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Objective: The aim of this in vitro study was to evaluate the pH of four bleaching agents based on high concentration hydrogen peroxide (30-35%) Whiteness HP Maxx (HPM), Lase Peroxide (LP), Whiteness HP Automixx (HPA) and Dash (DA) in different clinical periods (baseline, 15', 30' and 45'). Materials and methods: 40 specimens (bovine teeth) were divided into 4 groups; one group for each bleaching agent. Each bleaching agent was prepared according to the manufacturer's instructions and was applied on the vestibular surface. The pH of the bleaching agent was measured with a digital pH meter at baseline, 15, 30 and 45 minutes. ANOVA, Friedman and Wilcoxon tests were applied. Results: The pH values showed a trend to decreasing from the initial time of application to the final time, except for the DA group, which showed increasing pH values over time. The HPM group showed significant differences between baseline and the remaining periods. The LP group LP showed significant difference between 15' and the other periods. The HPA group showed significant differences between baseline and the remaining periods. Finally, the DA group, showed a significant difference between baseline and 45'. Conclusions: The pH values of 3 of the bleaching agents decreased over time, with the exception of Dash which increased in the different time periods.

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RESUMEN: El objetivo de este estudio in vitro fue evaluar la eficacia en el aclaramiento dental de tres enjuagues orales que contienen peróxido de hidrógeno en diferentes períodos de inmersión en comparación con el peróxido de carbamida al 10 %. Cuarenta muestras de premolares humanos se dividieron aleatoriamente en cuatro grupos según el agente al que se expuso: G1: Colgate Plax®Whitening, G2: Listerine®Whitening Extreme y G3: Oral B® 3D White™ se sumergieron dos minutos al día durante 28 días y G4: Peróxido de carbamida al 10 %, ocho horas al día durante 14 días. La medición de color se realizó con un espectrofotómetro Vita Easyshade usando la escala CIELab inicialmente, a los 14, 28 y 35 días de evaluación. Las comparaciones entre los grupos se realizaron utilizando las pruebas Kruskal-Wallis y U Mann-Whitney, mientras que entre los tiempos las pruebas Friedman y Signo-Rango de Wilcoxon. Los resultados revelaron que a los 14 días, los cuatro grupos mostraron cambios de color, pero no se evidenció mayor eficacia de alguno sobre el otro (p>0,05). Sin embargo, a los 28 y 35 días se observó una clara eficacia del peróxido de carbamida sobre los enjuagues (p<0,05). Los enjuagatorios orales aclaran los dientes a partir de los 28 días, con los protocolos indicados; sin embargo no llegan a tener resultados similares a un aclaramiento profesional con gel de peróxido de carbamida al 10 %.

ABSTRACT: The objective of this in vitro study was to evaluate the efficacy in dental toothbleaching of three mouthwashes containing hydrogen peroxide in different periods of immersion compared to 10 % carbamide peroxide. Forty samples of human premolars were randomly divided into four groups according to the agent to which they were exposed: G1: Colgate Plax®Whitening, G2: Listerine®Whitening Extreme and G3: Oral B® 3D White ™ were immersed two minutes a day during 28 days and G4: 10 % carbamide peroxide, eight hours a day for 14 days. The color measurement was performed with a Vita Easyshade spectrophotometer using the CIELab scale initially, at 14, 28 and 35 days of evaluation. The comparisons between the groups were made using the Kruskal-Wallis and U Mann-Whitney tests. While between the times the tests Friedman and Sign-Range of Wilcoxon. The results revealed that at 14 days, the four groups showed color changes, but no greater effectiveness was shown of one over the other (p>0,05). However, at 28 and 35 days a clear efficacy of carbamide peroxide was observed on the rinses (p<0,05). Mouthwashes clear the teeth after 28 days, with the indicated protocols; however, they do not reach similar results to a professional clarification with 10 % carbamide peroxide gel.

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Objective: The aim of this study was to compare several non-vital dental bleaching agents for their in vitro cytotoxicity to human gingival fibroblasts primary cell line. Methods: The cells were cultivated in DMEM and were seed in plates of 96 wells; then, it was exposed to the conditioned medium according to the experimental groups (n = 12): G1 - SP (sodium perborate) + distilled water; G2 - SP + 20% CP (carbamide peroxide); G3 - 20% CP; G4 - SP + 35% HP (hydrogen peroxide); G5 - 35% HP. In the control group (n = 12), corresponded to the curve of cell growth and viability, the cells did not receive any treatment. Cell viability was measured photometrically using a MTT assay after a 24 h and 48 h of exposure period. Data were submitted to ANOVA and Tukey’s tests. Results: All the experimental groups presented high cytotoxicity statically in comparison to the control group. The rank of the most to the least toxic material after 24 h was: SP + DW > 35% PH > PS + 20% PC > PS + 35% PH > 20% PC; and after 48 h was: SP + DW > PS + 20% PC > 35% PH > PS + 35% PH > 20% PC. Conclusion: All the bleaching agents had presented cytotoxicity effects, reducing significantly the cell viability, however, in the conditions that the study was conducted the association of sodium perborate with distilled water was the most toxic bleaching agent

Objetivo: O objetivo deste estudo foi comparar a citotoxicidade de agentes clareadores de uso interno em linhagem primária de fibroblastos humanos. Material e Método: As células foram cultivadas em meio DMEM e semeadas em placas de 96 poços. Em seguida, foram expostas aos meios de cultura condicionados de acordo com os grupos experimentais (n = 12): G1 - PS (perborato de sódio) + água destilada; G2 - PS + PC 20% (peróxido de carbamida); G3 - PC 20% ; G4 - PS + PH 35% (peróxido de hidrogênio); G5 - PH 35%. No grupo controle (n = 12), correspondente à curva de crescimento e viabilidade celular, as células não receberam nenhum tratamento. A viabilidade celular foi verificada por espectofotômetro utilizando o ensaio de MTT, após um período de 24 e 48 h de exposição aos agentes clareadores. Os dados foram submetidos aos testes de ANOVA e Tukey. Resultados: Todos os grupos experimentais apresentaram alta citotoxicidade em relação ao grupo controle. O rank de citotoxicidade dos agestes clareadores após 24 h foi: PS + AD > PH 35% > PS + PC 20% > PS + PH 35% > PC 20% e após 48h foi: PS + AD > PS + PC 20%> 35% PH > PS +PH 35% > 20% PC. Conclusão: Todos os agentes clareadores apresentaram efeitos citotóxicos, reduzindo significativamente a viabilidade da celular. Entretanto, nas condições em que o estudo foi conduzido a associação do perborato de sódio com água destilada, foi o agente clareador mais tóxico

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OBJECTIVES: The purpose of this study was to evaluate the bleaching agent action on color stability, surface roughness and microhardness of composites (Charisma, Filtek Supreme and Heliomolar - A2) submitted to accelerated artificial aging (AAA). METHODS: A Teflon matrix (12 x 2 mm) was used to fabricate 18 specimens (n=6) which, after polishing (Sof-Lex), were submitted to initial color reading (ΔE), Knoop microhardness (KHN) (50 g/15 s load) and roughness (R(a)) (cut-off 0.25 mm) tests. Afterwards, the samples were submitted to AAA for 384 hours and new color, microhardness and roughness readings were performed. After this, the samples were submitted to daily application (4 weeks) of 16% Carbamide Peroxide (NiteWhite ACP) for 8 hours and kept in artificial saliva for 16 hours. New color, microhardness and roughness readings were made at the end of the cycle, and 15 days after bleaching. RESULTS: Comparison of the ΔE means (2-way ANOVA, Bonferroni, P<.05) indicated clinically unacceptable color alteration for all composites after AAA, but without significant difference. Statistically significant increase in the KHN values after AAA was observed, but without significant alterations 15 days after bleaching. For R(a) there was no statistically significant difference after AAA and 15 days after bleaching. CONCLUSIONS: The alterations promoted by the bleaching agent and AAA are material dependent.

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This study examined the effect of 10% and 16% carbamide peroxide bleaching agents on the surface microhardness of micro-particulate feldspathic ceramics (VM7 and VM13, Vita Zahnfabrik). Forty specimens (8-mm diameter, 2-mm thickness) were divided into four groups (n=10): G1- VM7 + 10% Whiteness, G2- VM7 + 16% Whiteness, G3- VM13 + 10% and G4- VM13 + 16% Whiteness. The home-use bleaching agents were applied for 8 hours on 15 days, and the specimens were stored in distilled water at 37°C. The Vickers hardness number (HV) was determined for each specimen. Data were analyzed by the Wilcoxon and Mann- Whitney tests (p<0.05). The microhardness values before exposure were: g1- 433 (57); g2- 486 (22); g3- 509 (28); g4- 518 (24), and after exposure: G1- 349 (32); G2- 496 (95); G3- 519 (38); G4- 502 (81). G2 exhibited a higher and significant difference than G1 in VM7 groups, and the effect of bleaching concentration was shown to be significant by the Mann-Whitney test. And for VM13, both the Wilcoxon and Mann-Whitney tests showed no significant differences. When using 10% carbamide peroxide, the microhardness of VM7 ceramic was affected, and there were no effect on the microhardness between VM7 and VM13 ceramics when 16% carbamide peroxide was used.

Este estudo examinou o efeito do agente clareador peroxido de carbamida a 10% e a 16% na microdureza superficial de ceramicas feldspaticas micro-particuladas (VM7 e VM13, Vita Zahnfabrik). Quarenta corpos-de-prova (8 mm de diametro, 2 mm de espessura) foram divididos em quatro grupos (n=10): G1- VM7 + 10% Whiteness, G2- VM7 + 16% Whiteness, G3- VM13 + 10% e G4- VM13 + 16% Whiteness. Os agentes clareadores foram aplicados por 8 horas durante 15 dias e os cp foram armazenados em agua destilada a 37°C. A dureza Vickers (HV) de cada cp foi determinada. Os dados foram analisados pelos testes de Wilcoxon e Mann-Whitney (p<0.05). Os valores da dureza antes da exposicao ao agente clareador foram: g1- 433 (57); g2- 486 (22); g3- 509 (28); g4- 518 (24), e depois da exposicao: G1- 349 (32); G2- 496 (95); G3- 519 (38); G4- 502 (81). G2 exibiu diferenca significante e microdureza maior comparado ao G1 nos grupos da VM7 e o efeito da concentracao do clareador foi significante, apresentados atraves dos testes Mann-Whitney. Para VM13, ambos testes, Wilcoxon e Mann-Whitney, nao apresentaram diferenca significante. Quando o peroxido de carbamida a 10% foi avaliado, a microdureza da ceramica VM7 foi afetada, e nao houve diferenca na microdureza entre as ceramicas VM7 e VM13 quando o peroxido de carbamida a 16% foi utilizado.

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Tooth-whitening agents are available for therapeutic use in the dental office or at home. However, whitening more severe stains, such as those caused by systemic ingestion of tetracycline, constitutes a challenge. The aim of this study was to evaluate, in an experimental model of growing rats, the efficacy of using ozone to lighten tetracycline-stained incisors. At weaning, male Wistar rats (n=40) were randomly assigned to one of three groups. Two control groups, C21 and C60 (n=8, each) were used to document the usual age-related color. The third group (n=24) received 0.25 g% of oxytetracycline (O) until 60 days of age. These rats were subsequently divided into three further groups: O0, O3 and O5 (n=8, each). These rats were anesthetized; O3 and O5 groups received ozone application to the lower incisors for 3 (group O3) or 5 minutes (group O5), respectively; while O0 did not receive the ozone treatment. Teeth were then photographed and the incisors from the control (C60) and treatment groups (O0, O3 and O5) were cut, and compared to a standard color guide (there were eight shades numbered 0 to 7, lightest to darkest) to assess the hue visually. The teeth were then placed in phosphoric acid to quantify the color by spectrophotometry. The data (mean ± SD) were analyzed by One-Way Analysis of Variance (ANOVA) followed by Tukey's test or Dunnett test. The visual observation, analyzed blindly by one investigator, showed that O3 and O5 groups had diminished yellowing of the teeth as compared to the untreated O0 group (P<0.001). The color quantified by spectrophotometry also detected significant differences among groups (O3 < O0, P<0.01; O5 < O0,P < 0.001 and O5 < O3, P<0.01). C21 and C60 were significantly different among groups (P<0.001). This is the first experimental study to show that ozone can be successfully used for lightening the yellowish tinge of tetracycline- stained rat incisors. Further studies are required for its potential use in the dental clinic.

Los agentes blanqueadores dentales estan disponibles para tratamientos que se realizan en el consultorio odontologico o en el domicilio. Sin embargo, aclarar manchas severas, como las causadas por la ingestion sistemica de tetraciclina, constituyen un desafio. El objetivo de este estudio fue evaluar en un modelo experimental de ratas en crecimiento, la eficiencia del uso de ozono para aclarar los incisivos oscurecidos por el uso de tetraciclina. Ratas macho Wistar al destete (N=40) fueron asignadas aleatoriamente a uno de tres grupos. Dos de ellos grupos controles, C21 y C60 (N=8, cada uno), para documentar el color habitual de los incisivos, correspondiente a la edad del animal. El tercer grupo (N = 24) recibio 0,25 % de oxitetraciclina (O) hasta los 60 dias de edad. Entonces, el grupo O se dividio aleatoriamente en tres grupos O0, O3 y O5 (N = 8, cada uno) y las ratas se anestesiaron. Los grupos O3 y O5 recibieron en los incisivos inferiores la aplicacion de ozono durante 3 y 5 minutos, respectivamente; mientras que O0 no recibio tratamiento. Los incisivos de C60, O0, O3 y O5 fueron fotografiados. Luego se cortaron y se contrastaron con una guia estandar de ocho colores (ordenados de 0 a 7, desde el mas claro a mas oscuro) para cuantificar visualmente el color de los incisivos. Luego, se colocaron en acido fosforico para cuantificar el color por espectrofotometria. Los resultados (media ± SD) se analizaron por medio de ANOVA y prueba de Tukey o Dunnett (α =0.05) para determinar el efecto del tratamiento. El analisis visual de las imagenes mostro que los grupos O3 y O5 disminuyeron el color amarillo intenso respecto a O0. Dicha diferencia de color fue evaluada a traves de la guia (G) y cuantificada mediante espectrofotometria (E). Segun G, la mayor diferencia de color respecto a C60 fue para O0 (P<0.001), disminuyo en O3 (P<0.001) y aun mas en O5 (P<0.01). De acuerdo a E, O3

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OBJECTIVES: To evaluate the cytotoxic effects of a bleaching agent composed of 0.01% carbamide peroxide (CP; 2.21mug/ml H(2)O(2)) on the MDPC-23 odontoblastic cell line, and to determine whether sodium ascorbate (SA) is capable of reducing, or even eliminating, the toxic effects caused by this bleaching agent. METHODS: The cells were seeded in wells and incubated for 48 hours. CP and SA were dissolved in a culture medium (DMEM) in order to obtain experimental extracts. Six groups of cells (n=10) were treated as follows: G1: no treatment (control); G2: 0.25 mM SA/60 min; G3: 0.5 mM SA/60 min; G4: 0.25 mM SA+0.01% CP/60 min; G5: 0.5 mM SA+0.01% CP/60 min; and G6: 0.01% CP/60 min. The cell metabolism was evaluated by MTT assay, and the cell morphology was assessed by scanning electron microscopy. The data obtained were analyzed by 2-way ANOVA and post-hoc Tukey's test (alpha=5%). RESULTS: THE PERCENTAGES OF CELL METABOLISM WERE AS FOLLOWS: G1 (control)=100%; G2=110.06%, G3=108.57%, G4=90.35%, G5=97.63%, and G6=66.88%. Group 6 presented a statistically lower cell metabolism than did the other groups, and the cells that remained on the substrate exhibited changes in their morphology. SA decreased the cytotoxic effects caused by CP, demonstrating its protective effect against the toxic components of this dental product. CONCLUSIONS: It was concluded that CP gel has cytopathic effects on MDPC-23 odontoblastic cells, even at low concentrations such as 0.01%. SA at 0.25 mM, and that 0.5 mM is able to protect these cultured cells against the cytotoxic effects of CP.