Influence of the activation mode on long-term bond strength and endogenous enzymatic activity of dual-cure resin cements

Claudia Mazzitelli,Edoardo Mancuso,Uros Josic,Allegra Comba,Lorenzo Breschi,Luigi Generali,Annalisa Mazzoni,Tatjana Maravic

doi:10.1007/s00784-021-04141-x

Abstract

ObjectiveTo investigate the long-term microtensile bond strength (µTBS), interfacial nanoleakage expression (NL), and adhesive stability of dual-cure resin cements with/out light activation to dentin.Materials and methodsComposite overlays (N = 20) were luted to deep dentin surfaces with RelyX Ultimate (RXU, 3M) or Variolink EstheticDC (VAR, Ivoclar-Vivadent). A universal adhesive was used for bonding procedures (iBond universal, Heraeus Kulzer). The resin cements were either self-cured (SC; 1 h at 37 °C) or dual-cured (DC; 20s light-cure followed by 15 min self-cure at 37 °C). Specimens were submitted to µTBS immediately (T0) or after 1 year of laboratory storage (T12). The fracture pattern was evaluated using scanning electron microscopy (SEM). Data were statistically analyzed with two-way ANOVA/Tukey test. Further, the NL was quantified and analyzed (chi-square test) and in situ zymography was performed to evaluate the endogenous enzymatic activity within the hybrid layer (HL) at T0 and T12 (Mann–Whitney test). The significance level for all statistical tests was set at p = 0.05.ResultsDC resulted in higher bond strength and decreased fluorescence at the adhesive interface, irrespective of the material and the storage period (p < 0.05). Significantly lower bonding performances (p < 0.05) and higher endogenous enzymatic activity (p < 0.05) were observed within the HL at T12 compared to T0 in all tested groups.ConclusionsLight-curing the dual-cure resin cements, more than the cement materials, accounted for good bonding performances and higher HL stability over time when used with a universal adhesive.Clinical significanceThe curing condition influences the bonding performances of dual-cure resin cements to dentin when used with a universal adhesive.

Highlights

Resin composite cements have a major role in operative dentistry, yielding enhanced esthetic and mechanical properties of the restoration
They can be classified according to the polymerization mode or based on the dental surface pre-treatment
There is evidence in the literature that the dual-cure mechanism should be favored for the cementation of indirect restorations as the polymerization reaction continues even in the absence of light, through a synergic combination of self- and light-polymerizing components [1, 4, 5]

Summary

Introduction

Resin composite cements have a major role in operative dentistry, yielding enhanced esthetic and mechanical properties of the restoration. They can be classified according to the polymerization mode (self-cure, light-cure, or dual-cure) or based on the dental surface pre-treatment (multi-step or self-adhesive cements). After the polymer formation, the viscosity of the material increases This increase limits the movements of the remaining monomers responsible for additional polymerization [7], reducing the likelihood of bimolecular termination [8]. Deficiencies in the chemical curing process can increase the density of unreacted double bonds, reduce the polymerization reaction, affect the hardness, and influence the solubility of the cement, which may alter the chemical stability in the oral cavity [9, 10]

Methods

Results

Conclusion