Universal adhesives and dual-cured core buildup composite material: adhesive properties.

Pâmela Malaquias,Taise Alessandra Hanzen,Thalita De Paris Matos,Mario Felipe Gutiérrez,Alessandra Reis,Alessandro Dourado Loguercio,Jorge Perdigão,Elisama Sutil

doi:10.1590/1678-7757-2020-0121

Abstract

Dual-cured buildup composites and simplified light-cured adhesive systems are mixed with a chemical activator to prevent the incompatibility between them.Objective:To evaluate microshear bond strength (μSBS) and nanoleakage (NL) of three universal adhesives used under buildup composites using different curing modes, at baseline and after 6-months (6m).Methodology:Dentin specimens of 55 molars were assigned to: Clearfil Universal Bond[CFU], Prime&Bond Elect[PBE] and One Coat 7 Universal[OCU]. All-Bond Universal[ABU] and Adper Scotchbond Multi-Purpose[SMP] were used as controls. CFU, PBE, and OCU were: light-cured [LC], dual-cured using a self-curing activator [DC], and self-cured, using a self-curing activator and waiting for 20 min [SC]. Upon the application of the adhesive, transparent matrices were filled with a dual-cured buildup composite and light cured, then tested in mSBS. For NL, the specimens were submersed in ammoniacal silver nitrate and sectioned to observe under the SEM. Three-way ANOVA and Tukey's test were applied (α=0.05).Results:OCU/LC-PBE/LC resulted in higher mean μSBS than ABU/LC. For SMP/DC higher mean μSBS were obtained than for both CFU/DC and OCU/DC (baseline). No universal adhesive was significantly affected by curing mode or storage time. CFU, PBE, and OCU did not undergo significant changes in any curing mode (p>0.05). NL (baseline) PBE/LC resulted in higher %NL compared to ABU/LC. SMP/DC resulted in higher %NL than CFU/DC-OCU/DC. CFU/LC/DC resulted in lower %NL than CFU/SC. PBE/SC resulted in lower %NL than PBE/DC. OCU/LC/SC showed lower %NL than OCU/DC. OCU showed significant lower %NL than CFU and PBE. All CFU groups, as well as OCU/SC, resulted in increased %NL at 6m when compared with baseline.Conclusion:For universal adhesives used in etch-and-rinse mode, self-cured activator and different curing modes did not influence μSBS. However, some interactions were observed for NL, but this influence was material-specific.

Highlights

The development of dental materials with increased strength and possibility to reestablish the ideal anatomy of fractured or caries-compromised teeth, especially endodontically treated teeth, represents a significant progress in restorative dentistry
When SC and DC core buildup resin composites are associated with simplified adhesives (2-step etch-and-rinse or 1-step self-etch), residual uncured acidic monomers from the oxygen-inhibited layer of the cured adhesives remain in direct contact with the resin composite material
This reaction results from the contact between the simplified adhesive and the basic catalytic components of chemically-cured composites,4-7 leading to a low rate of polymerization8 and possibly affecting bond strength of simplified adhesive systems

Summary

Introduction

The development of dental materials with increased strength and possibility to reestablish the ideal anatomy of fractured or caries-compromised teeth, especially endodontically treated teeth, represents a significant progress in restorative dentistry. When SC and DC core buildup resin composites are associated with simplified adhesives (2-step etch-and-rinse or 1-step self-etch), residual uncured acidic monomers from the oxygen-inhibited layer of the cured adhesives remain in direct contact with the resin composite material.. When SC and DC core buildup resin composites are associated with simplified adhesives (2-step etch-and-rinse or 1-step self-etch), residual uncured acidic monomers from the oxygen-inhibited layer of the cured adhesives remain in direct contact with the resin composite material.4 This reaction results from the contact between the simplified adhesive and the basic catalytic components (aromatic tertiary amines) of chemically-cured composites, leading to a low rate of polymerization and possibly affecting bond strength of simplified adhesive systems.. The adverse acid-base reaction and adhesive permeability may contribute to the incompatibility between simplified adhesives and both SC and DC core composite materials

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Conclusion