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

Effect of endodontic sealers on push-out bond strength of CAD-CAM or prefabricated fiber glass posts

Abstract This study aimed to evaluate the effect of endodontic sealer (ES) on bond strength (BS) of prefabricated or milled-CAD-CAM (computer-aided design and computer-aided manufacturing) glass-fiber-posts (GFP). Canals of 90 single-rooted teeth were prepared for filling by the single-cone technique with gutta-percha and one of the following ES: AH Plus (epoxy resin), Endofill (zinc-oxide and eugenol), and Bio-C Sealer (calcium-silicate). After post-space preparation, tooth-specimens were equally divided in half according to type of GFP to be used. In the half to receive milled-CAD-CAM posts, tooth specimens were molded with acrylic resin to obtain replicas. These were scanned to enable the laboratory to produce the milled-CAD-CAM GFPs (Fiber CAD Lab, Angelus) by the subtractive technique. The other half of samples received prefabricated GFPs (Exacto, Angelus) (n=15). The GFPs were cemented with dual-cure resin cement (Panavia F2.0, Kuraray). Each root was sectioned into two slices per root region (cervical, middle, apical) that were subjected to the push-out BS test, in a universal testing machine. Failure mode (FM) was classified by scores. The BS data were submitted to generalized linear model analyses, while FM was analyzed using the chi-square test (a=0.05). BS showed no significant difference among the three ES (p > 0.05). BS was significantly higher for prefabricated (mean 10.84 MPa) versus milled-CAD-CAM GFPs (mean 6.94 MPa) (p <0.0001), irrespective of ES. The majority showed mixed failures. It could be concluded that type of ES did not affect BS of GFPs to dentin, and prefabricated-GFPs had higher bond-strength than customized-milled-CAD-CAM GFPs.

Interplay between resin cements and surface-treated Poly-Ether-Ether-Ketone (PEEK): effect of aging

Aim: This study assessed the effect of thermal aging on the interfacial strength of resin cements to surface-treated PEEK. Methods: Ninety-six PEEK blocks were allocated into 4 groups (n=24), according to following surface treatments: SB - sandblasting with aluminum oxide; SA - acid etched with 98% sulfuric acid; CA ­ coupling agent (Visio.link, Bredent) and CO - control group (untreated). Surface roughness (Ra) was measured and one cylinder (1-mm diameter and height) of Rely-X Ultimate - ULT (3M/ESPE) and another one of Panavia V5 - PAN (Kuraray) were constructed on the treated or untreated PEEK surfaces. Half of the samples of each group were thermal aged (1,000 cycles). Samples were tested at a crosshead speed of 1 mm/min in shear mode (µSBS). Ra and µSBS data were compared using one- and three-way ANOVA, respectively, and Tukey's tests. Results: SA and SB samples had the roughest surfaces, while CA the smoother (p<0.001). Thermal aging reduced µSBS regardless the surface treatment and resin cement used. There was interaction between surface treatment and resin cement (p <0.001), with ULT showing higher µSBS values than PAN. SA provided higher µSBS than SB for both resin cements, while for CA µSBS was higher (PAN) or lower than SB (ULT). Conclusion: Aging inadvertently reduces interfacial strength between PEEK and the resin cements. If ULT is the resin cement of choice, reliable interfacial strength is reached after any PEEK surface treatment. However, if PAN is going to be used only SA and CA are recommended as PEEK treatment

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

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

Diagnostic methods for stained pits and fissures caries lesions on the occlusal surface / Métodos diagnósticos para lesões de cárie com sulcos pigmentados em superfície oclusal

ABSTRACT Objective: The aim of this study was to compare methods for in vitro diagnosis of pigmented pits and fissures on the occlusal surface. Methods: Forty-one human molars and premolars extracted with pigmentation in pits and fissures were used. The teeth were evaluated with artificial illumination for classification according to ICDAS, followed by fluorescent laser evaluation. For the radiographic evaluation, the teeth were positioned to obtain interproximal images, adopting the criterion of Rodrigues et al. 2008 for diagnosis of lesions. For histological evaluation, the teeth were sectioned in the mesiodistal direction in the occlusal sulcus region and evaluated in a 20-fold stereoscopic magnifying glass, using the criterion of Ekstrand et al. (1997) for evaluation. The methods were compared with the histological evaluation, obtaining values of accuracy, sensitivity and specificity regarding the response variables "presence / absence" of enamel caries. Results: When comparing visual inspection with histological analysis, 65.85% accuracy, 40% sensitivity and 90.48% specificity were observed with false positive and negative probability of 20% and 38.71%. When comparing the fluorescent laser with the histological analysis, the accuracy was 58.54%, sensitivity 70% and specificity 47.62%. Comparing the radiographic analysis with the histological analysis, it was obtained 53.66% accuracy, sensitivity of 42.11% and specificity of 73.68%. Conclusion: The ROC curve and the Yuden index showed that visual inspection presented the best combination of sensitivity and specificity than fluorescent laser and radiographic analysis for diagnosis, which represented the best method for detecting inactive carious lesions in enamel.

RESUMO Objetivo: O objetivo deste estudo foi comparar métodos para diagnóstico in vitro de sulcos pigmentados em superfície oclusal. Métodos: Foram utilizados 41 molares e pré-molares humanos extraídos com pigmentação em sulcos e fissuras. Os dentes foram avaliados com iluminação artificial para classificação quanto ao critério ICDAS, seguida por avaliação com laser fluorescente. Para a avaliação radiográfica, os dentes foram posicionados para obtenção de imagens interproximais, adotando-se o critério de Rodrigues et al. (2008) para diagnóstico. Para avaliação histológica, os dentes foram seccionados no sentido mésio-distal na região de sulco oclusal e avaliados em lupa estereoscópica com aumento de 20 vezes, adotando-se o critério de Ekstrand et al. (1997). Os métodos foram comparados com a avaliação histológica, obtendo-se valores de acurácia, sensibilidade e especificidade quanto às variáveis de resposta "presença/ausência" de lesão de cárie em esmalte. Resultados: Ao comparar a inspeção visual com a análise histológica, observou-se acurácia de 65,85%, sensibilidade de 40% e especificidade de 90,48%. Ao comparar o laser fluorescente com a análise histológica, a acurácia foi de 58,54%, sensibilidade de 70% e especificidade de 47,62%. Na comparação da análise radiográfica com a histológica, obteve-se acurácia de 53,66%, sensibilidade de 42,11% e especificidade de 73,68%. Conclusão: A curva ROC mostrou que a inspeção visual apresentou a melhor combinação de sensibilidade e especificidade que o laser fluorescente e que a análise radiográfica para o diagnóstico, representando o melhor método para detecção de cárie em lesões com sulcos pigmentados em esmalte

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.

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

Effect antioxidants application on microshear bond strength of universal adhesive to bleached enamel / Efeito da aplicação de antioxidantes na resistência de união do adesivo universal ao esmalte clareado

Purpose: To evaluate, in vitro, the influence of antioxidants (green tea extract - GT and sodium ascorbate - SA) on microshear bond strength (µSBS) of a universal adhesive system ­ self-etching mode (UAS) to bleached enamel. Material and Methods: After obtaining 50 fragments of human dental enamel (4 mm x 4 mm), forty fragments were submitted to at-home bleaching technique using 10% carbamide peroxide (Opalescence PF, Ultradent) for two h/day, for four weeks. They were randomly divided in four groups (n = 10): GT - 10% aqueous GT solution (60 min); SA - 10% SA solution (10 min); Negative control - no antioxidant agent, immediately restored; PC1 (positive control 1) - no antioxidant agent, restored 14 days the bleaching procedure. Ten enamel fragments were assigned to PC2 group (positive control 2), in which the adhesive procedures were realized in non-bleached enamel. The UAS (Adper Single Bond Universal, 3M ESPE) was applied on enamel surface according to manufacturer's instructions and two cylinders (0.8 mm diameter) of nanoparticulate composite resin (Z350, 3M ESPE) were made on each sample. After 24 h, the cylinders were submitted to µSBS in a universal test machine (0.5 mm/min). Fracture mode was evaluated in stereomicroscope (30x magnification). SBS data, in MPa, was submitted to one-way ANOVA and fracture mode to Chi-square test (α = 0.05). Results: There was no statistical difference between the experimental groups (p = 0.545) and fracture mode (p = 0.16424). There was predominance of adhesive fracture in all groups. Conclusion: Neither the bleaching procedure nor the application of antioxidants to bleached enamel interfered in the bond strength of the tested universal adhesive system (AU)

Objetivo: Avaliar, in vitro, a influência de antioxidantes (extrato de chá verde - GT e ascorbato de sódio - SA) na resistência de união ao microcisalhamento (µSBS) de um sistema adesivo universal - modo de autocondicionamento (UAS) ao esmalte clareado. Material e Métodos: Realizou-se a obtenção de 50 fragmentos de esmalte dental humano (4 mm x 4 mm), sendo que desses, quarenta fragmentos foram submetidos à técnica de clareamento caseiro utilizando peróxido de carbamida a 10% (Opalescence PF, Ultradent) por duas horas/dia, durante quatro semanas. Eles foram divididos aleatoriamente em quatro grupos (n= 10): Expostos a GT - solução aquosa de GT a 10% (60 min); expostos a SA - solução 10% SA (10 minutos); Sem exposição ao agente antioxidante e imediatamente restaurado - (controle negativo); Sem exposição ao agente antioxidante e restaurado 14 dias após o clareamento - PC1 (controle positivo 1). Os dez fragmentos de esmalte restantes foram atribuídos ao grupo PC2 (controle positivo 2), no qual os procedimentos adesivos foram realizados em esmalte não clareado. O UAS (Adper Single Bond Universal, 3M ESPE) foi aplicado na superfície do esmalte de acordo com as instruções do fabricante e dois cilindros (0,8 mm de diâmetro) de resina composta nanoparticulada (Z350, 3M ESPE) foram feitos em cada amostra. Após 24 h, os cilindros foram submetidos ao µSBS em uma máquina de teste universal (0,5 mm/min). O modulo de fratura foi avaliado em estereomicroscópio (aumento de 30x). Os dados do SBS, em MPa, foram submetidos à ANOVA unidirecional e ao modo fratura ao teste do qui-quadrado (α = 0,05). Resultados: Não houve diferença estatística entre os grupos experimentais (p = 0,545) e modulo de fratura (p = 0,16424). Houve predomínio de fratura adesiva em todos os grupos. Conclusão: Nem o procedimento de clareamento nem a aplicação de antioxidantes no esmalte clareado interferiram na resistência de união do sistema adesivo universal testado. (AU)

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.

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.

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

Oval versus circular-shaped root canals: bond strength reached with varying post techniques

Abstract The aim of this study was to compare the bond strength (BS) of glass fiber posts (GFP) luted to oval and circular-shaped root canals rehabilitated using varying post techniques, at different intraradicular levels. Ninety 16-mm-long roots of human mandibular premolars, classified either as having oval or circular-shaped canals, were endodontically treated and prepared for restoration using one of three different post techniques (n=15): 1) single GFP; 2) resin-relined GFP; 3) main GFP associated with accessory posts. GFPs were luted with a dual polymerizing resin cement (RelyX ARC) after the canal had been treated with a 3-step etch-and-rinse adhesive system (Adper Scothbond Multipurpose). The samples were sectioned into three 1-mm-thick sections, which were differentiated by the root level (cervical, middle and apical) and tested for push-out BS. Assessment of failure mode was made under a stereomicroscope. Data were analyzed using repeated measures three-way ANOVA and Tukey's test. The root canal cross-section had a significant influence on BS (p<0.001), with the lowest values being observed in oval-shaped canals. The post technique also significantly affected the BS (p=0.018), with the resin-relined GFPs providing the highest BS values in both oval and circular-shaped canals. Irrespective of the cross-section of the root canal and post technique, there was no significant difference in BS in the cervical, middle and apical third of the root canal (p=0.084). In oval-shaped canals, the BS to intraradicular dentin at cervical, middle or apical level could be increased when the GFPs posts were relined.

Resumo O objetivo deste estudo foi comparar a resistência de união (RU) de pinos de fibra de vidro (PFV), cimentados a condutos com secção transversal ovalada ou circular reabilitados com diferentes técnicas de restauração com PFVs, em função do nível intrarradicular. Noventa raízes de pré-molares inferiores humanos, com 16 mm de altura, classificadas como possuindo canais ovais ou circulares, foram tratadas endodonticamente e preparadas para serem reabilitadas com uma das três técnicas de restauração com PFVs (n=15): 1) PFV único, 2) PFV reembasado com resina composta, e 3) PFV principal associado a pinos acessórios. Os PFVs foram cimentados com um agente resinoso de polimerização dupla (RelyX ARC), após o canal ter sido tratado com um sistema adesivo de condicionamento total de três passos (Adper Scothbond Multiuso). As amostras foram seccionadas em três fatias de 1 mm de espessura, de acordo com o nível da raiz (cervical, médio e apical)e foram submetidas ao teste de RU por push-out. A análise do modo de falha foi realizada com auxílio de um estereomicroscópio. Os dados foram analisados utilizando-se a ANOVA a três critérios para medidas repetidas e o teste de Tukey. A secção do conduto apresentou influência na RU (p<0,001), com os menores valores sendo observados nos condutos ovalados. A técnica de restauração com PFVs afetou significativamente a RU (p=0,018), tendo o PFV reembasado proporcionado os maiores valores de RU, tanto em condutos ovais quanto circulares. Independentemente da secção transversal do conduto radicular e da técnica de restauração com PFV, não houve diferença significativa na RU nos terços cervical, médio e apical (p=0,084). Nos canais de secção transversal ovalada, a RU à dentina intrarradicular nos níveis cervical, médio ou apical aumentou com o emprego de PFVs reembasados.

Sour Gummy Candies and their Effect on Salivary pH kinetics

Objective: This randomized controlled crossover clinical trial monitored the kinetics of salivary pH over time following the consumption of sour gummy candy. Material and Methods: Twenty participants underwent saliva assessment for flow, pH and buffer capacity. Following a two-arm crossover layout, the participants chewed a piece of a sour and a piece of an ordinary (control) gummy candy for 20 seconds. Participants expectorated saliva at 18 time points: immediately after ingesting the candies; then after every 15 second interval, for up to 1 minute; 30 seconds up to 4 minutes; 60 seconds up to 10 minutes; and at 15 minutes. The pH of the collected samples was measured with a pH microelectrode. The data concerning the pH measurements of the whole saliva samples collected over time following chewing of sour and ordinary gummy candies underwent repeated-measures three-way analysis of variance (ANOVA) using a significance level of 5%. Results: Repeated-measures three-way analysis of variance demonstrated a significant interaction between the type of candy and time (p<0.001). Tukey's test revealed that with the consumption of sour gummy candy, the salivary pH showed an initial marked exponential drop and remained lower than that observed with the consumption of the ordinary version for up to 120 seconds. Conclusion: The consumption of sour gummy candy induces a major, transient fall in salivary pH, which may represent a risk factor for dental erosion.

Whitening mouthwash containing hydrogen peroxide decreases enamel microhardness in vitro

Aim: To assess the effect of a mouthwash containing hydrogen peroxide (HP) on Knoop microhardness (KMH) of bovine enamel. Methods: Fifty-one enamel slabs were polished and divided into groups (n=17), according to the product used during 28 days: HP ­ mouthwash containing 1,5% of HP (4 min, once/day); CP - 10% carbamide peroxide gel (2 hours/day); AS - no treatment (kept in artificial saliva (AS). Each fragment was submitted to KMH test (three indentations/fragment, with a 50 g load for 5 sec) four times: before (baseline); during (14 and 28 days) and after (7 days immerged in AS) the bleaching treatment. The data were submitted to repeated-measures two-way ANOVA (α=0.05). Results: There was no effect of the interaction between the time and treatment factors (p=0.327). No significant effect was observed from the time factor (p = 0.054). The factor treatment showed significant effect (p =0.002). Regardless of time, the KMH of the enamel submitted to HP was lower than the value observed with the use of CP, which did not differ significantly from the control group (AS). Conclusion: Although there was a trend of decreasing enamel microhardness over time, only the mouthwash containing hydrogen peroxide had a significant effect (AU)

Resistência à tração uniaxial de copings fundidos e cimentados sobre munhões cone-morse com diferentes diâmetros e alturas / Uniaxial tensile strength of cast cemented copings for cone-morse prosthetic implant abutments with different diameters and heights

Objetivo: avaliar a resistência à tração de copings fundidos cimentados sobre pilares cone-morse com diferentes alturas e diâmetros. Material e métodos: quatro grupos (G1: 3,5 mm x 4 mm; G2: 3,5 mm x 6 mm; G3: 4,5 mm x 4 mm; e G4: 4,5 mm x 6 mm) com cinco amostras cada tiveram seus copings encerados, fundidos (liga de Ni-Cr) e cimentados (Panavia F, carga de 6 Kfg durante cinco minutos) sobre os respectivos pilares já torqueados com 25 Ncm. Depois, as amostras foram imersas em água destilada a 37oC ± 2oC durante 24 horas e submetidas ao ensaio de tração até soltura das restaurações. Os dados obtidos foram analisados estatisticamente quanto ao atendimento das pressuposições de normalidade e de homogeneidade de variância, pelos testes de Shapiro-Wilk, Levene e Anova dois critérios (α=5%). Resultados: os valores (média ± desvio-padrão) de resistência à tração (em Newtons) foram: G1: 108,9 ± 37,2; G2: 168,6 ± 43,9; G3: 143,4 ± 57,1; G4: 236,8 ± 52,2. Não houve interação estatisticamente significativa entre as variáveis diâmetro e altura (p=0,446). Ao se comparar os valores de resistência à tração, notou-se efeitos estatisticamente significativos entre o diâmetro (p=0,030) e a altura (p=0,003) dos munhões cone-morse. Munhões com 4,5 mm de diâmetro proporcionaram resistência à tração significativamente superior àquela obtida na condição em que foram empregados munhões com 3,5 mm, tanto nas condições 4 mm quanto 6 mm de altura. A resistência à tração foi aumentada (37%) com munhões 4,5 mm comparados aos munhões 3,5 mm. A resistência à tração foi aumentada (60,7%) com a altura de 6 mm, comparada à altura de 4 mm. Conclusão: pilares para implantes cone-morse com maiores dimensões proporcionam maior segurança e estabilidade às coroas cimentadas sobre implantes.

Objective: to evaluate the tensile strength of cemented copings on cone-morse abutments with different heights and diameters. Material and methods: four groups (G1: 3.5 mm x 4 mm; G2: 3.5 mm x 6 mm; G3: 4.5 mm x 4 mm; and G4: 4.5 mm x 6 mm) with five samples each had their waxed copings and cast in Ni-Cr alloy, being cemented (Panavia F, 6 Kgf-load, 5 minutes) on their respective already torqued abutments (25 Ncm). Then, samples were immersed in distilled water (37oC ± 2oC) for 24 hours and subjected to the tensile test until restorations being separated. The data obtained were analyzed statistically for normality and homogeneity of variances by the Shapiro-Wilk and Levene tests. Comparisons were made using the 2-way Anova test (α=5%). Results: the values (mean ± standard deviation) of tensile strength (in Newtons) were: G1: 108.9 ± 37.2; G2: 168.6 ± 43.9; G3: 143.4 ± 57.1; G4: 236.8 ± 52.2. There was no statistically significant interaction between the variables diameter and height (p=0.446). When comparing values of tensile strength, we observed statistically significant effects for diameter (p=0.030) and height (p=0.003). Abutments with a 4.5 mm diameter provide significantly higher tensile strength to those obtained with 3.5 mm in both 4 mm and 6 mm height conditions. The tensile strength was increased (37%) for the 4.5 mm compared to the 3.5 mm condition. The tensile strength was increased (60.7%) with a height of 6 mm, compared to height of 4 mm. Conclusion: abutments for cone-morse implants with larger dimensions provide greater safety and stability for cemented crowns.

The In Situ Effect of Titanium Tetrafluoride Gel on Erosion/Abrasion Progression in Human Dentin

Abstract Erosion incidence is increasing and its control is still a challenge in clinical practice. This study evaluated 4% TiF4-gel effects on eroded human dentin subjected to in situ erosive/abrasive episodes. Seventy-two previously eroded dentin slabs (0.05 M citric acid, pH 2.3, 20 min) were allocated to 6 groups (n=12) according to the treatment to be performed during the in situ phase and number of erosive/abrasive cycles, as follows: 4% TiF4-gel applied once (TiF41), twice (TiF42) or three times (TiF43) followed by 1, 2 and 3 erosive/abrasive cycles, respectively. Gel was applied before the beginning of the next cycle. Control groups were subjected to 1 (C1), 2 (C2) and 3 (C3) erosive/abrasive cycles only. A seventh group (n=12) comprised in vitro uneroded samples (UN) subjected to 3 erosive/abrasive cycles. Each cycle corresponded to 2 days of erosive (citric acid 0.5%, pH 2.6, 6x/day) and abrasive (electric toothbrush, 10 s/sample, 1 x/day) challenges. Samples were evaluated under profilometry and environmental scanning electron microscopy (ESEM). Atomic force microscopy images (AFM) were also made (n=3). Repeated measures 2-way ANOVA and Tukey test (p<0.001) showed that TiF42, which did not differ from TiF41 and TiF43, revealed a significant reduction in surface loss compared to all control groups. TiF41 and TiF43 showed no significant difference from C1, but both groups demonstrated significantly smaller surface loss than C2 and C3. ESEM and AFM micrographs suggested alterations on treated surfaces compared to samples from control groups, showing reduced diameters of dentinal tubules lumens. Therefore, TiF4 was able to reduce the progression of erosive/abrasive lesions.

Resumo A incidência da erosão tem aumentado e o seu controle ainda é um desafio na prática clínica. Este estudo avaliou os efeitos do gel de TiF4 a 4% sobre a dentina humana erodida submetida a episódios erosivos/abrasivos in situ. Setenta e dois fragmentos de dentina previamente erodida (ácido cítrico 0,05 M, pH 2,3, 20 min) foram distribuídas em 6 grupos (n=12) de acordo com o tratamento a ser realizado durante a fase in situ e o número de ciclos erosivos/abrasivos, como descrito a seguir: gel de TiF4 a 4% aplicado uma (TiF41), duas (TiF42) ou três vezes (TiF43) seguido de 1, 2 e 3 ciclos erosivos/abrasivos, respectivamente. As aplicações dos géis foram realizadas antes do início do ciclo erosivo seguinte. Grupos controle foram submetidos a 1 (C1), 2 (C2) e 3 (C3) ciclos erosivos/abrasivos apenas. Um sétimo grupo (n=12) compreendia amostras sem erosão in vitro (UN) submetidas a 3 ciclos erosivos/abrasivos. Cada ciclo correspondia a 2 dias de desafios erosivos (ácido cítrico a 0,5%, pH 2,6, 6x/dia) e abrasivos (escova de dentes elétrica, 10 s/amostra, 1x/dia). As amostras foram avaliadas em perfilômetro e Microscopia Eletrônica de Varredura Ambiental (MEV). Imagens de microscopia de força atômica (AFM) também foram capturadas (n=3). ANOVA a 2-fatores para medidas repetidas e o teste de Tukey (p<0,001) demonstraram que TiF42, que não diferiu do TiF41 e TiF43, revelou redução significativa na perda de superfície quando comparado a todos os grupos controle. TiF41 e TiF43 não apresentaram diferença estatisticamente significativa em relação ao C1, mas ambos os grupos demonstraram perda de superfície significativamente menor que C2 e C3. Micrografias de MEV e AFM sugeriram alterações nas superfícies tratadas quando comparadas a amostras dos grupos controle, apresentando redução no diâmetro das luzes dos túbulos dentinários. Portanto, o TiF4 foi capaz de reduzir a progressão das lesões erosivas/abrasivas.

Long-term bond strength of a self-adhesive resin cement to intraradicular dentin pretreated with chlorhexidine and ethanol / Resistência de união ao longo do tempo de um cimento resinoso autoadesivo à dentina intrarradicular pré tratadas com clorexidina e etanol

Introduction: Self-adhesive resin cements do not require prior preparation of the tooth surface, therefore dentin pretreatments may influence long-term bond strength. Objective: To evaluate the influence of 100% ethanol (ET) and 2% chlorhexidine (CL) treatment of intraradicular dentin on the long-term bond strength (BS) of a self-adhesive resin cement (SRC). Material and method: 80 bovine roots were restored with fiber posts and SRC (U200 3M/ESPE) and distributed into 4 groups according to dentin treatment: Group 1 – without treatment; Group 2 – 2% CL for 1 minute; Group 3 – 100% ET for 1 minute; Group 4 – 2% CL, followed by 100% ET. The samples were cross-sectioned to obtain two sections (0.7 mm) thick for each root third: coronal, middle and apical. The immediate push-out test was carried out after 48 hours, and the long-term push-out test, after 180 days. Result: The three-way ANOVA test for randomized blocks showed no difference between the BS values at 48 hours and 80 days, irrespective of the treatment and the third (p>0.05). The interaction of the treatment/third pairing was significant (p = 0.041) since the treatment with CL promoted lower BS in the coronal third, while treatment with ET promoted better BS in the apical third. Conclusion: Treatment with CL and ET, separately or combined, promoted no differences between the BS values of the SRC to root dentin over time.

Introdução: Cimentos resinosos autoadesivos não necessitam de tratamento prévio da superfície dental, por esta razão o pré tratamento da dentina pode influenciar a longevidade da resistência adesiva. Objetivo: Avaliar a influência do tratamento dentinário com etanol (ET) 100% e clorexidina (CL) 2% na resistência de união (RU) de um cimento resinoso autoadesivo (CRA) à dentina intrarradicular. Material e método: 80 raízes bovinas restauradas com pino de fibra de vidro e CRA (U200 3M/ESPE) foram distribuídas em 4 grupos, de acordo com o tratamento prévio da dentina intrarradicular: Grupo 1 – nenhum tratamento; Grupo 2 – CL2% por 1 minuto; Grupo 3 – ET100% por 1 minuto; Grupo 4 – CL2% seguido pelo ET100%. As amostras foram seccionadas no sentido radial para obtenção de duas secções de aproximadamente 0,7 mm de espessura em cada terço – cervical, médio e apical. Após 48 horas e 180 dias foi realizado o teste push-out. Resultado: A ANOVA a três critérios para blocos casualizados demostrou que não houve diferença entre os valores de resistência de união nos tempos 48 h e 180 dias, independentemente do tratamento e do terço (p>0,05). A interação tratamento-terço foi significativa (p = 0,041) sendo que o tratamento com CL promoveu menor RU no terço cervical e o tratamento com ET promoveu melhor RU no terço apical. Conclusão: Os tratamentos com CL e ET individualmente ou associados não promoveram diferenças entre os valores de RU do CRA à dentina intrarradicular ao longo do tempo.

Chitosan in different concentrations added to a two-step etch-and-rinse adhesive system: influence on bond strength to dentin / Quitosana em diferentes concentrações adicionada a um sistema adesivo convencional de dois passos: influência na resistência de união à dentina

Objectives: the aim of the present study was to evaluate the influence of adding different concentrations of chitosan to an experimental two-step etch-and-rinse adhesive system on the bond strength and failure mode to dentin. Material and Methods: thirty-two flat dentin surfaces were obtained from extracted human third molars and divided into four groups (n=8) for application of the adhesive systems: AD - conventional two-step adhesive system (Adper Single Bond 2); EXP ­ experimental two-step etch-and-rinse adhesive system; Chi0.2% - EXP with addition of 0.2% Chitosan; Chi0.5% - EXP with addition of 0.5% Chitosan. Resin composite build-ups were made and the composite/ dentin specimens were sectioned to obtain rectangular beams with a bond area of approximately 1mm2 . After 24 hours, the sticks were submitted to microtensile bond strength tests in a universal test machine. The fracture pattern was evaluated under a stereoscopic loupe at 40X magnification. Results: one-way analysis of variance showed that the type of adhesive system had no significant effect on the bond strength values (p = 0.142), showing the mean bond strength values (standard deviation), in MPa, for the groups as follows: AD=20.1 (5.4); EXP=16.6 (2.3); Chi0.2%=16.1 (2.8); Chi0.5%=16.9 (2.3). In all the groups there was predominance of cohesive fractures in dentin, representing 68 to 82% of the failure modes. Conclusion: the addition of 0.2 or 0.5% of chitosan had no influence on the bond strength and failure mode of an experimental two-step etch-andrinse adhesive system to dentin. (AU)

Objetivo: o objetivo deste estudo foi avaliar a influência da incorporação de diferentes concentrações de quitosana em um sistema adesivo experimental convencional de dois passos na resistência de união à dentina e modo de falha. Material e Métodos: trinta e duas superfícies de dentina planificadas foram obtidas de terceiros molares e separadas em quatro grupos (n=8) para aplicação dos sistemas adesivos: AD - sistema adesivo convencional de dois passos (Adper Single Bond 2); EXP ­ sistema adesivo convencional de dois passos experimental; Chi0,2% - EXP com incorporação de quitosana a 0,2%; Chi0,5% - EXP com incorporação de quitosana a 0,5%. Blocos de resina composta foram confeccionados e os espécimes de resina composte/ dentina foram seccionados para se obter palitos retangulares com interface adesiva foi seccionada para obtenção de palitos com área de união de aproximadamente 1mm2 . Após 24 horas, os palitos foram submetidos aos testes de resistência de união por microtração em máquina universal de ensaios. O modo de falha foi avaliada em lupa estereoscópica com aumento de 40 vezes. Resultados: análise de variância a um critério mostrou que o tipo de sistema adesivo não apresentou efeito significativo nos valores de resistência de união (p = 0,142), observando-se os respectivos valores de média (desvio-padrão), em MPa, para os grupos: AD=20,1 (5,4); EXP=16,6 (2,3); Chi0,2%=16,1 (2,8); Chi0,5%=16,9 (2,3). Para todos os grupos houve predominância de fraturas coesivas em dentina, representando 68 a 82% dos modos de falhas. Conclusão: a incorporação de quitosana a 0,2 ou 0,5% na influenciou a resistência de união à dentina e o modo de falha de um sistema adesivo convencional de dois passos experimental à dentina. (AU)