Determination of the slow crack growth susceptibility coefficient of dental ceramics using different methods

Abstract

This study compared three methods for the determination of the slow crack growth susceptibility coefficient (n) of two veneering ceramics (VM7 and d.Sign), two glass-ceramics (Empress and Empress 2) and a glass-infiltrated alumina composite (In-Ceram Alumina). Discs (n = 10) were prepared according to manufacturers' recommendations and polished. The constant stress-rate test was performed at five constant stress rates to calculate n(d) . For the indentation fracture test to determine n(IF) , Vickers indentations were performed and the crack lengths were measured under an optical microscope. For the constant stress test (performed only for d.Sign for the determination of n(s) ) four constant stresses were applied and held constant until the specimens' fracture and the time to failure was recorded. All tests were performed in artificial saliva at 37°C. The n(d) values were 17.2 for Empress 2, followed by d.Sign (20.5), VM7 (26.5), Empress (30.2), and In-Ceram Alumina (31.1). In-Ceram Alumina and Empress 2 showed the highest n(IF) values, 66.0 and 40.2, respectively. The n(IF) values determined for Empress (25.2), d.Sign (25.6), and VM7 (20.1) were similar. The n(s) value determined for d.Sign was 31.4. It can be concluded that the n values determined for the dental ceramics evaluated were significantly influenced by the test method used.

Effect of pH variation on the subcritical crack growth parameters of glassy matrix ceramics

“…Further research is necessary to elucidate the subcritical crack growth behavior of glass‐ceramics in simulated oral environments other than water. In spite of that, the “ n ” values found for feldspar in water agree well with the findings of other studies …”

Effect of fiber addition on slow crack growth of a dental porcelain

“…The slow crack growth (SCG) parameters were evaluated by the constant stress-rate test using five different rates: 10 À 2 , 10 À 1 , 10 0 , 10 1 and 10 2 MPa/s (Gonzaga et al, 2011b). For all groups, 10 specimens were tested at each stress rate, except for 1 MPa/s stress rate, in which 30 specimens were tested to perform Weibull analysis (Ritter, 1995a;Weibull, 1939).…”

Evaluation of glass viscosity of dental bioceramics by the SciGlass information system

“…Glass-based bioceramics used in dental restorations, such as porcelains, glass-ceramics and glass-infiltrated ceramic composites, were introduced in the dental market due to their good biocompatibility, superior aesthetic qualities, high chemical stability, high wear resistance, high resistance to staining, and good mechanical properties [1][2][3]. Porcelains used in monolithic restorations or as a veneering layer over metal or ceramic frameworks are usually processed by sintering and the final microstructure may be completely vitreous or contain an aluminosilicate glassy matrix with crystalline particles, usually leucite (KAlSi 2 O 6 ) [4][5][6].…”