Title: 0109 - Efficacy and Peroxide Diffusion of Ultrasound Enhanced Tooth Whitening


Linchuan Wang, University of Rochester
Xiaoyi Zhao, University of Rochester
Songmei Zhang, University of Rochester
Hans Malmström, University of Rochester Eastman Institute for Oral Health
Yan-Fang Ren (Presenter)
University of Rochester


Objectives: To assess the efficacy of a novel ultrasound enhanced tooth whitening technology and evaluate its effect on diffusion of hydrogen peroxide through dental enamel.

Methods: Fifty-four enamel disks 1.0mm in thickness were prepared from bovine incisors. Half of the enamel disks were immersed in coffee solution (55oC) for 24h, washed for 30s to create discolored enamel specimens, which were divided into 3 groups and subjected to whitening with 35%H2O2 gel alone (GEL), 35%H2O2+light (GEL/LT), and 35%H2O2+light+40KHz ultrasound (GEL/LT/US), respectively. Whitening efficacies were measured with a spectrophotometer at 5, 15, 30, 45 and 60 minutes. The remaining 27 specimens were divided into 3 groups and mounted on artificial pulp chambers placed in sterile cells containing 1.0ml acetate buffer. To assess peroxide diffusion, enamel surfaces were treated with GEL, GEL/LT and GEL/LT/US as above, and diffused peroxide concentration (μg/ml) was calculated at different treatment intervals using a leucocrystal violet/horseradish peroxidase assay. CIE Lab color changes (ΔE) and peroxide diffusion were compared among the 3 groups.

Results: There were no significant differences in ΔE at 5 minutes among the three groups, but ΔE were statistically significant higher in GEL/LT and GEL/LT/US than in GEL at 15 minutes, and higher in GEL/LT/US than in GEL and GEL/LT at 30, 45 and 60 minutes. It took 30 minutes for ΔE to reach 17.5 in GEL/LT/US (an equivalent of 10 shades change from A4 to A2), as compared to 60 minutes in GEL/LT group (Table 1). Diffusion of peroxide through enamel was significantly higher in GEL/LT/US than in GEL and GEL/LT at 5 and 10 minutes. GEL/LT and GEL/LT/US showed significantly higher diffusion of peroxide than in GEL throughout experimental period (Table 2).

Conclusions: Ultrasound enhanced efficacy of light-assisted tooth whitening and accelerated diffusion of hydrogen peroxide through dental enamel in vitro.


Group** 5 min 15 min 30 min 45 min 60 min
GEL 3.8±3.1a 7.3±2.8b 9.3±3.2d 11.5±4.3e 13.2±4.0f
GEL/LT 4.7±1.6a 9.2±1.4c 11.6±2.3d 13.7±3.3e 17.5±4.5f
GEL/LT/US 4.4±2.7a 11.8±4.0c 17.6±6.5e 21.3±8.0f 23.5±8.7g
Group 5 min 10 min 15 min 30 min 45 min 60 min
GEL 0.3±0.1a 0.9±0.5b 1.2±0.5e 4.6±0.9g 6.6±0.9j 8.6±0.5m
GEL/LT 1.4±0.6b 2.2±1.2c 5.4±1.2f 6.8±0.9h 9.3±0.8k 10.2±0.7n
GEL/LT/US 3.2±0.6c 4.6±1.1d 5.5±1.0f 6.9±0.5h 9.4±0.6k 10.2±.0.6n

This abstract is based on research that was funded entirely or partially by an outside source:
This study is a trainee research project funded by the authors' institution. We thank Beyond International Inc. Stafford, TX for donating the study materials.

Disclosure Statement:
The submitter must disclose the names of the organizations with which any author have a relationship, the nature of the relationship, and the clinical or research area involved. The following is submitted: None