Aim: A clinical assessment the color regression of bleached teeth for one year .
Materials and methods: Thirty nonsmoker patients (18-23) having A4 shad sound anterior upper and lower segments were selected. The shades were measured using visual standardized shade guide and confirmed by spectrophotometer. The sixty Segments were distributed into 2 groups (30 segments each) according to the bleaching system used, Group I: Chemical activated bleaching system 40% HP & Group II: light activated bleaching system, mixed 32% HP. Each gp involved 15 upper and 15 lower segments at the 30 pts. Every group was distributed into 2 subgroups according to the location whether upper or lower segments. Every tooth shade was documented before bleaching, momently after bleaching, at 3 months intervals for a year .the collected data was c statistically analyzed.
Results:
There was a significant difference between follow up periods in both groups I & II at the upper segments appeared after 12 months &9 months. Also the shades of lower teeth recorded a significant difference between group I & II . There was no significant difference appeared between group I vs II at every perceptions periods. After comparing between upper vs lower segments, there was non-significant in both groups I & II .
Conclusion:
The whitening degree was nearly the same with the two used bleaching systems with non-significant difference in color between upper and lower segments. Faster regression of color was observed with light activated bleaching than with chemically activated bleaching. Chemical activated, Light activated