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Background: In an in vivo study, the authors tested the hypothesis that no difference in enamel surface roughness is detectable either during or after bleaching with a high-concentration in-office whitening agent., Methods: The authors performed profilometric and scanning electron microscopic (SEM) analyses of epoxy resin replicas of the upper right incisors of 20 participants at baseline (control) and after each bleaching treatment with a 38 percent hydrogen peroxide whitening agent, applied four times, at one-week intervals. The authors used analysis of variance for repeated measures to analyze the data statistically., Results: The profilometric analysis of the enamel surface replicas after the in vivo bleaching protocol showed no significant difference in surface roughness parameters (P > .05) compared with those at baseline, irrespective of the time interval. Results of the correlated SEM analysis showed no relevant alteration on the enamel surface., Conclusions: Results of this in vivo study support the tested hypothesis that the application of a 38 percent hydrogen peroxide in-office whitening agent does not alter enamel surface roughness, even after multiple applications., Clinical Implications: The use of a 38 percent hydrogen peroxide in-office whitening agent induced no roughness alterations of the enamel surface, even after prolonged and repeated applications.

This study evaluated the morphological effects produced in vivo by two in-office bleaching agents on enamel surface roughness using a noncontact profilometric analysis of epoxy replicas. The null hypothesis tested was that there would be no difference in the micromorphology of the enamel surface during or after bleaching with two different bleaching agents. Eighteen subjects were selected and randomly assigned to two treatment groups (n=9). The tooth whitening materials tested were 38% hydrogen peroxide (HP) (Opalescence Xtra Boost) and 35% carbamide peroxide (CP) (Rembrandt Quik Start). The bleaching agents were applied in accordance with manufacturer protocols. The treatments were repeated four times at one-week intervals. High precision impressions of the upper right incisor were taken at baseline as the control (CTRL) and after each bleaching treatment (T0: first application, T1: second application at one week, T2: third application at two weeks and T3: fourth application at three weeks). Epoxy resin replicas were poured from impressions, and the surface roughness was analyzed by means of a non-contact profilometer (Talysurf CLI 1000). Epoxy replicas were then observed using SEM. All data were statistically analyzed using ANOVA and differences were determined with a t-test. No significant differences in surface roughness were found on enamel replicas using either 38% hydrogen peroxide or 35% carbamide peroxide in vivo. This in vivo study supports the null hypothesis that two in-office bleaching agents, with either a high concentration of hydrogen or carbamide peroxide, do not alter enamel surface roughness, even after multiple applications.

This study evaluated tooth whitening and sensitivity that occurred during and after 14 days of overnight bleaching with 15% carbamide peroxide gel with potassium nitrate and fluoride (Opalescence 15% PF, OP) and 16% carbamide peroxide with amorphous calcium phosphate (Nite White 16%, NW). Thirty-two subjects bleached their teeth using custom trays. The subjects had a baseline evaluation and returned after 7, 14, 21, 35 and 90 days for subjective and objective color evaluations. The subjects also recorded daily tooth and gingival sensitivity. The treatments were compared for differences in mean L*, a*, b* and shade guide rank order at baseline and each appointment thereafter, using repeated measures analysis of variance (ANOVA). OP and NW showed significant tooth whitening. Subjects using OP were significantly lighter in b* and E* than those using NW, while exhibiting no difference in tooth or gingival sensitivity overall or during any evaluation.

Purpose: This clinical evaluation compared a neutral sodium fluoridated whitening product to a neutral non-fluoridated whitening product in terms their effects on human enamel surface microhardness (SMH) and human enamel/resin composite shear bond strength (SBS) following various treatment times., Materials and Methods: Subjects were evaluated for enamel SMH and enamel/resin SBS following 15% carbamide peroxide (CP) with and without potassium nitrate and fluoride (PF). Twenty subjects (80 first or second premolars), who were treatment-planned for premolar extraction due to orthodontic therapy, were allocated into two groups, A and B. Group A received 15% CP, while Group B received 15% CP with PF. Each patient had a control tooth, a 14-day treatment + 14-day recovery tooth, a 14-day treatment + no recovery tooth and a 4-day + no recovery tooth. Each tooth was further divided into two testing surfaces; the facial surface was used for SMH, while the lingual surface was used for SBS., Results: The results of this study determined that there was no statistically significant difference between the effects of the two products on SMH and enamel/resin SBS. Additionally, there was no statistically significant difference between the treatment specimens compared to the controls in terms of SMH. However, there was a significant difference between the treatment groups compared to the controls in terms of enamel/resin SBS., Conclusion: Within the limitations of this clinical study, 15% CP with and without PF does not seem to alter the SMH of human enamel. However, 15% CP with and without PF significantly reduced enamel/resin SBS immediately following tooth whitening therapy, up to 14 days post-treatment.

This study evaluated the histological changes in dental pulp after nightguard vital bleaching with 10% carbamide peroxide gel. Fifteen patients between 12 and 26 years of age with caries-free first premolars scheduled for orthodontic extraction were treated with 10% Opalescence (Ultradent Products, Inc). Tooth #5 had four days of bleaching, tooth #12 was treated for two weeks, tooth #21 was bleached for two weeks followed by two weeks without treatment and tooth #28, serving as the control, was without treatment. All teeth were extracted at the same time. Immediately after extraction, 4 mm of the most apical portion of the root was sectioned off and each specimen was placed in a vial containing 10% neutral buffered formalin. The samples were prepared for histological evaluation at the Scandinavian Institute of Dental Materials (NIOM) and microscopically examined independently at both NIOM and Indiana University School of Dentistry (IUSD). Pulp reactions were semi-quantitatively graded as none, slight, moderate and severe. Slight pulpal changes were detected in 16 of the 45 bleached teeth. Neither moderate nor severe reactions were observed. The findings indicate that the slight histological changes sometimes observed after bleaching tend to resolve within two weeks post-treatment. Statistical differences existed only between the untreated control and the four-day (p=0.0109) and two-week (p=0.0045) treatment groups. The findings from this study demonstrated that nightguard vital bleaching procedures using 10% carbamide peroxide might cause initial mild, localized pulp reactions. However, the minor histological changes observed did not affect the overall health of the pulp tissue and were reversible within two weeks post-treatment. Therefore, two weeks of treatment with 10% carbamide peroxide used for nightguard vital bleaching is considered safe for dental pulp.

This in vivo study determined the kinetics of 3% hydrogen peroxide in a bleaching gel within the first hour. The material used in this study was 3% hydrogen peroxide gel (Perfecta 3/15, Premier Dental Products Co) and the study involved 10 subjects who met the inclusion and exclusion criteria. Each subject wore the tray with gel six different times on separate days. Evaluation of the remaining amount of hydrogen peroxide was calculated by the method stated in US Pharmacopoeia. The study results indicate that the mean percentage of hydrogen peroxide recovered for 5, 10, 20, 30, 45 and 60 minutes was 61, 56, 49, 44, 38 and 32, respectively. The amount of hydrogen peroxide in the saliva sample after one hour was 0.42 mg. Excluding the first 10 minutes, the kinetics of hydrogen peroxide in the tray and teeth sample was exponential.

Objective: The degree of color change and the dental sensitivity associated with the use of different concentrations (10%, 15%, and 20%) of carbamide peroxide every night for 6 months was evaluated in tetracycline-stained teeth., Method and Materials: Fifty-nine subjects were shown how to place two different concentrations of carbamide peroxide in the custom trays with reservoirs. For a period of 6 months, the patients were to insert the tray every evening before retiring. Patients returned in 1 and 2 weeks and at 1, 2, 3, 4, 5, 6, 7, 8, and 9 months for evaluation of the degree of color change by subjective shade matching and by photographic means. Sensitivity of hard or soft tissues was self-reported., Results: Fifty-two subjects attended more than 90% of the recalls. A colorimeter was used to convert shade guide tabs to Commission Internationale de l'Eclairage color spaces (CIELAB). The most rapid whitening occurred in the first month. At 3 and 9 months, 91% and 85% of the subjects, respectively, were at least "a little pleased" with the results of the bleaching. In the professional evaluation, 90% of the teeth were deemed to have an excellent or satisfactory esthetic result. The higher the concentration of carbamide peroxide, the more rapidly the lightness value and color difference changed. There was no difference among the three concentrations in resulting gingival sensitivity. Patients experienced less tooth sensitivity with 10% gel than they did with 15% and 20% gels., Conclusion: Bleaching with 10%, 15%, and 20% carbamide peroxide is effective for removing tooth staining caused by tetracycline. The 10% concentration has the most advantages and the fewest disadvantages.

This article will address the breakdown or lowering of active bleaching agent concentration during use in the mouth. A greater than expected degradation occurs during the first 5 minutes followed by an exponential rate loss. Subjects have a large variation in degradation rates. After 2 and 6 hours there was 52% and 24% respectively, of the active agent present in a carbamide peroxide gel. The presence or absence of the pellicle did not affect the rate of degradation. The relationship of gel degradation to the whitening capability of a gel is yet to be determined.