The degree of tooth www.selleckchem.com/products/ABT-888.html hypersensitivity after bleaching was also evaluated. It was hypothesized that both techniques would be the same regarding these clinical issues. In this single blind study, only one examiner who measured the color after bleaching protocol was blinded to the experimental conditions. The CIELAB system was used to measurement of color difference in bleached teeth. This system is a 3D uniform color space with equal distances corresponding to equally perceived color differences. This system has three axes: The L* axis represents lightness and extends from 0 (black) to 100 (white); and a* and b* represent the redness-greenness and yellowness-blueness axis, respectively. When a* and b* coordinates approach zero, the colors become neutral. The spectrophotometer was considered more reliable by Matis et al.
 because this method is more objective and sensible than a visual scale and photos. ��E is the color difference between two objects and can be calculated within the CIELAB color system. The naked eye is able to distinguish color differences if the ��E value is more than 3.3. Based on the CIE* L a* b* system the results of this study showed that both treatment groups significantly lightened the teeth because ��E1 (Bleaching effectiveness) showed values more than 3.3 with power bleach (6.9337 �� 2.59) as well as with at-home bleach (7.1244 �� 3.32). Results showed that there was no significant difference between groups regarding the degree of whitening (��E1). Therefore, the first null hypothesis of this study stating that the ��degree of bleached teeth in both groups are statistically the same,�� was accepted.
Indeed, both protocols were effective in promoting tooth bleaching. This finding is in agreement with one previous study carried out by Almeida et al. who compared the effectiveness of at-home and in-office bleaching techniques. They found no statistical difference between both methods regarding the degree of teeth whitening. As stated in the statistical analysis of this study, there was no significant difference between both methods regarding regression of the whitening immediately after bleaching and at the 2 week, 1 month and 3 month follow-up periods. For this reason, the values of ��E2 represented in Table 1 relates only to the 6 month time interval. A comparison between groups in terms of color regression showed a value significantly less than 3.
3 for at-home bleaching (��E2 = 0.5368) compared with the power bleach technique (��E2 = 3.3560). Hence, the second null hypothesis of the study stating ��having an identical durability Dacomitinib of the whitening in treated teeth�� for power bleaching was not accepted, while it was accepted for at-home bleaching because this technique showed a ��E2 = 0.5368 �� 1.34 < 3.3.