title: The effect of in-office vital bleaching and patient perception of the shade change.
abstract: OBJECTIVE
  This study aimed to evaluate the degree of colour change after an in-office vital tooth bleaching procedure with a 35% hydrogen peroxide gel using a spectrophotometer. The study also determined the patients' perceptions of the colour change and assessed the post operative sensitivity during the first week of the intervention.
  
  
  METHODS
  The maxillary teeth (from 15 to 25) of 22 patients comprising of 11 males and 11 females were bleached with a 35% hydrogen peroxide (HP) gel in a single visit treatment procedure (Yotuel Special, Biocosmetics Laboratories, Spain). Colour readings of the two maxillary central incisors were obtained using a spectrophotometer (CM-2600d Konica, Minolta) before and after the bleaching procedure. All the patients were requested to complete a form regarding post-operative tooth sensitivity and to record their perceptions toward the success of the bleaching treatment.
  
  
  RESULTS
  The quantitative effect of the bleaching material on tooth colour showed an increase in the L* values and a decrease in the a* and b* values. The changes were significant (Wilcoxon Signed Rank Sum Test; p < 0.05) from baseline until one month, except for the b* values one month after the bleaching procedure which were only significant at p < or = 0.1. The median overall colour change (deltaE) between baseline and after the bleaching procedure was 3.56. The mean value of the patients' colour perception was found to be 2.14 immediately after bleaching on a 3 point visual analogue scale. A Spearman correlation test showed a positive relationship between the deltaE values immediately and one week after bleaching and a weak relationship one week and one month after the bleaching procedure. There was a significant consistency in the patients' colour perception data immediately and one week after the bleaching process and a weak relationship between the deltaE values and the patients' colour perception one month after bleaching. Ten out of the twenty two patients experienced tooth sensitivity on the first day, immediately after the bleaching procedure. However only five patients experienced sensitivity on the second day, four patients on the third day and only one patient experienced sensitivity on the fourth and the fifth days after bleaching which was described as mild.
  
  
  CONCLUSIONS
  Yotuel Special 35% HP was able to bleach the patients' teeth with a perceptive colour change noticeable by the patients; however colour regression was evident quantitatively from the first week. Tooth sensitivity was a temporary side effect. The material cost is reasonable, it was easy to use and the procedure is not dependant on light activation.
  
  
  CONCLUSIONS
  A single application of this product may not be sufficient to give patients the bright smile they desire. However it is important to monitor the rebound effect after this procedure. Patients may experience some tooth sensitivity after the use of this bleaching material but the sensitivity is of a transient nature.
authors: Department of Restorative Dentistry, University of the Western Cape, South Africa.
authors: Y M Y
authors: YM
authors: Salem
authors: Y I
authors: YI
authors: Osman