infused ceramic fabricated from two different powders, to investigate the effect of themocycling on flexural strength of resin-infused ceramic and the fatigue resistance of CAD/CAM fabricated resin-infused ceramic crowns. Materials: Two ceramic powders were used in this study. Urethane dimethacrylate and silane solution were used for fabricating resin-infused ceramics. For cyclic fatigue testing, monolithic crowns were made from resin-infused RIC, resin-infused MK, Vitablocs Mark II, Paradigm MZ1OO, IPS Empress CAD, IPS e.max CAD. Methods: die-pressed porous ceramic blocks were prepared from two different ceramic powders, RIC and MP powder. The blocks were sintered at different temperatures and the density was measured. The porous ceramic blocks were infused with UDMA (Urethane dimethacrylate) resin under vacuum condition. The polymerized resin-infused ceramic blocks were cut into bar-shaped specimens according to ISO 6872 (15 x 2 x 4 mm3) and subjected to three-point bending flexural strength test. Specimens were categorized into two main groups (RIC and MP). In each main group, there were 5 subgroups according to the percent of the ceramic phase (60, 65, 70, 75, and 100%). For a study of themocycling effect, specimens were thermocycled between water temperature of 5[degrees]C and 55[degrees]C in a custom fabricated thermocycling machine. After being thermocycled, specimens were subjected to 3-point bend test. The data were analyzed by using one-way ANOVA, Tukey multiple comparisons and Weibull analysis. Results and Conclusions: The percent ceramic phase showed a significant effect on the flexural strength of resin-infused RIC (p = 0.00). On the other hand, the percent ceramic phase has no significant effect on the flexural strength of resin-infused MK. Thermocycling has a significant effect on both resin-infused RIC and MK (P = 0.00). The load to failure of the fatigued resin-infused RIC, IPS Empress CAD and e.max CAD CAD/CAM mi11ed crowns decreased 20, 10, and 12 %, respectively compared to without cyclic fatigue group. There is no significant effect of the cyclic fatigue on the load to failure of resin-infused MK CAD/CAM milled crowns