Comparative Evaluation of the Staining Resistance of Two Single-Shade Composites in Coffee and Chlorhexidine: A Spectrophotometric Analysis.

INTRODUCTION

Color stability is a critical factor for the longevity of composite restorations, especially in esthetic dentistry. Single-shade universal composites have been designed to blend seamlessly with natural tooth structures. This study aimed to compare the staining resistance of Omnichroma (Tokuyama Dental, Tokyo, Japan) and Vittra Unique (FGM Dental Group, Joinville, Santa Catarina, Brazil) over a 30-day period using spectrophotometric analysis to assess color changes. The null hypothesis was that no significant difference would be observed between the two composites in terms of staining resistance.

MATERIALS AND

METHODS

An in vitro study was conducted using 40 disc-shaped composite specimens divided into two groups: Group A (Omnichroma) and Group B (Vittra Unique). Each group was further divided into two subgroups based on the staining solution used (coffee and 0.2% chlorhexidine). The specimens were prepared using standardized molds, light-cured, polished, and stored in artificial saliva for 24 hours prior to immersion. Each specimen was exposed to its respective staining solution for eight hours daily for 30 days, followed by rinsing and solution replacement. Thermal cycling was performed to simulate the oral conditions. Quantification of color alteration (ΔE values) was done using a spectrophotometer (Vita Easyshade 2.0, VITA Zahnfabrik, Germany) at baseline and after 30 days. Statistical analysis was conducted using independent t-tests and analysis of variance (ANOVA), with a significance level of p < 0.05.

RESULTS

A significant difference in staining resistance was observed between groups (p = 0.001). Vittra Unique exhibited higher ΔE values than Omnichroma, indicating greater discoloration. The highest color change was found in the Vittra coffee subgroup (ΔE = 2.70 ± 0.56), while the lowest was in the Omnichroma coffee subgroup (ΔE = 1.25 ± 0.17). Chlorhexidine also caused staining, albeit to a lesser extent than coffee did.

CONCLUSION

Omnichroma demonstrated superior resistance to staining compared with Vittra Unique, particularly against coffee-induced discoloration. These findings suggest that Omnichroma may be a more suitable choice for patients frequently exposed to staining agents. Further research is recommended to explore the long-term color stability under varying conditions.