Date of Graduation


Document Type


Degree Type



School of Dentistry


Not Listed

Committee Chair

Matthew Bryington

Committee Member

Bryan Weaver

Committee Member

Bryan Dye


Objective: To determine the visual and spectrophotometric effect external tooth bleaching has on natural tooth structure and OMNiCHROMA composite at various number of treatments. Variables were compared to determine if there is a detectable difference between the composite and the tooth before and after bleaching.

Methods: Preparation and restoration of 25 previously extracted teeth was completed. OMNiCHROMA composite was used. Each tooth was measured visually with a VITA shade guide and a colorimeter. Measurements were recorded before bleaching, after 5 and 10 treatments. Statistical analysis was completed and ΔE values between the composite and tooth were compared between the 3 treatment intervals.

Results: ΔE values were significantly different between the 0 and 10 treatment groups but not significantly different from the 0 to 5 treatment groups. The tooth/composite ΔE was significantly lower at 10 treatments than at 5 and 0 treatments. The mean ΔE was greater for the tooth than the composite at 5 treatments and 10 treatments. When compared using the visual shade guide, on average, a larger number of shade changes were noted in the tooth compared to the composite at 5 and 10 treatments.

Conclusions: In the present study, there was a significant decrease in the ΔE value from 0 to 10 treatments. This indicates that the shade difference between the composite and the tooth decreases as the tooth becomes brighter. The composite demonstrated the ability to change shade as the surrounding tooth structure became brighter - both visually and with the use of the colorimeter.