Patients often express their satisfaction with tooth color after whitening procedures, even though sometimes they can`t fully perceive the change in tooth color. The aim of this study was to determine in which degree tooth color changes a year after tooth whitening, and if the patients could perceive it. Study was conducted as a double blind, placebo controlled randomized trial. There were 60 respondents, by 30 in the experimental and control group. After a year all the data of 50 respondents (26 control group) at the age of 19 to 28 (78% women) were analyzed. The experimental group had their front teeth bleached with a gel and a heating lamp in a time period of 30 minutes while the control group went through the same procedure but without the active component. The measurement of color elements L*a*b* were made on a tooth 11 with the spectrophotometer. Patients satisfaction on the other hand was estimated on a five-point Likter scale (1=completely satisfied; 5=completely dissatisfied). A short-term color change was significantly bigger in the active then in the placebo group (p<0,001; r=0,543), but in the long-term, this difference decreases. Final results show bigger color change in the active than in the control group with smaller effect size (p=0,025; r=0,318). Short-term satisfaction in color change significantly increases in both groups (p<0,001; r=0,765-0,804), after witch in the long-term it is significantly reduced in the active group (p=0,001; r=0,609), while the placebo group stays the same. Final results show a significant increase in satisfaction in both groups, with smaller effect in the experimental (p=0,012; r=0,492) then in placebo group (p<0,001; r=0,702). Tooth whitening causes color change, but patient don’t perceive the change. Long-term results show that whitened tooth color is not stable, and that patients perceive the change in color