Effect of sandblasting on the long‐term performance of dental ceramics

Abstract

A study has been made of the effects of sandblasting on the strength of Y-TZP and alumina ceramic layers joined to polymeric substrates and loaded at the top surfaces by a spherical indenter, in simulation of occlusal contact in ceramic crowns on tooth dentin. The sandblast treatment is applied to the ceramic bottom surface before bonding to the substrate, as in common dental practice. Specimens with polished surfaces are used as a control. Tests are conducted with monotonically increasing (dynamic) and sinusoidal (cyclic) loading on the spherical indenter, up to the point of initiation of a radial fracture at the ceramic bottom surface immediately below the contact. For the polished specimens, data from the dynamic and cyclic tests overlap, consistent with a dominant slow crack growth mode of fatigue. Strengths of sandblasted specimens show significant reductions in both dynamic and cyclic tests, indicative of larger starting flaws. However, the shift is considerably greater in the cyclic data, suggesting some mechanically assisted growth of the sandblast flaws. These results have implications in the context of lifetimes of dental crowns.

Effect of air-particle abrasion protocols on the biaxial flexural strength, surface characteristics and phase transformation of zirconia after cyclic loading

“…However, data concerning the strength of zirconia after surface conditioning protocols specifically using abrasives are limited (Kosmac et al, 1999(Kosmac et al, , 2000Zhang et al, 2004Zhang et al, , 2005Zhang et al, , 2006. Therefore, this study was undertaken to evaluate the effect of deposition of different particle types on the mechanical properties and structure of zirconia.…”

“…Larsson et al (2007) subjected FDPs to mechanical cycling for 10.000 cycles at 1 Hz under loads ranging between 30 and 300 N. Since the aim of this study was to evaluate the effect of cyclic loading on zirconia without fracturing the specimens prior to flexural tests, it was decided to perform 20.000 cycles with a 50 N load. Zhang et al (2004) stated that the strengths of air-abraded zirconia specimens show significant reduction in strength after both dynamic and cyclic tests where the specimens presented large starting flaws. In that study, zirconia specimens were air-abraded using 50 µm Al 2 O 3 .…”

“…Silica-modified particle deposition is chemically more reactive to the resin as they require application of silane coupling agents promoting wettability of the resin, the so-called tribochemical silica coating (Guggenberger, 1989). Against its advantages, while increasing the surface roughness of a zirconia (Della Bona et al, 2007), air-particle abrasion may cause flaws and defects on 4 zirconia (Zhang et al, 2004(Zhang et al, , 2005(Zhang et al, , 2006. Despite the phase transformation and compressive stresses that could prevent crack growth, its strength decreases.…”

“…Moreover, it has been shown that under cycling loading in a wet medium, the crack propagation velocity increases (De Aza et al, 2002;Zhou et al, 2007;Huang et al, 2008). There have been some concerns regarding the application of air-abrasion protocols on the long-term behaviour of zirconia (Kosmac et al, 1999(Kosmac et al, , 2000Zhang et al, 2004Zhang et al, , 2005Zhang et al, , 2006.…”

“…In fact, abrasive particles vary in morphology and it can be anticipated that their impact on the zirconia surface may vary as a function of their morphology and other deposition parameters. Previous studies concentrated mainly on the effect of most commonly used Al 2 O 3 particles (Kosmac et al, 1999(Kosmac et al, , 2000Zhang et al, 2004Zhang et al, , 2005Zhang et al, , 2006 but to the authors` best knowledge, it is not known whether small size silica coated particles with more favorable morphology may result in less transformation into a monoclinic phase or not. Since surface conditioning of cementation surfaces of zirconia FDPs is a common practice in dentistry, the maintenance of mechanical properties of zirconia after these procedures is essential.…”