Discolouration of microhybrid composite resin is a common problem faced by both dental practitioners and patients. The accumulation of plaque, penetration of colourant particles from foods and beverages, dietary habits and the smoothness of restorations have been known to influence the quality of the aesthetic restoration. The purpose of this study was to determine the effects of polishing systems on surface roughness that led to discolouration of the microhybrid composite resin. Methods: Forty five samples of microhybrid composite resin (Filtex Z100) restorations were polished with two different polishing systems; one-step polishing (OP) system on the distal surface and multiple-step polishing (MP) system on the mesial surface. All samples were then immersed in two common beverages: black coffee and cocoa, for 20 minutes daily throughout 28 days of the experimental period. Results: Data on visual colour measurement and spectrometer colour spectrum was subjected to one-way ANOVA test at a significance level of 0.05. Both solutions were found to cause a significant colour change (p=0.0195) on the microhybrid composite resin. Black coffee solution obtained the highest score (71.6) of visual colour change and the lowest reflectance value (62.818) on the distal surface. Surface roughness evaluation using a scanning electron microscope (SEM) had presented that both polishing systems used produced low level of surface roughness. Conclusion: Although MP system produced a smoother surface compared to OP system, a prolonged exposure to colourant particle found to cause an unacceptable discolouration of microhybrid composite resin.
Introduction: Colour stability of the material is an essential factor that contributes to the selection of a flexible den- ture material. Staining effects on the denture may result in unattractive appearance, the dissatisfaction of the wearer, and limited usage period of the denture. This study aims to identify the colour stability of the Valplast flexible denture material using three types of beverages. Methods: A total of 32 disc-shaped flexible resin materials (20 +/- 0.1 mm in diameter and thickness 3 +/- 0.1 mm) were prepared based on the manufacturer instructions. The samples were randomly divided into 4 groups of immersion: distilled water (control), coffee solution, tea solution and red wine. The samples were left in the specified immersion solution for up to 60 days. Colour changes were measured after 1, 3, 7, 14, 21, 30, 45 and 60 days of immersion. Results: The samples immersed in coffee solution changed from S1 to S2, whereas samples in tea solution changed from S1 to S3. Additionally, samples in red wine changed from S1 to S4, as observed using the Valplast colour tone guide. The highest reflection measured using spectroscopy was 65.146 at 385.19 nm of the control samples, whereas the lowest reflection was 1.974 at the wavelength of 385.97 nm on the samples immersed in the red wine. Conclusion: The most significant difference can be observed in the red wine group, followed by samples in tea and coffee solutions. Moreover, increasing the immersion period causes increasing staining effect of the denture.