Color stability of low-fusing porcelains for titanium

The resistance to staining of two low-fusing porcelains (Procera and Duceratin) for use with titanium and one conventional feldspathic porcelain (Vita VMK 68) were examined visually according to a protocol similar to the ADA Specification No. 69. The color deviation was also quantified using a colorimeter. Forty samples of each product were prepared using manufacturer's instructions and the samples divided into two groups of 20. The samples of one group were immersed in methylene blue, and the control group in distilled water. Of the twenty samples from each group, ten were ground to remove the glaze. The color values for each sample were recorded prior to and after immersion in the staining medium. The color deviation value, Delta E, for each sample was calculated. Visually discernible stain was present on the unglazed samples of all three porcelain products immersed in methylene blue. No stain was visually detectable on the glazed samples or the unglazed samples immersed in distilled water for all three porcelain products. The objective evaluation confirmed that the unglazed porcelain products had statistically higher color deviation after immersion in methylene blue.