Abstract
In metallic restorations, the polymerization of dual-curing resin cements depends exclusively on chemical activation. The effect of the lack of photoactivation on the strength of these cements has been rarely studied. This study evaluated the influence of activation modes on the diametral tensile strength (DTS) of dual-curing resin cements. Base and catalyst pastes of Panavia F, Variolink II, Scotchbond Resin Cement, Rely X and Enforce were mixed and inserted into cylindrical metal moulds (4 x 2 mm). Cements were either: 1) not exposed to light (chemical activation = self-cured groups) or 2) photoactivated through mylar strips (chemical and photo-activation = dual-cured groups) (n = 10). After a 24 h storage in 37 masculineC distilled water, specimens were subjected to compressive load in a testing machine. A self-curing resin cement (Cement-It) and a zinc phosphate cement served as controls. Comparative analyses were performed: 1) between the activation modes for each dual-curing resin cement, using Students t test; 2) among the self-cured groups of the dual-curing resin cements and the control groups, using one-way ANOVA and Tukeys test (alpha = 0.05). The dual-cured groups of Scotchbond Resin Cement (53.3 MPa), Variolink II (48.4 MPa) and Rely X (51.6 MPa) showed higher DTS than that of self-cured groups (44.6, 40.4 and 44.5 MPa respectively) (p < 0.05). For Enforce (48.5 and 47.8 MPa) and Panavia F (44.0 and 43.3 MPa), no significant difference was found between the activation modes (p > 0.05). The self-cured groups of all the dual-curing resin cements presented statistically the same DTS as that of Cement-It (44.1 MPa) (p > 0.05), and higher DTS than that of zinc phosphate (4.2 MPa). Scotchbond Resin Cement, Variolink II and Rely X depended on photoactivation to achieve maximum DTS. In the absence of light, all the dual-curing resin cements presented higher DTS than that of zinc phosphate and statistically the same as that of Cement-It (p > 0.05).
Highlights
Dual-curing resin cements have been used for luting indirect esthetic restorations, but most recently for luting metal castings such as crowns and fixed partial dentures, as an alternative to zinc phosphate and glass ionomer cements.Some advantages of resin cements are low solubility[24], adequate consistency and film thickness[5,21], superior mechanical properties[14,22], optimal bonding to dental structures and restoring materials by adhesive systems[10] and reduced microleakage[23].some studies have shown that dual-curing resin cements depend on photoactivation to achieve a high degree of conversion
Some studies have shown that dual-curing resin cements depend on photoactivation to achieve a high degree of conversion. This was investigated with four dual-curing resin cements using Fourier Transform Infrared Spectrometry (FTIR), and none of the studied cements presented similar results comparing self-cured and dual-cured groups[18]
Due to the importance of this research area and the scarcity of studies that evaluate the strength of dual-curing resin cements that are not photoactivated, the purpose of the present study was to evaluate the influence of activation modes on the diametral tensile strength (DTS) of five dual-curing resin cements
Summary
Some studies have shown that dual-curing resin cements depend on photoactivation to achieve a high degree of conversion. Another study using six dual-curing resin cements, analysed by FTIR, showed that, in five cements, the degree of conversion of the self-cured groups was significantly lower than that of the groups photoactivated through mylar strips or porcelain spacers[4]. This lower degree of conversion demonstrated by the dual-curing resin cements which receive reduced (or no) light intensity is reflected in the hardness of the cement[9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
