Can low-fusing glass application affect the marginal misfit and bond strength of Y-TZP crowns?

Monize Carelli Felipe Antunes,Rodrigo Othávio De Assunção E Souza,Ronaldo Luís Almeida De Carvalho,Fabíola Pessôa Pereira Leite,Jean Soares Miranda,Rodrigo Furtado De Carvalho,Estevão Tomomitsu Kimpara

doi:10.1590/1807-3107bor-2018.vol32.0034

Monize Carelli Felipe Antunes, Rodrigo Othávio De Assunção E Souza + Show 5 more

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https://doi.org/10.1590/1807-3107bor-2018.vol32.0034

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Abstract

To evaluate the effect of different surface treatments on the marginal misfit and retentive strength between Y-TZP crowns and an epoxy resin. Forty (40) epoxy resin (G10) abutments (height: 5mm, conicity: 60, finish line: large chamfer) with equal dimensions were milled and included in polyurethane to simulate the periodontal ligament. Next, 40 Y-TZP crowns (thickness: 1mm) were milled (Cerec in Lab) and randomly divided into four groups (n=10) according to the surface treatment: GS(glaze spray), GP(glaze powder/liquid), P(zirconia primer) and RS(tribochemical silica coating). The conditioned surfaces were cemented with dual self-adhesive cement, light cured and submitted to thermomechanical cycling (2x106, 100N, 4Hz, 5°/55°C). Marginal misfit was analyzed by a stereomicroscope and SEM. Retentive strength test was performed (1mm/min) until crown debonding. Glaze layer thickness was also performed to GS and GP groups. Marginal misfit data were analyzed by Kruskal Wallis and Dunn tests; one-way ANOVA and Tukey (5%) analyzed the tensile strength data. The marginal misfit of the GS (48.6±19.9μm) and GP (65.4±42.5μm) were statistically lower than the RS (96±62.9μm) and P (156±113.3μm) (p=0.001). The retentive strength of the GP (470.5±104.1N) and GS (416.8±170.2N) were similar to the P (342.1±109.7N), but statistically higher than those of the RS (208.9±110N). The GS and GP glaze layer was 11.64μm and 9.73μm respectively. Thus, glaze application promoted lower marginal discrepancy and higher retentive strength values than conventional techniques.

Highlights

An important factor for successful ceramic restorations is a correct cementation protocol
Several surface treatments have been proposed to improve bonding between Y-TZP and adhesive cements such as sandblasting with aluminum oxide particles,[3,4] Er:YAG laser irradiation,[1,5] sandblasting with aluminum oxide particles coated with silica followed by silanization,[2,6,7,8] use of MDP monomer-based resin cement,[5,7,8,9] metallic primers,[1,3,4,5,8,9,10,11,12] selective infiltration,[8,13] and plasma spraying.[7,8]
Another proposed treatment is the vitrification of the Y-TZP surface through the application of a thin layer of glaze on the inner surface of the crown, which can be etched by hydrofluoric acid and silanized, creating micro retentions and chemical reactivity similar to the union mechanisms of vitreous ceramics

Summary

Introduction

An important factor for successful ceramic restorations is a correct cementation protocol. The ideal cementation protocol for Y-TZP ceramic crowns is still not well defined, since these ceramics cannot be etched by hydrofluoric acid, as occurs with silica-based ceramics.[1,2] several surface treatments have been proposed to improve bonding between Y-TZP and adhesive cements such as sandblasting with aluminum oxide particles,[3,4] Er:YAG laser irradiation,[1,5] sandblasting with aluminum oxide particles coated with silica followed by silanization,[2,6,7,8] use of MDP (methacryloxydecyl dihydrogen phosphate) monomer-based resin cement,[5,7,8,9] metallic primers,[1,3,4,5,8,9,10,11,12] selective infiltration,[8,13] and plasma spraying.[7,8]. Vanderlei et al.,[18] concluded that vitrification significantly improved adhesion between Y-TZP and resin cement

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