Colour changes and topography of resin modified glass ionomer cements with the addition of zinc oxide nanoparticles

Background: Resin-modified glass ionomer cement (RMGIC) is one of the restorative materials for cavity restoration in the anterior and cervical areas where aesthetics are crucial, especially for class III (anterior) cavity restorations. Adding zinc oxide nanoparticles (ZnONP) may enhance its mechanical and physical properties. 

Objective: This study aims to evaluate the color change of RMGIC after the addition of ZnONP as much as 5%, 10% and 15% of the total mixture of RMGIC and ZnONP powder also to examines the topography of ZnONP distribution within RMGIC’s interstitial space using scanning electron microscope (SEM). 

Methods: Four groups of RMGIC were studied, a control group without ZnONP powder, 3 treatment groups with ZnONP powder as much as 5%, 10%, and 15%. Each group consists of 4 cylindrical samples (diameter of 10 mm, height of 2 mm). Color change was measured using VITA Easyshade V spectrophotometer and SEM was used for topography analysis. Data were analyzed with one-way ANOVA test and Tukey HSD post hoc test. 

Results: One-way ANOVA test showed significant color differences (p<0.05) among all groups. Tukey HSD test showed significant color differences (p<0.05) in color change between control group and treatment groups also between group 2 and group 4. SEM observations confirmed ZnONP distribution in RMGIC’s interstitial space in treatment groups. 

Conclusion: Addition of 5%, 10%, and 15% ZnONP powder of the total mixture of RMGIC and ZnONP powders changed RMGIC’s color to be brighter (lightness) and more saturated (chroma) also ZnONP distributed within RMGIC’s interstitial space.