Effect of water storage on the flexural properties of three dual-cure core buildup composite resins

Li Ya-nan; Cai Qing; Jia Xiao-long; Deng Xu-liang; Yang Xiao-ping

doi:10.3969/j.issn.2095-4344.2014.08.011

Abstract：BACKGROUND:Hydrothermal condition of oral environment has an effect on the mechanical properties of dental core materials. <br> OBJECTIVE:To evaluate effect of water storage on the weight change rates and flexural properties of three dual-cure core buildup composite resins. <br> METHODS: Rectangular specimens (25 mm×2 mm×2 mm) were prepared from three dual-cure core buildup composite resins (LuxaCore Smartmix Dual, Para core and Clearfil DC Core). Specimens were stored in distiled water at 37℃ for 0, 1 day, 1, 2, 3 weeks and 1 month, respectively, weighted and then subjected to three-point bending test in a universal testing machine. <br> RESULTS AND CONCLUSION: Weight change rates of the three composite resins increased with immersion time; at the same immersion time, weight change rates of three composite resins ranked as the folowing order: LuxaCore Smartmix Dual > ParaCore > Clearfil DC Core. The flexural strength of LuxaCore Smartmix Dual decreased with immersion time. The flexural strength of ParaCore showed no significant change during 3 weeks immersion (P > 0.05), while it showed a significant decreasing after 1 month immersion (P < 0.05). There was no significant change on the flexural strength of Clearfil DC Core in the whole immersion process(P > 0.05). The flexural modulus of LuxaCore Smartmix Dual showed a decreased trend in the whole immersion process, but it showed that there was no significant change during the first 2 weeks(P > 0.05), while a significant decrease occurred after 3 weeks and 1 month (P < 0.05). Compared with original specimens, the flexural modulus of ParaCore and Clearfil DC Core showed a decreased trend, but this change was not significant (P > 0.05); the flexural properties of three composite resins showed a fluctuant decreased trend along with weight changes increased. To sum up, Clearfil DC Core showed the best water resistance among three composite resins.