The study aimed to compare the whitening efficacy of a strip and gel containing 2.9% hydrogen peroxide, using a tooth whitening light activator. The whitening effect was compared through in vitro and in vivo studies. In the in vitro study, we used stained hydroxyapatite (HAP) specimens as artificial teeth. HAP specimens were made using HAP powder and polyvinyl alcohol solution, and stained by modified Stookey's method. A whitening gel and whitening strip were applied to the respective specimens for 20 minutes, with a light activator. The color changes were measured using a colorimeter. In the in vivo study, one group (test 1) used the gel with a light activator and the other group (test 2) used a strip with the same activator for 15 minutes a day, for four consecutive days. An organoleptic evaluation using a Vita shade guide and instrumental evaluation using a Shade eye-NCC (Shofu Co., Japan) were performed. The color change values (∆E*) in the in vitro study revealed the strip with the light activator to be more effective than the gel with the same activator (p＜0.001). In the in vivo study, even though there was no significant difference between the groups with respect to the ∆E*, using either the Shade eye-NCC or the Vita shade guide, the change in yellowness (∆b*) was statistically significant (p=0.024). In conclusion, test 2 group that used 2.9% hydrogen peroxide strip with a light activator, showed a tendency towards increased whitening than test 1 group that used the gel with the same activator; however further studies are needed to validate the above finding.

As the first study to develop a brush-off type oral care patch, the polymer-blended films composed of ethyl cellulose (EC) and hydroxypropyl methylcellulose (HPMC) were prepared by a solvent casting method. Contact angle measurements, tensile strength tests and optical topography measurements were performed to assess the suitability of the polymer blends as a brush-off patch film. The physicochemical properties of the polymer films were dependent profoundly on their composition. The morphologies of the blended polymer film were significantly altered upon contact with water over time. In terms of mechanical strength and hydration property, the polymer-blended films of EC and HPMC with a mass ratio of 1:1 or 2:1 were found to be highly suitable for a 30 min brush-off patch. We believe that this study can provide a new and versatile methodology of both designing and evaluating a brush-off film patch for oral care substance delivery.