Surface conditioning of a composite used for inlay/onlay restorations: effect on muTBS to resin cement

To assess the effect of the composite surface conditioning on the microtensile bond strength of a resin cement to a composite used for inlay/onlay restorations.

Forty-two blocks (6 x 6 x 4 mm) of a microfilled composite (Vita VMLC) were produced and divided into 3 groups (N = 14) by composite surface conditioning methods: Gr1--etching with 37% phosphoric acid, washing, drying, silanization; Gr2--air abrasion with 50-lm Al203 particles, silanization; Gr3--chairside tribochemical silica coating (CoJet System), silanization. Single-Bond (one-step adhesive) was applied on the conditioned surfaces and the two resin blocks treated with the same method were cemented using RelyX ARC (dual-curing resin cement). The specimens were stored for 7 days in water at 37 degrees C and then sectioned to produce nontrimmed beam samples, which were submitted to microtensile bond strength testing (muTBS). For statistical analysis (one-way ANOVA and Tukey's test, alpha = 0.05), the means of the beam samples from each luted specimen were calculated (n = 7).

muTBS values (MPa) of Gr2 (62.0 +/- 3.9a) and Gr3 (60.5 +/- 7.9a) were statistically similar to each other and higher than Gr1 (38.2 +/- 8.9b). The analysis of the fractured surfaces revealed that all failures occurred at the adhesive zone.

Conditioning methods with 50-lm Al203 or tribochemical silica coating allowed bonding between resin and composite that was statistically similar and stronger than conditioning with acid etching.