Influence of light-curing on the translucence change and color stability of amine-free dual-cured resin cements

Choi, Sung Hyeon; Lee, Bo Ram; Lee, Bin Na; Chang, Hoon Sang; Hwang, Yun Chan; Oh, Won Mann; Hwang, In Nam

Abstract

The aim of this study was to investigate the influence of light-curing on the translucency change and color-stability of amine(tertiary)-free dual-cured resin cements after accelerated aging. Two curing modes (dual-curing and self-curing) were applied on three dual-cured resin cements (Duo-Link Universal [DLU], Nexus Third Generation [NX3] and RelyX Ultimate [RXU]) in this study. Ten specimens were fabricated for each group. In dual-cured groups only, light-activation was performed with polywave-LED curing unit (Bluphase, Ivoclar Vivadent, Schaan, Liechtenstein), where each sides of the samples were photo-polymerized for 60 seconds. Self-cured groups were kept in the dark storage for 24 hours. The color of the specimens was measured with spectrocolorimeter (NF999, Nippon Denshoku, Japan) after 24 hours of making samples. After the initial color measurements, the specimens were subjected to accelerated aging procedure. Spectrophotometric analysis was carried out on day 7, day 14, day 21 and day 28 of accelerated aging in 60 â„ƒ of distilled water. The color characteristics, color difference (Î”E*), and translucency parameter (TP) of specimens were calculated according to the CIE L*a*b* color system before and after aging. All the Î”E* values and TP values were analyzed by 2-way analysis of variance. After aging, all groups revealed clinically perceptible color differences (Î”E*>3.3). Differences in Î”E* values of self-cured groups were significantly higher than those of dual-cured groups in NX3 and RXU. But there were no significant differences in Î”E* between dual-cured mode and self-cured mode of DLU. All mean b* values increased after aging. All mean L* values decreased after aging except for self-cured RXU cement. TP values also decreased with aging. TP values of self-cured groups were significantly lower than those of dual-cured groups in NX3 and RXU. Hence, in conclusion, despite the absence of tertiary amine in the dual-cured resin cements, such resin cements should be polymerized with the dual-cure modes to ensure long-term color-stability.