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

Abstract

Objective To 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 methods Composite 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. Results DC 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. Conclusions Light-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 significance The curing condition influences the bonding performances of dual-cure resin cements to dentin when used with a universal adhesive.

Color Stability of Resin Cements after Water Aging

“…The absence of tertiary amines in light-cured cements has been described to be the main cause for this favorable behavior [ 35 , 37 , 38 ]. On the other hand, self-cured or dual-cured cements have been found to be preferred when the light transmission is hindered by the presence of restorations of a certain thickness or by clinical and anatomical criticality [ 39 , 40 , 41 , 42 ].…”

“…The adsorption of water into the cement causes expansion and matrix swelling. The disruption at the resin matrix–inorganic filler level caused by water sorption can create microcracks formations [ 41 , 45 ] with consequent risk of discoloration of the cement [ 37 ]. This sequence of detrimental events has been ascribed to the chemical composition of the cements, and particularly to their organic matrices and polymerization modes [ 13 , 44 , 46 , 47 ].…”

Effect of Fluorographene Addition on Mechanical and Adhesive Properties of a New Core Build-Up Composite

“…On dentin, paired 10-MDP molecules joined by stable MDP-Ca salt formation generate arrays of self-assembled, nano-layered structures that are responsible for long-term adhesion. This bonding mechanism occurs without depleting the hydroxyapatite crystals from the collagen fibrils [ 37 , 38 ], hindering the collagen degradation phenomena observed with etch and rinse dentin adhesives [ 39 , 40 ] that, conversely, require collagen exposure to generate bonding.…”

Modeling Liquids and Resin-Based Dental Composite Materials—A Scoping Review

“…The latter has been enthusiastically received by clinicians because of their clinical versatility, being able to be applied in both etch-and-rinse, self-etch, and selective enamel etching modes, as well as possibilities for application to both dental tissues and different restorative materials in a simple and time-saving manner [ 4 ]. While the simplification of adhesive systems has brought unquestionable operational advantages, the chemical complexity they refer to in order to incorporate into a single product all the components necessary for conditioning and adhesion can create incompatibility phenomena and result in a deficit in restoration durability [ 6 , 7 ].…”