Aim: To evaluate the effect of the organic acid solution on color stability of the facing heat-cured
acrylic resin. Materials and methods: Two heat-cured facing acrylic resins were used in this study.
Sixty four rectangular shape specimens were prepared to evaluate the color changes of the heat-cured
acrylic resin after immersion in three organic acids (acetic, citric and lactic acids). The specimens were
divided into two groups according to tested resin materials, and then subdivided into four tested groups
according to immersion solution, eight specimens for each subgroup. The assessment of color property
(opacity) done by using ultra-violet visible spectrophotometer at wavelength 345 nm. Mean values
were compared statistically with one way analysis of variance (ANOVA) followed by Duncan , s multiple
range test to determine the significant difference among the tested groups at (p