Improved Resin–Zirconia Bonding by Room Temperature Hydrofluoric Acid Etching

Abstract

This in vitro study was conducted to evaluate the shear bond strength of “non-self-adhesive” resin to dental zirconia etched with hydrofluoric acid (HF) at room temperature and to compare it to that of air-abraded zirconia. Sintered zirconia plates were air-abraded (control) or etched with 10%, 20%, or 30% HF for either 5 or 30 min. After cleaning, the surfaces were characterized using various analytical techniques. Three resin cylinders (Duo-Link) were bonded to each treated plate. All bonded specimens were stored in water at 37 °C for 24 h, and then half of them were additionally thermocycled 5000 times prior to the shear bond-strength tests (n = 12). The formation of micro- and nano-porosities on the etched surfaces increased with increasing concentration and application time of the HF solution. The surface wettability of zirconia also increased with increasing surface roughness. Higher concentrations and longer application times of the HF solution produced higher bond-strength values. Infiltration of the resin into the micro- and nano-porosities was observed by scanning electron microscopy. This in vitro study suggests that HF slowly etches zirconia ceramic surfaces at room temperature, thereby improving the resin–zirconia bond strength by the formation of retentive sites.

Chemical interaction mechanism of 10-MDP with zirconia

“…However, HF etching is less effective at zirconia3. Recently, several studies revealed that to be effective HF etching of zirconia requires a longer application time, a higher concentration of HF and/or a higher temperature, such as 9.5% HF at 80 °C for 1 min or at 25 °C for 1 h, or 48% HF at 25 °C for 30 min4, 20% or 30% HF for 30 min5, or 48% HF at 100 °C for 25 min6. Therefore, recent investigations have recommended alumina air-abrasion to increase the bond strength of composite cement to zirconia; it increases the surface area for micro-mechanical interlocking78.…”

Surface wettability and nano roughness at different grit blasting operational pressures and their effects on resin cement to zirconia adhesion

“…Contact angle tensiometer (Theta Lite, Dyne Technology, Staffordshire, UK) was used to estimate the differences in contact angle between grit-blasted ZrO 2 surfaces at different air pressures. The water contact angle was measured after 30 s according to the study protocols 7,16) .…”

“…Today, yttria (Y2O3)-stabilized polycrystalline tetragonal zirconia (Y-TZP) is a frequently used ceramic material for fixed prosthodontics, largely because of its favorable mechanical properties 7,8) . However, the relative inertness of ZrO2 renders its surface less reactive 7,9) .…”

“…Today, yttria (Y2O3)-stabilized polycrystalline tetragonal zirconia (Y-TZP) is a frequently used ceramic material for fixed prosthodontics, largely because of its favorable mechanical properties 7,8) . However, the relative inertness of ZrO2 renders its surface less reactive 7,9) . Various surface treatment methods have been advocated to roughen and/or activate the ZrO 2 surface for adhesion with resin cements 8,10) .…”

Efeitos de diferentes tratamentos de superfície nas características superficiais, resistência adesiva, estabilidade da adesão e sobrevida de coroas/pilares de Y-TZP obtidos por CAD/CAM após ciclagem termomecânica e fadiga termomecânica acelerada

“…Pesquisas têm sido desenvolvidas na perspectiva de utilização de ácidos em concentrações e tempos distintos para promover micromodificações na superfície da zircônia e favorecer o processo de adesão (Zarone et al, 2006;Xie et al, 2013;Menani et al, 2014;Sriamporn et al, 2014;Zandparsa et al, 2014;Lee et al, 2015;Cho et al, 2017). Menani et al, 2014, mostraram que o ácido fluorídrico 40% (HF 40%) aplicado por 210 segundos na superfície da Y-TZP foi capaz de aumentar significativamente a resistência adesiva à dentina bovina quando utilizado em associação ao cimento resinoso Panavia F. Ácidos com concentrações elevadas parecem ser capazes de condicionar a superfície de zircônia, promover microretenções e favorecer o processo de adesão.…”