| 1877 Effects of A Tooth Whitener on Enamel - Microhardness and SEM | ||
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W. ZHANG1, A. DEVARAJ1, J. HOU2, and Y. LI1, 1Loma Linda University, CA, USA, 2Anhui Medical University, Hefei, China Purpose: To evaluate effects of Day White 15% Whitening Gel on human enamel of extracted teeth using microhardness and electron scanning microscopy (SEM). Methods: Fifteen enamel samples were prepared from extracted human incisors without lesions and restorations. An enamel core was removed from the tooth using a diamond core drill. The samples were mounted, ground, polished, and randomly assigned to two groups: Day White 15% whitening Gel (N=10) and saline control (N=5). Ten samples received 28 bleaching treatments (15-min/ea) at 37oC in 100% humidity following manufacturer's instructions. To simulate the clinical application, samples were covered by pooled human saliva for 30-min between two treatments. The control samples were treated with the saline using the same procedures. The pre- and post-treatment Knoop microhardness (KHN) was measured using a Leco Microhardness Tester (M-400-H1, St. Joseph, Michigan) at 200 grams of loading for 15 seconds. Samples were then processed for the SEM evaluation of enamel surface morphology using an SEM (XL30-FEG Phillips, Netherlands). The within and between effects as well as the changes in the KHN for each group were analyzed using the Student t-Test. Results: The average baseline KHN values are within the normal range of the published data and the historical results of this laboratory. There were no significant differences in the pre- and post-treatment KHN measurements as well as their changes between the two groups. The SEM observation found no significant differences in the enamel surface morphology of the samples treated with Day White 15% Whitening Gel compared to that of the control specimens at either 200x or 2,000x magnifications. Conclusion: Under conditions of the study, the treatment with Day White 15% Whitening Gel for up to 28 times, each at 15 minutes, does not adversely affect the microhardness and the surface morphology of human enamel. | ||
| Seq #205 - PTT Poster Session #2 2:00 PM-3:15 PM, Friday, March 23, 2007 Ernest N. Morial Convention Center Exhibit Hall I2-J | ||
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