Flexural properties and fatigue resistance of resin-infused feldspathic porcelain

Abstract

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.