Aim To determine if the artificial staining with black tea (BT) influences the enamel microhardness before in-office bleaching and if BT staining is necessary to evaluate the efficacy of bleaching with 35% hydrogen peroxide Methods Enamel/dentin blocks were randomized into groups according to the staining protocol (n=5/group): (CO) control – maintained in artificial saliva solution (AS); (BT4) immersed in black tea solution for 4 h; (BT24) immersed in black tea solution for 24 h. After the staining protocols, all specimens were kept in AS for one week, followed by bleaching (three sessions of HP application for 40 min). Knoop surface microhardness (kgF/mm2) was determined at baseline (T0), after staining (T1), after 7 days of storage in AS (T2), and after bleaching (T3). The color (∆E00) and coordinate changes (∆L, ∆a, ∆b) were measured using a digital spectrophotometer at T0 and T3. Data were submitted to one-way (∆E00, ∆L, ∆a, ∆b) or two-way ANOVA repeated measures (kgF/mm2) and Tukey’s test (a=5%). Results The staining protocols (BT4 and BT24) promoted significantly lower microhardness (T1 and T2, p<0.05) than CO, whereas CO was the only group to maintain microhardness values over time. Bleaching promoted perceptible ∆E00 without a significant difference among the groups regardless of the staining protocol (p=0.122). CO and BT4 showed no differences in terms of ∆L and ∆a (p>0.05), but BT4 displayed a higher ∆b than CO. Conclusion The artificial staining with BT negatively affected the enamel surface microhardness and was not essential to evaluate the efficacy of 35% hydrogen peroxide bleaching.

Aim To evaluate the marginal fit of protocol bars milled from digital models obtained by conventional molding followed by bench scanning or digital molding with an intraoral scanner. Methods Four morse-cone implants and the mini-pillars were installed in a 3D printed mandible model (master model). Digital models of the master model were obtained by (n=10): (Group A - Conventional) conventional (analog) molding of the master model followed by bench scanning or (Group B - Digital) molding of the master model with an intraoral scanner. All-on-four protocol bars were designed and milled from the digital models for both groups and screwed into the master model. Scanning electron microscopy (SEM) images from the distal, central, and mesial regions of each implant were obtained and the implant-protocol bar marginal fit was measured in an image software (Image J). The mean misfit of each region was analyzed by two-factor ANOVA, Tukey test, and Student’s t-test (0,05 = 0.05). Results The digital approach (B) showed higher misadaptation than the conventional approach (A, p < 0.05), regardless of the region evaluated. In group A, the central region showed higher maladjustment than the mesial region (p<0.05), however, there were no differences among regions of group B (p>0.05). Conclusion The conventional method of acquiring digital models using the bench scanner produced bars for the All-On-Four protocol with better marginal fit than the digital models obtained with an intraoral scanner.

RESUMO O clareamento dental é uma das técnicas estéticas mais conservadoras no âmbito odontológico. Técnicas de clareamento caseira ou de consultório, ou a combinação de ambas, podem ser realizadas para alcançar o prognóstico desejado. Esta combinação das técnicas pode ser realizada por meio de diferentes abordagens, como apresentado neste relato de casos. Um paciente do gênero masculino, 24 anos de idade, cujos incisivo central superior e caninos apresentaram cor A2 e A3, respectivamente, foi inicialmente submetido à técnica de clareamento de consultório de duração por sessão de 40 mim com gel de peróxido de hidrogênio (PH) 40%, em duas sessões. Posteriormente, a técnica de clareamento caseira foi realizada durante duas semanas com gel de peróxido de carbamida (PC) a uma concentração de 10%.A cor final dos incisivos centrais superiores foi alterada para 1M1, enquanto a dos caninos para B1. Por outro lado, uma paciente do gênero feminino, 30 anos de idade, foi inicialmente submetida ao clareamento caseiro (durante a noite, por 4 semanas- PC 10%), e subsequentemente, com aplicação pontual de agente clareador (PH 35%) em consultório, em sessão de 45 min. A cor do incisivo central superior da paciente, mudou de A1 para 0,5M1 e do canino superior de A3 para B1. As escalas de cor VITA Classic (A1-D4), e VITA Bleachedguided 3D-MASTER foram utilizadas nesta série de casos para determinar a coloração dos dentes durante os tratamentos. Em ambos os tratamentos, os pacientes não reportaram sensibilidade dental significante, e suas expectativas finais foram atendidas.

ABSTRACT Tooth bleaching is one of the most conservative aesthetic techniques. At-home and in-office bleaching may be performed, as well as the combination of both techniques. As this combination may be done in different manners, distinct orders of combinations were proposed in this report. A 24 years-old man, whose upper central incisor and canine shades were A2 and A3 respectively, was initially treated by chair-side with 40-min application of 40% hydrogen peroxide (HP) for two sessions. Afterwards, an two-week overnight at-home bleaching was performed with 10% carbamide peroxide (CP). The shade of upper central incisors changed to 1M1 and canine was B1. Conversely, a 30 years-old woman was firstly conducted with at-home bleaching (overnight 4-weeks 10% CP) and, subsequently, with a single appointment of in-office bleaching for 45 minutes (35% HP). The shade of her upper central incisor changed from A1 to 0.5M1 and the upper canine from A3 to B1. The VITA classical (A1-D4) shade guide and VITA Bleached guide 3D-MASTER were used to determine the tooth color during the treatments. In both bleaching treatments, patients reported no significant tooth sensitivity and the final outcomes met their expectation.

Abstract: This study developed experimental gels containing titanium tetrafluoride (TiF4) combined with commercial 35% hydrogen peroxide (HP), and evaluated bleaching efficacy and pH of the gels, and mineral content and morphology of enamel submitted to these treatments. In phase-1, different stock gels mixed with TiF4 were combined with HP. In phase-2, the selected gels were tested on enamel/dentin specimens (n=8): HP; HP and Natrosol+TiF4 (HPnT); HP and Natrosol+Chemygel+TiF4 (HPncT); HP and Aristoflex+TiF4 (HPaT). Bleaching was performed in four sessions (3x15min-application/session). Color (CIEL*a*b*) and whiteness index (WID) were measured after each session, whereas whiteness index differences (ΔWID), color alteration (CIELab–ΔE, CIEDE2000-ΔE00), enamel morphology and pH, at end of bleaching therapy. The change in Knoop microhardness (ΔKHN) was compared before and after bleaching. Data were analyzed by two-way repeated measures ANOVA and Bonferroni (CIEL*, a*, b*), one-way ANOVA and Tukey (ΔWID, ΔE, ΔE00), and LSD (ΔKHN) tests (α=5%). SEM and pH measurements were submitted to descriptive analysis. No differences were observed in lightness (L*) or WID among the groups (p > 0.05), but HP exhibited lower b* values (p<0.05), higher ΔWID than HPnT, and the highest ΔE among the groups (p < 0.05). No differences in ΔE00 were observed between HP and HPncT (p > 0.05), and HPncT showed higher ΔKHN than HP (p < 0.05). HP presented pH values closer to neutral (6.9), whereas experimental agents showed acidic pH values (2.3–3.9). No morphological changes were observed in HP or HPncT groups. HPncT was able to bleach the enamel and maintain enamel microhardness and surface integrity, even at low pH.

Abstract Objective This study evaluated the clinical effect of violet LED light on in-office bleaching used alone or combined with 37% carbamide peroxide (CP) or 35% hydrogen peroxide (HP). Methodology A total of 100 patients were divided into five groups (n=20): LED, LED/CP, CP, LED/HP and HP. Colorimetric evaluation was performed using a spectrophotometer (ΔE, ΔL, Δa, Δb) and a visual shade guide (ΔSGU). Calcium (Ca)/phosphorous (P) ratio was quantified in the enamel microbiopsies. Measurements were performed at baseline (T 0 ), after bleaching (T B ) and in the 14-day follow-up (T 14 ). At each bleaching session, a visual scale determined the absolute risk (AR) and intensity of tooth sensitivity (TS). Data were evaluated by one-way (ΔE, Δa, ΔL, Δb), two-way repeated measures ANOVA (Ca/P ratio), and Tukey post-hoc tests. ΔSGU and TS were evaluated by Kruskal-Wallis and Mann-Whitney, and AR by Chi-Squared tests (a=5%). Results LED produced the lowest ΔE (p<0.05), but LED/HP promoted greater ΔE, ΔSGU and Δb (T 14 ) than HP (p<0.05). No differences were observed in ΔE and ΔSGU for LED/CP and HP groups (p>0.05). ΔL and Δa were not influenced by LED activation. After bleaching, LED/CP exhibited greater Δb than CP (p>0.05), but no differences were found between these groups at T 14 (p>0.05). LED treatment promoted the lowest risk of TS (16%), while HP promoted the highest (94.4%) (p<0.05). No statistical differences of risk of TS were found for CP (44%), LED/CP (61%) and LED/HP (88%) groups (p>0.05). No differences were found in enamel Ca/P ratio among treatments, regardless of evaluation times. Conclusions Violet LED alone produced the lowest bleaching effect, but enhanced HP bleaching results. Patients treated with LED/CP reached the same efficacy of HP, with reduced risk and intensity of tooth sensitivity and none of the bleaching protocols adversely affected enamel mineral content.

Resumo Este estudo avaliou a taxa de decomposição (DR), pH, alteração da cor do esmalte (∆E) e índice de clareamento (DWI) promovido por agentes clareadores caseiros e de consultório. A superfície do esmalte foi submetida a (n=10): agentes caseiros (10%, 15%, 20% de peróxido de carbamida - CP e 6% de peróxido de hidrogênio - HP) e três agentes a base de HP a 35% comirradiação por luz (LED, laser e halógena) ou sem tratamento (controle). A DR e pH dos agentes foi mensurada após 0, 2, 4, 6 e 8h (agentes caseiros) e após 5, 15, 20, 30 e 40 min (agentes de consultório). Parâmetros de cor (L*, a*, b*, DE e DWI) foram determinados inicialmente e após clareamento. Os dados da DR, pH, L*, a*, b* foram analisados por ANOVA um fator (agentes caseiros) ou dois fatores (agentes de consultório) de medidas repetidas e teste Tukey. ΔE e DWI por ANOVA um fator (agentes caseiros) e dois fatores (agentes de consultório) e teste Tukey. A DR dos agentes clareadores caseiros foi similar após 6 e 8 h (p>0.05), com pH próximo ao neutro (6,5 a 6,9 - CP) ou ácido (5,9- HP 6%). De 4 a 8 h, a ∆E foi maior para CP 15% e 20% comparado ao CP 10% (p<0.05). Após 40 min, a DR dos agentes HP 35% foi similar e todos exibiram ∆E significante em uma aplicação (p<0.05), independente da aplicação de luz. DWI indicou efeito clareador, sem diferenças entre os grupos (p>0.05). Um agente HP 35% exibiu pH alcalino, e os outros, pH<5.5. Os agentes clareadores caseiros poderiam ser aplicados por 2 h (15%, 20% CP e 6% HP) e 4 h (CP 10%), e os agentes clareadores de consultório, até 40 min em uma aplicação, sem luz.

Abstract This study evaluated the decomposition rate (DR), pH, enamel color alteration (DE) and whiteness index (DWI) promoted by at-home and in-office bleaching. Enamel surface was submitted to (n=10): at-home (10%, 15%, 20% carbamide peroxide - CP, 6% hydrogen peroxide -HP) and three 35% HP agents with light irradiation (LED, laser, and halogen) or no treatment (control). The DR and pH of agents were measured after 0, 2, 4, 6 and 8 h (at-home) or after 5, 15, 20, 30 and 40 min (in-office). Color parameters (L*, a*, b*, DE, DWI) were determined at baseline and after bleaching. DR, pH, L*, a*, b* data were analyzed by one-way (at-home) or two-way (in-office) repeated measures ANOVA and Tukey test. DE and DWI, by one-way (at-home) or two-way (in-office) ANOVA and Tukey test. DR of at-home agents was similar after 6 and 8 h (p>0.05), with pH close to neutral (6.5 to 6.9, CP) or acid 5.9 (6% HP). From 4 to 8 h, DE was higher for 15% and 20% CP compared with 10% CP (p<0.05). After 40 min, DR of 35% HP agents was similar and all exhibited significant DE in one application (p<0.05), regardless light irradiation. DWI indicated whitening effect with no differences among groups (p>0.05). One 35% HP showed alkaline pH, and the others, pH < 5.5. At-home agents could be applied for 2 h (15%, 20% CP, 6% HP) and 4 h (10% CP) and the in-office agents, up to 40 min in one application, without light.

Abstract High concentrations of hydrogen peroxide can cause adverse effects on composition and structure of teeth. However, the addition of calcium and fluoride in bleaching agents may reduce enamel demineralization. Objective: To evaluate chemical changes of sound and demineralized enamels submitted to high concentrations of hydrogen peroxide containing fluoride (F) or calcium (Ca). Material and Methods: Enamel blocks of bovine incisors with standard dimensions were obtained and half of them were submitted to pH-cycling to promote initial enamel caries lesions. Sound and demineralized enamel samples were divided into (n=10): (C) Control (no whitening treatment); (HP) 35% hydrogen peroxide; and two experimental groups: (HPF) 35% HP+0.2% F and (HPC) 35% HP+0.2% Ca. Experimental groups were submitted to two in-office bleaching sessions and agents were applied 3 times for 15 min to each session. The control group was kept in remineralizing solution at 37°C during the bleaching treatment. The surface mineral content of sound and demineralized enamels was determined through Fourier Transform Raman spectroscopy (FT-Raman), Energy dispersive Micro X-ray fluorescence spectroscopy (μ-EDXRF); and the subsurface, through cross-sectional microhardness (CSMH). In addition, polarized light microscopy (PLM) images of enamel subsurface were observed. Results: According to three-way (FT-Raman and μ-EDXRF analyses) or two-way analysis of variance (ANOVA) (CSMH) and Tukey test (α=5%), the calcium or fluoride added to high-concentrated bleaching agents increased phosphate and carbonate concentrations on sound and demineralized enamels (p<0.05). However, HPC and HPF were unable to completely reverse the subsurface mineral loss promoted by bleaching on sound and demineralized enamels. The calcium/ phosphate (Ca/P) ratio of sound enamel decreased after HP treatment (p<0.001). Conclusion: Even though experimental bleaching agents with Ca or F reduced mineral loss for both sound and demineralized enamel surfaces, these agents were unable to reverse the enamel subsurface demineralization.

This study evaluated the influence of fluoride-containing carbamide peroxide (CP) bleaching agents and adhesive systems on bonded enamel interfaces that are part of the dynamic pH cycling and thermal cycling models. The buccal surfaces of 60 bovine incisors were restored with a composite resin and bonded with three- and two-step, etch-and-rinse, fluoride-containing adhesives, Optibond FL (FL) and Optibond Solo Plus (SP), respectively. Restored teeth were subjected to thermal cycling to age the interface. Both SP and FL adhesive-restored teeth were bleached (n = 10) with 10% CP (CP) and 10% CP + fluoride (CPF) or were left unbleached (control). Bleaching was performed for 14 days simultaneously with pH cycling, which comprised of 14 h of remineralization, 2 h of demineralization and 8 h of bleaching. The control groups (FL and SP) were stored in remineralizing solution during their bleaching periods and were also subjected to carious lesion formation. Parallelepiped-shaped samples were obtained from the bonded interface for microtensile bond strength (∝TBS) testing. The enamel ∝TBS of the FL and SP groups (control, not bleached) were higher (p < 0.05) than those of the bleached interfaces (FL > FL + CPF = FL + CP and SP > SP + CPF = SP + CP). The groups subjected to treatment with the fluoride-containing bleaching agents exhibited similar ∝TBS compared to regular bleaching agents. Bleaching agents, regardless of whether they contained fluoride, decreased enamel bond strength.

OBJETIVO: Avaliar um método estratégico nas aulas práticas, utilizando micro câmeras e monitores de vídeo para transmitir demonstrações da técnica operatória, comparando-o com o método de ensino aprendizagem clássico. METODOLOGIA: Foram aplicados 52 questionários direcionados aos alunos do 4º ano (grupo 1) submetidos a esta nova prática e aos do 3º ano (grupo 2) submetidos a metodologia de ensino tradicional. Este questionário também possibilitou detectar os principais problemas enfrentados pelos discentes durante o aprendizado desta etapa operatória. RESULTADOS: A fase de cirurgia de acesso foi considerada de difícil execução por ambos os grupos (G1- 30,8 % e G2- 34,6%), sendo a manobra de localização dos orifícios de entrada dos canais a etapa mais complicada. Quanto à avaliação da metodologia empregada no 3º ano, 23,1% dos alunos a consideraram excelente, 38,4% ótima, e 38,5% boa, ao passo que nenhum dos estudantes (0%) consideraram o método como regular, ruim ou péssimo. Uma menor ocorrência de erros (P<0,05), foi relatada pelos alunos do 3º ano (G1- 50% e G2- 34.6%). CONCLUSÃO: A nova estratégia de ensino favoreceu a aprendizagem, diminuiu a incidência de erros e foi considerada eficaz pelos alunos.

PURPOSE: To evaluate a strategic method of real time visual demonstration of the operatory procedures using an intraoral camera system and monitor videos, comparing them to those of conventional laboratory classes. METHODS: Fifty-two structured, multiple choice questionnaires were applied to undergraduate students of the 4th year (G1) and 3rd year (G2) submitted to the traditional and strategic teaching methods, respectively. These tests were also able to detect the main problems faced by the students during the training of this operatory phase. RESULTS: Students of both groups (G1- 30.8% and G2- 34.6%) considered the access cavity to be one of the most difficult phase of endodontic treatment. The results of the evaluation among the 3rd year students demonstrated that 23.1% graded the new method as excellent, 38.4% as very good and 38.5 % as good, whereas none of the students (0%) considered the method to be regular, bad or very bad. A minor accident occurrence (P<0.05) was reported by the 3rd year students (G1- 50% and G2- 34.6%). CONCLUSION: The new strategy was found to favor learning, reduce the incidence of errors and was appraised as efficient by the students.

The aim of this study was to observe the influence of two light polymerization units (LED or halogen light) on the degree of conversion (DC) of three dental composites with lighter shades and a different photoinitiator system. The top (T) and bottom (B) surfaces of 60 discs of composite resin (Filtek™ Supreme, Filtek™ Z250, Tetric™ Ceram Bleach) cured either by LED or by halogen lamp (HL) were studied using an FT-Raman spectrometer. The degree of conversion (DC) was evaluated by following the changes in the intensity of the methacrylate C=C stretching mode at 1640 cm-1. The calculated DC ranged from 54.2% (B) to 73.4% (T) and from 60.2% (B) to 76.6% (T) for the LED and HL, respectively. LED and halogen devices were able to produce an adequate DC for all the resins tested.

Os objetivos deste estudo foram determinar a sorção de água (SA) e solubilidade (SO) de 3 resinas compostas que contêm diferentes conteúdos de partículas de carga. Adicionalmente, o tamanho, formato, tipo e outras características das partículas foram analisados em microscopia eletrônica de varredura (MEV). As resinas foram selecionadas de acordo com o tamanho das partículas: Filtek Supreme nanoparticulado (3M ESPE), Esthet-X microhíbrido (Dentsply Caulk) e Renamel microparticulado (Cosmedent Inc.). Dez espécimes com formato de disco de cada compósito foram confeccionados e armazenados em dessecador até obtenção de massa constante. Em seguida, os espécimes foram armazenados em água por 7 dias e a massa mensurada novamente. Os espécimes foram desidratados novamente e a massa final mensurada. A SA e a SO foram calculados a partir destas medidas. As partículas de carga dos compósitos foram observadas em MEV, após a remoção da matriz orgânica com solventes orgânicos. Os dados foram analisados por ANOVA e teste de Tukey (?=0.05). As médias de SA das resinas compostas foram semelhantes. A SO foi menor para o compósito Filtek Supreme. Os materiais contêm diferentes conteúdos de carga, em termos de formato e tamanho das partículas. As resinas compostas mostraram similar SA, enquanto o compósito nanoparticulado apresentou a menor SO. As características das partículas de carga foram diferentes entre os compósitos estudados.

The goals of this study were to measure the water sorption (WS) and solubility (SO) of 3 composite resins containing different filler contents. Additionally, the size, shape, type and other characteristics of fillers were analyzed by scanning electron microscopy (SEM). Three composites, classified according to filler size, were selected: Filtek Supreme nanofill (3M/ESPE), Esthet-X minifill (Dentsply/Caulk) and Renamel microfill (Cosmedent Inc.). Ten disk-shaped specimens of each resin composite were made and stored in desiccators until constant mass was achieved. Specimens were then stored in water for 7 days, and the mass of each specimen was measured. The specimens were dried again and dried specimen mass determined. The WS and SO were calculated from these measurements. Data analyzed by one-way ANOVA and Tukey's post-hoc test (?=0.05). Composite filler particles were observed under SEM after removal of resin matrix by organic solvents. WS values were not significantly different among the resins; however, SO values were lower for Filtek Supreme. The materials presented differences in filler contents (e.g. particle size and shape). The composite resins had similar WS, while the SO was lower for the nanofill than for mini and microfill resins. The filler characteristics varied and were different among the materials.

Este estudo analisou o efeito do peróxido de carbamida a 10% (PC) na microdureza Knoop de superfície (KHN) e morfologia do esmalte hígido e com lesões iniciais de cárie artificial (EC), após modelo de ciclagem de pH (cpH). Blocos de esmalte dental humano foram divididos aleatoriamente em 6 grupos (n=10): 1- esmalte hígido clareado (EHC) com PC (Rembrandt/Den-Mat); 2- EHC e submetido a cpH; 3- EC clareado com PC; 4- EC armazenado em saliva artificial e submetido a cpH; 5- EC tratado com gel placebo e submetido a cpH; 6- EC clareado com PC e submetido a cpH. Blocos de esmalte com a KHN conhecida eram desmineralizados (grupos 3 a 6) e submetidos a cpH (grupos 2, 4, 5 e 6). KHN foi determinada após a desmineralização e os tratamentos. Os espécimes foram examinados através de Microscopia Eletrônica de Varredura (MEV). Os dados foram analisados através de ANOVA e teste de Tukey (p<0,05). Os resultados indicaram que entre os grupos com EC (3 a 6) somente o grupo 3 apresentou remineralização após os tratamentos. Os grupos EHC (1 e 2) mostraram maior KHN e menor formação porosidades quando comparados aos grupos EC após os tratamentos. Os procedimentos clareadores no esmalte com lesão de cárie não exacerbaram a desmineralização, entretanto precisam ser indicados com cautela.

This study evaluated the effect of 10% carbamide peroxide (CP) bleaching on Knoop surface microhardness (KHN) and morphology of sound enamel and enamel with early artificial caries lesions (CL) after pH-cycling model (pHcm). Human dental enamel blocks were randomly divided into 6 groups (n=10): 1 - sound enamel bleached (S) with CP (Rembrandt/Den-Mat); 2 - S and submitted to pHcm; 3 - CL bleached with CP; 4 - CL stored in artificial saliva and submitted to pHcm; 5 - CL treated with placebo gel and submitted to pHcm; 6 - CL bleached with CP and submitted to pHcm. Enamel blocks with known initial KHN values were demineralized (groups 3 to 6) and submitted to 12 day pHcm (groups 2, 4, 5 and 6). After demineralization and treatments, KHN was determined and the specimens were examined using scanning electron microscopy (SEM). Data were analyzed statistically by ANOVA and Tukey's test at 5% significance level. The results showed that among CL groups (3 to 6) only the group 3 presented remineralization after treatments. S groups (1 and 2) showed higher KHN and presented less formation of porosities on enamel surface than CL groups after treatments. In conclusion, bleaching procedures on enamel with CL did not exacerbate the demineralization, but should be indicated with caution.

Concern has been expressed regarding the staining of enamel surface by different beverages after bleaching. This study investigated the influence of 35% hydrogen peroxide bleaching agents on enamel surface stained with wine after whitening treatments. Flat and polished bovine enamel surfaces were submitted to two commercially available 35% hydrogen peroxide bleaching agents or kept in 100% humidity, as a control group (n = 10). Specimens of all groups were immersed in red wine for 48 h at 37°C, immediately, 24 h or 1 week after treatments. All specimens were ground into powder and prepared for the spectrophotometric analysis. Data were subjected to two-way analysis of variance and Fisher's PLSD test at 5% significance level. The amount of wine pigments uptake by enamel submitted to bleaching treatments was statistically higher than that of control group, independently of the evaluation time. Results suggested that wine staining susceptibility was increased by bleaching treatments.

OBJETIVO: O propósito deste estudo foi avaliar os efeitos de agents clareadores à base de peróxido de carbamida (CPG) contendo fluoreto (CF) e cálcio (CCa) na resistência à tração do esmalte (UTS). MÉTODO: Um bloco de resina composta foi confeccionada na superfície oclusal de vinte e dois terceiros molars hígidos para facilitar a preparação dos espécimes para o teste de micro-tração. Os dentes restaurados foram seccionados com disco diamantado no sentido vestíbulo-lingual em fatias de aproximadamente 0,7 mm de espessura. Com uma ponta diamantada, foi realizada uma constrição na região de esmalte da vertente oclusal interna. Os espécimes apresentaram aproximadamente 0,5 mm² de área na secção transversal da região de constrição e foram divididos em 12 grupos (n=11). Os grupos controles não foram submetidos ao regime clareador e os experimentais foram tratados com gel de CPG 10% ou com formulações de CPG 10% contendo CF (0,2% e 0,5%) ou CCa (0,05% e 0,2%). Os grupos clareadores receberam a aplicação dos CPGs por 6 horas/dia a 37ºC, durante 14 dias consecutivos e foram armazenados em saliva artificial (AS) ou em umidade relativa 100% (RH), entre as aplicações do gel clareador. Após o clareamento, os espécimes foram testados através do método de micro-tração (0,5 mm/min). Os dados foram analisados pela ANOVA (2 fatores) e teste Tukey (5%). RESULTADOS: Nenhuma diferença foi observada entre os grupos armazenados em AS ou RH. Os espécimes tratados com CPG com CF ou Cca apresentaram similar UTS aos grupos controles não clareados. CONCLUSÃO: Ambos CPGs 10% CF or CCa não alteraram a UTS após o tratamento clareador.

OBJECTIVE: The aim of this study was to evaluate the effects of carbamide peroxide-based bleaching agents (CPG) containing fluoride (CF) or calcium (CCa) on the ultimate tensile strength of enamel (UTS). METHOD: A "cube-like" resin composite structure was built-up on the occlusal surface of twenty-two sound third molars to facilitate specimen preparation for the micro-tensile test. The restored teeth were serially sectioned in buccal-lingual direction in slices with approximate 0.7 mm thickness. Each slice was trimmed with a fine diamond bur to reduce the buccal, internal slope enamel of the cusps to a dumb-bell shape with a cross-sectional area at the "neck" of less than 0.5 mm². The samples were randomly divided into 12 groups (n=11). The control groups were not submitted to the bleaching regimen. Specimens were treated with 10% CPG gel or with 10% CPG formulations containing CF (0.2% and 0.5%) or CCa (0.05% and 0.2%). Bleached groups received the application of the 10% CPGs for 6 hours/day at 37º C, during 14 consecutive days and were stored in artificial saliva (AS) or 100% relative humidity (RH) among each application. After bleaching, specimens were tested with the microtensile method at 0.5 mm/min. Data were analyzed by two-way ANOVA and Tukey test (5%). RESULTS: No significant difference was observed between groups stored in AS or RH. Specimens treated with CF or CCa presented similar UTS as unbleached control groups. CONCLUSION: Either 10% CPG formulations containing CF or CCa can preserve the UTS after bleaching regimen.

Este estudo avaliou a resistência de união de dois sistemas adesivos ao esmalte e à dentina após a aplicação de agente clareador sobre a união compósito-dente. Dezesseis terceiros molares humanos foram usados nos procedimentos restauradores. Single Bond (SB) e Clearfil SE Bond (CB) foram aplicados no esmalte e na dentina de acordo com as instruções dos fabricantes. Um bloco de compósito foi construído nas superfícies tratadas com os adesivos. Os dentes restaurados foram seccionados em fatias com espessura de 0,7 mm, que receberam constrição na interface de união num formato de ampulheta, com área de secção transversal de ± 0,5 mm². Os espécimes foram distribuídos em 8 grupos (n = 10) de acordo com os fatores em estudo: substrato dental (esmalte e dentina); sistema adesivo (SB e CB) e tratamento (peróxido de carbamida a 10% e controle). O agente clareador (Opalescence) foi aplicado na interface de união por 6 horas durante 14 dias e, após o tratamento diário, os espécimes foram armazenados em saliva artificial. Os espécimes não clareados foram mantidos em saliva artificial por 14 dias. Os espécimes foram testados e os dados foram analisados pela ANOVA (três fatores) e pelo teste Tukey (p < 0,05). A resistência à tração do esmalte tratado com o adesivo CB foi reduzida após aplicação do peróxido de carbamida, entretanto, a resistência de união em dentina para ambos os adesivos não foi modificada. Os resultados sugerem que o clareamento afeta a resistência de união do CB ao esmalte, mas nenhuma influência foi observada em dentina.

In this bond strength study, a bleaching agent containing 10% carbamide peroxide was applied over composite-teeth bonded interfaces of two adhesive systems applied to enamel and dentin. Sixteen human third molars were used for bonding procedures. Single Bond (SB) and Clearfil SE Bond (CB) were applied to enamel and dentin according to the manufacturers' instructions. A resin composite cube-like structure was incrementally built on the bonded surfaces. The restored teeth were sectioned into 0.7 mm thick slices that were trimmed at enamel or dentin bonded interfaces to an hourglass shape with a cross-sectional area of approximately 0.5 mm². Specimens were assigned to 8 groups (n = 10) according to the following factors under study: dental substrate (enamel and dentin); adhesive system (SB and CB) and treatment (10% carbamide peroxide and not bleached/control). The bleaching gel (Opalescence) was applied at the bonded interfaces for 6 hours during 14 days and after daily treatment specimens were stored in artificial saliva. Unbleached specimens were stored in artificial saliva for 14 days. Specimens were tested for tension and the data were analyzed by three-way ANOVA and Tukey's test (p < 0.05). Enamel tensile bond strength of CB was reduced after carbamide peroxide application. The bleaching treatment did not alter dentin bond strength of both adhesives. The results suggest that bleaching significantly affects bond strength of CB to enamel, but no influence on bond strength to dentin was noted for both adhesive systems.