Color Stability of Single-shade Composite Resins with Color-matching Ability

Abstract

 Purpose: Recently, single-shade composite resins (CRs) with color-matching ability have been developed to simplify the shade-taking for direct composite restoration. One of the problems with CR is discoloration caused by pigmented foods, drinks, and saliva, but there are few reports on the evaluation of color stability of single-shade CRs with color-matching ability. In this study, the color stability of single-shade CRs with color-matching ability and conventional CRs were evaluated by toothbrush abrasion test and immersion test.

 Method: As six single-shade CRs, Omnichroma (Tokuyama Dental, OMC), Omnichroma Flow (Tokuyama Dental, OMF), Beautifil Unishade (Shofu, BUN), Clearfil Majesty ES Flow Universal U (Kuraray Noritake Dental, CLM), Clearfil Majesty ES Flow Universal UD (Kuraray Noritake Dental, CLD), and Clearfil Majesty ES Flow Universal UW (Kuraray Noritake Dental, CLW), six conventional CRs as the control group, Estelite Σ Quick (Tokuyama Dental, EST), Estelite Universal Flow (Tokuyama Dental, ESF), Beautifil Ⅱ (Shofu, BFⅡ), Beautifil Flow Plus X (Shofu, BFF), Clearfil Majesty ES-2 (Kuraray Noritake Dental, CMP) and Clearfil Majesty ES Flow (Kuraray Noritake Dental, CMF) were used in this study. For these 12 types of CRs, samples for the abrasion group and the non-abrasion group were prepared, and the color difference ΔE^*ab was calculated by immersing the samples in coffee and distilled water for 28 days. In addition, other samples were prepared, and water sorption and water solubility were calculated by immersing the samples in distilled water for 28 days.

 Results: In the coffee immersion experiment, BUN containing S-PRG filler showed significantly higher ΔE^*ab values in both the non-abrasion and abrasion groups after 28 days of immersion compared to the other CRs (p<0.05). Also, when comparing ΔE^*ab values between the non-abrasion and abrasion groups for each CR in the coffee immersion experiment, CLM, CLW, EST, ESF, BFF, and CMP in the non-abrasion group showed significantly higher values than the abrasion group after 28 days of immersion (p<0.05). On the other hand, the distilled water immersion experiment showed no significant difference in ΔE^*ab values between all CRs and between the non-abrasion and abrasion groups for each CR (p>0.05). Water sorption was significantly higher in BFF than in the other CRs (p<0.05) and was negatively correlated with inorganic filler content. Water solubility was highest for CMP with a significant difference (p<0.05) compared to CLM, CLD, CLW, and CMF, but there was no correlation with inorganic filler content.

 Conclusion: BUN containing S-PRG filler showed noticeable higher ΔE^*ab values in the coffee immersion experiment, suggesting that the color stability of single-shade CRs is affected not only by the resin component but also by the filler properties.