Methods: As test teeth, 27 mandibular anterior teeth extracted from bovine were used. After the teeth were thawed immediately before use, they were cut at the dental cervical parts and the crowns were used as samples. The enamels on the crown labial side were polished more expediently and used for the bleaching and measurements. The bleaching period was seven days. The group setting and application methods were as follows (n=9). 1 2 3 4 5 6 7 (days) Agroup O H H H H H O Bgroup H H H H H H H Hchome bleaching Cgroup O O H H H H O Ocoffice bleaching Control - - - - - - -
We used a spectro-color difference meter for microfaces VSS 300H (Japan Denshoku Industries). The measurements were repeated five times at the same site, and the mean level was made the measured level. The L*, a*, and b* of the Lab color system were measured. The color difference (DE*ab) was calculated from the L*, a*, and b* levels.
Results: The L level increased in all groups (A, B, and C), compared with the controls. The a levels hardly changed. The b level tended to decrease slightly. Conclusions: From the DE*ab levels of each group, it was found that all groups experienced macroscopical effects.