Time dependent effects of various staining agents on colour of artificial teeth

The purpose of this in vitro study was to evaluate the colour changes in six brands of porcelain and of acrylic teeth after their immersion in tea, filtered coffee and cola for 1 day, 1 week, 2 weeks and 4 weeks. The study comprised three brands of porcelain and three brands of acrylic teeth. Five central maxillary incisors from the six types of artificial denture teeth were distributed equally into four groups (n=30) according to the four immersion solutions. Colour measurements on each tooth were made before their immersion, and repeated after 1 day, 1 week, 2 week and 4 week immersions in the four solutions using the CIE L*a*b* colour measuring system. The colourimetric data were converted to National Bureau of Standards units. The data were analysed statistically by repeated measures analysis of variance (ANOVA), one-and two-way ANOVA, and Tukey honestly significant difference (HSD) multiple comparison tests. It was found that tea was more chromogenic than either filtered coffee or cola, and that acrylic teeth that had been immersed in tea for 4 weeks displayed the greatest colour change when compared to porcelain teeth. Tea is more chromogenic than filtered coffee and cola. The colour stability of porcelain teeth is greater than that of acrylic teeth. The degree of discolouration of acrylic and porcelain teeth after their immersion in tea, filtered coffee and cola is time dependent.