Effect of whitening toothpastes with different hydrogen peroxide concentrations: Penetration into the pulp chamber and color change.

OBJECTIVES: This study evaluated the efficacy of simulated brushing with toothpastes containing different concentrations of hydrogen peroxide (HP) in pulp chamber penetration and color change. Also, physical-chemical properties (concentration, pH and viscosity) were evaluated. METHODS: Forty-nine premolars were divided into seven groups (n = 7): untreated (control); whitening gel (White Class 6 %, 6 %BG) with one 90  min application (6 %BG 90  min) and 14 applications of 90  min (6 %BG 14×90 min); toothpastes (Colgate Luminous White Glow 3 %, 3 %TP; Crest 3D White Brilliance 4 %, 4 %TP; Colgate Optic White Pro-Series 5 %, 5 %TP) and 6 %BG toothbrushing for 14 applications of 90 s. HP penetration into the pulp chamber was measured through UV-Vis spectrophotometry and color change with a spectrophotometer (ΔEab, ΔE00, and ΔWID). Initial concentration, pH, and viscosity were measured through Titration, Digital pH-meter, and Rheometer, respectively. Statistical analysis used one-way ANOVA and Tukey's test (α = 0.05). RESULTS: 6 %BG (14×90 min) and 4 %TP groups showed acidic pH and higher concentrations of HP in the pulp chamber compared to the other groups (p < 0.05). On the other side, 3 %TP and 5 %TP groups showed alkaline pH, higher viscosity between the toothpastes and lower HP penetration (p < 0.05). The 6 %BG AH (14×90 min) group exhibited the most significant color change (ΔEab, ΔE00, and ΔWID) (p < 0.05). CONCLUSIONS: Brushing with whitening toothpaste with an acidic pH leads to greater HP penetration into pulp chamber; but, even when a high concentrated HP whitening toothpaste was used, a lower whitening effect was observed when compared to a two-week at-home bleaching. CLINICAL SIGNIFICANCE: Whitening toothpastes containing up to 5 % HP produced lower whitening effect than two-week at-home bleaching. Additionally, HP was detected within the pulp chamber which can potentially impact in tooth sensitivity.

Dentifrícios branqueadores contendo Blue covarine: revisão de literatura / Bleaching dentifrices containing "Blue covarine" literature review

Introdução: O efeito branqueador dos dentifrícios contendo Blue covarine é fundamentado no seu mecanismo de ação, caracterizado pela sua deposição na superfície dentária, alterando a percepção da cor. Objetivo: Revisar a literatura e buscar evidência científica sobre o efeito branqueador do Blue Covarine em tecidos mineralizados e materiais restauradores estéticos. Materiais e métodos: Para a revisão da literatura foram feitas buscas nas bases de dados PubMed, LILACS, BBO, SciELO e MEDLINE para identificar estudos clínicos e laboratoriais que avaliassem a ação branqueadora do agente óptico Blue covarine. Como estratégia de busca foram utilizados os descritores "Blue covarine", "Blue covarine e pasta de dentes", "Blue covarine and toothpaste", "Blue covarine e dentifrícios", "Blue covarine and dentifrices", "Blue covarine e dentifrícios branqueadores", "Blue covarine and whitening dentifrices", "Blue covarine e dentifrícios clareadores", "Blue covarine and bleaching dentifrices", "Blue covarine e pasta de dentes branqueadoras", "Blue covarine and whitening toothpaste", "Blue covarine e pasta de dentes clareadoras", "Blue covarine and bleaching toothpaste". Resultados: Dois pesquisadores selecionaram e analisaram criticamente 31 artigos, sendo 2 revisões da literatura, 4 estudos clínicos e 25 estudos laboratoriais. Divergências quanto ao desenho de estudo, métodos, amostra, critérios clínicos e parâmetros laboratoriais foram observados, além de conflitos de interesse. Conclusão: O Blue Covarine presente nos dentifrícios branqueadores parece ser efetivo na promoção do branqueamento dentário apenas quando associado aos agentes abrasivos presentes nas formulações, evidenciando que ensaios clínicos e laboratoriais, com metodologias semelhantes, são necessários para se obter evidência científica conclusiva sobre o efeito deste agente branqueador.(AU)

Introduction: The whitening effect of dentifrices containing Blue Covarine is based on its mechanism of action, characterized by its deposition on the tooth surface, altering the perception of color. Objective: To review the literature and seek scientific evidence on the whitening effect of Blue Covarine on mineralized tissues and aesthetic restorative materials. Materials and methods: For the literature review, searches were carried out in the PubMed, LILACS, BBO, SciELO and MEDLINE databases, in order to identify clinical and laboratory studies that evaluated the whitening action of the optical agent Blue Covarine. As a search strategy, the descriptors "Blue Covarine", "Blue Covarine and toothpaste", "Blue Covarine and dentifrices", "Blue Covarine and whitening dentifrices", "Blue Covarine and bleaching dentifrices", "Blue Covarine and whitening toothpaste", "Blue Covarine and bleaching toothpaste". Results: Two researchers selected and critically analyzed 31 articles, including 2 literature reviews, 4 clinical studies and 25 laboratory studies. Differences in study design, methods, sample, clinical criteria and laboratory parameters were observed, in addition to conflicts of interest. Conclusion: Blue Covarine present in whitening dentifrices seems to be effective in promoting dental whitening only when associated with abrasive agents present in the formulations, showing that clinical and laboratory tests, with similar methodologies, are necessary to obtain conclusive scientific evidence on the effect of this bleaching agent.(AU)

Effect of Salivary Flow on Bleached Enamel Roughness and Mineral Content: an In Situ and In Vitro Study.

This study aimed to evaluate the effect of human saliva in vitro and salivary flow in situ on the roughness and mineral content of bleached enamel. Dental specimens were divided into five groups (n=15): not bleached (NB); bleached (35% hydrogen peroxide) and exposed to distilled water (DW); human saliva in vitro (IV); normal salivary flow in situ (NSF); and low salivary flow (LSF) in situ. Enamel roughness (Ra, Rz) and calcium/phosphorus contents were evaluated with laser profilometry and energy-dispersive spectroscopy, respectively, at baseline (T1), after bleaching (T2), and after seven days (T3). Salivary pH and buffer capacity were evaluated with colorimetric strips and salivary calcium and phosphorus with absorbance spectrophotometry. Data were analyzed with non-parametric tests and linear regression (α=0.05). After contact with saliva, Ra and Rz of LSF=DW>IV=NSF=NB was found. For DW and LSF, the roughness of T1

Chemical behavior of 20%-22% carbamide peroxide gels in at-home bleaching: Randomized crossover in situ trial.

OBJECTIVE: To evaluate if distinct 20%-22% carbamide peroxide bleaching gels present similar decomposition pattern and pH during the clinical use in both arches, as well as gels viscosity. METHODS: Participants randomly received treatments with carbamide peroxide gels (n = 10): OPF (OpalescencePF-20%); PNT (Polanight-22%); and WPC (Whiteness Perfect-22%) in three different days, with 2-day washout. Decomposition pattern was assessed by peroxide concentration. Both PC and pH of bleaching gels were measured in different time points in upper and lower trays during a total of 120 min of clinical use. Viscosity of bleaching gels was measured in triplicate. ANOVA and Tukey's test were applied (α = 0.05). RESULTS: Regarding decomposition pattern, no significant differences were observed for the interaction between gel, time, and tray position factors. The peroxide concentration progressively reduced until 120 min of trays use (p < 0.001), being overall more notable in lower trays (p < 0.001). Regarding pH, the lowest values were verified in WPC within time. At 120 min, an increase of pH was observed for both WPC and OPF (p < 0.001) compared to baseline means. PNT exhibited constant pH values over time. The values of viscosity were: OPF (1.682.000 ± 19 cP)a, WPC (1.388.667 ± 172.63 cP)ab, PNT (579.567 ± 0.98 cP)b. CONCLUSIONS: The bleaching gels presented overall decomposition pattern clinically equivalent, being more notable in lower trays over time. Nevertheless, distinct pH and viscosities were observed among the products. CLINICAL SIGNIFICANCE: Although the manufacturers recommend different times of use for bleaching gels with similar peroxide concentrations, the commercial products tested did not exhibit clinically relevant difference in the decomposition pattern during the 120 min of clinical procedure.

Use of Computerized Microtomography, Energy Dispersive Spectroscopy, Scanning Electron Microscopy, and Atomic Force Microscopy to Monitor Effects of Adding Calcium to Bleaching Gels.

OBJECTIVES: The aim of this study was to evaluate the mineral content, expressed by calcium (Ca) and phosphate (P), in dental enamel exposed to bleaching agents using micro-computed tomography (micro-CT), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and atomic force microscopy (AFM). METHODS: Sixty bovine dental enamel specimens were randomly divided into three groups (n=20): HP35ca (bleached using 35% hydrogen peroxide with Ca); HP35wca (bleached using 35% hydrogen peroxide without Ca); and control (without bleaching). Five specimens from each group were used for SEM and EDS analyses, 10 specimens were used for AFM analysis, and the remaining five specimens were used for micro-CT analysis. The pH of the gels was measured using a pH meter. The EDS and micro-CT data were analyzed using one-way ANOVA and Pearson's correlation test. The AFM data were analyzed using one-way ANOVA (α=0.05). RESULTS: The weight percentages of Ca and P obtained using EDS were similar between the bleached and control groups. Small, superficial changes were observed by SEM in the HP35wca group. The HP35ca group showed similar patterns to the control group. AFM results showed no significant changes in the enamel roughness in any of the tested groups. No significant difference in the volume or depth of structural enamel loss was found between gels with and without Ca. No mineral loss was observed in the dentin substrate. The EDS and micro-CT analysis data exhibited a high correlation (p<0.001). CONCLUSION: The addition of Ca to the bleaching gel had no beneficial effect on the bleached tooth enamel in terms of composition, mineral loss, and surface roughness. Micro-CT results exhibited a high correlation with the EDS results.

Effects of incorporating 45S5 bioactive glass into 30% hydrogen peroxide solution on whitening efficacy and enamel surface properties.

OBJECTIVES: This study aimed to evaluate the effects of 30% hydrogen peroxide (HP) solution containing various contents of 45S5 bioactive glass (BAG) on whitening efficacy and enamel surface properties after simulating the clinical bleaching procedure. MATERIALS AND METHODS: A total of 60 bovine enamel specimens discolored with black tea were divided into five groups treated with distilled water (DW), HP, 0.01 wt.% BAG + HP, 1.0 wt.% BAG + HP, and 20.0 wt.% BAG + HP (n = 12). The pH change was observed for 20 min immediately after mixing the experimental solutions, which were applied for 20 min/week, at 37 °C over 21 days. Color, gloss, roughness, microhardness, and micromorphology measurements were conducted before and after bleaching treatment. RESULTS: All groups containing BAG experienced an increase in pH from 3.5 to 5.5 in less than 1 min, and the final pH increased as the BAG content increased. The ΔE of all experimental groups was significantly higher than that of the DW group (p < 0.05), but there were no significant differences between different BAG contents (p > 0.05). Gloss significantly decreased in all experimental groups compared to the DW group, and the increased BAG content had significantly affected the decrease in gloss (p < 0.05). There was no statistical difference in surface roughness (p > 0.05), but hardness increased significantly with BAG content after bleaching treatment (p < 0.05). CONCLUSIONS: HP containing 45S5 BAG showed efficacy in tooth whitening. Also, the pH value of the HP remained acidic near 3.5 for 20 min, while the HP containing the 45S5 BAG showed an increase in pH, which inhibited the demineralization of the enamel surface, and maintained the surface morphology. CLINICAL RELEVANCE: These novel materials are promising candidates to minimize enamel surface damage caused by HP during bleaching procedure in dental clinic.

Effect of accelerated stability on the physical, chemical, and mechanical properties of experimental bleaching gels containing different bioadhesive polymers.

OBJECTIVE: To evaluate the physical-chemical (weight, pH, quantification of hydrogen peroxide) and mechanical (texture profile and rheology tests) properties of the experimental bleaching gel based on the bioadhesive polymer Aristoflex® AVC, after accelerated stability testing. MATERIALS AND METHODS: A total of 300 syringes of bleaching gels were divided into 5 groups (n = 60): Whiteness Perfect® 10%-FGM (WP); carbamide peroxide 10% with aristoflex (CPa); carbamide peroxide 10% with Carbopol (CPc); aristoflex thickener (A); and Carbopol thickener (C). According to the following requirements and time, the accelerated stability test was performed: in an incubator at 40 °C and 75% humidity per 1, 3, and 6 months, and baseline (refrigerator at 5 °C and 25% humidity). The variables were analyzed following the statistical tests: Two-way ANOVA and Tukey's test were applied to pH; weight data were analyzed using a mixed model for repeated measurements over time and the Tukey-Kramer test; one-way ANOVA and Tukey's test analyzed the rheology test; generalized linear models were used to quantify the peroxide amount and texture profile data. A significance level of 5% was considered. RESULTS: The experimental bleaches CPa and CPc had the highest pH values when compared to the others in 6 months. Thickeners A and C did not change the pH, weight, and active content over the accelerated stability times (p > 0.05). Furthermore, there was weight loss after 3 months of storage for CPa and CPc (p < 0.05). In the quantification of hydrogen peroxide, the WP group showed the highest values over time (p < 0.0001), only showing a significant loss after the 3rd month. Meanwhile, CPa and CPc showed a reduction in quantification from the 1st month. CONCLUSIONS: Temperature and humidity directly influenced the active content and properties of bleaching gels. In addition, the presence of components regardless of thickeners, such as stabilizers, in the commercial gel allowed for greater stability over time. CLINICAL RELEVANCE: The development of experimental bleaching gels for clinical use requires careful testing. Therefore, accelerated stability testing represents a valuable tool in the development and evaluation of cosmetic formulations.

Uso do fluoreto de sódio como dessensibilizante no clareamento dental: uma revisão de literatura / Use of sodium fluoride as a desensibilizer in dental bleaching: a literature review

Objetivo: Verificar, por meio de uma revisão de literatura, a efetividade do uso do fluoreto de sódio como dessensibilizante para casos de sensibilidade induzida por clareamento dental. Resultados: O clareamento dentário tornou-se um dos procedimentos estéticos mais procurados na odontologia. Atualmente, existem duas técnicas supervisionadas por dentistas: o clareamento caseiro e o de consultório. Os materiais mais utilizados são o peróxido de carbamida e o de hidrogênio, respectivamente. O clareamento dental baseia-se na premissa de que o peróxido de hidrogênio penetra na estrutura dentária para interagir com os cromóforos orgânicos. Embora o protocolo de clareamento exija o uso de agentes oxidantes de baixa concentração, a sensibilidade dentária ainda está presente e pode ser considerado o principal efeito adverso da técnica de clareamento. Para minimizar este problema, a aplicação tópica de dessensibilizantes antes e após o clareamento dentário tem mostrado bons resultados na redução da intensidade de sensibilidade. Considerações finais: Mediante revisão apresentada, constatou-se que fluoreto de sódio quando utilizado após o protocolo clareador, como dessensibilizante, não elimina a sensibilidade, mas diminui a intensidade da dor. Quando utilizado antes do clareamento dental, não apresenta resultados positivos. Ademais, salienta-se que quando o fluoreto é incorporado no gel clareador, resulta em menor desmineralização do esmalte dentário.(AU)

Objective: To verify, through a literature review, the effectiveness of using sodium fluoride as a desensitizer for cases of sensitivity induced by tooth whitening. Literature review: Teeth whitening has become one of the most desired aesthetic procedures in dentistry. Currently, there are two techniques supervised by dentists: home whitening and office whitening. The most used materials are carbamide peroxide and hydrogen peroxide, respectively. Teeth whitening is based on the premise that hydrogen peroxide penetrates the tooth structure to interact with organic chromophores. Although the whitening protocol requires the use of low concentration oxidizing agents, tooth sensitivity is still present and can be considered the main adverse effect of the whitening technique. To minimize this problem, the topical application of desensitizers before and after tooth whitening has shown good results in reducing the intensity of sensitivity. Final considerations: Upon the review presented, it was found that sodium fluoride, when used after the whitening protocol, as a desensitizer, does not eliminate sensitivity, but reduces the intensity of pain. When used before tooth whitening, it has no positive results. Furthermore, it should be noted that when fluoride is incorporated into the whitening gel, less enamel demineralization is induced.(AU)

Photothermal-Enhanced Fenton-like Catalytic Activity of Oxygen-Deficient Nanotitania for Efficient and Safe Tooth Whitening.

The growing demand for charming smiles has led to the popularization of tooth bleaching procedures. Current tooth bleaching products with high-concentration hydrogen peroxide (HP, 30-40%) are effective but detrimental due to the increased risk of enamel destruction, tooth sensitivity, and gingival irritation. Herein, we reported a less-destructive and efficient tooth whitening strategy with a low-concentration HP, which was realized by the remarkably enhanced Fenton-like catalytic activity of oxygen-deficient TiO2 (TiO2-x). TiO2-x nanoparticles were synthesized with a modified solid-state chemical reduction approach with NaBH4. The Fenton-like activity of TiO2-x was optimized by manipulating oxygen vacancy (OV) concentration and further promoted by the near-infrared (NIR)-induced photothermal effect of TiO2-x. The TiO2-x sample named BT45 was chosen due to the highest methylene blue (MB) adsorption ability and Fenton-like activity among acquired samples. The photothermal property of BT45 under 808 nm NIR irradiation was verified and its enhancement on Fenton-like activity was also studied. The BT45/HP + NIR group performed significantly better in tooth whitening than the HP + NIR group on various discolored teeth (stained by Orange II, tea, or rhodamine B). Excitingly, the same tooth whitening performance as the Opalescence Boost, a tooth bleaching product containing 40% HP, was obtained by a self-produced bleaching gel based on this novel system containing 12% HP. Besides, negligible enamel destruction, safe temperature range, and good cytocompatibility of TiO2-x nanoparticles also demonstrated the safety of this tooth bleaching strategy. This work indicated that the photothermal-enhanced Fenton-like performance of the TiO2-x-based system is highly promising in tooth bleaching application and can also be extended to other biomedical applications.

Clinical Evaluation of 6-Month Efficacy of 40% in-Office Whitening Treatment

ABSTRACT Objective: To assess the 6-month efficacy of natural tooth color change in in-office bleaching treatment in terms of time by using a spectrophotometer. Material and Methods: A total of 20 participants were chairside treated with 40% hydrogen peroxide (HP), three applications each 20 minutes, in one appointment. Instrumental color measurement was performed on six anterior maxillary teeth before bleaching (baseline-t0), immediately after in-office bleaching and rehydration of the teeth (t1), 3 months (t2), and 6 months after bleaching treatment (t3). The spectrophotometer measured the tooth shades based on the CIE L*a*b* color notation system and Bleach index during the period of observation. CIE L*a*b* (ΔEab) color differences were calculated. Results: The color change at t1 was ΔEab = 3.2, at t2 was ΔEab = 1.8, at t3 was ΔEab = 1.2 and overall color change of in-office method was ΔEab = 3.6 (p<0.05). A significant effect for the mean CIEL*a*b* values was detected as within time b* values decreased significantly (p<0.05). Bleach index values significantly decreased during the time of observation, too (p<0.05). Conclusion: The in-office bleaching treatment using 40% hydrogen peroxide was effective, and the results showed a statistically significant decrease in color change during the period of 6-month observation.

Microencapsulación de peróxido de hidrógeno para la elaboración de un caramelo de goma blanqueador dental y evaluación in vitro mediante un método colorimétrico / Microencapsulation of hydrogen peroxide for the development of a dental whitening gummy candy and in vitro evaluation using a colorimetric method

INTRODUCCIÓN: La apariencia y el color de los dientes es una preocupación común para los pacientes por lo que hay una creciente necesidad de contar con tratamientos que mejoren la estética dental. Por esa razón, en los últimos 20 años la ciencia dental ha buscado nuevas técnicas y materiales capaces de reducir la discoloración dental. MÉTODO: Se prepararon pastillas de goma fantasía, caramelos de goma o gominolas que contenían dos concentraciones diferentes (7% y 14% m/v) de peróxido de hidrógeno microencapsulado por gelificación iónica. Durante 30 días se realizó un tratamiento diario de blanqueamiento dental in vitro para evaluar la acción blanqueadora de las dos formulaciones. La medición del color de la superficie de los dientes tratados se llevó a cabo utilizando una técnica colorimétrica. RESULTADOS: Se encontraron diferencias significativas entre los tratamientos de blanqueamiento con las dos formulaciones elaboradas en comparación con un grupo de control, siendo el esquema de dos procedimientos diarios con la formulación al 7% de peróxido de hidrógeno más efectivo que el de un único procedimiento diario con la formulación al 14%. CONCLUSIONES: Las dos formulaciones desarrolladas en este estudio tuvieron un mayor efecto de blanqueamiento in vitro en comparación con un grupo de control, y además se encontró que se logran mejores resultados al disminuir la concentración de peróxido si el número de aplicaciones aumenta para dosis diarias iguales

INTRODUCTION: The appearance and color of the teeth are common concerns for patients and are associated with an increased need for treatments that can improve dental aesthetics. For this reason, in the past 20 years, dental science has been searching for new techniques and materials able to reduce dental discoloration. METHOD: Gummy candies containing two different concentrations (7% and 14% w/v) of hydrogen peroxide microencapsulated by ionic gelation were prepared. In vitro tooth whitening treatment was carried out for 30 days to test the bleaching action of these formulations. The surface color of the treated teeth was measured using a colorimetric technique. RESULTS: Significant differences were found on comparing the whitening treatments for the two formulations with a control group, with two daily treatments using the formulation with 7% hydrogen peroxide being more effective for whitening than a daily single treatment using the formulation with 14 %. CONCLUSIONS: The two formulations developed had an in vitro higher bleaching effect in comparison with the control group, and in addition, better results were achieved if the daily dose was provided by more applications at a lower concentration of hydrogen peroxide

Effect of bleaching protocols on surface roughness and color change of high- and low-viscosity bulk-fill composite resins.

The aim of this in vitro study was to evaluate the effect of bleaching protocols on the surface roughness (Ra), color change and surface micromorphology of a low-viscosity bulk-fill composite (Filtek Bulk Fill Flow, 3M ESPE), a highviscosity bulk-fill composite (Filtek Bulk Fill, 3M ESPE) and a conventional nanoparticulate composite resin (control) (Filtek Z350 XT, 3M ESPE). Forty samples of each composite (disks 5 mm in diameter and 2 mm thick) were randomly divided into four groups (n=10), according to bleaching protocol: a) 10% carbamide peroxide gel (Opalescence, Ultradent Products) (2 h/ day, for 14 days); b) 40% hydrogen peroxide gel (Opalescence Boost, Ultradent Products) (three bleaching sessions, once a week, 45 min/session); c) whitening rinse (Listerine Whitening Extreme, Johnson & Johnson) (2 min/day, for 14 days); and d) distilled water (control). The samples were submitted to triplicate readings (Ra and color [CIELAB parameters]) before and after contact with bleaching protocols. Micromorphology was analyzed in a scanning electron microscope (SEM). Ra and color parameters (ΔL, Δa, Δb and ΔE) were analyzed by generalized linear models (α=0.05). The Ra of the high-viscosity bulk-fill was significantly higher than that of the other composites (p<0.05). Ra increased significantly (p<0.05) and surface became more irregular (SEM analysis) in all the composite resins, regardless of the bleaching protocol (p<0.05). The high-viscosity bulk-fill composite resin group had significantly lower ΔE (p<0.05) than the nanoparticulate composite resin group immersed in distilled water. It was concluded that the characteristics of each resin significantly influenced the Ra more than the bleaching protocol. The high-viscosity bulk-fill resin presented minor color change.

Este estudo in vitro teve objetivo de avaliar o efeito de protocolos clareadores sobre a rugosidade de superfície (Ra), alteração de cor e micromorfologia de resina bulk-fill de baixa viscosidade (Filtek Bulk Fill Flow, 3M ESPE), alta viscosidade (Filtek Bulk Fill, 3M ESPE) e de uma resina composta nanoparticulada (controle) (Filtek Z350 XT, 3M ESPE). Quarenta amostras de cada resin composta (discos de 5 mm de diâmetro e 2 mm de espessura) foram aleatoriamente divididas em quatro grupos , de acordo com protocolo clareador (n=10): a) Gel de peróxido de carbamida (Opalescence, Ultradent Products) (2 horas/dia, por 14 dias); b) Gel de peróxido de hidrogênio (Opalescence Boost, Ultradent Products) (3 sessões de clareamento, uma por semana, 45 min/sessão); enxaguatório clareador (Listerine Whitening Extreme, Johnson & Johnson) (2 min/dia, por 14 dias); d) água destilada (controle). As amostras foram submetidas a leituras, em triplicata (Ra e cor (parâmetros CIELab) antes e depois do contato com os protocolos clareadores. A micromorfologia de superfície foi conduzida em microscópio eletrônico de varredura (MEV). Ra e parâmetros de cor (ΔL, Δa, Δb e ΔE) foram analisados por modelos lineares generalizados (α=0.05). A Ra da resina bulk-fill de alta viscosidade foi significantemente superior do que para os outros compósitos (p<0.05). A Ra aumentou significantemente (p<0.05) e a superfície ficou mais irregular (MEV) para todos os compósitos, independente do protocolo clareador (p<0,05). A resina bulk-fill de alta viscosidade obteve menor ΔE (p<0.05) do que a resina composta nanoparticulada, imersa em água destilada. Pode-se concluir que as características de cada resina composta influenciaram de forma mais significativa a Ra do que o protocolo clareador. A resina bulk fill de alta viscosidade apresentou menor alteração de cor.

Effect of bleaching protocols on surface roughness and color change of high- and low-viscosity bulk-fill composite resins / Efeito de protocolos clareadores na rugosidade de superfície e alteração de cor de resinas compostas bulk-fill de alta e baixa viscosidade

ABSTRACT The aim of this in vitro study was to evaluate the effect of bleaching protocols on the surface roughness (Ra), color change and surface micromorphology of a low-viscosity bulk-fill composite (Filtek Bulk Fill Flow, 3M ESPE), a highviscosity bulk-fill composite (Filtek Bulk Fill, 3M ESPE) and a conventional nanoparticulate composite resin (control) (Filtek Z350 XT, 3M ESPE). Forty samples of each composite (disks 5 mm in diameter and 2 mm thick) were randomly divided into four groups (n=10), according to bleaching protocol: a) 10% carbamide peroxide gel (Opalescence, Ultradent Products) (2 h/ day, for 14 days); b) 40% hydrogen peroxide gel (Opalescence Boost, Ultradent Products) (three bleaching sessions, once a week, 45 min/session); c) whitening rinse (Listerine Whitening Extreme, Johnson & Johnson) (2 min/day, for 14 days); and d) distilled water (control). The samples were submitted to triplicate readings (Ra and color [CIELAB parameters]) before and after contact with bleaching protocols. Micromorphology was analyzed in a scanning electron microscope (SEM). Ra and color parameters (ΔL, Δa, Δb and ΔE) were analyzed by generalized linear models (α=0.05). The Ra of the high-viscosity bulk-fill was significantly higher than that of the other composites (p<0.05). Ra increased significantly (p<0.05) and surface became more irregular (SEM analysis) in all the composite resins, regardless of the bleaching protocol (p<0.05). The high-viscosity bulk-fill composite resin group had significantly lower ΔE (p<0.05) than the nanoparticulate composite resin group immersed in distilled water. It was concluded that the characteristics of each resin significantly influenced the Ra more than the bleaching protocol. The high-viscosity bulk-fill resin presented minor color change.

RESUMO Este estudo in vitro teve objetivo de avaliar o efeito de protocolos clareadores sobre a rugosidade de superfície (Ra), alteração de cor e micromorfologia de resina bulk-fill de baixa viscosidade (Filtek Bulk Fill Flow, 3M ESPE), alta viscosidade (Filtek Bulk Fill, 3M ESPE) e de uma resina composta nanoparticulada (controle) (Filtek Z350 XT, 3M ESPE). Quarenta amostras de cada resin composta (discos de 5 mm de diâmetro e 2 mm de espessura) foram aleatoriamente divididas em quatro grupos , de acordo com protocolo clareador (n=10): a) Gel de peróxido de carbamida (Opalescence, Ultradent Products) (2 horas/dia, por 14 dias); b) Gel de peróxido de hidrogênio (Opalescence Boost, Ultradent Products) (3 sessões de clareamento, uma por semana, 45 min/sessão); enxaguatório clareador (Listerine Whitening Extreme, Johnson & Johnson) (2 min/dia, por 14 dias); d) água destilada (controle). As amostras foram submetidas a leituras, em triplicata (Ra e cor (parâmetros CIELab) antes e depois do contato com os protocolos clareadores. A micromorfologia de superfície foi conduzida em microscópio eletrônico de varredura (MEV). Ra e parâmetros de cor (ΔL, Δa, Δb e ΔE) foram analisados por modelos lineares generalizados (α=0.05). A Ra da resina bulk-fill de alta viscosidade foi significantemente superior do que para os outros compósitos (pp<0.05). A Ra aumentou significantemente (p<0.05) e a superfície ficou mais irregular (MEV) para todos os compósitos, independente do protocolo clareador (pp<0,05). A resina bulk-fill de alta viscosidade obteve menor ΔE (pp<0.05) do que a resina composta nanoparticulada, imersa em água destilada. Pode-se concluir que as características de cada resina composta influenciaram de forma mais significativa a Ra do que o protocolo clareador. A resina bulk fill de alta viscosidade apresentou menor alteração de cor.

Experimental gel containing bioactive glass-ceramic to minimize the pulp damage caused by dental bleaching in rats.

OBJECTIVES: This study evaluated if the use of a bioactive glass-ceramic-based gel, named Biosilicate (BS), before, after or mixed with bleaching gel, could influence the inflammation of the dental pulp tissue of rats' molars undergoing dental bleaching with hydrogen peroxide (H2O2). METHODOLOGY: The upper molars of Wistar rats (Rattus norvegicus, albinus) were divided into Ble: bleached (35% H2O2, 30-min); Ble-BS: bleached and followed by BS-based gel application (20 min); BS-Ble: BS-based gel application and then bleaching; BS/7d-Ble: BS-based gel applications for 7 days and then bleaching; Ble+BS: blend of H2O2 with BS-based gel (1:1, 30-min); and control: placebo gel. After 2 and 30 days (n=10), the rats were euthanized for histological evaluation. The Kruskal-Wallis and Dunn statistical tests were performed (P<0.05). RESULTS: At 2 days, the Ble and Ble-BS groups had significant alterations in the pulp tissue, with an area of necrosis. The groups with the application of BS-based gel before H2O2 had moderate inflammation and partial disorganization in the occlusal third of the coronary pulp and were significantly different from the Ble in the middle and cervical thirds (P<0.05). The most favorable results were observed in the Ble+BS, which was similar to the control in all thirds of the coronary pulp (P>0.05). At 30 days, the pulp tissue was organized and the bleached groups presented tertiary dentin deposition. The Ble group had the highest deposition of tertiary dentin, followed by the Ble-BS, and both were different from control (P<0.05). CONCLUSION: A single BS-based gel application beforehand or BS-based gel blended with a bleaching gel minimize the pulp damage induced by dental bleaching.

Do commercial whitening dentifrices increase enamel erosive tooth wear?

OBJECTIVE: This in vitro study evaluated the effect of commercial whitening dentifrices on erosive tooth wear (ETW) of bovine enamel samples, in comparison with commercial regular dentifrices. METHODOLOGY: Sixty bovine crowns were embedded in acrylic resin, polished and then had their baseline profile determined. They were randomly assigned to 5 groups (n=12/group), according to the type of commercial dentifrice to be tested: GI - Crest Anti-cavity Regular; GII - Crest 3D White; GIII - Colgate Total 12 Clean Mint; GIV - Colgate Optic White; GV - Placebo (negative control, fluoride-free dentifrice). The samples were submitted to daily erosive and abrasive challenges for 3 days. The erosive challenges were performed 3 times a day by immersing the specimens in 0.1% citric acid solution (pH 2.5) for 90 s. Each day after the first and last erosive challenges, the specimens were subjected to the abrasive challenge for 15 s, using a toothbrushing machine (Biopdi, São Carlos, SP, Brazil), soft toothbrushes and slurry (1:3 g/ml) of the tested toothpastes (1.5 N). The specimens were kept in artificial saliva between the challenges. The final profile was obtained and the ETW (µm) was calculated. Data were analyzed by Kruskal-Wallis and Dunn's tests (p<0.05). RESULTS: All dentifrices tested significantly reduced the enamel wear in comparison with the Placebo, except GIII. The median (95% CI) ETW was 1.35 (1.25-1.46)bc for GI, 1.17 (1.01-1.34)cd for GII, 1.36 (1.28-1.45)ab for GIII, 1.08 (1.04-1.14)d for GIV and 2.28 (2.18-2.39)a for GV. CONCLUSION: When dentifrices from the same manufacturer were compared, the whitening dentifrices led to similar or less wear than the regular ones.

Experimental gel containing bioactive glass-ceramic to minimize the pulp damage caused by dental bleaching in rats

Abstract Objectives This study evaluated if the use of a bioactive glass-ceramic-based gel, named Biosilicate (BS), before, after or mixed with bleaching gel, could influence the inflammation of the dental pulp tissue of rats' molars undergoing dental bleaching with hydrogen peroxide (H2O2). Methodology The upper molars of Wistar rats (Rattus norvegicus, albinus) were divided into Ble: bleached (35% H2O2, 30-min); Ble-BS: bleached and followed by BS-based gel application (20 min); BS-Ble: BS-based gel application and then bleaching; BS/7d-Ble: BS-based gel applications for 7 days and then bleaching; Ble+BS: blend of H2O2 with BS-based gel (1:1, 30-min); and control: placebo gel. After 2 and 30 days (n=10), the rats were euthanized for histological evaluation. The Kruskal-Wallis and Dunn statistical tests were performed (P<0.05). Results At 2 days, the Ble and Ble-BS groups had significant alterations in the pulp tissue, with an area of necrosis. The groups with the application of BS-based gel before H2O2 had moderate inflammation and partial disorganization in the occlusal third of the coronary pulp and were significantly different from the Ble in the middle and cervical thirds (P<0.05). The most favorable results were observed in the Ble+BS, which was similar to the control in all thirds of the coronary pulp (P>0.05). At 30 days, the pulp tissue was organized and the bleached groups presented tertiary dentin deposition. The Ble group had the highest deposition of tertiary dentin, followed by the Ble-BS, and both were different from control (P<0.05). Conclusion A single BS-based gel application beforehand or BS-based gel blended with a bleaching gel minimize the pulp damage induced by dental bleaching.

Do commercial whitening dentifrices increase enamel erosive tooth wear?

Abstract Objective This in vitro study evaluated the effect of commercial whitening dentifrices on erosive tooth wear (ETW) of bovine enamel samples, in comparison with commercial regular dentifrices. Methodology Sixty bovine crowns were embedded in acrylic resin, polished and then had their baseline profile determined. They were randomly assigned to 5 groups (n=12/group), according to the type of commercial dentifrice to be tested: GI - Crest Anti-cavity Regular; GII - Crest 3D White; GIII - Colgate Total 12 Clean Mint; GIV - Colgate Optic White; GV - Placebo (negative control, fluoride-free dentifrice). The samples were submitted to daily erosive and abrasive challenges for 3 days. The erosive challenges were performed 3 times a day by immersing the specimens in 0.1% citric acid solution (pH 2.5) for 90 s. Each day after the first and last erosive challenges, the specimens were subjected to the abrasive challenge for 15 s, using a toothbrushing machine (Biopdi, São Carlos, SP, Brazil), soft toothbrushes and slurry (1:3 g/ml) of the tested toothpastes (1.5 N). The specimens were kept in artificial saliva between the challenges. The final profile was obtained and the ETW (µm) was calculated. Data were analyzed by Kruskal-Wallis and Dunn's tests (p<0.05). Results All dentifrices tested significantly reduced the enamel wear in comparison with the Placebo, except GIII. The median (95% CI) ETW was 1.35 (1.25-1.46)bc for GI, 1.17 (1.01-1.34)cd for GII, 1.36 (1.28-1.45)ab for GIII, 1.08 (1.04-1.14)d for GIV and 2.28 (2.18-2.39)a for GV. Conclusion When dentifrices from the same manufacturer were compared, the whitening dentifrices led to similar or less wear than the regular ones.

Increased whitening efficacy and reduced cytotoxicity are achieved by the chemical activation of a highly concentrated hydrogen peroxide bleaching gel.

OBJECTIVE: This study was designed for the chemical activation of a 35% hydrogen peroxide (H2O2) bleaching gel to increase its whitening effectiveness and reduce its toxicity. METHODOLOGY: First, the bleaching gel - associated or not with ferrous sulfate (FS), manganese chloride (MC), peroxidase (PR), or catalase (CT) - was applied (3x 15 min) to enamel/dentin discs adapted to artificial pulp chambers. Then, odontoblast-like MDPC-23 cells were exposed for 1 h to the extracts (culture medium + components released from the product), for the assessment of viability (MTT assay) and oxidative stress (H2DCFDA). Residual H2O2 and bleaching effectiveness (DE) were also evaluated. Data were analyzed with one-way ANOVA complemented with Tukey's test (n=8. p<0.05). RESULTS: All chemically activated groups minimized MDPC-23 oxidative stress generation; however, significantly higher cell viability was detected for MC, PR, and CT than for plain 35% H2O2 gel. Nevertheless, FS, MC, PR, and CT reduced the amount of residual H2O2 and increased bleaching effectiveness. CONCLUSION: Chemical activation of 35% H2O2 gel with MC, PR, and CT minimized residual H2O2 and pulp cell toxicity; but PR duplicated the whitening potential of the bleaching gel after a single 45-minute session.

Effectiveness of over-the-counter tooth-whitening strips and toothbrushing for stain removal / Eficácia da utilização de tiras de clareamento dental e da escovação na remoção de manchas dentais

Objective: The present study compared the effectiveness of over-the-counter tooth-whitening strips and too-thbrushing for stain removal. Materials and method: Forty bovine teeth were subjected to initial color re-adings and divided into two groups: 20 teeth were stained with grape juice for seven days and 20 did not receive any treatment (control). Each group was subdivided into two groups (n=10) according to treatment: whitening strips twice/day (30 minutes/7 days) and mechanical brushing with toothpaste (one year). After the treatments, final color readings were taken and color stability (ΔEab), coordinates (ΔL, Δa, Δb), and whitening index (WID) were calculated and analyzed statistically (two-way ANOVA, Bonferroni α=0.05). Results: Statis-tical differences were found for ΔEab and all coordinates between the Control and Stained groups, with major changes in the Stained groups for both treatments. In the Control group, whitening strips produced greater changes in Δb (p <0.05), indicating decrease of yellowness. For the Stained group, whitening strips produced greater changes in Δa (p <0.05), indicating redness reduction. Conclusion: Both treatments were effective for removing stains, and whitening strips were more efficient and effective for changing the color of teeth without previous staining. (AU)

Objetivo: o presente estudo comparou a eficácia das tiras de clareamento dentário e da escovação na remoção de manchas. Materiais e método: quarenta dentes bovinos foram submetidos à lei-tura inicial de cor e divididos em dois grupos: 20 manchados com suco de uva por 7 dias e 20 não receberam tratamento (controle). Cada grupo foi subdividido em 2 grupos (n=10) de acordo com o tratamento: tiras de clareamento 2 vezes/dia (30 minutos/7 dias) e escovação mecânica com cre-me dental (1 ano). Após os tratamentos, leituras finais de cor foram realizadas. Então, a estabili-dade de cor (ΔEab), as coordenadas (ΔL, Δa, Δb) e o índice de clareamento (WID) foram calculados e analisados estatisticamente (two-way ANOVA, Bonferroni α=0,05). Resultados: diferenças es-tatísticas foram encontradas em ΔEab e todas as coordenadas entre os grupos controle e mancha-dos, com maior alteração no grupo manchado, independente do tratamento. No grupo controle, o clareamento produziu maior alteração em Δb (p <0,05), indicando redução do croma amarelo. Nos dentes manchados, ocorreu maior alteração em Δa nos dentes clareados (p <0,05), indicando diminuição do croma vermelho. Conclusão: am-bos os tratamentos foram eficazes na remoção de manchas e o clareamento dentário mostrou-se um método mais eficiente e efetivo para alteração de cor de dentes que não haviam sido submetidos à pigmentação prévia. (AU)

Effect of different surface treatment on the shear bond strength of metal brackets to bleached and desensitized enamel.

INTRODUCTION: The aim of this study was to determine the effect of bleaching and desensitizing on shear bond strength (SBS) of metal brackets to enamel. METHODS: One hundred extracted human premolar were randomly assigned to 5 groups of 20. In the first group (control), no bleaching or desensitizing agent was used. Groups 2 to 5 were bleached with 37.5% hydrogen peroxide and desensitized with 6.0% potassium nitrate. Surface treatment comprised of etching for 15seconds in groups 1, 2 and 3, Er:yag laser irradiation and etching in group 4 and sandblasting and etching in group 5. Premolar brackets were bonded with Transbond XT and cured for 20seconds and the SBS was tested using a universal testing machine. Adhesive remnant index (ARI) score was used to record the mode of bond failure. RESULTS: No significant difference was found between the mean SBS (MPa) in groups 1(15.22), 4(14.02), and 5(12.62). SBS in group 4 was significantly higher than group 2 (8.15) (P<0.001). Also, SBS in groups 2 (P<0.001) and 3(11.74) (P=0.012) were significantly lower than group 1. An increased frequency of ARI score of 2 and 3 was observed in groups 1, 4 and 5. CONCLUSIONS: Bleaching plus desensitizing significantly decreased the SBS of orthodontic brackets. Delaying the bonding procedure for at least 2 weeks or alternative surface treatment methods such as combined laser and acid etching or combined sand blasting and acid etching can improve the SBS.