Peroxide Gel Research Articles

Deionized water can substitute common bleaching agents for nonvital tooth bleaching when treated with non-thermal atmospheric plasma.

The bleaching efficacy of common bleaching agents and deionized water treated with non-thermal atmospheric pressure plasma in the pulp chamber for nonvital tooth bleaching was evaluated. A total of 120 extracted human maxillary first incisors were stained using human blood. Teeth were randomly divided into eight groups (n = 15). In the first four groups, teeth were bleached using 35% hydrogen peroxide gel, 37% carbamide peroxide gel, 2:1 (w/v) sodium perborate paste, and deionized water for 30 min. In the remaining groups, bleaching agents were treated with non-thermal atmospheric plasma for 5 min inside the pulp chamber. Overall color changes (∆E) were determined using Commission Internationale de L'Eclairage Lab Colour System. The plasma-assisted tooth bleaching has not increased tooth temperature beyond 37°C. Bleaching efficacies of bleaching agents were significantly improved when treated with non-thermal atmospheric plasma compared to their application (P < 0.05). A remarkable bleaching effect was obtained when bleaching agents were substituted with water and when treated with non-thermal atmospheric plasma. Non-thermal atmospheric plasma treatment could be a novel tool for activation of bleaching agents in the pulp chamber for nonvital tooth bleaching procedure. Moreover, water could be used as a novel bleaching agent when treated with the non-thermal atmospheric plasma to eliminate possible risks which might arise from peroxide-containing agents.

The degree of tooth colour change after using different concentrations of carbamide peroxide

Background: Depending on the cause of discoloration, bleaching materials and other factors, vital dental bleaching techniques may be professional (in-office dental bleaching), at-home night-guard bleaching and combined. The main objective of this study was to determine, in vitro, tooth colour change using external dental bleaching techniques with 16% and 30% carbamide peroxide gel and to investigate the effect of concentration of carbamide peroxide gel on the bleaching success. Method: This study included 20 extracted intact human teeth. Teeth were divided into two groups of ten each: the first group was bleached with 16% and the second group with 30% carbamide peroxide gel. The procedure was repeated three times for each tooth. The existing colour on each tooth was recorded using VITA classical shade guide A1-D4 before treatment, after each session and after bleaching was completed. Results: A significant difference (p < 0.01) was found between the first and the second bleaching treatment, for both concentrations (Exact binomial test). A significant difference (p <0.05) was also present between the second and the third treatment, while no statistically significant difference was found between the first and the third bleaching treatment, for both concentrations. There was no statistically significant difference between groups based on degree of tooth shade (χ2 test). Conclusion: The teeth bleaching technique with 16% carbamide peroxide gel and the teeth bleaching technique with 30% carbamide peroxide gel have shown the same efficiency in changing the tooth colour.

Radicular Peroxide Penetration from Different Concentrations of Carbamide Peroxide Gel during Intracoronal Bleaching—An In vitro Study

The aim of this study is to evaluate and compare the amount of radicular peroxide penetration when various concentrations of carbamide peroxide (CP) bleaching gels (10, 15, and 35%) and a mixture of 30% hydrogen peroxide (HP) with sodium perborate are used for intracoronal bleaching. Fifty extracted single-rooted premolars from young adults were used. The specimens were then divided into five groups such that teeth with varying sizes were equally distributed in all groups. Group I-distilled water (control group), group II-10% CP, group III-15% CP, group IV-35% CP, and group V-30% HP with sodium perborate. Intermediate restorative material (IRM) was used to seal access cavities and left for a week at 37 °C in an incubator. Following the bleaching process, suspended teeth from plastic tubes containing distilled water were removed and the water was used to determine the amount of peroxide levels. A UV-visible spectrophotometer at a wavelength of 480 nm was used to determine the quantity of peroxide based on the optical density. Results showed the highest peroxide leakage in group V, followed by group IV, and then group III, whereas the least peroxide penetration was found in group II, and the control group or group I showed no penetration. The Kruskal-Wallis test showed a significant difference between the various groups tested. The Mann-Whitney test was done to find in which pair of groups there exists a significant difference. It was found that all the groups when compared among themselves showed a significant difference. The present study concluded that lower concentrations of CP 10 and 15% produced lower peroxide leakage. Hence, it could be tried as an alternate to traditional agents in cases with compromised tooth which shows cervical tooth defects where the risk of external root resorption is higher. The management of discolored teeth involves different techniques; among various techniques, bleaching is considered to be a safe, effective, and relatively noninvasive technique to lighten discolored teeth and it also conserves dental hard tissue.

A randomized controlled trial of topical benzoyl peroxide 2.5% gel with a low glycemic load diet versus topical benzoyl peroxide 2.5% gel with a normal diet in acne (grades 1-3)

The improvement in insulin resistance and acne lesions on low glycemic load diets in various studies suggests that diet plays a significant role in acne pathogenesis. To compare the efficacy of a low glycemic load diet plus topical benzoyl peroxide 2.5% gel with that of only topical benzoyl peroxide 2.5% gel in grades 1, 2 and 3 of acne vulgaris. In a randomized controlled trial, 84 patients with grades 1, 2 and 3 acne vulgaris were divided into two groups, to receive a low glycemic load diet and no dietary intervention respectively. Acne lesions (face) were scored and graded at baseline and 4, 8 and 12 weeks. Homeostasis model assessment of insulin resistance and body mass index were measured during the first and last visits. Statistical analysis was done with Statistical Package for the Social Sciences, version 17.0. Both groups showed significant reduction in acne counts at 12 weeks (P = 0.931) with no statistically significant difference between the groups. The differences in body mass index and homeostasis model assessment of insulin resistance between the groups were statistically significant (P = 0.0001). Group 1 showed reductions in body mass index and homeostasis model assessment of insulin resistance values at the end of the study, whereas group 2 did not. Application of mild topical cleanser in both the groups might have contributed to the improvement in epidermal barrier function, and topical application of 2.5% of benzoyl peroxide gel in both groups contributed to the improvement in acne counts. A low glycemic load diet did not result in any significant improvement in acne counts.

Effect of Remineralizing Agents on Tooth Color after Home Bleaching.

Objectives:The purpose was to investigate the effect of casein phosphopeptide-amorphous calcium phosphate fluoride (CPP-ACPF) paste, Remin Pro paste, and 0.05% sodium fluoride (NaF) mouthwash on teeth discoloration after home bleaching.Materials and Methods:In this in-vitro study, 48 intact and unstained human incisors were divided into four groups (n=12): control (Group 1), CPP-ACPF paste (Group 2), Remin Pro paste (Group 3), and 0.05% NaF mouthwash (Group 4). The specimens were bleached using 20% carbamide peroxide gel for 21 days and were subjected to pH cycling and surface treatment with remineralizing agents for one month. The color of the specimens was determined according to the CIELAB color space at baseline, after bleaching, and after surface treatment. Data were analyzed using one-way analysis of variance (ANOVA), post-hoc least significant difference (LSD) test, and one-sample t-test (P=0.05).Results:ANOVA showed a significant difference in the mean ΔE of the four groups after surface treatment (P<0.05). Post-hoc LSD test showed a significant difference between the mean ΔE of the control group and those of the treatment groups (P<0.05) with no significant difference between the treatment groups, except for Remin Pro. The mean ΔE and ΔL of the Remin Pro group showed less change than those of the CPP-ACPF and NaF groups, indicating that Remin Pro has the lowest potential for post-bleaching tooth discoloration.Conclusion:CPP-ACPF paste, Remin Pro paste, and 0.05% NaF mouthwash cause noticeable teeth discoloration immediately after bleaching. Remin Pro has less effect on tooth color than the other two products.

Preliminary Assessment of Hydrogen Peroxide Gel as an Oxidizer in a Catalyst Ignited Hybrid Thruster

In regard to propulsion system applications, the stability of liquid propellants in long-term storage is of increasing importance, and this had led to a greater interest in gelation technology. As part of a preliminary test to determine the feasibility of using a gel propellant in a rocket with a catalyst bed, a hybrid rocket with a catalyst reactor using a gel propellant as an oxidizer was tested for the first time in this study. Experiments were conducted with two different oxidizers: one with liquid phase hydrogen peroxide and the other with gel phase hydrogen peroxide, as well as high-density polyethylene as fuel for a 250 N class hybrid thruster performance test. The thruster was designed with the catalyst ignition system, and a catalyst was manufactured to be inserted into the catalyst reactor to facilitate oxidizer decomposition. While the test result with neat hydrogen peroxide indicated sufficient decomposition efficiency using a manganese dioxide/alumina catalyst and successful autoignition of the fuel via the decomposed product, gel hydrogen peroxide exhibited insufficient decomposition and there were difficulties in operating the thruster as a part of the catalyst was covered in the gelling agent. This preliminary study identifies the potential challenges of using a gel phase oxidizer in a catalyst ignited hybrid thruster and discusses the technical issues that should be addressed in regard to a gel propellant hybrid thruster design with a catalyst reactor.

The effects of at-home whitening on patients\u2019 oral health, psychology, and aesthetic perception

BackgroundThe aesthetic self-perception and psychosocial impact of whitening is poorly explored in the literature; it is even less clear whether the effect of whitening may influence the psychology or social relations of patients. Therefore, the aim of this trial is to evaluate the impact of an at-home whitening procedure on patients’ quality of life. Also, this study’s secondary objective is the adaptation and validation of the Spanish version of the OES questionnaire (OES-SP).MethodsFifty eight patients underwent whitening with 10% carbamide peroxide (CP) gel for 1 h daily for 3 weeks. For these participants, the OHIP-Esthetics, PIDAQ, and OES surveys were applied before, one week after, and one month after the whitening procedure. Oral health-related quality of life was measured using the OHIP-Esthetics survey and the psychosocial impact using the PIDAQ survey. The orofacial aesthetics was measured by OES and validated for the Spanish Chilean context. The treatment efficacy (ΔE and ΔSGU) and data from the OHIP-Esthetics PIDAQ and OES surveys were compared using the Wilcoxon Signed-Rank test.ResultsThe whitening procedure was effective (ΔE = 5.9 ± 1.8). The OHIP-Esthetics results were significant when comparing the initial baseline survey prior to the treatment and one week after whitening (p < 0.001) and when comparing the baseline and one-month results (p < 0.001). The overall score on the PIDAQ, after one week post-whitening, was separated into factors and all factors were statistically significant (p < 0.03); the factors for the one-month results were also all statistically significant (p < 0.001), except the social impact factor. The OES questionnaire had statistically significantly increased scores both one week and one month post-treatment (p < 0.0001). The reliability, validity, and responsiveness of the OES-SP were satisfactory.ConclusionThe at-home whitening procedure with carbamide peroxide 10% had a positive effect on patients’ oral health-related quality of life, psychology, and aesthetic perception after one month post-whitening. The Chilean Spanish version of the OES showed satisfactory psychometric characteristics to evaluate dental whitening.Trial registrationNCT02605239. Date that the study was retrospectively registered: 11-11-2015.

Effect of At-Home Bleaching on Oxygen Saturation Levels in the Dental Pulp of Maxillary Central Incisors.

The present study assessed oxygen saturation (SaO2) levels before, during, and after at-home bleaching treatment in the pulps of healthy maxillary central incisors. SaO2 levels were measured in 136 healthy maxillary central incisors using a pulse oximeter. The bleaching protocol consisted of 10% carbamide peroxide gel placed in individual trays and used for four hours daily for 14 days. SaO2 levels were assessed before bleaching (T0), immediately after the first session (T1), on the 7th day of treatment (T2), on the 15th day (the day following the last session) (T3), and 30 days after completion of the bleaching protocol (T4). Data were statistically analyzed using generalized estimating equations (GEE), Student's t test (p<0.05) and Pearson's correlation. Mean pulp SaO2 levels were 85.1% at T0, 84.9% at T1, 84.7% at T2, 84.3% at T3, and 85.0% at T4. Gradual reductions in SaO2 levels were observed, with significant differences (p<0.001) during the course of home bleaching treatment. However, 30 days after the end of the bleaching protocol, SaO2 levels returned to baseline levels. Home bleaching caused a reversible transient decrease in SaO2 levels in the pulps.

Effect of hydrogen peroxide on color and whiteness of resin-based composites.

To evaluate the influence of a 35% hydrogen peroxide gel on color and whiteness changes of resin-based composites (RBC). Discs (n = 10; shade A3.5 enamel; and 8 mm diameter and 2 mm thick) were fabricated from three RBC (DF- Durafill, Heraeus Kulzer; ED- IPS Empress Direct, Ivoclar Vivadent; and AP- Amelogen Plus, Ultradent Products). Three subgroups were obtained for each RBC: before bleaching (T0 ) and after first (T1 ) and second (T2 ) bleaching applications. A dental spectrophotometer (VITA Easyshade, Vita Zahnfabrik) was used to obtain CIELAB color coordinates and whiteness index for dentistry (WID ) in all periods. CIELAB ( ) and CIEDE2000 (ΔE00 ) color differences were also obtained. Perceptibility (PT) and acceptability (AT) thresholds were used to analyze values of , ΔE00 , and ΔWID . Two-way analysis of variance (ANOVA; for L*, a*, b*, and WID ) and one-way ANOVA and Tukey tests (for and ΔE00 ) were used to analyzed the results (α = 0.05). L* and WID values from all RBC did not change after bleaching applications (T1 and T2 ) (P > .05). There were no significant differences in color differences ( and ΔE00 ) among all RBC evaluated after bleaching applications (T1 -T0 and T2 -T0 ; P > .05). Regardless of the RBC, mean values of ΔE00 between all different periods were always below 50%:50% PT value. The 35% hydrogen peroxide bleaching gel influences on color and whiteness of resin-based composites. However, color changes were not clinically perceived and whiteness variations were clinically acceptable. Patients should be advised that existing composite restorations might not match the natural tooth color after bleaching, and their replacement may be required.

Effects of Enzymatic Activation of Bleaching Gels on Hydrogen Peroxide Degradation Rates, Bleaching Effectiveness, and Cytotoxicity.

The aim of this study was to evaluate the effect of horseradish peroxidase (HRP) on the release of free radicals, bleaching effectiveness, and indirect cytotoxicity of a 35% hydrogen peroxide (HP) bleaching gel. First, HP degradation rates and free radical release were evaluated for 35% HP in contact or not with HRP (10 mg/mL). The bleaching gel associated or not with HRP was then applied (3 × 15 minutes) to enamel/dentin discs adapted to artificial pulp chambers, and the culture medium in contact with dentin surfaces (extract) was collected and exposed to cultured odontoblast-like cells. Membrane damage and viability of cells as well as oxidative stress were evaluated. Residual HP/free radical diffusion was quantified, and bleaching effectiveness (ΔE) was assessed. Unbleached discs served as negative controls. The addition of HRP to the 35% HP bleaching gel enhanced the release of free radicals in comparison with plain HP gel. The 35% HP-mediated cytotoxicity significantly decreased with HRP in the bleaching gel and was associated with reduced HP/free radical diffusion through the enamel/dentin discs. ΔE values increased every bleaching session for HRP-containing gel relative to positive control, accelerating the whitening outcome. The enzymatic activation of a 35% HP bleaching gel with HRP accelerated HP degradation mediated by intensification of free radical release. This effect optimized whitening outcome as well as minimized residual HP and free radical diffusion through enamel and dentin, decreasing the harmful effects on odontoblast-like cells.

In-office and walking bleach dental treatments on endodontically-treated teeth: 25 years follow-up.

Many techniques have been evolved for the purpose of managing discoloured non-vital tooth such as dental bleaching, restorative and prosthetic treatment. In order to achieve better control on the patients, in-office and intra-coronal bleaching procedures were introduced in clinical practice. Such techniques usually use higher whitening agent concentrations activated by means of heat or light sources, resulting in improved color stability in the long term. The aim of this study was to evaluate the color stability, after 25 years, of endodontically-treated teeth subjected to in-office and walking bleach dental treatments with carbamide peroxide. A population of patients with a single endodontic treatment on an incisor teeth was recruited. All the teeth selected for the study were subjected to both in-office intra-coronal dental bleaching and walking bleach technique with 10% carbamide peroxide gel. The patients were recalled at follow-up every 12 months for a total observational period of 25 years. After 25 years of clinical service on 40 patients, an optimal tooth color stability in relation to adjacent teeth was evidenced in 34 patients, while 6 patients were classified as failures, since a color mismatch of two or more shades were noticed. Consequently, a success rate of 85% was reported after 25 years. Ten percent carbamide peroxide proved to be an effective dental whitening agent in the long-term for endodontically-treated.

Immediate clinical evaluation of a 940-nm diode laser-assisted in-office bleaching technique

Evaluate the clinical performance of currently available dental bleaching technologies concerning their efficacy and safety features. This study aimed to evaluate the clinical outcome of a 940-nm diode laser-assisted in-office bleaching technique for vital teeth. Subjects were assigned to treatments in a split-mouth study design. A 38% hydrogen peroxide gel photoactivated by 940 nm [400 μm fiber tip, 7 W; maximum energy of 210 J per tooth (smaller teeth received less energy than 210 J), maximum period of 30 s] (LaserWhite20, Biolase, USA) and a 38% hydrogen peroxide conventional gel (Power Whitening, WHITEsmile, Germany) were tested. The photoactivated system was evaluated on the right quadrants of upper and lower jaws, while the conventional hydrogen peroxide system was evaluated on the left quadrants. Gels were fixed in place for 10 min and then rinsed. The degree of color change was evaluated using a spectrophotometer based on VITAscale (Shade Star, Degudent, Germany) immediately after treatments. Data were analyzed using one-way ANOVA, followed by Tukey’s test or paired t test, setting a significance level of 5%. Both treatments were effective in promoting tooth whitening (p 0.05). The laser-assisted system resulted in lower shade values in both upper and lower jaws (p < 0.05). Few patients experienced tooth sensitivity in the treated areas upon completion of the treatment. The dental pulp viability of the treated teeth was maintained more than 1 year after the completion of the treatments. The 940-nm diode laser-assisted tooth whitening has been shown to be effective in a short-term post-bleaching assessment.

Effectiveness of Dental Bleaching With 37.5% and 6% Hydrogen Peroxide and Its Effect on Quality of Life.

This study investigated whether it is possible to achieve equally satisfactory results between 37.5% hydrogen peroxide (HP) gel and 6% HP gel. We also assessed the psychosocial impact and self-perception of esthetics generated by extracoronal tooth whitening. A prospective, double-blind, randomized clinical trial was carried out. A total of 33 patients were selected from the clinic of the Faculty of Dentistry at the University of Chile. The patients included men and women over 18 years old without prior tooth whitening treatments, tooth decay, or restorations of the maxillary anterior teeth. The patients had tooth colors of A3 or less according to the Vita Classical scale, which was determined with a Vita Easy Shade spectrophotometer. The study was carried out with a "split-mouth" design. One side of each mouth was randomly treated with 37.5% HP, and the other side was bleached with 6% HP. Each group received 3 to 12 minutes of treatment with the respective gel applications. Two sessions of bleaching were carried out each week. A spectrophotometer was used to measure the total variation of color (ΔE), and a subjective evaluation was made with Vita Classical scale (ΔSGU) between the baseline (session 1) and different measurement times. We compared ΔE and ΔSGU for both agents using the Mann-Whitney test ( α=0.05). In both groups, there was variation among the initial color and the color in the different measurement times. In the month after the treatment was completed, ΔE was 9.06 in the 37.5% HP group and 5.69 in the 6% HP group. The difference between the two groups was statistically significant starting in the second session ( p=0.000). There was a significant difference between the effectiveness of the bleaching gel concentrations of 37.5% and 6% HP according to spectrophotometer measurements and subjective evaluations. There was also a positive effect on psychosocial impact and esthetic self-perception among patients.

The effects of hybrid light activation and enamel acid etching on the effectiveness, stability and sensitivity after a single session in-office bleaching: A 12-month clinical trial.

The use of hybrid-light (HL) during in-office teeth bleaching can provide faster and reliable results after a single bleaching session, especially if associated with previous acid etching. The present in vivo, interventional, split-mouth, triple-blinded and randomized study evaluated the efficiency of a HL, with and without prior enamel acid etching, assessing the gel application time, degree of color change, sensitivity and treatment stability up to 12 months. Thirty-four patients were selected and randomly divided into four groups. The color was evaluated using a spectrophotometer with the CIELab color system, and a VAS questionnaire was used to evaluate the sensitivity. Both upper and lower hemiarches (GI and III) received enamel acid etching with 37% phosphoric acid for 15 s prior to the application of 35% hydrogen peroxide gel (HP). For GI and II, HP was applied on both dental arches for 3-4 consecutive applications and activated by HL (2 × 3' activations with 1' interval); and 3 × 15' (HP) for GIII and IV without HL. Patients returned in 24 h, 1 week, 1-, 6- and 12-months intervals. The clinical operator was different from the clinical measurements operator. After 3-way ANOVA, Tukey's, Wilcoxon and Mann-Whitney tests, all with p < 0.05, no statistical differences were observed between the groups regarding color change (ΔE) and sensitivity in all evaluations. The lowest gel application time was observed for GII (acid etch + HL), followed by GI (HL). The present study's results reveal the advantages of HL associated with acid etching prior to in office bleaching.

At-home Bleaching With 10% vs More Concentrated Carbamide Peroxide Gels: A Systematic Review and Meta-analysis.

To perform a systematic review to answer the following research question: Is at-home bleaching in adults with more concentrated carbamide peroxide (CP) gels as effective and safe as bleaching performed with 10% carbamide peroxide gels? A comprehensive search was carried out in the MEDLINE via PubMed, Scopus, Web of Science, LILACS, BBO, Cochrane Library and SIGLE, without restrictions. IADR abstracts (1990 to 2016) and unpublished and ongoing trial registries, dissertations and theses (ProQuest Dissertations and Periodicos Capes Theses Databases) were also searched. The risk of bias of the included studies was analyzed using the Cochrane Risk of Bias tool from the Cochrane Collaboration. We meta-analyzed the data using the random effects model to compare 10% CP and more concentrated CP gels in terms of color change (ΔSGU or ΔE) and risk and intensity of tooth sensitivity (TS). The quality of the evidence was rated using the GRADE approach. After the database screening, 182 articles remained, and this number was reduced to 17 after examination of the abstracts and/or full texts. Four articles were follow-ups of earlier studies, and thus we collected 13 studies. Ten studies were at unclear risk of bias, while three were at low risk of bias. Lower risk and intensity of TS was observed for 10% CP. The odds ratio for the risk of TS was 0.41 (95% CI 0.20 to 0.84, p=0.01), and the difference in means for TS intensity was 0.44 (95% CI 0.67 to -0.20, p=0.0003). No significant difference was observed in terms of color change in ΔSGU (difference in means 0.29; 95% CI 0.25 to 0.83, p=0.29) and for ΔE (difference in means -0.16; 95% CI 0.38 to 0.06, p=0.16). Except from the ΔSGU, for which the evidence was graded as low quality, the other outcomes were considered at moderate quality. At-home bleaching with 10% CP showed similar bleaching efficacy with lower risk and intensity of TS in comparison with more concentrated carbamide peroxide gels.

Teeth whitening with 6% hydrogen peroxide and its impact on quality of life: 2years of follow-up.

This study aimed to evaluate color longevity after 2years of whitening gel (6% hydrogen peroxide (HP), blue LED/infrared laser activation system) in comparison to a control 35% concentration in a split-mouth study and investigate the long-term effect on quality of life (QOL).Thirty-one patients were treated. Whitening using 6% or 35% HP gel was performed on half of the upper jaw in each patient. The color was measured at baseline and 1week, 1month, 1 and 2years after treatment using the Easyshade Vita spectrophotometer and the Vita Bleached and Vita Classical Shade Guides organized by value. During 2years of follow-up, color was evaluated before and after dental prophylaxis. Oral Health of Impact Profile (OHIP 14) and Psychosocial Impact Dental Aesthetics Questionnaire (PIDAQ) surveys measured QOL. Nineteen patients were evaluated at the 2-year follow-up. Significant differences in ΔE were measured between the two groups at all time points (p < 0.05). No significant differences in ΔSGU were observed at any time point (p > 0.05). The positive effect of bleaching on QOL was maintained in patients treated with a low concentration of the whitening gel. The two compounds remained effective after 2years. An objective color difference was found between the groups, but no difference was observed in subjective reports. The positive effect on QOL remained after 2years of follow-up in this cohort of patients.ClinicalTrials.gov identifier NCT02353611.

Effect of Remineralizing Gels on Microhardness, Color and Wear Susceptibility of Bleached Enamel.

To evaluate the effect of a remineralizing gel combining fluoride and calcium silicate/phosphate or a sodium fluoride gel on bleached enamel microhardness, color, and wear susceptibility. Two hundred forty bovine enamel-dentin samples were prepared. Baseline analysis of Knoop microhardness, color coordinates (L*a*b*), and surface profile were performed. According to the baseline microhardness values, specimens were stratified into six groups (n=40): NC (negative control)-no treatment; BL (positive control)-bleaching with 40% hydrogen peroxide gel (Opalescence Boost, Ultradent); BL/Rs-bleaching + application of calcium silicate/phosphate gel (Regenerate Serum, Unilever - Rs); Rs/BL-Rs + bleaching; Rs/BL/Rs-Rs + bleaching + Rs; and BL/F-bleaching + 2% sodium fluoride gel. After the treatment described for each group, color change (ΔE) and microhardness were evaluated again. To evaluate abrasion susceptibility, samples were randomly divided into two subgroups, according to the toothpaste used (Cp-Close Up or Rt-Regenerate), and underwent 100,000 brushing strokes. The profile of each sample was evaluated and the mean wear calculated. The data were analyzed by ANOVA and Tukey tests. All bleached groups showed a significant reduction of microhardness in relation to the negative control. The groups treated with remineralizing gels showed a significantly higher microhardness and less wear than the positive control, although nonsignificant differences were observed among them. Nonsignificant differences in ΔE were found among bleached groups. The groups brushed with Regenerate toothpaste showed significantly less wear than those brushed with Close Up toothpaste. The remineralizing gels did not interfere with bleaching efficacy. However, all the treatments minimized the surface hardness reduction caused by the bleaching procedure and enamel loss after abrasion. Regenerate toothpaste resulted in less enamel abrasion.

In-office tooth bleaching with 38% hydrogen peroxide promotes moderate/severe pulp inflammation and production of ll-1β, TNF-β, GPX, FGF-2 and osteocalcin in rats.

Objectives:To study the intensity of inflammatory infiltrate and production of interleukin-1β (ll-1β), tumor necrosis factor-β (TNF-β), fibroblast growth factor-2 (FGF-2), glutathione peroxidase (GPX), and osteocalcin in response to in-office tooth bleaching in rats.Material and Methods:Twenty male Wistar rats were randomized into four groups (n=5) according to the received treatment (tooth bleaching or no treatment - control) and the period of euthanasia after treatment (24 h or 10 days). We performed tooth bleaching using a 38% hydrogen peroxide gel on maxillary and mandibular incisors. After euthanasia, incisors (20 per group) were processed for histological analysis, immunohistochemistry staining of ll-1β, TNF-β, FGF-2 and GPX and osteocalcin by immunofluorescence. We analyzed data using the Mann-Whitney and Kruskal-Wallis/Dunn tests (p<0.05).Results:The bleached groups presented statistically significant differences regarding the pulp inflammation stage compared with the control groups. Bleached teeth showed moderate/severe inflammatory infiltrate and control groups presented absent inflammatory cells or a negligible number of mononuclear cells (p<0.001) at two times (24 h and 10 days). There was strong staining for ll-1β, TNF-β, and GPX in bleached groups at 24 h and strong staining for ll-1β, TNF-β, GPX and FGF-2 at 10 days. After 10 days of tooth bleaching, the bleached group showed a statistically superior amount of osteocalcin than the other groups (p<0.01).Conclusions:Tooth bleaching with 38% hydrogen peroxide causes severe pulp inflammation, but characteristics of tissue repair after 10 days.

PR097: Clinical evaluation of effects of local application of hydrogen peroxide gel (1.7%) as an adjunct to scaling and root planing in patients with chronic periodontitis: a split‐mouth single‐blind randomized controlled clinical trial

PR097: Clinical evaluation of effects of local application of hydrogen peroxide gel (1.7%) as an adjunct to scaling and root planing in patients with chronic periodontitis: a split‐mouth single‐blind randomized controlled clinical trial

Benzoyl peroxide gel stains synthetic fabrics less than they stain cotton

To the Editor: Benzoyl peroxide (BPO) is a widely used over-the-counter topical treatment recommended by dermatologists for acne.1 BPO can stain clothing and sheets.2 This may contribute to patient dissatisfaction, leading to decreased adherence and suboptimal treatment. We evaluated the staining effect of 10% BPO gel on clothing. Six different black fabrics were chosen: 100% polyester, fleece (100% polyester), 100% cotton, 75% nylon/25% spandex, 100% rayon, and 55% linen/45% rayon. Identical 8 x 8-inch fabric swatches were used, and 4-inch segments were delineated on each swatch.