Comparison of Tooth Whitening Efficacy between Gel and Strip with Light Activator / 치위생과학회지

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 (ΔE*) 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 ΔE*, using either the Shade eye-NCC or the Vita shade guide, the change in yellowness (Δb*) 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.

Effects of a whitening strip combined with a desensitizing primer on tooth color / 대한구강보건학회지

OBJECTIVES: The purpose of this study was to evaluate the efficacy of a 2.9% hydrogen peroxide (HP) whitening strip with a desensitizing agent as a primer. METHODS: This study was approved by the Institutional Review Board of Kyungpook National University Hospital. A total of 144 subjects (mean age: 21.7 years) were recruited after they provided informed consent for participation in the study. All participants used the whitening strip and primer for 1.5 h a day for 14 days. ShadeEye-NCC and Vita classical shade guide were used to determine the color changes, with respect to baseline, after 1, 3, 5, 7, and 14 days. A self-administered questionnaire was used to collect data on satisfaction after bleaching and irritating symptoms during the 14 days. All collected data were analyzed with repeated measures ANOVA and one-way ANOVA using SPSS 20.0 for windows. RESULTS: Brightness (ΔL*) was significantly higher in groups 2 and 3 than in the control group after 3 days of the experiment. Chroma (Δb*) started to decrease in groups 2 and 3, compared to control, after 1 day. Perceived symptoms of irritation were significantly lower in groups using the strip combined with the desensitizing primer than in the control group. Satisfaction after bleaching was higher in the experimental groups than in control. CONCLUSIONS: The HP whitening strip with a desensitizing agent as a primer is clinically effective in bleaching human enamel after 3 days of use. It also reduces the prevalence of gingival irritation.

The effects of tooth bleaching agents on microhardness of enamel in situ / 대한치과보존학회지

The objective of this in situ study was to evaluate the effects of whitening strip (Claren, LG Household & Health Care Ltd, 2.6% hydrogen peroxide) and gel (Opalescence, Ultradent, 10% carbamide peroxide) on microhardness of enamel in comparison with untreated control. Extracted twenty human upper incisors were disinfected, cleaned, and labial side of each incisor sectioned into 3 fragments by 2 x 2 mm size. After sectioning, labial sides of fragments were flattened and fixed to orthodontic bracket using flowable composite resin. Specimens prepared from each tooth were attached to the labial side of upper incisors of twenty volunteers one by one and treated by three different methods: (1) untreated control (2) treated with whitening strip for 14 days (3) treated with whitening gel for 14 days. Microhardness (Microhardness tester, Zwick) of each specimen was measured at the baseline of pre-treatment, immediate after bleaching treatment, 14 days after bleaching treatment and Knoop Hardness Number was determined. Microhardness changes of experimental groups were compared. The results show that tooth whitening strip and gel used in this study does not effect the micro-hardness of enamel during bleaching procedure.