Introduction: The selection of porcelain is based on high biocompatibility, endurance, superficial texture and aesthetics. Nevertheless, the innate fracture charateritics of porcelain is the main cause of the intra oral fractures. Electing a suitable porcelain restorative system in terms of stability of color is important. For this reason, this study aimed to examine the color changes of common porcelain repair materials .

Methods: Using a silicon mold, 30 pieces of feldspathic porcelain in A3 color, 10mm of diameter and 2 mm of thickness were prepared. The samples were randomly distributed into three groups :

Group 1: Porcelain-Silane-Bonding-Composite

Group 2: Porcelain-Silane-Bonding-Panavia F 2.0-Bonding-Silane-Porcelain

Group 3: Porcelain-Silane-Bonding-Choice 2 -Bonding-Silane-Porcelain

The aging process was accomplished with thermocyling (3000 cycles, 5/55 degree), incubation in 37° and 100° humidity. Thereafter, discoloration was assessed In CIE system via designation of color transforming matrix in MATLAB environment .

Results: The average quantitative amount of discoloration at day 0, 90 and 180 were 76.8±0.57, 79.15±0.52, 80.13±0.6 for Choice, 78.03±0.9, 79.42±0.82, 80.17±0.51 for Panavia, and 78.41±1.53, 79.59±0.77, 81.03±0.63 for Composite, respectively. The color changes by the time were significant for the all three groups (p<001).Calculating day 0-180 color changes, mean color differences for Choice, Panavia and Composite groups were 3.33±0.83 , 2.13±1.23, and 2.61±1.6, respectively. The color changes did not differ in the studied groups (p<0.133).

Conclusions: Post-aging color changes were significant, although all samples had color changes less than 3.5,Considering the clinical significance of color changes of more than 3.5, these results were acceptable and all three restorative materials could reliably be applied in the daily clinical use .