Methods: The CIE Lab values of all shade samples at three, non-used VITA 3D-Master Shade guides were measured with Vita easy shade. Two chemical disinfectants (Mikrozid AF Liquid, sodium-hypochlorite solution) and autoclave were used for disinfection. In order to simulate 180 and 360 day usage, the first and second shade guides were immersed into disinfectant solutions for 5minX180 and 5minX360. The third shade guide was autoclaved at 135°C/10minX180 and 135°C/10minX360. CIE Lab measurements of all guides were repeated at 180 and 360 day periods. In order to measure the color changes at shade guides, 180 and 360 day CIE Lab values were compared with initial measurements by using the formula of “Delta E=([L1-L2]2+[ a1-a2]2+[ b1-b2]2)1/2”. Data were analyzed with Repeated Measures Anova test.
Results: Mean Delta E for the groups are as follows: Autoclave Delta E=1.35, Mikozid AF Liquid Delta E=0.62, sodium-hypochlorite solution Delta E=0.52. There were no significant differences among the time periods at any disinfection methods (p=0.262). All the disinfection methods caused a color change however mean Delta E values obtained with autoclave technique was significantly different from the others (p=0.000).
Conclusions: Within the limitations of this in vitro study, sodium-hypochlorite solution can be recommended for sterilization of the shade guides.