Tooth whitening has become an emergent and popular dental procedure in Dental offices over recent years with light assisted tooth whitening one of the more prevalent in-office procedures. Objectives: The purpose of this clinical study was to compare the effectiveness of TiON (GC America) light activated whitening system when applied in a single application to three applications of whitening gel. Methods: IRB consent approval was obtained. 30 subjects randomly divided into 2 gps. Teeth were isolated, gel and light applied, gel removed, evaluated for shade and sensitivity, MI Paste (GC America) applied. Gp 1 received 1-20 min, and Gp.2 received 3-20 min. gel applications. Shade evaluations were taken pre-, immediate post-. 2 Wk, and 4 Wk. post-treatment using value ordered shade tab comparison, and electronic measurement converted to L*a*b* data. Sensitivity was evaluated at each shade evaluation interval. The data was analyzed using Mann-Whitney U at a=0.05, Two-sample t test at a=0.05 and two way ANOVA. Results:

L*a*b*Δ Data

	ΔD1-BL)	ΔW2-BL)	ΔW4-BL)	ΔW2-D1)	ΔW4-D1)	ΔW4-W2)
Gp 1	3.45±2.14	2.34±1.21	2.39±1.16	4.21±12.26	1.97±1.42	1.19±0.43
Gp 2	4.11±1.26	6.99±16.23	3.24±1.38	1.76±0.91	1.92±1.18	1.34±0.59

Value ordered Shade Tab Data

	Pre	Day 1	Week 2	Week 4
Gp 1	8.65±2.73	4.28±3.05	4.70±3.63	5.71±3.25
Gp 2	9.34±3.02	3.91±3.65	5.49±3.66	5.96±3.62

Analysis shows that for L*, a*, b* and Δ values, and for valued ordered shade tab comparison, there is no significant difference between treatment (Gp. 1, or Gp. 2)or time interval, (pre treatment, Immediate post treatment, 2 weeks, 4 weeks). No sensitivity was detected at any evaluation interval. Conclusion: This study did not demonstrate any significant shade difference between a single application and 3 applications of whitening gel. This study was partially supported by GC Corporation