Abstract
This study evaluated the exposure time of light-curing of the polymers used for cementation on microhardness test in different storage times. The polymers (specifically called resin cements) were RelyX ARC, RelyX U100, and SET. Five specimens of each group were prepared and photo-polymerized with exposure times of 20 s and 180 s, using a LED polymerization unit with wavelength of 440 ~ 480 nm and light output was consistently 1,500 mW/cm2. The Vickers hardness test was performed in a MMT-3 Microhardness Tester. Data were submitted to ANOVA and Tukey's test (α = 0.05). The values of RelyX ARC showed statistically significant difference to groups with light exposure when considering only chemical cure (p < 0.05). The groups with light exposure (20 s and 180 s) showed no significant difference between them (p > 0.05). The RelyX U100 cured only chemically showed statistically significant difference between 48 h and 7 days (p < 0.05). The SET resin cement showed no significant difference to groups without light exposure for all storage times (p > 0.05). The values of hardening of the dual-cured resin cements improved after setting by light and chemical activation demonstrating the importance of light curing.
Highlights
Dental polymers, resin cements, have been used considerably in recent years due to a larger application of dental adhesive procedures [1,2].There are a variety of currently available cements on the market, though none is ideal for all clinical situations
The purpose of this study was to investigate the exposure time of light-curing of the dual-cured resin cements on microhardness test at different storage times
Others storage times showed no difference when compared with same light exposure (Figure 2)
Summary
Resin cements, have been used considerably in recent years due to a larger application of dental adhesive procedures [1,2].There are a variety of currently available cements on the market, though none is ideal for all clinical situations. Factors, such as exposure time of light-curing and type of light-curing unit can influence the characteristic of the resin cement, changing the final quality of the restorations [4]. The dental resin cements can be classified based on the type of their cure such as chemical-, lightor dual-cure [5]. The dual-cured resin cement is formulated to not depend only on light activation; the cure is started by photo-and chemical-initiators.
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