Effect of surface treatment on the shear bond strength of a resin-based cement to porcelain

Marcos Paulo Nagayassu,José Eduardo Junho De Araújo,Eduardo Shigueyuki Uemura,Luciana Keiko Shintome

doi:10.1590/s0103-64402006000400005

Abstract

The purpose of this in vitro study was to evaluate the effect of different surface treatments on the shear bond strength of a resin-based cement to porcelain. Sixty pairs of 50% aluminous porcelain discs were fabricated. In each pair, one disc measured 6 mm in diameter X 3 mm thickness (A) and the other measured 3 mm in diameter X 3mm thickness (B). The specimens were randomly assigned to 6 groups (n=10 pairs of discs), according to the surface treatment: etching with 10% hydrofluoric acid for 2 or 4 min (G1 and G2); 50-microm particle aluminum oxide sandblasting for 5 s (G3); sandblasting followed by etching for 2 or 4 min (G4 and G5) and control--no treatment (G6). A silane agent was applied to the treated surface of both discs of each pair. Bistite II DC dual-cure resin cement was applied and the B discs were bonded to their respective A discs. Specimens were stored in distilled water at 37 degrees C for 24 h and were tested in shear strength at a crosshead speed of 2 mm/min. Means in MPa were: G1: 14.21 +/- 4.68; G2: 8.92 +/- 3.02; G3: 10.04 +/- 2.37; G4: 12.74 +/- 5.15; G5: 10.99 +/- 3.35; G6: 6.09 +/- 1.84. Data were compared by one-way ANOVA and Tukey's test at 5% significance level. Bond strength recorded after 2-min acid etching was significantly higher than 4-min etching (p<0.05) and control (p<0.05), but did not differ significantly from sandblasting alone (p>0.05) or followed by etching for 2 or 4 min (p>0.05). Within the limitations of an in vitro study, it may be concluded that 2-min hydrofluoric acid etching produced a favorable micromechanical retention that enhanced resin cement bond strength to porcelain.

Highlights

When cavities exceed the limits recommended for direct composite fillings, indirect restorations employing tooth-colored materials have been indicated in order to minimize the effects of polymerization shrinkage and provide and adequate proximal contouring
The increasing use of ceramic restorations has led to the development of a wide array of resin cements in order to provide improved esthetics and optimal bond strength
Chemical retention is achieved with the use of silane agents that reacts with the vitreous compounds of the ceramic and with the composite organic matrix [2]

Summary

Introduction

When cavities exceed the limits recommended for direct composite fillings, indirect restorations employing tooth-colored materials have been indicated in order to minimize the effects of polymerization shrinkage and provide and adequate proximal contouring. The use of ceramic restorations became widespread due to the possibility of bonding these restorations to enamel and dentin with an adhesive system. Aluminous porcelain presents 40-50% more aluminum oxide crystals than feldspathic porcelain, increasing the hardness and reducing the thermal expansion coefficient. This kind of material is indicated for laminate veneers, inlays/onlays and as covering material for porcelain crowns. The increasing use of ceramic restorations has led to the development of a wide array of resin cements in order to provide improved esthetics and optimal bond strength. The clinical performance of ceramic restorations, is directly related to the properties and type of luting agent employed

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