Does the combination of whitening toothpaste and hydrogen peroxide bleaching increase the surface roughness and change the morphology of a nanofilled composite?

Aim: To evaluate changes in the surface roughness and morphology of a nanofilled composite following toothbrushing with a whitening (WT) or regular toothpaste (RT), alone or combined with 35% hydrogen peroxide bleaching (HP). Methods: Seventy disc-shaped nanofilled composite (Filtek Z350XT) specimens were randomly divided into groups (n=10): WT, RT, TB (without toothpaste ­ control) or the combinations WT/ HP, RT/HP, TB/HP and HP. All groups underwent toothbrushing simulation (60,000 cycles) and bleaching treatment (4 sessions). Mean surface roughness (Ra, µm) was measured before (T0) and after treatments (TB). Surface morphology was assessed by scanning electron microscopy (SEM) at TB. Mean Ra was analyzed using general mixed models and multiple comparisons by the Tukey-Kramer test (α=5%). Results: HP caused no surface roughness changes on the nanofilled composite after treatment (p>0.05). RT toothbrushing, combined or not with HP, increased the surface roughness (p<0.05). WT and WT/ HP protocols had no effect on the surface roughness of the composite (p>0.05). The nanofilled composite submitted to RT toothbrushing combined with HP (RT/HP) presented substantial surface alterations under SEM, showing deep depressions and round-shaped defects. Toothbrushing with RT combined with the bleaching agent increased exposure of the inorganic fillers. Conclusion: WT toothbrushing, regardless of HP combination, or the single HP protocol had no effect on the surface roughness of the nanofilled composite. However, RT combined with HP negatively affected surface roughness and presented the most noticeable surface changes among groups

Stability of dentin matrix treated with caffeic acid phenethyl ester at different concentrations

Aim: The aim of this study was to investigate the impact of pretreatment with ethanolic solutions of caffeic acid phenethyl ester (CAPE) at varying concentrations on the dentin collagen matrix, specifically focusing on its biomodification potential. This was assessed through evaluations of the modulus of elasticity and changes in mass. Methods: Seventy dentin collagen matrices (demineralized sticks) were prepared to receive treatments with ethanolic solutions of CAPE at concentrations of 0.05%, 0.1%, 0.5%, or 2.5%, or with control treatment solutions (distilled water or ethanol) for one hour. The dentin matrices were evaluated for modulus of elasticity and mass before (baseline), immediately after treatment (immediately), and after storage in Simulated Body Fluid (SBF) for time intervals of 1 and 3 months. Results: Generalized linear models for repeated measures over time indicated no significant differences between groups (p=0.7530) or between different time points (p=0.4780) in terms of the modulus of elasticity. Regarding mass variation, no differences were observed in the time interval between 1 month and the immediate time (p=0.0935). However, at the 3-month mark compared to the immediate time, the 0.1% CAPE group exhibited less mass loss compared to the water group (p=0.0134). Conclusion: This study concludes that various concentrations of CAPE in an ethanolic solution did not affect the modulus of elasticity of dentin, suggesting that CAPE lacks biomodifying potential in this context. However, it was observed that 0.1% CAPE positively influenced the variation in mass over different evaluation time intervals

Physicochemical evaluation of hydrogen peroxide bleaching gels containing titanium dioxide catalytic agent, and their influence on dental color change associated with violet LED.

BACKGROUND: The purpose of this study was: 1) to analyze the physical-chemical properties of hydrogen peroxide (HP) agents at 7.5% (HP7) and 35% (HP35), and the association with or without TiO2 nanotubes; 2) to evaluate dental bleaching effectiveness by using HP7 and HP35 together with or without TiO2 nanotubes, and applied with or without violet LED (VL). METHODOLOGY: 80 bovine incisors were treated according to groups (n = 10): HP35; HP35 + VL; HP35T (HP35 + TiO2); HP35T + VL; HP7; HP7 + VL; HP7T (HP7 + TiO2); HP7T + VL. Bleaching effectiveness was measured at 4 time points according to the Vita Classical, CIEL*a*b*, CIEDE2000, and WID parameters. HP35, HP35T, HP7, and HP7T were evaluated for mass change, pH, mean particle size (P), polydispersity (PDI), and zeta potential (ZP), over 6 months of storage. RESULTS: The pH of HP35 thickener was higher when associated to TiO2. At baseline, both of the bleaching gels containing TiO2 had lower P, PDI, and PZ (p < 0.05). All groups showed a significant decrease in Vita Classical color scores (p = 0.0037). There was a higher L* value, and lower b* values for HP7 when associated to VL after the 3rd session. (p < 0.05). HP35T showed higher color change (ΔEab, ΔE00), and lower a* value in the presence of VL (p < 0.05). ΔWID presented lower values for both gels, when TiO2 was incorporated (p ≤ 0.05). CONCLUSION: The incorporation of TiO2 to the bleaching gel showed good stability with minimal variations in physical-chemical properties. The color change in HP35 was more effective than in HP7, but the VL boosted the bleaching effectiveness of HP7, whereas TiO2 did not increase bleaching effectiveness.

Dentin permeability after pretreatment with titanium tetrafluoride and self-etching or universal adhesive systems

Aim: To evaluate dentin permeability after pretreatment with 2.5% aqueous solution of titanium tetrafluoride (TiF4), followed by a self-etching universal adhesive system. Methods: Forty dentin discs (1.5 mm thick) were randomly divided into groups according to the application or non-application of a pretreatment, and the type of adhesive system to be tested (two-step self-etching/ Clearfil SE Bond/ Kuraray Medical, or universal adhesive system/ Single Bond Universal/ 3M ESPE). Both sides of the discs were conditioned with 37% phosphoric acid to remove the smear layer. The first hydraulic conductivity measurement (L1) was performed in a permeability machine, under 5 PSI pressure. The samples were sanded again to form a standardized smear layer. The teeth designated for pre-treatment with TiF4 received the TiF4 solutions applied actively for 60 seconds, and the adhesive systems were applied according to the manufacturer's instructions. Then, a new hydraulic conductivity measurement (L2) was performed for the purpose of calculating the hydraulic conductance at a later time, considering the water viscosity and the thickness of the specimen. The percentage (L) of dentin permeability after application of the adhesive system was obtained (L (%) = [(L1-L2) x100] / L1). The Mann-Whitney non-parametric test was applied. Results: There was no difference between the two adhesive systems, or between the groups with or without pretreatment, as regards dentin permeability (p>0.05). Conclusion: Pretreatment with 2.5% TiF4 did not influence dentin permeability, irrespective of the adhesive system used

Antifungal analysis of incorporation of the essential oil of Cymbopogon citratus (D.C.) Stapf into polymethyl methacrylate / Análise antifúngica da incorporação do óleo essencial de Cymbopogon citratus (d.c.) Stapf em polimetacrilato de metila

ABSTRACT Objective: Evaluated the antifungal effect of the incorporation of different concentrations of the essential oil Cymbopogon citratus (capim santo), into polymethylmethacrylate (PMMA) against Candida albicans. Methods: Fifty specimens were fabricated and divided into five groups: Group 1, PMMA + 10% essential oil (n=10); Group 2, PMMA + 15% essential oil (n=10); Group 3, PMMA + 20% essential oil (n=10); Group 4, PMMA + 25% essential oil (n=10); Group 5, PMMA (n=10). PMMA powder was mixed with the monomer and the mixture was placed in disc-shaped cavities measuring 15 mm in diameter, 2 mm thick. To evaluate the antifungal activity of the experimental specimens, the standard strain of Candida albicans was tested. After incubation, the colony count of each plate was performed using a digital colony counter, obtaining the number of colony forming units (CFU) and the Kruskal-Wallis test was applied. Results: There was statistically significant difference in the CFU count of Candida albicans as a consequence of the addition of Cymbopogon citratus essential oil to PMMA (p < 0.001) and values were significantly higher in comparison with those of all the other groups, when the essential oil was incorporated as incorporated into the PMMA in the concentration of 20%. In the other concentrations, no difference in values was observed in comparison with the Control Group without essential oil of Cymbopogon citratus. Conclusion: The acrylic resin with the essential oil incorporated into it in different concentrations provided no effect against development of the genus Candida.

RESUMO Objetivo: Avaliar o efeito antifúngico da incorporação de diferentes concentrações do óleo essencial Cymbopogon citratus (capim santo), em polimetilmetacrilato (PMMA) contra Candida albicans. Métodos: Cinquenta corpos de prova foram confeccionados e divididos em cinco grupos: Grupo 1, PMMA + 10% de óleo essencial (n=10); Grupo 2, PMMA + 15% de óleo essencial (n=10); Grupo 3, PMMA + 20% de óleo essencial (n=10); Grupo 4, PMMA + 25% de óleo essencial (n=10); Grupo 5, PMMA (n=10). O pó de PMMA foi misturado ao monômero e a mistura foi colocada em cavidades em forma de disco medindo 15 mm de diâmetro por 2 mm de espessura. Para avaliar a atividade antifúngica dos espécimes experimentais, foi testada a cepa padrão de Candida albicans. Após a incubação, foi realizada a contagem de colônias de cada placa por meio de um contador digital de colônias, obtendo-se o número de unidades formadoras de colônias (UFC) e para isso foi aplicado o teste de Kruskal-Wallis. Resultados: Houve diferença estatisticamente significativa na contagem de UFC de Candida albicans como consequência da adição do óleo essencial de Cymbopogon citratus ao PMMA (p < 0,001) e os valores foram significativamente maiores em comparação com todos os outros grupos, quando o essencial óleo foi incorporado como incorporado ao PMMA na concentração de 20%. Nas demais concentrações, não houve diferença nos valores em relação ao Grupo Controle sem óleo essencial de Cymbopogon citratus. Conclusão: A resina acrílica com o óleo essencial incorporado a ela em diferentes concentrações não apresentou efeito contra o desenvolvimento do gênero Candida.

Effect of thermocycling on internal microhardness of high and low viscosity bulk fill composite resins in class I cavities / Efeito da termociclagem na microdureza interna de resinas compostas bulk fill de alta e baixa viscosidade aplicadas em cavidades classe I

ABSTRACT Objective: To evaluate the effect of thermocycling on the Knoop internal microhardness of high- and low viscosity bulk fill resins applied in Class I cavities. Methods: Thirty third molars with Class I cavity preparations were randomly divided into 3 groups according to the restorative system: nanoparticulated composite resin (Filtek™ Z350 XT 3M ESPE) (oblique increments of 2mm); low viscosity bulk fill resin (Filtek™ Bulk fill Flow, 3M ESPE) (3mm increments covered with a 1-mm layer of nanoparticulated resin); high viscosity bulk fill resin (Filtek™ Bulk fill, 3M ESPE) (single 4-mm increment). After 24h, half of samples was submitted to thermocycling (1,000 cycles). All samples (n=5) were sectioned in half to measure the internal microhardness at bottom and top of restoration. Results: Analysis of variance indicated that, for nanoparticulated composite resin, without thermocycling, the microhardness at the top was statistically lower than at the bottom. After thermocycling, there was no difference in microhardness between the top and the bottom. For low viscosity bulk fill resin, without thermocycling, there was no significant difference in microhardness means between the top and the bottom. After thermocycling, significantly higher microhardness was found at the top than at the bottom (p <0.05). For high viscosity bulk fill resin there was no significant difference between the microhardness values at the top and bottom, regardless of thermocycling (p> 0.05). In all composite resins, an increase in microhardness was observed after thermocycling (p <0.05). Conclusion: Thermocycling increased the internal microhardness of resin restorations, and, for the low viscosity bulk fill resin, the microhardness at the top was higher than at the bottom after thermocycling.

RESUMO Objetivo: Avaliar o efeito da termociclagem na microdureza Knoop interna de resinas bulk fill de alta e baixa viscosidade aplicadas em cavidades classe I. Métodos: Trinta terceiros molares com cavidades Classe I foram divididos aleatoriamente em três grupos de acordo com o sistema restaurador: Resina composta nanoparticulada (Filtek™ Z350 XT 3M ESPE) (incrementos oblíquos de 2mm); resina bulk fill de baixa viscosidade (Filtek™ Bulk fill Flow, 3M ESPE) (incremento de 3mm mais 1mm de resina nanoparticulada); resina bulk fill de alta viscosidade (Filtek ™ Bulk fill, 3M ESPE) (único incremento de 4mm). Após 24h, metade das amostras foi submetida a termociclagem (1.000 ciclos). Todas as amostras (n=5) foram seccionadas ao meio para mensuração da microdureza interna na base e topo da restauração. Resultados: Análise de variância indicou que, para a resina composta nanoparticulada e antes da termociclagem, a microdureza no topo foi estatisticamente inferior do que na base (p<0,05). Após a termociclagem, não houve diferença entre topo e base. Já para a resina bulk fill de baixa viscosidade, antes da termociclagem, não se constatou diferença significativa nos valores de microdureza entre topo e base. Após termociclagem, valores significativamente mais elevados de microdureza foram encontrados no topo do que na base (p<0,05). Para resina bulk fill de alta viscosidade, não houve diferença significativa na microdureza entre topo e base, realizando-se ou não termociclagem (p>0,05). Em todas as resinas compostas foi verificado aumento de microdureza após termociclagem (p<0,05). Conclusão: A termociclagem aumentou a microdureza para todas as resinas compostas, sendo que para a resina bulk fill de baixa viscosidade a microdureza no topo foi maior do que na base após termociclagem.

Influence of restorative materials on occlusal and internal adaptation of CAD-CAM inlays

Aim: To evaluate the occlusal and internal marginal adaptation of inlay restorations made of different materials, using CAD-CAM. Methods: Preparations were made for MOD inlays of one-third intercuspal width and 4 mm depth in 30 third human molars. The teeth were restored using CAD-CAM materials (n=10) of nanoceramic resin (Lava Ultimate), polymer-infiltrated ceramic network (VITA ENAMIC), or lithium disilicate glass-ceramic (IPS e.max CAD). The specimens were cemented with dual resin cement and sectioned at the center of the restoration, after which the two halves were evaluated, and photographed The occlusal and internal discrepancy (µm) was determined at five points: cavosurface angle of the occlusal-facial wall (CA-O); center of the facial wall (FW); faciopulpal angle (FPA); center of the pulpal wall (PW); and center of the lingual wall (LW). The data were submitted to the Kruskal-Wallis and the Dunn tests (α=0.05). Results: No difference was observed among the materials regarding the occlusal discrepancy at the CA-O, FPA, or PW internal points. The e.max CAD measurement at FW showed larger internal discrepancy than that of Lava (p=0.02). The internal discrepancy at LW was greater for e.max CAD than VITA ENAMIC (p=0.02). Conclusion: Lithium disilicate glass-ceramic presented greater internal discrepancy in relation to the surrounding walls of the inlay preparations

Effect of different polishing systems and staining solution on surface roughness and color stability of bulk fill resin composites.

PURPOSE: To evaluate the effect of polishing systems (discs or rubbers) on surface roughness (Ra) and color change (ΔE) of two bulk fill and one conventional resin composite after immersion in a dye solution. METHODS: 180 samples (10 mm x 2 mm) were separated into three groups: (1) Resin composite: Filtek One Bulk Fill (FO), Tetric N-Ceram Bulk Fill (TNC), Filtek Z350 XT (FXT) (n= 60); (2) polishing system: unpolished (control); aluminum oxide discs (Sof-Lex, AOD); cup-shaped abrasive rubber polishers (Astropol, CSA) (n= 20), and (3) immersion solutions: coffee or distilled water (n= 10). Immersion was under 5 mL of each solution for 3 hours daily, for 30 days. Measurement of Ra and ∆E was made considering two times: initial (after polishing) and final (after immersion), in addition to surface analysis by scanning electron microscopy at the end. Kruskal-Wallis, Mann-Whitney, and Dunn (α= 0.05) was used. RESULTS: For the unpolished samples after immersion in coffee, TNC (P= 0.007) showed lower ΔE than FXT and FO. For polished samples with CSA and immersed in coffee, TNC followed by FXT showed lower ΔE than in the absence of polishing. Polishing with AOD and immersed in coffee: FO had smaller ΔE than when not polished. For Ra, TNC and FO had lower values after using AOD, whereas for FXT lower Ra was noted with CSA. CLINICAL SIGNIFICANCE: The roughness and color stability of resin composites are mediated by the polished material, polishing system and dye solution. The best results were found for Tetric N-Ceram polished with aluminum oxide discs.

Effect of acid challenge and photoactivation distance on microhardness and roughness of flow bulk-fill composite resins / Efeito do desafio ácido e distância de fotoativação na microdureza e rugosidade de resinas compostas bulk-fill flow

Abstract Introduction composite resins are indicated to the reconstruction of proximal walls and the evaluation of properties of flow bulk-fill composite resins exposed to acid challenge is necessary. Objective to evaluate the microhardness and roughness at different depths of photoactivation of bulk-fill flow composites (Filtek Bulk Fill Flow; SureFil SDR Flow; Tetric N Ceram Bulk fill) and conventional composite resin (control, Filtek Z350 XT) subjected to acid challenge. Material and method forty composites brick shaped specimens (3x3x4 mm) were made using a polyacetal matrix. To simulate pH challenges, the samples were immersed in a demineralizing solution. Each sample had Knoop microhardness (KHN) and roughness (Ra) evaluated at three depths (superficial, medium, and cervical), considering the lateral surface of the sample. Data were submitted to Kruskal-Wallis, Friedman's and Dunn's tests with a significance level of 5%. Result comparing the composites among themselves, in superficial (p=0.693), medium (p=0.053) and cervical (p=0.176) regions, there was no difference in the KHN values. There were also no differences in roughness between the composites in superficial (p=0.356), medium (p=0.734) and cervical (p=0.207) regions. Only the Filtek Z350 XT (p=0.027) showed less difference in KHN in the middle region caused by acid challenge. Changes in roughness showed that the greatest difference was at the cervical region for Bulk Fill Flow SDR (p=0.014) and Tetric N-Ceram Bulk Fill (p = 0.003) with an increase after acid challenge. Conclusion after acid challenge, bulk-fill flow composites showed alterations similar to those presented by the conventional nanoparticulate resin composite.

Resumo Introdução as resinas compostas são indicadas para reconstrução de paredes proximais e a avaliação das propriedades das resinas compostas bulk-fill flow expostas ao desafio ácido mostra-se necessária. Objetivo avaliar a microdureza e rugosidade em diferentes profundidades de fotoativação de resinas compostas bulk-fill flow (Filtek Bulk Fill Flow; SureFil SDR Flow; Tetric N Ceram Bulk fill) e convencional (controle, Filtek Z350 XT) submetidas ao desafio ácido. Material e método quarenta amostras retangulares (3x3x4 mm) foram confeccionadas utilizando uma matriz de poliacetal. Para simular o desafio ácido, as amostras foram imersas em uma solução desmineralizante. Cada amostra teve a microdureza Knoop (KHN) e rugosidade (Ra) avaliadas em três profundidades (superficial, média e cervical), considerando a superfície lateral da amostra. Os dados foram submetidos aos testes de Kruskal-Wallis, Friedman e Dunn com nível de significância de 5%. Resultado comparando as resinas compostas entre si, nas regiões superficial (p=0,693), média (p=0,053) e cervical (p=0,176), não houve diferença nos valores de KHN. Também não houve diferenças na rugosidade entre os materiais nas regiões superficial (p=0,356), média (p=0,734) e cervical (p=0,207). Apenas o Filtek Z350 XT (p=0,027) apresentou menor diferença de KHN na região intermediária causada pelo desafio ácido. As mudanças na rugosidade mostraram que a maior diferença foi na região cervical para Bulk Fill Flow SDR (p=0,014) e Tetric N-Ceram Bulk Fill (p=0,003), com aumento após o desafio ácido. Conclusão após desafio ácido, as resinas compostas bulk-fill flow apresentaram alterações semelhantes às apresentadas pela resina composta convencional nanoparticulada.

Influence of calcium lactate and sodium fluoride solution mouthwashes on enamel microhardness and dentin permeability during in-office bleaching / Influência das soluções enxaguatórias de lactato de cálcio e fluoreto de sódio na microdureza do esmalte e permeabilidade dentinária durante o clareamento em consultório

Objective: This study evaluated the influence of calcium lactate and sodium fluoride mouthwashes on enamel microhardness and dentin permeability during in-office bleaching. Material and Methods: For the microhardness evaluation, enamel blocks were randomly submitted to different treatments associated with in-office bleaching agent using 40% hydrogen peroxide (Opalescence Boost PF 40%/ Ultradent; 3 sessions x 40-minute each) (n = 10): 1) Control: application of bleaching agent; 2) Calcium lactate: 1-minute immersion before bleaching treatment; 3) Sodium fluoride: immersion for 1 minute before bleaching treatment; 4) Calcium lactate + sodium fluoride: 1 minute immersion in calcium lactate solution, followed by 1 minute immersion in sodium fluoride before bleaching treatment. Dentin discs received the same treatment protocols (n = 10) to evaluate permeability. Knoop microhardness and dentin permeability assessments were performed twice (at baseline and 48 hours after the end of bleaching treatment). Results: The generalized linear model considering the design of repeated measures over time showed that there was no significant difference between treatments (p = 0.9577) and between assessments (p = 0.3267) regarding Knoop microhardness. Kruskal Wallis and Dunn tests showed that calcium lactate immersion before bleaching treatment provided higher dentin permeability than other groups (p = 0.0009). Conclusion: The use of sodium fluoride solution and calcium lactate in association with in-office bleaching treatment did not influence the microhardness of tooth enamel, although calcium lactate may increase dentin permeability. (AU)

Objetivo: Este estudo avaliou a influência dos enxaguatórios bucais com lactato de cálcio e fluoreto de sódio na microdureza do esmalte e na permeabilidade da dentina durante o clareamento em consultório. Material e Métodos: Para avaliação da microdureza, blocos de esmalte foram submetidos aleatoriamente a diferentes tratamentos associados a agente clareador em consultório com peróxido de hidrogênio 40% (Opalescence Boost PF 40% / Ultradent; 3 sessões x 40 minutos cada) (n = 10): 1) Controle: aplicação de agente clareador; 2) Lactato de cálcio: imersão de 1 minuto antes do tratamento clareador; 3) Fluoreto de sódio: imersão por 1 minuto antes do tratamento clareador; 4) Lactato de cálcio + fluoreto de sódio: 1 minuto de imersão em solução de lactato de cálcio, seguido de 1 minuto de imersão em fluoreto de sódio antes do tratamento clareador. Os discos de dentina receberam os mesmos protocolos de tratamento (n = 10) para avaliar a permeabilidade. As avaliações da microdureza Knoop e da permeabilidade dentinária foram realizadas duas vezes (no início do estudo e 48 horas após o término do tratamento clareador). Resultados: O modelo linear generalizado considerando o delineamento de medidas repetidas ao longo do tempo mostrou que não houve diferença significativa entre os tratamentos (p = 0,9577) e entre as avaliações (p = 0,3267) em relação à microdureza Knoop. Os testes de Kruskal Wallis e Dunn mostraram que a imersão de lactato de cálcio antes do tratamento clareador proporcionou maior permeabilidade dentinária do que os outros grupos (p = 0,0009). Conclusão: O uso de fluoreto de sódio e lactato de cálcio associado ao clareamento em consultório não influenciou a microdureza do esmalte dentário, embora o lactato de cálcio possa aumentar a permeabilidade dentinária (AU)

Effect of different concentrations of green tea extract solutions on bonding durability of etchand- rinse adhesive system to caries affected dentin

Aim: The in vitro study evaluated the effect of different concentrations of green tea extract solution (GT) on the bonding durability of etch-and-rinse adhesive system to caries dentin affected (CAD). Methods: Dentinal surfaces of human third molars were polished and submitted to a microbiological caries induction protocol for 14 days. After removal of the infected dentin layer, the samples were randomly divided into 4 groups (n= 10), according to the concentration of GT solution applied in CAD, after acid etching: 0.05%; 0.2%; 2% and NT (no treatment ­ control). After application of a etch-and-rinse adhesive system (Adper Single Bond 2, 3M ESPE), composite resin restorations were performed on the dentin. After 24 hours, the resin-dentin blocks were sectioned 1mm2 specimens, which were subjected to the microtensile test immediately or after 6 months of storage in water. Data were submitted to two-way ANOVA for randomized blocks and Tukey test (α= 5%). Results: There was no effect of double interaction (p= 0.934). The application of 0.2% GT promoted a statistically significant increase in dentin bond strength values in comparison to the condition where GT was not used (p=0.012). There was a significant decrease of bond strength after 6 months of storage, regardless of dentin pretreatment (p = 0.007). The G test identified that there was no statistical difference regarding failure mode (p= 0.326). Conclusion: The concentration of 0.2% improved the bond strength of an etch-and-rinse adhesive system to caries affected dentin, however, none of dentin pretreatments could prevent the decrease in bond strength over time

Color stability of a bulk-fill composite resin light-cured at different distances.

The aim of this in vitro study was to evaluate the color stability of a bulk-fill (Filtek One Bulk Fill, 3M ESPE) and a conventional (Filtek Z350 XT, 3M ESPE) composite resin light-cured at different distances, before and after being submitted to staining with a coffee solution. Sixty specimens of each composite resin were prepared and light-cured at distances of 0, 2 and 4 mm, using a LED light-curing unit (Valo, Ultradent). The specimens were separated (n = 10) for immersion in either distilled water or coffee solution (10 minutes a day for 8 days) to stimulate staining. Color evaluations were performed before and after immersion in the solutions, according to CIELab (△Eab), CIEDE2000 (△E00) and the Whiteness Index for Dentistry (△WID). Kruskal Wallis and Dunn tests, Mann-Whitney tests and Wilcoxon test were applied (α = 5 %). The a* value for conventional composite resin showed a significant increase after immersion in coffee and distilled water (p < 0.05). Both composite resins showed greater b* values when immersed in coffee than in distilled water, with no significant difference among the light-activation distances (p > 0.05). There was no significant difference for L* among the light-activation distances; both resins showed significant decrease in L* after immersion in coffee (p < 0.05). Color change (△Eab, △E00) and difference in whiteness (△WID) were higher for conventional resin when immersed in the coffee solution at all the light-activation distances. Conventional composite resin presented a higher staining value than bulk-fill composite resin, regardless of the light-activation distance.

Titanium dioxide nanotubes incorporated into bleaching agents: physicochemical characterization and enamel color change.

OBJECTIVE: Titanium dioxide nanotubes are nanostructures that can accelerate the oxidation reaction of bleaching procedures and promote a more effective whitening effect. This study evaluated physicochemical properties of bleaching agents incorporated with titanium dioxide (TiO2) nanotubes, and the effects on tooth color change at different periods. METHODOLOGY: 40 premolars were treated according to the following groups (n=10): CP - 10% carbamide peroxide (1 hour daily/21 days); CPN - CP incorporated into TiO2; HP - 40% hydrogen peroxide (three 40-minute sessions/7 days apart); HPN - HP incorporated into TiO2. Color shade was evaluated at five different periods (baseline, after 7, 14 and 21 days of bleaching, and 7 days after end of treatment) according to Vita Classical, CIELab and CIEDE2000 scales. Mean particle size (P), polydispersity (PO) and zeta potential (ZP) were evaluated using dynamic light scattering. Data on the different variables were analyzed by mixed model tests for measures repeated in time (ZP e L*), generalized linear models for measures repeated in time (P, PO, Vita Classical and b*), and Friedman and Mann-Whitney tests (a* and color change/ΔE and ΔE00). RESULTS: CP and CPN presented higher P, higher PO and lower ZP than HP and HPN (p≤0.05). All groups showed a significant decrease in Vita Classical color scores after 7 days of bleaching (p<0.05), and HPN presented a greater significant reduction than the other groups. L* increased in TiO2 presence, in all groups, without any differences (p>0.05) in bleaching time. A significant reduction occurred in the a* and b* values for all the groups, and HPN presented lower a* and b* values (p<0.05) than CPN. ΔE was clinically noticeable after 7 days, in all groups, and all groups resulted in a perceptible color change according to ΔE00. CONCLUSION: TiO2 did not influence physicochemical properties of the bleaching agents. HPN presented more effective tooth bleaching than CPN.

Color stability of a bulk-fill composite resin light-cured at different distances

Abstract The aim of this in vitro study was to evaluate the color stability of a bulk-fill (Filtek One Bulk Fill, 3M ESPE) and a conventional (Filtek Z350 XT, 3M ESPE) composite resin light-cured at different distances, before and after being submitted to staining with a coffee solution. Sixty specimens of each composite resin were prepared and light-cured at distances of 0, 2 and 4 mm, using a LED light-curing unit (Valo, Ultradent). The specimens were separated (n = 10) for immersion in either distilled water or coffee solution (10 minutes a day for 8 days) to stimulate staining. Color evaluations were performed before and after immersion in the solutions, according to CIELab (△Eab), CIEDE2000 (△E00) and the Whiteness Index for Dentistry (△WID). Kruskal Wallis and Dunn tests, Mann-Whitney tests and Wilcoxon test were applied (α = 5 %). The a* value for conventional composite resin showed a significant increase after immersion in coffee and distilled water (p < 0.05). Both composite resins showed greater b* values when immersed in coffee than in distilled water, with no significant difference among the light-activation distances (p > 0.05). There was no significant difference for L* among the light-activation distances; both resins showed significant decrease in L* after immersion in coffee (p < 0.05). Color change (△Eab, △E00) and difference in whiteness (△WID) were higher for conventional resin when immersed in the coffee solution at all the light-activation distances. Conventional composite resin presented a higher staining value than bulk-fill composite resin, regardless of the light-activation distance.

Titanium dioxide nanotubes incorporated into bleaching agents: physicochemical characterization and enamel color change

Abstract Titanium dioxide nanotubes are nanostructures that can accelerate the oxidation reaction of bleaching procedures and promote a more effective whitening effect. Objective This study evaluated physicochemical properties of bleaching agents incorporated with titanium dioxide (TiO2) nanotubes, and the effects on tooth color change at different periods. Methodology 40 premolars were treated according to the following groups (n=10): CP - 10% carbamide peroxide (1 hour daily/21 days); CPN - CP incorporated into TiO2; HP - 40% hydrogen peroxide (three 40-minute sessions/7 days apart); HPN - HP incorporated into TiO2. Color shade was evaluated at five different periods (baseline, after 7, 14 and 21 days of bleaching, and 7 days after end of treatment) according to Vita Classical, CIELab and CIEDE2000 scales. Mean particle size (P), polydispersity (PO) and zeta potential (ZP) were evaluated using dynamic light scattering. Data on the different variables were analyzed by mixed model tests for measures repeated in time (ZP e L*), generalized linear models for measures repeated in time (P, PO, Vita Classical and b*), and Friedman and Mann-Whitney tests (a* and color change/ΔE and ΔE00). Results CP and CPN presented higher P, higher PO and lower ZP than HP and HPN (p≤0.05). All groups showed a significant decrease in Vita Classical color scores after 7 days of bleaching (p<0.05), and HPN presented a greater significant reduction than the other groups. L* increased in TiO2 presence, in all groups, without any differences (p>0.05) in bleaching time. A significant reduction occurred in the a* and b* values for all the groups, and HPN presented lower a* and b* values (p<0.05) than CPN. ΔE was clinically noticeable after 7 days, in all groups, and all groups resulted in a perceptible color change according to ΔE00. Conclusion TiO2 did not influence physicochemical properties of the bleaching agents. HPN presented more effective tooth bleaching than CPN.

At-home, in-office and combined dental bleaching techniques using hydrogen peroxide: Randomized clinical trial evaluation of effectiveness, clinical parameters and enamel mineral content.

PURPOSE: To conduct a clinical evaluation of dental bleaching techniques using hydrogen peroxide (HP), regarding tooth sensitivity, gingival irritation, subject's perception of color change, and calcium (Ca) and phosphorous (P) concentrations in enamel. METHODS: 75 volunteers were distributed according to the bleaching technique (n=25): (a) at-home: 10%HP (Opalescence GO) for 15 days of continuous use (1 hour per day); (b) in-office: 40%HP (Opalescence Boost) in three clinical sessions (40 minutes each session); (c) combined: one initial session with 40%HP, and the rest with 10%HP for 15 days of continuous use. Clinical evaluations and Ca and P concentration collections were obtained before, during bleaching treatment, and 15 days after conclusion of treatment. The generalized linear models were used to evaluate the data for VITA Classical scale, CIELAB, tooth sensitivity, degree of acceptability of the technique, Ca and P concentrations and to determine the ΔE variables and color change perception. Gingival irritation was analyzed by Fisher's Exact test. The total frequencies for each time interval (regardless of bleaching technique) were compared at 50% by the chi-square test. RESULTS: The in-office technique presented the lowest tooth sensitivity, but all techniques caused an increase in sensitivity over time (P< 0.0001). All techniques resulted in lower Ca and P concentrations in enamel at each time point, compared with the baseline concentrations. Calcium concentrations did not differ significantly among the treatments (P= 0.9360). Phosphorus concentration at the 8th day was higher for the in-office technique group (P< 0.05). All the bleaching techniques were effective in altering color, with ΔE values higher than 3.3, without any significant differences (P= 0.3255). Higher occurrence of gingival irritation was observed for at-home and combined techniques. The combined technique seemed to promote a color change faster than the other techniques. CLINICAL SIGNIFICANCE: All the dental bleaching techniques proved equally effective in promoting tooth color change. These techniques may reduce calcium and phosphorous content in enamel. The at-home and the combined techniques may cause greater dental sensitivity than the in-office technique, and led to a higher prevalence of gingival irritation.

Remineralizing effect of commercial fluoride varnishes on artificial enamel lesions.

The aim of this study was to evaluate soluble and insoluble fluoride concentrations in commercial varnishes, and their remineralization effect on artificial caries enamel lesions using surface and cross-sectional microhardness evaluations. Forty bovine enamel blocks were separated into four groups (n=10): control (no treatment), Enamelast (Ultradent Products), Duraphat (Colgate-Palmolive) and Clinpro White Varnish (3M ESPE). Surface enamel microhardness evaluations were obtained, artificial enamel caries lesions were developed by dynamic pH-cycling, and the varnishes were then applied every 6 days, after which the enamel blocks were submitted to dynamic remineralization by pH cycles. After removal of the varnishes, the enamel surfaces were reassessed for microhardness. The blocks were sectioned longitudinally, and cross-sectional microhardness measurements were performed at different surface depths (up to 300 µm depth). Polarized light microscopy images (PLMI) were made to analyze subsurface caries lesions. The fluoride concentration in whole (soluble and insoluble fluoride) and centrifuged (soluble fluoride) varnishes was determined using an extraction method with acetone. The data were analyzed to evaluate the surface microhardness, making adjustments for generalized linear models. There was a significant decrease in enamel surface microhardness after performing all the treatments (p<0.0001). Enamelast and Duraphat showed significantly higher enamel microhardness values than the control and the Clinpro groups (p = 0.0002). Microhardness loss percentage was significantly lower for Enamelast (p = 0.071; One-way ANOVA). PLMI showed that subsurface caries lesions were not remineralized with the varnish treatments. No significant differences in the in-depth microhardness levels (p = 0.7536; ANOVA) were observed among the treatments. Enamelast presented higher soluble and insoluble fluoride concentrations than the other varnishes (p < 0.0001; Kruskal-Wallis and Dunn tests). Enamelast and Duraphat varnishes promoted enamel surface remineralization, but no varnish remineralized the subsurface lesion body. Although insoluble and soluble fluoride concentration values did not correspond to those declared by the manufacturer, Enamelast presented higher fluoride concentration than the others.

The effect of heat treatment on sliding mechanics of stainless steel orthodontic wires

Aim: The aim of this study was to evaluate the effect of heat treatment (tempering) on the sliding mechanics of stainless steel Chrome Nickel (CrNi) orthodontic wires. Methods: A universal testing machine EMIC DL 2000 was used at a speed of 10 mm/minute for reading-out the sliding strength and friction between brackets and wires, by simulating the sliding mechanics in a fixed orthodontic appliance. The results were submitted to ANOVA variance test for statistical analysis at the level of 5% (p<0.05). Results: The results indicated that depending on the type of bracket, wire and type of treatment, the groups without heat treatment showed higher mean static friction values, except for groups with CrNi GAC wire and conventional brackets, which showed no significant difference with and without heat treatment; and the group with self-ligated brackets and CrNi GAC wires that showed the lowest mean static friction values with heat treatment. Conclusion: The heat treatment reduced the static friction values on CrNi Morelli wires for any combination of brackets (conventional and self-ligated types) and commercial brands. For the CrNi GAC wires, there was a reduction in friction values only in the combination with In-Ovation R/GAC self-ligated brackets

Do metal alloy primers increase the bond strength of orthodontic tubes?

Aim: To evaluate the bond strength (BS) and failure mode of orthodontic tubes treated with different alloy primers at the interface among enamel, resin and orthodontic tubes. Methods: Orthodontic tubes were bonded to the enamel of 80 bovine incisors with the orthodontic resin (Transbond XT, 3M Unitek). Prior to bonding, the tubes were chemically treated with (n=20) Metal/Zirconia Primer (MZ, Ivoclar), Scothbond Universal (SB, 3M Espe); Orthoprimer (OP, Morelli) or left untreated (Control - C). Specimens were submitted to 5,000 thermal cycles (5 and 55o C) to age the bonded interface. A shear BS test and failure modes were conducted, and the results were analyzed using one-way analysis of variance and Fisher's exact test, respectively. Results: No differences were observed among groups regardless of the type of alloy primer used (p = 0.254). However, no differences were observed among the failure modes of the groups tested (p=0.694). The adhesive failure mode between the resin and enamel was the most prevalent failure (45%) for groups OP and C, whereas cohesive failure in the orthodontic resin was the most prevalent failure (40%) for groups SB and MZ. Conclusion: Alloy primers were unable to increase the BS of the orthodontic tubes to enamel

Remineralizing effect of commercial fluoride varnishes on artificial enamel lesions

Abstract: The aim of this study was to evaluate soluble and insoluble fluoride concentrations in commercial varnishes, and their remineralization effect on artificial caries enamel lesions using surface and cross-sectional microhardness evaluations. Forty bovine enamel blocks were separated into four groups (n=10): control (no treatment), Enamelast (Ultradent Products), Duraphat (Colgate-Palmolive) and Clinpro White Varnish (3M ESPE). Surface enamel microhardness evaluations were obtained, artificial enamel caries lesions were developed by dynamic pH-cycling, and the varnishes were then applied every 6 days, after which the enamel blocks were submitted to dynamic remineralization by pH cycles. After removal of the varnishes, the enamel surfaces were reassessed for microhardness. The blocks were sectioned longitudinally, and cross-sectional microhardness measurements were performed at different surface depths (up to 300 μm depth). Polarized light microscopy images (PLMI) were made to analyze subsurface caries lesions. The fluoride concentration in whole (soluble and insoluble fluoride) and centrifuged (soluble fluoride) varnishes was determined using an extraction method with acetone. The data were analyzed to evaluate the surface microhardness, making adjustments for generalized linear models. There was a significant decrease in enamel surface microhardness after performing all the treatments (p<0.0001). Enamelast and Duraphat showed significantly higher enamel microhardness values than the control and the Clinpro groups (p = 0.0002). Microhardness loss percentage was significantly lower for Enamelast (p = 0.071; One-way ANOVA). PLMI showed that subsurface caries lesions were not remineralized with the varnish treatments. No significant differences in the in-depth microhardness levels (p = 0.7536; ANOVA) were observed among the treatments. Enamelast presented higher soluble and insoluble fluoride concentrations than the other varnishes (p < 0.0001; Kruskal-Wallis and Dunn tests). Enamelast and Duraphat varnishes promoted enamel surface remineralization, but no varnish remineralized the subsurface lesion body. Although insoluble and soluble fluoride concentration values did not correspond to those declared by the manufacturer, Enamelast presented higher fluoride concentration than the others.