Comparison of color changes of new generation composite resins

Color selection is a critical factor in the success of aesthetic restorations. Reducing the color selection to a single step will provide a significant convenience to both clinicians and patients, contributing to the reduction of both composite using and chair time. Therefore, it is aimed to restore all cavities with a single-shade composite. The aim of this thesis is to investigate the effects of tooth color and coloring solutions on the color stability and color matching of composites with different color systems. In the study, 240 double-layered acrylic teeth (Ardiş Color G2, Dentaş, Ankara, Turkey) were divided into three main groups according to the VITA Classic scale: A1, A2 and A3 (n=80). The teeth were then divided into two subgroups according to the immersion solutions: coffee and distilled water (n=40). The specimens were divided into four subgroups according to the composites to be tested: three chameleon- effect monochromatic composite resins Omnichroma, (Tokuyama, Japan), Zenchroma (President, Germany), Charisma Diamond One (Kulzer, Germany) and a multicolor composite resin G-aenial Anterior (GC, Japan) as a control group (n=10). Both tooth and composite restoration color measurements were performed by recording the L*, a*, and b* values using a spectrophotometer (Vita Easyshade V, Vita Zahnfabrik, Bad Säckingen, Germany) immediately after placing the composite restorations on the teeth, and following immersion procedures on days 1, 7, and 30. The color stability was calculated with the CIEDE2000 formula by comparing the measured values obtained from composite resins at different time periods with the initial values. In addition, color matching was calculated with the CIEDE2000 formula by comparing the initial and 30th day measurements of the tooth and composite restoration. Statistical analysis of the data was performed by Mann-Whitney U test, Kruskal-Wallis test and post hoc tests (α = 0.05). In this study, multicolor composite resins demonstrated lower and more stable discoloration in distilled water compared to monochromatic composites. Charisma composite resin exhibited a statistically significant (p<0.05) and clinically unacceptable level of discoloration at the A3 shade. When Zenchroma was immersed in distilled water, the color matching with the teeth in all color groups exceeded the acceptable limit; however, the difference in color matching between baseline and day 30 was not statistically significant (p>0.05). In the coffee solution, all composite and color groups exhibited increasing color changes over time; however, only monochromatic composites showed clinically unacceptable changes from day 7 onward. By day 30, all composites had exceeded the clinical limit. When Omnichroma was immersed in coffee, the color matching with the teeth in all color groups exceeded the acceptable limit; however, the difference in color matching between baseline and day 30 was not statistically significant (p>0.05). Additionally, the shade matching of monochromatic composites varied based on tooth shade; better matching was achieved in lighter shades, while matching decreased in darker shades. Based on our findings, the type of composite, the tooth color to which it was applied, and the duration of exposure to the solution were found directly affect color stability and color matching ability. Across all analyses, multicolor composite resins were found more stable and exhibited significantly less color change compared to monochromaticcomposites(p<0.05). Keywords: multicolor composite, monochromatic composite, color stability, color matching, chameleon effect