Fractographic and Microhardness Evaluation of All-Ceramic Hot-Pressed and CAD/CAM Restorations after Hydrothermal Aging

Abstract

All-ceramic dental restorations have great advantages, such as highly esthetical properties, a less complex fabrication, and a similar abrasion resistance to enamel. Despite these advantages, ceramic materials are more prone to fracture due to their brittle microstructure. The main aim of this in vitro study was to determine the difference in hot-pressed and milled glass-ceramic mechanical properties such as fracture resistance and microhardness (VHN). Four types of ceramics, two hot-pressed and two milled, feldspathic glass-ceramics and zirconia-reinforced glass-ceramics were selected in this study and tested using the static loading test and Vicker’s testing. Hydrothermal aging, consisting of different baths with temperatures between 5 degrees Celsius and 55 degrees Celsius, was chosen as the in vitro aging method. Statistical analyses are performed using SPSS Statistics software at a significance level of p < 0.05. Micro-hardness values decrease after hydrothermal aging. The static loading test reveals a significant difference between the feldspathic hot-pressed glass-ceramic, which fractures at lower forces, and milled zirconia-reinforced lithium silicate glass-ceramic, which fractures at greater forces (N). Fractographic analysis of the fractured fragments resulted in the static loading test revealing different surface features about the crack origins and propagations under a stereomicroscope.

XANES, EXAFS, Voltammetric, and Microhardness Studies of Manganese Dioxide–Lead–Lead Dioxide Vitroceramics

“…Materials prepared and analyzed as working electrode in the electrolyte solution (5M H 2 SO 4 ) were investigated to determine their Vickers hardness [ 16 ]. This measurement is used to evaluate the defects or micro-cracks occurring after the introduction of electrode materials into the electrolyte solution.…”

Zirconia-Reinforced Lithium Silicate Ceramic in Digital Dentistry: A Comprehensive Literature Review of Our Current Understanding

“…Over the years, different studies investigated the mechanical behavior of ZLS restorations by analyzing the material's physical properties, such as fracture toughness, flexural strength, elastic modulus, or hardness. The majority of in vitro studies have revealed that ZLS restorations exhibit better mechanical properties compared to lithium disilicate ceramics [13,[59][60][61] but worse properties compared to translucent or high-translucency zirconia [62]. Abu-Izze et al [63] conducted a study focusing on the fatigue strength of minimally invasive tabletop restorations.…”

Influences of Different CAD/CAM Ceramic Compositions and Thicknesses on the Mechanical Properties of Ceramic Restorations: An In Vitro Study

“…Monolithic millable blocks provide the definitive restoration of single materials, unlike the multiple layering of the ceramic restoration. This results in higher material qualities, such as a high fracture toughness, hardness, acceptable esthetics, and minimal adjustments in the oral cavity, limiting the extent of ceramic fracture or chipping [ 3 , 4 ]. The improvement in the clinical performance of monolithic restorations may be attributed to the lack of differences in their flexural strength, modulus of elasticity, and thermal expansion coefficient, unlike multilayered ceramic restorations that are composed of several ceramic layers of different compositions [ 5 , 6 ].…”