Influence of zirconia surface treatments of a bilayer restorative assembly on the fatigue performance

Abstract

This study evaluated the influence of different surface treatments of zirconia used to enhance bonding with veneering porcelain, and thermocycling on the resistance to porcelain cracking and delamination during fatigue test. Methods: Bilayer ceramic discs were made from zirconia blocks (IPS e.max Zircad MO, Ivoclar Vivadent-0.7 mm thickness) and randomized into 8 groups (n= 15) according to two factors: 'zirconia surface treatment' (Control; Grinding-diamond bur; Air-abrasion-aluminum oxide particles; and Liner-application of a ceramic liner [IPS e.max Zirliner, Ivoclar Vivadent]); and 'thermocycling' (presence-12,000 thermal cycles; 5-55ºC; or absence). The discs were veneered with porcelain (IPS e.max Ceram, Ivoclar Vivadent-0.7 mm; totaling 1.4 mm thickness) according to ISO 6872:2015 for biaxial flexure strength testing. Fatigue tests (step-stress approach; 20 to 100 MPa; step of 10 MPa; 10,000 cycles per step; 10 Hz frequency) were run, followed by the data analysis (Kaplan-Meier and Mantel-Cox post-hoc tests). Analysis of roughness, topography, crystallographic phase arranges and fractography were also executed. Results: The surface treatment and thermocycling did not influence the porcelain crack nor delamination resistance. When only comparing the surface treatments for crack resistance outcome, the liner application depicted the worst fatigue performance in comparison to grinding and air-abrasion, while all groups were similar for delamination. Conclusions: Neither the surface treatment of the zirconia nor the thermocycling influences the porcelain crack resistance or the resistance to delamination of the bilayer porcelain-veneered zirconia specimens.

Bonding Effectiveness of Zirconia to Veneering Ceramic after Different Sandblasting Treatments

“…Harding et al supported previous studies that revealed that sandblasting with alumina particles did may affect roughness [20,23] but, on the other hand, may decrease flexural strength [23]. Valandro et al stated that neither the surface treatment of zirconia nor the thermocycling influences the porcelain crack resistance or the resistance to delamination of bilayer porcelain-veneered zirconia specimens [39].…”

“…The tribochemical silica coating achieved by using the Cojet system spread a silica layer on the ceramic surface, due to the high-pressure impact of alumina particles modified by silica on the conditioned substrate [21,38]. Such a technique is supposed to provide ultrafine mechanical retention by embedding treated surfaces with silica particles and improve chemical bonding [21,39,40]. Different punctual micro-analysis conducted on the cross section of the specimens at the interface zirconiaveneering ceramic pointed out that silica coating generated a reaction area.…”

Fracture strength of porcelain veneer on surface-treated zirconia

“…In contrast, we prepared the specimens in the present study by either diamondgrinding or sandblasting to isolate the influence of each treatment. Machado et al also investigated the crack and delamination resistance of bilayered zirconia and compared three surface-treatment groups: sandblasted, ground, and liner-applied 33) . The liner-applied zirconia exhibited the lowest fatigue performance in terms of crack resistance; however, no statistical differences in delamination resistance were observed among the groups.…”