Effect of Two Vital Bleaching Agents on the Color Properties of the Low-Fusing Dental Ceramics

Statement of the problem: The effects of vital bleaching agents on color properties of dental tissues and direct restorative materials are well documented. However, there is a lack of information about the effects of these agents on low-fusing dental ceramics.

Objective: The aim of the present study is the in vitro evaluation of the effects of two vital bleaching agents on the color features of three different dental ceramic materials.

Materials &Methods:60 sample discs of two different feldspathic ceramics and a full ceramic system were fabricated 12mm in diameter according to the manufacturers’ instructions. The 1st feldspathic group was designated as C (n=20), the 2nd V (n=20), and the full ceramic group F (n=20). Prior to bleaching, L*a*b* values of each glazed sample were measured using a colorimeter. Each sample group was divided in two for the bleaching in two different derivations. Whereas the subgroups exposed to 10% carbamide peroxide were designated CR, VR, and FR; subgroups exposed to 16% carbamide peroxide were entitled CN, VN, and FN. Following bleaching, color measurements were repeated. Descriptive analysis of all data, consisting L*a*b*, ?L*, ?a*, ?b*, and ?E values of the two measurements, were performed. Obtained results were statistically analyzed with Kruskal-Wallis test.

Conclusion: Vital bleaching agents have the potential to alter the color features of ceramic materials.

Results: Comparisons revealed no significant difference between the ?L*, ?a*, ?b* values of the 6 groups. Also no significance was found between the ?E results of the FR, FN and VN, VR groups (P = 0.1, P = 0.3). However, there was a significant difference between the ?E values of the groups CN and CR (P = 0.001).