Effect of microslit retention on the bond strength of zirconia to dental materials

Abstract

The aim of this study was to investigate the effect of microslits formed by Nd:YVO4 laser beam machining on the bond strength between two types of zirconia, yttria-partially stabilized zirconia (Y-TZP) and ceria-partially stabilized zirconia/alumina nanocomposite (Ce-TZP/A), and porcelain or two types of resin. Zirconia disks were divided into three groups: 1) non-treated (NT); 2) blasted with alumina particles (AB); 3) microslits fabricated on a zirconia surface by laser beam machining (MS). After veneering porcelain or resins on zirconia specimens, halves of the resin specimens were thermocycled up to 20,000 cycles. The shear bond strength between porcelain and both types of zirconia was not improved by the microslits. Before and after thermocycling, the bond strength between an indirect composite resin or acrylic resin and Y-TZP with microslits was the highest. It was concluded that the microslits on Y-TZP enabled micromechanical interlocking and improved the bond strength and durability of the resins.

Laser-Milled Microslits Improve the Bonding Strength of Acrylic Resin to Zirconia Ceramics

“…When acrylic resin bonds to a metal alloy (after priming and air-abrasion), the literature SBS values obtained after thermal cycling were 2.48 ± 0.66 MPa (cobalt-chromium alloy), 1.96 ± 0.78 MPa (titanium alloy), and 1.07 ± 0.74 MPa (gold alloy) [17]. In the case of acrylic resin bonded to zirconia ceramics, as shown by Iwaguro et al [25], even after priming and air-abrasion treatment, the SBS values obtained after thermocycling could not be evaluated (0 MPa). The results of the present study are in accordance with the previously mentioned reports (SBS values < 2 MPa) and infer that the bond strength might not be sufficient for long-term usage.…”

“…However, computer numerical control (CNC) lasers are widely used in the field of engineering science for tasks such as the manufacturing of molds or lettering, and the production of microscopic surface textures on various materials. Therefore, we utilized a CNC laser with neodymium-doped yttrium orthovanadate (Nd: YVO 4 ) to make microslits on the surface of zirconia ceramics [25]. The reproducibility of the microslit topography was improved by adjusting laser parameters [25].…”

“…Therefore, we utilized a CNC laser with neodymium-doped yttrium orthovanadate (Nd: YVO 4 ) to make microslits on the surface of zirconia ceramics [25]. The reproducibility of the microslit topography was improved by adjusting laser parameters [25]. Three isometric grid microslits (Figure 1) of different sizes (50, 75, and 100 µm) were created on the surface of the zirconia ceramics in order to analyze the effect of microslit size on bonding strength.…”

“…In the last decade, with the advancement of laser techniques, the use of lasers as an alternative pretreatment method for dental procedures has become prevalent, such as by applying laser treatment to dental materials to improve the bonding properties between materials and resin-based luting agents [24] or materials and porcelain [25]. This resulted in the attempted use of lasers as a surface treatment method for zirconia ceramics, in order to enhance the bonding strength and durability of a number of dental materials by altering the surface microstructures [26][27][28].…”

“…Some studies have reported that lasers improve the bond strengths of zirconia ceramics and other substrate materials; however, other studies have shown contradictory results [29][30][31]. Furthermore, studies evaluating the bonding between zirconia ceramics and acrylic resin are limited; there is only one related published study on the effect of microslit retention on the bond strength of zirconia to dental materials [25]. Therefore, research in the area of laser-milled microslits is critical for improving RPDs and will ultimately serve the future of clinical dentistry.…”