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The Effects of Exposure Time on the Surface Microhardness of Three Dual-Cured Dental Resin Cements
Department of Restorative Dentistry, Faculty of Dentistry, University of São Paulo State, Rua Humaitá n° 1740, Centro, Araraquara—SP, CEP: 14.801-385, Brazil
Department of Periodontology, Faculty of Dentistry, University of São Paulo State, Rua Humaitá n° 1740, Centro, Araraquara—SP, CEP: 14.801-385, Brazil
Department of Restorative Dentistry, Faculty of Dentistry, Federal University of Maranhão, Av. dos Portugueses S/N, São Luis—MA, CEP: 65.085-580, Brazil
Department of Post-graduation, University of Maranhão, Av. José Montello n° 1, Renascença II, São Luis—MA, CEP: 65.075-120, Brazil
* Author to whom correspondence should be addressed.
Received: 20 May 2011; in revised form: 13 June 2011 / Accepted: 20 June 2010 / Published: 28 June 2011
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.
Keywords: polymers; photo-responsive polymers; hardness
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Aguiar, T.C.; Saad, J.R.C.; Pinto, S.C.S.; Calixto, L.R.; Lima, D.M.; Silva, M.A.S.; Bandéca, M.C. The Effects of Exposure Time on the Surface Microhardness of Three Dual-Cured Dental Resin Cements. Polymers 2011, 3, 998-1005.
Aguiar TC, Saad JRC, Pinto SCS, Calixto LR, Lima DM, Silva MAS, Bandéca MC. The Effects of Exposure Time on the Surface Microhardness of Three Dual-Cured Dental Resin Cements. Polymers. 2011; 3(3):998-1005.
Aguiar, Tatiana C.; Saad, José R. C.; Pinto, Shelon C. S.; Calixto, Luiz R.; Lima, Darlon M.; Silva, Marcos A. S.; Bandéca, Matheus C. 2011. "The Effects of Exposure Time on the Surface Microhardness of Three Dual-Cured Dental Resin Cements." Polymers 3, no. 3: 998-1005.