Experimental investigation of effect of staining solutions on the color stability of dental composite resins and primary teeth enamel

Introduction: Composite resins have been widely used since their introduction due to their excellent esthetic properties. However, a major disadvantage is their discoloration after prolonged exposure to the oral environment. Unacceptable color match is a primary reason for replacement of composite resin restoration. Staining solution can cause discoloration in teeth and composite resin; however, the most of previous studies have involved the assessment of “adult” type beverages (ie, red wine, coffee, Chlorhexidine, etc.). The purpose of this study is investigating the effect of 4 staining solutions on the color stability of 2 dental composite resins and primary teeth enamel. Materials: An experimental study was performed to investigate the influence of staining solution on color stability if composite resins. The information were obtained by taking digital photographs and processing them by Adobe Photoshop software. 40 disk-shaped specimens (7×2 mm) of each of 2 composite resins, Premise Flowable and Premise Trimodal Nanofilled, were prepared. Afterwards, the specimens were divided into 5 groups of 8 specimens. Each one immersed in 4 staining solutions (tea, cola, iron drop, multivitamin) or distilled water (control) for 3 hours daily over a 40day test period. In order to prepare dental specimens, the crowns of 8 primary canine teeth were divided into three parts by a bur and handpiece and immersed in 2 staining solutions (iron drop and multivitamin) or distilled water (control). Digital images were prepared from each specimen before and after staining; in the next step, images were analyzed by Adobe Photoshop CS5 software. All color testing were carried out to CIE-Lab color system. L^* characterizes the lightness of the color, a^* defining a color on a red-green axis, and b^* describing the blue-yellow part of the color. Finally, the color differences (∆E) were estimated. For statistical evaluation, analysis of variance (ANOVA) and Tukey HSD tests were used at a significance level of 0.05. Results: For both tested restorative materials, the lowest ∆E values were observed in the distilled water (〖∆E〗_f=1.12,〖∆E〗_n=2), while ∆E had the highest values in tea group (〖∆E〗_f=28,〖∆E〗_n=29.43). In the tooth specimens, iron drop caused the highest color changes (∆E=17.41), while color change for distilled water was minimum (∆E=2.04). There were no significant differences between two tested composite resins (p>0.05), while differences between composites and teeth were significant (p<0.05). Conclusion: The highest discoloration was observed in tea group for composite resins and iron drop group for teeth. The distilled water group caused the least discoloration in all groups. The staining solution caused discoloration in composite resins and tooth specimens; therefore, the drinking habits of the patients must be considered while choosing restorative resin-based materials, specially on the anterior region of the mouth. Moreover, it was concluded that digital photography is a simple and affordable technique to evaluate the color changes.