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

Saiji Shimoe,Hiroto Takenaka,Shogo Iwaguro,Yuki Wakabayashi,Masato Kaku,Tzu-Yu Peng

doi:10.3390/polym12040817

Abstract

Heightened aesthetic considerations in modern dentistry have generated increased interest in metal-free “zirconia-supported dentures.” The lifespan of the denture is largely determined by the strength of adhesion between zirconia and the acrylic resin. Thus, the effect on shear bond strength (SBS) was investigated by using an acrylic resin on two types of zirconia ceramics with differently sized microslits. Micromechanical reticular retention was created on the zirconia surface as the novel treatment (microslits (MS)), and air-abrasion was used as the control (CON). All samples were primed prior to acrylic resin polymerization. After the resin was cured, the SBS was tested. The obtained data were analyzed by using multivariate analysis of variance(α = 0.05). After the SBS test, the interface failure modes were observed by scanning electron microscopy. The MS exhibited significantly higher bond strength after thermal cycles (p < 0.05) than the CON. Nevertheless, statistically comparisons resulted in no significant effect of the differently sized microslits on SBS (p > 0.05). Additionally, MS (before thermal cycles: 34.8 ± 3.6 to 35.7 ± 4.0 MPa; after thermal cycles: 26.9 ± 3.1 to 32.6 ± 3.3 MPa) demonstrated greater SBS and bonding durability than that of CON (before thermal cycles: 17.3 ± 4.7 to 17.9 ± 5.8 MPa; after thermal cycles: 1.0 ± 0.3 to 1.7 ± 1.1 MPa), confirming that the micromechanical retention with laser-milled microslits was effective at enhancing the bonding strength and durability of the acrylic resin and zirconia. Polycrystalline zirconia-based ceramics are a newly accessible material for improving removable prosthodontic treatment, as the bond strength with acrylic resin can be greatly enhanced by laser milling.

Highlights

Metal alloys, such as cobalt-chromium, titanium, and gold, are widely used in removable prosthodontic treatment as materials for the frameworks of removable particle dentures (RPDs).These metal alloys possess favorable characteristics, such as excellent mechanical strength and thermal conductivity
The current study did not conduct experiments pertaining to the surface roughness; other published papers have reported that the surface roughness of the air-abrasion with Al2 O3 was approximately 0.23 μm for yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) and 0.24 μm for Ce-TZP/A [23]
The findings of this study confirmed that laser treatment is an effective mechanical process that can improve the bonding strength of acrylic resin and zirconia ceramics

Summary

Introduction

Metal alloys, such as cobalt-chromium, titanium, and gold, are widely used in removable prosthodontic treatment as materials for the frameworks of removable particle dentures (RPDs). These metal alloys possess favorable characteristics, such as excellent mechanical strength and thermal conductivity. The demand for metal-free treatments has increased due to various factors, such as escalating precious metal prices [1], concerns regarding metal allergies [2], and increased emphasis on aesthetics [3]. Due to factors such as health, anatomy, psychology, and economics, Polymers 2020, 12, 817; doi:10.3390/polym12040817 www.mdpi.com/journal/polymers. RPD treatment may reduce the physical and mental burden on elderly patients, before and after treatment, and rehabilitate the oral function and improve the psychological and social adaptation

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