Abstract Quantification of collagen degradation is an important parameter to evaluate dentin caries for preventive aid. Objectives: Evaluate preventive methods against root collagen degradation by the hydroxyproline assay (HYP) and microradiography technique (MRT). Methodology: Five bovine root dentin blocks were obtained and subjected to an artificial demineralization process by acetate buffer (pH 5) to induce carious lesion formation. Samples were subjected to the following therapeutic treatments: 1) 0.12% chlorhexidine for 1 min, 2) 2% fluoride for 1 min, 3) Nd:YAG Laser (400 μm diameter optical fiber, 10 Hz frequency, 60 mJ/pulse energy, 48 J/cm2 energy density, in noncontact mode for 10 s), 4) deionized water (control) for 1 min, 5) MRT control group (without treatment and removal of collagen). Samples were exposed to degradation by a collagenase enzyme for five days. The enzyme solution was collected, by colorimetry in a spectrophotometer, from the collagen matrix for the hydroxyproline release analysis. The same samples were subjected to an additional two days of demineralization to induce the progression of mineral loss. Samples were analyzed by MRT for the visualization of their degraded areas (estimation of lesion depth and mineral loss). ANOVA was applied to compare hydroxyproline release rates. MRT data were subjected to the Kruskal-Wallis test, followed by the Dunn’s test. Comparisons between the initial five-day and the subsequent two-day demineralization processes were performed by repeated t-test or Wilcoxon (p<0.05) measurements. Results: The amount of HYP released from the dentin samples failed to show significant differences among the groups (p=0.09). Fluoride and chlorhexidine were able to interact with the samples, reducing the progression of dentin caries after removal of the demineralized organic matrix. CHX was the only treatment able to show significant lower lesion depth than the negative control. Conclusion: Chlorhexidine and fluoride were effective in reducing root caries progression.

ABSTRACT Objective: To determine the initial mechanical stabilization of conventional glass ionomer cements (GICs) indicated for the atraumatic restorative treatment (ART) in different storage periods. Material and Methods: Specimens were divided according to the GIC (n=12): IZ - Ion-Z, KM - Ketac Molar Easymix, RS - Riva Self Cure, and GL - Gold Label 9. They were prepared and stored in distilled water. Superficial microhardness (SMH) was evaluated (KHN) in three phases: (A) after 1, (B) 3, and (C) 7 days of storage. Data were submitted to 2-way ANOVA and Tukey tests (α = 5%). Results: The average KHN values for phases A, B, and C were, respectively, 33.05 ± 9.74; 33.21 ± 10.31 and 52.07 ± 11.75 (IZ); 50.35 ± 11.39; 66.05 ± 10.48 and 67.77 ± 13.80 (KM); 89.63 ± 15.59; 71.31 ± 23.86 and 57.70 ± 16.89 (RS); 42.18 ± 9.03; 68.54 ± 6.83 and 57.95 ± 8.24 (GL). Significant differences were observed: GIC, time, and interaction of both (p<0.05). KHN values differed between the groups, except in the GIC parameter for KM and GL. The time parameter values of phase A were lower than those of B and C, except for IZ and RS. Conclusion: The initial mechanical stabilization differed between the types of GIC tested and the storage time, and after the final period, all had similar SMH.

Abstract Objective To compare the effectiveness of ART restorations using High Viscosity Glass-ionomer cement (HVGIC) with conventional restorations using resin composite in Class II cavities of permanent teeth, in a 2-year follow-up. Methodology Seventy-seven restorations were made with each restorative material, Equia Fil-GC Corporation (ART restorations) and Z350-3M (conventional restoration), in 54 participants in this parallel and randomized clinical trial. Restorations were evaluated at 6 months, 1 and 2 years using the ART and the modified United States Public Health Service (USPHS) criteria. Chi-square test and Survival Analysis (p<0.05) were used for statistical analysis. Results The success rates for ART restorations were 98.7% (6 months) and 95.8% (1 year) for both criteria. At 2 years, success rate was 92% and 90.3% when scored by the modified USPHS and ART criteria (p=0.466), respectively. The success rates for conventional restorations were 100% (6 months), 98.7% (1 year) and 91.5% (2 years) for both assessment criteria. ART restorations presented a lower survival rate by the criterion of ART (83.7%) when compared to the modified USPHS criterion of (87.8%), after 2 years (p=0.051). The survival of conventional restorations was 90.7% for both evaluation criteria. Conclusion At the 2-years follow-up evaluation, no statistically significant difference was observed between the success rate of ART restorations with HVGIC compared to conventional restorations with resin composite in Class II cavities of permanent teeth.

ABSTRACT This study evaluated the influence of different levels of power density on resin polymerization in the staining of composite resins. Thirty-six specimens were made with composite resin (Z350 3M ESPE) with cylindrical Teflon matrix (8 mm X 1 mm). The light curing was performed with different degrees of power density for each group (n=12): 300mW/cm², 700mW/cm² e 1000mW/cm². Afterwards, the specimens had their color checked, with the help of a spectrophotometer and immersed in coffee solution during 7 days. After, a new measuring was done (CIEL*a*b* color system). Results showed, for Δa, only G1000 group obtained a significantly lower value, and the same result was found in the evaluation of Δb. For ΔE and ΔL, no significant differences were found between groups. It is concluded that, low and medium power density entails more reddish and bluish composite resin, while the specimens submitted to high power density and then immersed in coffee did not present color change in a short term.

Abstract Objective: This clinical study sought to evaluate the effectiveness of passive ultrasonic activation (PUA) in eliminating microorganisms in primary endodontic infection (PEI) after instrumentation of root canals using microbiological culture and checkerboard DNA-DNA hybridization. Methodology: Twenty root canals with PEI and apical periodontitis were selected. The root canals were instrumented and then randomly divided into 2 groups, according to the irrigation method: PUA and conventional needle irrigation (CNI). Microbiological samples were collected before instrumentation (S1), after instrumentation (S2) and after irrigation with 17% EDTA (S3). The samples were subjected to anaerobic culture technique and checkerboard DNA-DNA hybridization analysis. Results: A statistically significant difference was found between CNI (23.56%) and PUA (98.37%) regarding the median percentage values for culturable bacteria reduction (p<0.05). In the initial samples, the most frequently detected species was S. constellatus (50%), and after root canal treatment was E. faecalis (50%). Conclusion: Both treatments significantly decreased the number of bacterial species compared with the initial sample. However, no statistical difference in the total microbial load between PUA and CNI groups was detected. The number of cultivable anaerobic bacteria reduced significantly using PUA, and the bacterial composition and number of bacterial species after using either CNI or PUA was similar.

Resumo Este estudo avaliou a influência dos acabamentos superficiais da zircônia no desgaste de um análogo de esmalte. 40 discos de zircônia foram divididos em quatro grupos: controle (sem acabamento); glazeado; polido; polido e glazeado. Todas as amostras foram submetidas ao desgaste contra antagonistas de esteatita. Os espécimes foram submetidos à análise de rugosidade, topografia, microscopia eletrônica de varredura (MEV) e análise de molhabilidade. Medidas quantitativas de desgaste foram realizadas nos antagonistas e nos discos de zircônia. Para medir o desgaste das esteatitas, foi mensurado o peso antes e depois do desgaste e o diâmetro após o teste. A análise de perfilometria mensurou o desgaste dos discos. Rugosidade, desgaste volumétrico e perda de massa foram analisados pelos testes de Kruskal-Wallis e Dunn (5%), enquanto os valores de ângulo de contato foram analisados com os testes One-way ANOVA e Tukey (5%). O grupo polido apresentou as menores médias de rugosidade, sendo estatisticamente diferente dos demais grupos (p-valor=0,0001). O grupo glazeado apresentou o menor desgaste volumétrico do antagonista (p-valor=0,0001), mas não foi estatisticamente diferente do grupo polido e glazeado, enquanto que esses grupos apresentaram o maior desgaste volumétrico da zircônia, com diferença estatisticamente diferente (p-valor=0,0002) em comparação com os outros. MEV mostrou irregularidades na superfície do grupo controle, sulcos no grupo polido e uma superfície homogênea para o grupo glazeado, com poucos poros. Todos os grupos apresentaram ângulos de contato menores que 90 graus, caracterizando superfícies hidrofílicas. Dentro das limitações deste estudo in vitro, é possível concluir que zircônia glazeada causou menos desgaste ao antagonista quando comparada a zircônia sem tratamento ou polida. Além disso, não foi encontrada diferença no desgaste do antagonista para os grupos de zirconia polida e controle.

Abstract This study evaluated the influence of zirconia surface finishes on the wear of an enamel analogue. 40 zirconia discs were divided into four groups: control (without finish); glazed; polished; polished and glazed. All samples were subjected to wear against steatite antagonists. The specimens underwent roughness, topographic, scanning electron microscopy (SEM) and wettability analyses. Quantitative wear measurements were performed on both steatites and discs. To measure wear of steatites the weight before and after the test and the diameter after the test were used. Profilometer measurements were performed to determine the wear on discs. Roughness, volumetric wear and mass loss were analyzed using the Kruskal-Wallis and Dunn tests (5%), while contact angle values were analyzed with One-way ANOVA and Tukey tests (5%). The polished group had the lowest roughness means, being statistically different from the other groups (p-value=0.0001). The glazed group presented the lowest steatite volumetric wear (p-value=0.0001), but not statistically different from the polished and glazed group, whereas these groups presented the highest zirconia volumetric wear, with statistically different (p-value=0.0002) compared to the others. SEM showed irregularities on the control groups surface, grooves on the polished group, and a homogeneous surface for the glazed group with a few pores. All groups presented contact angles lower than 90 degrees, characterizing hydrophilic surfaces. It can be concluded that just glazed zirconia caused less wear on the antagonist when compared to no finish and polished zirconia.

Resumo O presente estudo objetivou comparar a eficácia do QMiX e do EDTA 17% associado à irrigação ultrassônica passiva (PUI) ou agitação manual (MA) na redução de E. faecalis, E. coli e LPS de canais radiculares. Quarenta dentes humanos unirradiculares foram divididos aleatoriamente em quatro grupos (n = 10), de acordo com o protocolo final de irrigação: EDTA+MA, QMiX+MA, EDTA+PUI, QMiX+PUI. Coletas das amostras foram obtidas a partir do conteúdo do canal radicular imediatamente antes do preparo (inicial-S1), após a instrumentação (S2), após o protocolo final de irrigação (S3) e 7 dias após a instrumentação e irrigação final (S4). A eficácia antimicrobiana e o conteúdo de endotoxina foram analisados por procedimento de cultura (UFC/mL) e ensaio LAL (EU/mL), respectivamente. Os resultados foram analisados estatisticamente pelo teste de Kruskal-Wallis e Friedman (α = 5%). QMiX+MA e QMiX+PUI reduziram 100% das bactérias E. coli e E. faecalis e também preveniram a recolonização de E. faecalis em S4. O EDTA reduziu significativamente E. coli, mas não foi eficaz na redução de E. faecalis. Todos os protocolos reduziram EU/mL quando comparados com S1, no entanto, no S4 houve uma redução significativa de EU/mL apenas nos grupos QMiX+MA e QMiX+PUI em relação a S3 e S2, respectivamente. A irrigação final com QMiX associada a MA ou PUI apresentou eficácia antibacteriana superior em relação ao EDTA, eliminando 100% das cepas de E. coli e E. faecalis. Além disso, QMiX+PUI reduziu 97,61% do conteúdo inicial de LPS.

Abstract The present study aimed to compare the effectiveness of QMiX and 17% EDTA associated to passive ultrasonic irrigation (PUI) or manual agitation (MA) on the reduction of E. faecalis, E. coli and LPS from root canals. Forty single rooted human teeth were randomly divided into four groups (n=10), according to the final irrigation protocol: EDTA+MA, QMiX+MA, EDTA+PUI, QMiX+PUI. Sample collections were obtained from the root canal content immediately before preparation (baseline-S1), after instrumentation (S2), after final irrigation protocol (S3) and 7 days after instrumentation and final irrigation (S4). The antimicrobial effectivity and on endotoxin content were analyzed by culture procedure (CFU/mL) and LAL assay (EU/mL), respectively. The results were statistically analyzed by Kruskal-Wallis and Friedman test (α=5%). QMiX+MA and QMiX+PUI reduced 100% of E. coli and E. faecalis bacteria and also prevented E. faecalisregrowth at S4. EDTA significantly reduced E. coli, but it was not effective in reducing E. faecalis. All protocols reduced EU/mL when compared to S1, however at S4 there was a significant reduction of EU/mL only in the QMiX+MA and QMiX+PUI groups in relation to S3 and S2, respectively. Final irrigation with QMiX associated with MA or PUI had superior antibacterial efficacy compared to EDTA, eliminating 100% of E. coli and E. faecalis strains. In addition, QMiX+PUI reduced 97.61% of the initial content of LPS.

Abstract This double-blind randomized controlled clinical trial evaluated the effectiveness of dentin pretreatment with 100% ethanol (EWBT – ethanol wet bonding technique) and different adhesive protocols in noncarious cervical lesions (NCCL) after 6 months. Patients presenting at least one NCCL were included. NCCLs (n=148) were randomly assigned to 4 groups: NE (Non-EWBT + three-step etch-and-rinse (Scotchbond Multi Purpose, 3M ESPE [MP]), E (EWBT + MP); EB (EWBT + [Bond – third step of MP]), and EU (EWBT + universal adhesive (Single Bond Universal, 3M ESPE). Conventional acid-etching (Condac 37%, FGM) and nanohybrid resin composite (Z350, 3M ESPE) were used. Trained and calibrated examiners (Kappa = 0.61) evaluated the restorations at baseline (7 days) and 6-month recall using the USPHS modified criteria. Data were subjected to Chi square (α = 0.05). Differences in the success rate were found for the treatments (p = 0.003). EB presented the lowest success rate compared with the other groups (p < 0.02). No significant differences were detected among NE, E, and EU (p > 0.49). The survival rates were 97.23%, 97.30%, 78.95%, and 97.30% for NE, E, EB, and EU, respectively. Regarding postoperative sensitivity, a significant reduction was found for groups E (p = 0.027) and EU (p < 0.01) after 6 months. After 6 months, EWBT associated to the hydrophobic adhesive system had the highest failure rate.

Abstract Objective The aim of this study was to compare two in vitro erosion protocols, in which one simulates in vivo conditions experienced by patients with gastroesophageal disorders or bulimia (HCl-pepsin protocol), and the other simulates the diet of an individual who consumes a high volume of erosive beverages (citric acid protocol). In addition, the mechanical properties and surface gloss of eroded human dentin were compared with those of sound human dentin. Materials and Methods Blocks of cervical dentin were used: sound human dentin (n=10), human dentin with erosive lesions (n=10), and bovine dentin (n=30). Twenty bovine blocks were subjected to either of two erosion protocols (n=10/protocol). In the first protocol, samples were demineralized using HCl-pepsin solution, then treated with trypsin solution. In the second protocol, samples were demineralized with 2% citric acid. Toothbrushing was performed in both protocols using a toothbrushing machine (15 s with a 150 g load). Ten bovine dentin blocks were not subjected to any erosive treatment. All samples of bovine and human dentin were analyzed to obtain Martens hardness values (MH), elastic modulus (Eit*) and surface gloss. One-way ANOVA and Tukey's test were performed to analyze the data (α=0.05). Results Sound human and eroded human dentin groups showed similar MH and Eit* values (p>0.05); however, sound human dentin showed a higher surface gloss value when compared to eroded human dentin (p<0.05). Sound bovine dentin and HCl-pepsin-treated bovine dentin treatments resulted in similar values for both MH and Eit* (p>0.05), but HCl-pepsin-treated bovine dentin and citric acid-treated bovine dentin resulted in lower surface gloss than sound bovine dentin (p<0.05). Conclusions The HCl-pepsin protocol modified bovine dentin properties that could be similar to those that occur on human dentin surfaces with erosive lesions.

Resumo O objetivo deste estudo foi avaliar in vitro a influência do extrato de gengibre 20% na resistência adesiva de pinos de fibra de vidro cimentados com cimentos resinosos convencional ou autocondicionantes. Quarenta e oito raízes bovinas foram padronizadas (17±0.5mm) e aleatoriamente divididas em dois grupos (n=24), de acordo com o irrigante utilizado durante o preparo biomecânico: NaOCl: hipoclorito de sódio 1%; e GEN: extrato glicólico de gengibre 20%. Os canais radiculares foram preparados e aleatoriamente distribuídos em dois subgrupos (n=12), conforme o protocolo de cimentação: autocondicionante (RelyX U200) e convencional (RelyX ARC). Após 48 h, as raízes foram seccionadas perpendicularmente (4 no terço cervical e 3 no terço médio) e submetidas ao teste de resistência adesiva push-out (50 kgf carga, 1.0 mm/min). O modo de falha foi analisado em MEV e estereomicroscopia. Os dados foram analisados pelos testes ANOVA 3-fatores e Tukey (p<0.05). ANOVA mostrou que não houve diferenças significativas entre U200 (2.01±0.17)B e ARC (1.93±0.12)B no grupo GEN, e no terço cervical para ambos os irrigantes (2.69±0.16A and 2.54±0.17A, respectivamente). O terço médio apresentou menor resistência adesiva que o terço cervical, independente do irrigante. Em geral, o terço cervical, independentemente do irrigante empregado, e a associação entre NaOCl e ARC apresentaram melhores desempenhos adesivos.

Abstract The aim of this study was to evaluate in vitro the influence of 20% glycolic ginger extract on the bond strength of glass-fiber post cemented with etch-and-rinse or self-etching resin cement. Forty-eight bovine roots were standardized (17±0.5 mm) and randomly divided into two groups, according to irrigant used during biomechanical preparation: NaOCl: 1% sodium hypochlorite and GEN: 20% glycolic ginger extract. Root canal was prepared and randomly assigned to one of two subgroups (n=12), according to luting protocol: self-etching (RelyX U200) and etch-and-rinse (RelyX ARC). After 48 h, the roots were sectioned perpendicularly (4 in cervical third and 3 in middle third) and submitted to push-out bond strength test (50 kgf load cell, 1.0 mm/min). Failure mode was analyzed in SEM and stereomicroscopy. Data were analyzed by three-way ANOVA and Tukey tests (p<0.05). ANOVA revealed that there were no significant differences between U200 (2.01±0.17)B and ARC (1.93±0.12)B in GEN group, and at the cervical third for both irrigants, 2.69±0.16A and 2.54±0.17A, respectively. Middle third showed lower bond strength than cervical third, regardless the irrigant. Overall, the cervical third regardless the irrigant employed and the association between NaOCl and ARC, presented better adhesive performance.

ABSTRACT This study evaluated the effect of different artificial aging on fluorescence of resin composites. Forty-five cylindrical specimens (6mm in diameter and 1mm thick) were made of each resin composite: IPS Empress Direct, Filtek™ Z350 XT, and Durafill. A baseline measurement of fluorescence by the direct method using the fluorescence spectrophotometer RF-5301 PC was performed. After, resin specimens were divided into 3 groups according to artificial aging protocol to be submitted: (1) aging by mechanical brushing: 30,000 cycles were performed, with fluorescence measurements after 10,000, 20,000 and 30,000 cycles; (2) chemical aging by ethanol: the samples were immersed in ethanol for 15 days, with measurements after 5, 10 and 15 days of immersion; (3) light aging: resin specimens were subjected to UV radiation for 216h with fluorescence readings after 72, 144, 216h. Data were submitted to one-way repeated measures ANOVA and Tukey’s test (α=0.05). Baseline fluorescence of the tested resins was ranked in this ascending order: Durafill < Filtek Z350 XT < IPS Empress Direct. Simulated toothbrushing and ethanol immersion reduced fluorescence, except for Z350 XT. For light exposition, fluorescence was reduced after 100h for Empress Direct and Durafill, while a reduction after 100h and 200h was detected for Z350 XT. Artificial aging protocols influenced the fluorescence and that this phenomenon is material dependent. In general, the fluorescence is reduced with aging.

Abstract The aim of this study was to evaluate the effect of ethanol on the bond longevity of a universal adhesive system to bovine dentin, under different modes of adhesive application and artificial aging. Bovine dentin was exposed, and the smear layer was standardized by sandpaper polishing. Specimens were randomly divided into 2 groups: ethanol (E) and non-ethanol (N). Groups were subdivided according to adhesive mode of application into etch-and-rinse (Er) and self-etching (S). Resin blocks were built onto the treated surface, and the specimens were stored in deionized water at 37°C for 48 h. Half of the specimens (n = 10) were subjected to thermomechanical aging (A for aged and Na for non-aged). Resin/dentin beams were obtained and subjected to microtensile test in a universal testing machine. Data were analyzed using a three-way ANOVA and Tukey’s tests (α = 5%). There was interaction among the three factors (p=0.0003). The use of ethanol resulted in higher values, except for the Er and Na groups (E_Er_Na = N_Er_Na). The mode of application was similar, except for the N and A groups (N_S_A > N_Er_A). For the A groups, the values were lower, except in the cases using ethanol, in which the results were not affected. The study concluded that the use of ethanol resulted in higher microtensile bond strength values, even after aging. The mode of adhesive application did not influence the results.

This study evaluated the cleanliness of post space after different irrigation protocols, associated or not to the use of ultrasound. Thirty-six single-rooted bovine roots were instrumented with rotary system, irrigated with 1 % hypochlorite and filled with Ah Plus sealer and gutta-percha cones. After seven days in stove at 37 °C, two-thirds of canal filling was removed by drilling and the post space preparation was irrigated with 2.5 % NaOCl (group NaOCl); 0.2 % chlorhexidine (group CLX); distilled water (group Water); 2.5 % NaOCl + ultrasound (group NaOCl-US); 0.2 % chlorhexidine + US (Group CLX-US); or water + US (Group Water-US). Roots were cleaved in mesiodistal direction, prepared for scanning electron microscope (SEM) to evaluate the smear layer and debris presence and for energy dispersive spectroscopy (EDS) analyses, to evaluate chemical components of dentin after treatment. The data were subjected to statistical analysis (two-way Anova and Tukey's test 5 %). EDS analysis showed the presence of chemical components of filling material in the samples from all groups. SEM images showed large amount of obliterated dentinal tubules. The use of ultrasound influenced the removal of some components of filling material (p<0.05), but not allowed for total cleaning. It was concluded that none of the irrigating solutions, associated or not to the use of ultrasound were able to completely clean the post space.

Este estudio evaluó la limpieza de la preparación para el espacio de los postes después de diferentes protocolos de irrigación, asociados o no al uso de ultrasonido. Treinta y seis raíces unirradiculares de bovinos fueron instrumentados con sistema rotatorio, irrigadas con un 1 % de hipoclorito y rellenadas con el sellador Ah Plus y conos de gutapercha. Después de siete días en horno a 37 °C, dos tercios de la obturación del canal se removió por perforación y la preparación del espacio para los postes fueron irrigadas con 2,5 % de NaOCl (grupo NaOCl); Clorhexidina 0,2 % (grupo CLX); agua destilada (grupo agua); 2,5 % NaOCl + ultrasonido (grupo NaOCl - US); 0,2 % de clorhexidina + US (Grupo CLX - US); y agua + US (grupo Agua - US). Las raíces se cortaron en dirección mesiodistal y se prepararon para el microscopio electrónico de barrido (MEB) con el fin de evaluar el barrillo dentinario y la presencia de restos; así como mediante el análisis de espectroscopía de energía dispersiva (EDS) para evaluar componentes químicos de la dentina después del tratamiento. Los datos fueron sometidos a análisis estadístico (pruebas ANOVA de dos factores y de Tukey al 5 %). El análisis EDS mostró la presencia de componentes químicos del material de relleno en las muestras de todos los grupos. Imágenes del MEB mostraron gran cantidad de túbulos dentinarios obliterados. El uso de la ultrasonido influyó en la eliminación de algunos de los componentes de material de relleno (p <0,05), pero no permitió la limpieza total. Se concluyó que ninguna de las soluciones de irrigación, asociadas o no a la utilización de los ultrasonidos fueron capaces de limpiar completamente el espacio para los postes.

Resumo: O objetivo deste estudo foi avaliar o efeito do clareamento com peróxido de hidrogênio na fluorescência e cor do esmalte e da dentina bovina. Vinte e cinco discos de dentina e 25 discos de esmalte, com 6 mm de diâmetro e 1 mm de espessura, foram obtidos. A fluorescência direta (Espectrofluorometria) e cor (espectrofotometria) foram avaliados. Depois da leitura inicial de cor e fluorescência, os espécimes foram imersos em solução de peróxido de hidrogénio a 35% (HP) durante 1 h. Este procedimento foi repetido após 7 dias. E as medições de fluorescência e de cor finais foram realizados após a segunda imersão. A caracterização química de 5 espécimes adicionais também foi realizada. Os dados foram submetidos à ANOVA de medidas repetidas e teste de Tukey para a fluorescência Teste e teste t não pareado para a cor e os componentes químicos (p<0,05). A fluorescência diminuiu significativamente nos espécimes de dentina após o clareamento. O esmalte apresentou fluorescência mais baixa do que a dentina na leitura inicial, mas esse parâmetro não diminuiu após o clareamento. Foram observadas alterações de cor para ambos os substratos, com significativamente maior efeito de clareamento em dentina (AE=10,37) (p<0,001). O clareamento com peróxido de hidrogênio provocou diminuição significativa na fluorescência da dentina e promoveu alterações de cor significativas na dentina e esmalte com resultados mais pronunciados em dentina.

Abstract: The aim of this study was to evaluate the effect of hydrogen peroxide whitening on fluorescence and color of bovine enamel and dentin. Twenty five dentin discs and 25 enamel discs, with 6 mm diameter and 1 mm thick, were obtained. Direct fluorescence (spectrofluorophotometry) and color (spectrophotometry) were assessed. After fluorescence and color baseline measurements, specimens were immersed in a 35% hydrogen peroxide (HP) solution for 1 h. This procedure was repeated after 7 days. Final fluorescence and color measurements were performed after the second immersion. Chemical characterization of 5 additional specimens was also performed. Data were submitted to repeated analysis of variance and Tukey´s test for fluorescence and unpaired t-test for color and chemical components (p<0.05). Fluorescence decreased significantly in dentin specimens after whitening. Enamel presented lower fluorescence than dentin at baseline, but this parameter did not decrease after whitening. Color changes were observed for both substrates, with significantly greater whitening effect in dentin (ΔE=10.37) (p<0.001). Whitening by hydrogen peroxide induced significant decrease in fluorescence of tooth dentin and promoted significant color changes in dentin and enamel with more accentuated outcomes in dentin.

Introdução Os cimentos de ionômero de vidro (CIV) são materiais com baixa resistência à tração e ao cisalhamento, mostrando-se, portanto, contraindicados para áreas sujeitas às grandes cargas oclusais. Objetivo Avaliar o efeito da incorporação de nanotubos de carbono em CIV por meio de dureza superficial Knoop. Material e método Foram confeccionados 48 espécimes, divididos em quatro grupos, de acordo com o tipo de CIV (n=12) – convencional ou de alta viscosidade, incorporados ou não de nanotubos de carbono (NC) a 2%: (A) Vidrion R; (B) Vidrion R + NC 2%; (C) Vitro Molar, e (D) Vitro Molar + NC 2%. Os espécimes foram preparados utilizando-se seringa Centrix, para inserção do material em moldes plásticos, e armazenados em água deionizada por 24 horas. Após polimento, realizou-se o teste de dureza superficial com penetrador do tipo Knoop. Foram realizadas cinco endentações em cada espécime, distanciadas entre si em 100 µm. Resultado Os valores médios de dureza foram 58,96 ± 8,29 (A), 34,81 ± 5,78 (B), 60,84 ± 4,91 (C) e 41,97 ± 5,45 (D). O teste ANOVA detectou diferenças estatisticamente significantes para os dois parâmetros estudados, tipo de material (p=0,016) e inclusão de NC (p<0,0001). Pelo teste de Tukey, observou-se que os grupos A e C foram estatisticamente semelhantes (p>0,05), enquanto os grupos B e D apresentaram diferenças significativas (p<0,05). Ao comparar o fator incorporação ou não de NC, observou-se diferença significativa entre os grupos A e B, e entre os grupos C e D (p<0,05). Conclusão A incorporação de nanotubos de carbono influenciou negativamente os valores de dureza superficial para os dois tipos de CIV utilizados.

Introduction Glass ionomer cements (GIC) are materials with low tensile and shear bond strength and therefore contraindicated in areas subjected to high occlusal stress loads. Aim To evaluate the effect of incorporation of carbon nanotubes in GICs, conventional or indicated for the Atraumatic Restorative Treatment (ART), through the superficial microhardness test. Material and method Forty-eight specimens were prepared and divided into 4 groups according to the type of GIC (n=12): conventional or high viscosity, embedded or not with 2% carbon nanotubes (CN): (A) Vidrion R, (B) Vidrion R + 2% CN, (C) Vitro Molar and (D) Vitro Molar + 2% CN. The specimens were inserted into plastic molds with Centrix syringe and stored in deionized water for 24 hours. After polishing, the superficial hardness was performed with a Knoop indenter. Five indentations were made on each specimen, with distance of 100 micrometers between indentations. Result The average hardness values were 58.96 ± 8.29 (A) 34.81 ± 5.78 (B) 4.91 ± 60.84 (C) 41.97 ± 5.45 (D). ANOVA detected significant difference for the two varibales, material (p=0,016) and CN inclusion (p<0,0001). Tukey test revealed that the groups A and C were statistically similar (p>0.05), while the B and D groups showed significant differences (p<0.05). When comparing the incorporation or not of factor CN, there was significant difference between groups A and B and between C and D groups (p<0.05). Conclusion The incorporation of CNTs negatively influenced the values of surface hardness for the two types of GIC used.