Abstract
BackgroundRepairs in composite resin restorations are common procedures in clinical practice. Many surface treatment options have been proposed to improve the adhesion between the old and new composite. The objective of this study was to evaluate the microtensile bond strength of repairs performed on aged bulk fill and conventional composites after different adhesion protocols.Material and MethodsFirst, 84 specimens (8x8x4 mm3) of a microhybrid composite and a high-viscosity bulk fill composite were prepared and aged. Afterward, they received a mechanical surface treatment by means of abrasion with a diamond bur, followed by division into six groups according to the adhesion protocol employed: PSA - etching with 35% phosphoric acid + silane + etch-and-rinse adhesive; SA - silane + etch-and-rinse adhesive; PA - etching with 35% phosphoric acid + etch-and-rinse adhesive; A - etch-and-rinse adhesive; PU - 35% phosphoric acid + universal adhesive; and U - universal adhesive. The repairs were performed with a microhybrid composite. Repaired resin blocks were cut into sticks (8x1x1 mm3) and submitted to a microtensile test. Fractured specimens were evaluated to determine the failure pattern (adhesive or cohesive). Data were analyzed by two-way ANOVA.ResultsNo statistically significant differences were found in bond strength values among different adhesion protocols and composite types.ConclusionsThe repair bond strength of a bulk fill composite was similar to that found in a conventional composite, with no distinction among adhesion protocols. Key words:Dental restoration repair, composite resins, adhesiveness.
Highlights
Resin-based composite restorations are routinely performed in clinical dental practice due to the favorable properties of the resinous materials, especially related to aesthetics and the evolution of adhesive systems that allow minimally invasive preparations (1,2)
The aim of this study was to assess the influence of six different types of adhesion protocols on microtensile bond strength of repairs performed on aged bulk fill and microhybrid composite resins
The repair bond strength of composites is usually measured by means of the shear bond or microtensile bond strength tests
Summary
Resin-based composite restorations are routinely performed in clinical dental practice due to the favorable properties of the resinous materials, especially related to aesthetics and the evolution of adhesive systems that allow minimally invasive preparations (1,2). To circumvent this issue and improve the union between the remaining restoration and the new restorative material, it is recommended to perform mechanical and/or chemical treatment of the surface to be repaired Several of these treatments have been proposed in the literature, such as diamond bur abrasion, aluminum oxide sandblasting, silica coating, phosphoric or hydrofluoric acid etching and application of silane and adhesive systems. Material and Methods: First, 84 specimens (8x8x4 mm3) of a microhybrid composite and a high-viscosity bulk fill composite were prepared and aged Afterward, they received a mechanical surface treatment by means of abrasion with a diamond bur, followed by division into six groups according to the adhesion protocol employed: PSA etching with 35% phosphoric acid + silane + etch-and-rinse adhesive; SA - silane + etch-and-rinse adhesive; PA - etching with 35% phosphoric acid + etch-and-rinse adhesive; A - etch-and-rinse adhesive; PU - 35% phosphoric acid + universal adhesive; and U - universal adhesive. Conclusions: The repair bond strength of a bulk fill composite was similar to that found in a conventional composite, with no distinction among adhesion protocols
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