Abstract
The objective of this study was to evaluate the tensile (sigma(t)) and shear bond strength (sigma(s)) of a glass-infiltrated alumina-based zirconia-reinforced ceramic (IZ--Vita In-Ceram Zirconia) to a composite resin, testing the hypothesis that silica coating (SC--Cojet, 3M-Espe) produces higher bond strength values than other ceramic surface treatments. Specimens were fabricated and tested according to the manufacturers' instructions, and to ISO6872 and ISO11405 specifications. Sixty IZ disk specimens were polished through 1 microm and divided into 3 groups (n = 20) according to the following surface treatments: HF - 9.5% hydrofluoric acid (Ultradent) for 1 min; SB--sandblasting with 25-microm aluminum oxide particles for 10 s; SC--silica coating for 10 s. Silane (3M-Espe), adhesive (Single Bond, 3M-Espe) and a composite resin cylinder (Z100, 3M-Espe) were applied and polymerized to the treated bonding area (3.5 mm in diameter). Ten specimens from each group (n = 10) were tested for sigma(t) and ten specimens were tested for sigma(s), using a universal testing machine (EMIC DL 2000) at a crosshead speed of 1 mm/min. The data were statistically analyzed by ANOVA and Tukey tests (alpha = 0.05). The mean and standard deviation values (MPa) and statistical groupings for sigma(t) were: HF - 3.5 +/- 1.0a; SB - 7.6 +/-1.2b; and SC - 10.4+/-1.8c. For sigma(s), the values were: HF - 10.4 +/- 3.1A; SB - 13.9+/- 3.1B; and SC - 21.6 +/- 1.7C (p < 0.05). The groups presented the same statistical ranking of mean values for both test methods. The SC-treated IZ ceramic presented a significant increase in mean bond strength values for both test methods, confirming the study hypothesis.
Highlights
Restoring partially destructed teeth using indirect ceramic restorations such as inlays, onlays and laminate veneers has been encouraged by the development of adhesive materials and techniques
The results revealed a higher bond strength after silica coating
Light microscopy analysis of the fractured surfaces demonstrated that all specimens fractured at the adhesive interface, leaving small areas of resin on the ceramic surface, characterizing a cohesive fracture at the interface
Summary
Restoring partially destructed teeth using indirect ceramic restorations such as inlays, onlays and laminate veneers has been encouraged by the development of adhesive materials and techniques. Adhesive techniques allow the brittle and “fragile” ceramic to become a reliable tooth-restoration system with an adequate stress distribution to the underlying tooth structure.[5]. In the fabrication of ceramic structures by the In-Ceram systems, an alumina-based porous framework is infiltrated with a lanthanum oxidebased glass.[10,16] This high crystalline content ceramic structure has a flexural strength that is three to four times higher than that of feldspathic ceramics.[10,22] The toughening mechanisms of the In-Ceram structure is based on crack deflection and impediment by the alumina particles, which deviate or block the crack propagation, and the pre-stressing mechanism where an area of compressive stress in the glass around alumina particles may lead to crack deflection.[10]
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