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Objetivo: Determinar in vitro si la microdureza superficial Knoop de las manchas blancas mejora con la infiltración de resinas de baja viscosidad en comparación con la microdureza del esmalte sano. Materiales y métodos: Se desmineralizaron 93 muestras de esmalte bovino simulando lesiones de manchas blancas, para luego ser tratadas mediante la infiltración de resinas. Se midió la microdureza Knoop de las muestras antes de desmineralizarlas, luego de este proceso y a continuación de la infiltración. Resultados: Las muestras desmineralizadas mostraron una disminución del 50% en la microdureza. La infiltración con resinas mejoró esta propiedad, aunque los valores obtenidos se encontraron muy por debajo de la microdureza del esmalte sano. El análisis estadístico, mediante análisis de varianza (ANOVA) y prueba post-hoc de Tukey, mostraron diferencias estadísticamente significativas entre los tres grupos (p<0.001). Conclusiones: El tratamiento de las lesiones de manchas blancas artificiales con resinas infiltrantes aumentó la dureza Knoop, pero sin recuperar totalmente los valores próximos a la dureza del esmalte sano. (AU)

Aim: Determine in vitro if the Knoop surface microhardness of white spots lesions improve with the infiltration of low viscosity resins and compare it with the microhardness of healthy enamel. Materials and methods: 93 samples of bovine enamel were demineralized simulating white spot lesions, and then treated by infiltration of resins. The Knoop microhardness of the samples was measured before demineralization, after this process and after infiltration. Results: Demineralized samples showed a decrease in microhardness of 50%. The infiltration with resins improved this property, although the obtained values were far below the microhardness of healthy enamel. The statistical analysis, through analysis of variance (ANOVA) and Tukey's posthoc test, showed statistically significant differences between groups (p<0.001). Conclusions: Treatment of artificial white spot enamel lesions with infiltrating resins increased Knoop hardness but failed to reach values close to the hardness of healthy enamel. (AU)

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Objectives: This study evaluated the effects of adding silver nanoparticles on the shear bond strength, microhardness, and surface roughness of orthodontic adhesives. Material and Methods: Fifty upper premolars were randomly allocated to five groups (n = 10). Orthodontic brackets were bonded with silver nanoparticle (AgNP)-modified adhesives (1 %, 0.5 %, 0.1 %, 0.05 %), and conventional adhesive was used as a control. The shear bond strength was recorded using a universal testing machine, and the adhesive remnant index was evaluated using a stereomicroscope. Ten discs of each adhesive were subjected to the microhardness and surface roughness tests. The Vickers microhardness values were measured under a constant load of 100 g for 30 s using a microhardness tester. The samples were analyzed using a surface profilometer, and the arithmetic average roughness was used as the measurement parameter. Data were analyzed using one-way analysis of variance and chi-square tests. A significance level of 5 % was considered significant. Results: AgNP concentration > 0.1 % significantly reduced the shear bond strength (p < 0.05). At higher AgNP concentration, the bonding failure pattern occurred mainly at the bracket-resin interface. The Vickers microhardness increased with increasing concentration, and significant differences were observed between the group with 1 % AgNP and the other groups (p < 0.05). The average roughness values were similar between the groups with AgNP concentrations > 0.1 % (p > 0.05). Conclusion: The incorporation of AgNP into an orthodontic adhesive has the potential to decrease the shear bond strength while increasing the microhardness and surface roughness.

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This study analyzed and compared the physicochemical and mechanical properties of preheated resin composite with light-cured resin cement for luting indirect restorations. 210 specimens of resin cement/resin composite were prepared according to preheating treatment heated (Htd) or not (NHtd). Light-cured resin cement (Variolink Veneer, Ivoclar), and resin composite (Microhybrid-Z100, 3 M; Nanohybrid-Empress direct, Ivoclar; and Bulk fill-Filtek One, 3 M) were used (n = 10). Resin cement specimens were not preheated. The response variables were (n = 10): film thickness, microhardness, liquid sorption and solubility. Data were analyzed by 2-way ANOVA and Tukey HSD post-test (α = 0.05). Bulk fill NHtd resin had the highest film thickness values (p < 0.001). Microhybrid and nanohybrid Htd resins had the smallest thicknesses and did not differ from the cement (p > 0.05). The highest microhardness values were found for Bulk fill NHtd and Bulk fill Htd resins. The nanohybrid and microhybrid Htd resins showed the lowest microhardness values, with no difference in cement (p > 0.05). For liquid sorption, there was no significant difference between the groups (p = 0.1941). The microhybrid Htd resin showed higher solubility values than the other materials (p = 0.0023), but it did not differ statistically from resin cement (p > 0.05). Preheating composite resins reduced the film thickness. After heating, nanohybrid and Bulk fill resins retained stable microhardness, sorption, and solubility values.

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This work presents the effect of CeO2 nanoparticles (CeO2-NPs) on Cu-50Ni-5Al alloys on morphological, microstructural, degradation, and electrochemical behavior at high temperatures. The samples obtained by mechanical alloying and spark plasma sintering were exposed to a molten eutectic mixture of Li2CO3-K2CO3 for 504 h. The degradation of the materials was analyzed using gravimetry measurements and electrochemical impedance spectroscopy. Different characterization techniques, such as X-ray diffraction and scanning electron microscopy, were used to investigate the phase composition, parameter lattice, and microstructure of Cu-Ni-Al alloys reinforced with CeO2-NPs. The hardness of the composite was also examined using the Vickers hardness test. Gravimetry measurements revealed that the sample with 1 wt.% CeO2-NPs presented the best response to degradation with a less drastic mass variation. Impedance analysis also revealed that by adding 1 wt.% CeO2-NPs, the impedance modulus increased, which is related to a lower porosity of the oxide film or a thicker oxide layer. The microhardness also significantly increased, incorporating 1 wt.% CeO2-NPs, which reduced with higher CeO2-NPs content, which is possibly associated with a more uniform distribution using 1 wt.% CeO2-NPs in the Cu-Ni-Al matrix that avoided the aggregation phenomenon.

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OBJECTIVES: To evaluate the effect of mono and multi-wave light-curing units (LCUs) on the Knoop hardness of resin-based composites (RBC) that use different photoinitiators. METHODS: Central incisor-shaped specimens 12 mm long, 9 mm wide, and 1.5 mm thick were made from 2 RBCs that use different photoinitiators: Tetric N-Ceram (Ivoclar Vivadent) - and Vittra APS (FGM), both A2E shade. They were light-cured with 4 different LCUs: two claimed to be multi-wave - VALO Grand (Ultradent) and Emitter Now Duo (Schuster); and two were monowave - Radii Xpert (SDI) and Elipar DeepCure-L (3 M Oral Care) using 2 different light exposure protocols: one 40 s exposure centered over the specimen; and two 20 s light exposures that delivered light from two positions to better cover the entire tooth. 16 groups with 10 specimens in each group were made. The Knoop hardness (KH, kg/mm2) was measured at the top and bottom of the specimen in the center and at the cervical, incisal, mesial, and distal peripheral regions. The active tip diameters (mm) and spectral radiant powers (mW/nm) of the LCUs were measured with and without the interposition of the RBC, as well as the radiant exposure beam profiles (J/cm²) delivered to the top of the RBCs. The data was analyzed using Three-way ANOVA and Tukey's tests (α = 0.05). RESULTS: The VALO Grand (1029 mW) emitted twice the power of the Radii Xpert (500 mW). The KH values of VI and TN resin composite specimens were significantly affected by the LCU used (p < .001), the measurement location (p < .001), and the surface of the specimen (p < .001). LCUs with wider tip diameters produced greater Knoop hardness values at the peripheries of the 12 mm of long, 9 mm wide specimens. In general, the VALO Grand produced the highest KH values, followed by Elipar DeepCure-L, then by Radii Xpert. The Emitter Now Duo LCU produced the lowest values. Exposing the veneers from two locations reduced the differences between the LCUs and the effect of the measurement location. Only the VALO Grand could fully cover the composite veneer with light when the two locations were used. SIGNIFICANCE: The light tip must cover the entire restoration to photocure the RBC beneath the light tip.

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Objetivo: Avaliar a profundidade de polimerização em diferentes espessuras da resina composta Tetric® N-Flow Bulk Fill com adição de xilitol em diferentes concentrações. Metodologia: A resina Tetric® N-Flow Bulk Fill foi misturada às concentrações do xilitol (0% [Controle], 2,5% e 5% g/g) por espatulação manual durante 1 min em uma câmara escura. Amostras cilíndricas foram confeccionadas em moldes de polimetilmetacrilato de 5 mm de diâmetro x 1 mm, 2 mm, 3 mm e 4 mm de espessura nas concentrações de xilitol propostas totalizando 12 grupos (n=3), fotoativadas por 10 s e armazenadas a 37º C por 24 h. Os espécimes foram submetidos ao teste de microdureza Vickers, sendo a profundidade de polimerização obtida por meio da razão base/topo. Foram utilizados testes não paramétricos de Kruskal Wallis para comparação das diferentes espessuras na mesma concentração e das diferentes concentrações na mesma espessura (p<0,05) através do software BioEstat 5.3. Resultados: Não houve diferença estatisticamente significativa entre as diferentes espessuras na mesma concentração, bem como entre as diferentes concentrações na mesma espessura (p=1,000). Todos os espécimes apresentaram profundidade de polimerização adequada (razão de dureza ≥80%), com exceção das amostras com 4 mm de espessura contendo 2,5 e 5% de xilitol, que apresentaram razão de dureza média de 79% e 74%, respectivamente. Conclusão: Nas condições deste estudo, pode-se concluir que a adição de xilitol a uma resina bulk fill fluida pode afetar a profundidade de polimerização em 4 mm (AU).

Objective: To evaluate the depth of cure at different thicknesses of the Tetric® NFlow Bulk Fill composite resin with the addition of xylitol at different concentrations. Materials and Methods: The Tetric™ N-Flow Bulk Fill resin was mixed with xylitol concentrations (0% [Control], 2.5%, and 5% g/g) by manual spatulation for 1 minute in a portable darkroom. Cylindrical samples were prepared in polymethyl methacrylate molds with diameters of 5 mm and thicknesses of 1 mm, 2 mm, 3 mm, and 4 mm at the proposed xylitol concentrations, totaling 12 groups (n=3), photoactivated for 10 seconds, and stored at 37°C for 24 hours. The specimens were subjected to Vickers microhardness testing, and the depth of cure was obtained by calculating the base/top ratio. Non-parametric Kruskal-Wallis tests were used to compare different thicknesses at the same concentration and different concentrations at the same thickness (p<0,05) using BioEstat 5.3 software. Results: There was no statistically significant difference between different thicknesses at the same concentration, as well as between different concentrations at the same thickness (p=1,000). All specimens exhibited adequate depth of cure (hardness ratio ≥80%), except for the samples with 4 mm thickness containing 2.5% and 5% xylitol, which showed average hardness ratios of 79% and 74%, respectively. Conclusion: Under the conditions of this study, it can be concluded that the addition of xylitol to a fluid bulk fill resin can affect the depth of cure at 4 mm (AU).

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OBJECTIVE: To evaluate the effect of activated charcoal-based (AC) products on color alteration, remineralizing potential and surface roughness of dental enamel. MATERIALS AND METHODS: Bovine incisors were cut into 6 × 6 × 2 mm fragments. Initial color (EasyShade, Vita) and surface roughness (Surfcorder SE1700, Kosakalab) readings were performed. Fragments were separated into five groups (n = 17) according to the treatment: Control: Fluoride toothpaste (Colgate Total 12, Colgate); Charcoal + NaF: AC toothpaste (ACT) with sodium fluoride (Colgate Natural Extracts, Colgate); Charcoal + MFP + n-HA: ACT with sodium monofluorophosphate and nanohydroxyapatite (Black is White, Curaprox); Charcoal: Fluoride-free ACT (ProActive, Hinode); and Charcoal powder: AC powder. Simulated toothbrushing was performed and final color and surface roughness readings were obtained. Fragments were then polished, and initial microhardness (HMV-2, Shimatzu) readings were done. Samples were artificially demineralized and brushed again. Final microhardness readings were taken. Data were statistically analyzed. RESULTS: Fluoride-free charcoal presented the lowest surface roughness alteration (p < 0.05). Charcoal powder had the lowest color change (p < 0.05) and negative values for whiteness index for dentistry alteration. All the groups presented values below whiteness acceptability threshold and negative relative microhardness values. Control showed the highest remineralizing potential (p < 0.05). CONCLUSIONS: ACPs did not produce color alteration different from the fluoride toothpaste, except for Charcoal powder that caused less color change. ACPs caused surface roughness alteration similar to the fluoride toothpaste. ACT with fluoride and AC powder did not have remineralizing potential. CLINICAL SIGNIFICANCE: Activated charcoal-based products (ACP) promise effective tooth whitening and quick results, without teeth damage. In addition, some ACPs contain fluoride in toothpaste composition and promise rehardening potential. However, ACPs are not as effective as other whitening agents and can alter the surface roughness of the enamel. Even if the ACPs contain fluoride or other remineralizing agents, they might be ineffective.

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Aim: The study evaluated the influence of tucupi on enamel surface roughness, microhardness, ultramorphology, and mass variation. Materials and Methods: Ninety healthy bovine incisors were divided into three experimental groups, according to the acidic challenge adopted, being: G1- tucupi, G2- cola-based soft drink, G3-distilled water. The enamel properties (surface roughness, microhardness, ultramorphology and mass variation) of all specimens were evaluated at times T0 (before any intervention), T10 (10 days after the proposed treatments), T20 (20 days after the proposed treatments) and T30 (30 days after the proposed treatments). After confirming the normality of the data (Shapiro-Wilk test), a two-way ANOVA (α = 5%) was performed, followed by Sidak post-test, with results described as mean and standard deviation. Results: The roughness means increased for all tested groups, with no statistical difference only in G3 for all evaluated times. Microhardness of all groups showed a significant decrease over the time, with the lowest average observed in G1 in T30. Considering enamel mass variation, the lowest average was in G2 at time T3, with no statistical difference only in G3 (distilled water) over the time. Regarding ultramorphology (scanning electron microscopy - SEM), only groups G1 and G2, that were exposed to acidic challenges, showed disorganization of the enamel surface layer. Conclusion: It was possible to conclude that tucupi has low pH and high titratable total acidity, being able to gradually decrease enamel microhardness, increasing surface roughness and causing loss of dental enamel.

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This study evaluated selected structural and physical properties, such as degree of conversion (DC), Vickers hardness (VHN), and compression strength (CS), of three new dual-cure bulk-fill resin-based composites (RBCs; ACTIVA, HyperFIL, and Fill-Up) and compared them to those of a conventional RBC (Filtek Z250) at three clinically relevant depths. Samples (n=180) were prepared in three depths (2,4, and 6mm). Fourier-transform infrared spectroscopy (FTIR) analysis and VHN and CS tests were performed. The DC value was calculated by considering the relative change in the aliphatic C=C peaks. The fractured surfaces of representative samples were characterized using scanning electron microscopy (SEM). Data were statistically evaluated using two-way analysis of variance and post hoc Bonferroni tests (p<0.05). According to the VHN results, Filtek Z250 showed the highest bottom/top hardness ratio (97.94±1.01) at 2mm thickness and ACTIVA showed the lowest bottom/top hardness ratio (43.48±5.64) at 6mm thickness (p<0.001). According to the FTIR results, the DC decreased with increasing thickness in all materials (p<0.05). Filtek Z250 showed the highest (301±12.4 MPa) and ACTIVA exhibited the lowest (232±17.2 MPa) CS values at 2mm thickness (p<0.05). The lowest CS values were obtained for ACTIVA, and the highest values were obtained for Filtek Z250 for samples with thicknesses of 4 and 6mm, respectively (p<0.05). The structural features of restorative composites, such as the resin chemistry and filler type and content, and the operational parameters (i.e., material thickness and curing conditions) strongly affect crosslinking reactions and thus the DC, VHN, and CS values.

Este estudio evaluó propiedades físicas y estructurales, como el grado de conversión (DC), la dureza Vickers (VHN) y la resistencia a la compresión (CS), de tres nuevos compósitos a base de resina de curado dual tipo bulk (RBC; ACTIVA , HyperFIL y Fill-Up) y los comparó con los de una resina compuesta convencional (Filtek Z250) en tres profundidades clínicamente relevantes. Se prepararon muestras (n=180) en tres profundidades (2,4 y 6mm). Se realizaron análisis de espectroscopia infrarroja por transformada de Fourier (FTIR) y pruebas VHN y CS. El valor de DC se calculó considerando el cambio relativo en los picos alifáticos C=C. Las superficies fracturadas de muestras representativas se caracterizaron mediante microscopía electrónica de barrido (MEB). Los datos se evaluaron estadísticamente mediante análisis de varianza de dos vías y pruebas post hoc de Bonferroni (p<0,05). De acuerdo con los resultados de VHN, Filtek Z250 mostró la relación de dureza inferior/superior más alta (97,94±1,01) con un espesor de 2mm y ACTIVA mostró la relación de dureza inferior/superior más baja (43,48±5,64) con un espesor de 6mm (p<0,001). De acuerdo con los resultados de FTIR, la DC disminuyó al aumentar el espesor en todos los materiales (p<0,05). Filtek Z250 mostró los valores de CS más altos (301±12,4 MPa) y ACTIVA los más bajos (232±17,2 MPa) a 2mm de espesor (p<0,05). Los valores más bajos de CS se obtuvieron para ACTIVA y los valores más altos para Filtek Z250 para muestras con espesores de 4 y 6mm, respectivamente (p<0,05). Las características estructurales de las resinas compuestas de restauración, como la química; además del tipo y contenido del relleno, y los parámetros operativos (es decir, el espesor del material y las condiciones de curado) afectan en gran medida las reacciones de interacción química y, por lo tanto, los valores de DC, VHN y CS.

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Abstract This study evaluated the effect of phytosphingosine (PHS) and bioactive glass-ceramic (Biosilicate) on dental enamel in terms of color alteration (ΔE), microhardness, and surface roughness when submitted to erosive challenge (EC). Sixty specimens of bovine teeth (6×6×2mm) were obtained. Initial color (Easyshade, VITA), KHN (HMV-2, Shimadzu), and Ra (SJ-201P, Mitutoyo) measurements were performed. Specimens were separated into groups according to treatments: PHS, 10% Biosilicate, PHS+10% Biosilicate, and artificial saliva (control) and submitted to EC with Coca-Cola for 2 min. This cycle was repeated 4 times daily/15 days. Between cycles, specimens remained in artificial saliva (2 h/37°C). After daily cycles, they were also stored in artificial saliva at 37ºC. Final color, microhardness, and surface roughness measurements were done. Color and KHN data were analyzed by one-way ANOVA, Tukey's test; and Ra, by 2-way ANOVA, repeated measures, and Tukey's test (p<.05). The highest ΔE occurred in Saliva+EC (p<.05). Groups treated with PHS presented lower color change than Saliva+EC (p<.05). All the groups presented mean values above the 50:50% perceptibility (50:50%PT) and acceptability (50:50%AT) thresholds, except for control that showed mean value above 50:50%PT but below 50:50%AT. Biosilicate+EC showed higher relative microhardness than Saliva+EC (p<.05), but was similar to PHS+EC and PHS+Biosilicate+EC. Final enamel surface roughness increased for all the groups (p<.05), except for the control. The Biosilicate may prevent enamel mineral loss induced by erosion better than saliva. The PHS associated or not to Biosilicate demonstrated better color stability than saliva.

Resumo Este estudo avaliou o efeito da Fitoesfingosina (PHS) e da vitrocerâmica bioativa (Biosilicato) sobre o esmalte dental em termos de alteração de cor (ΔE), microdureza (KHN) e rugosidade superficial, quando submetido a desafio erosivo (DE). Sessenta espécimes de dentes bovinos (6×6×2mm) foram obtidos. Foram realizadas leituras de cor inicial (Easyshade, VITA), microdureza (HMV-2, Shimadzu) e rugosidade superfícial (SJ-201P, Mitutoyo). Os espécimes foram separados em grupos de acordo com os tratamentos: PHS, Biosilicato a 10%, PHS+Biosilicato a 10%, e saliva artificial (controle). Em seguida, foram submetidos a DE com Coca-Cola por 2 min. Esse ciclo foi repetido 4 vezes/dia por 15 dias. Entre os ciclos, as amostras foram mantidas em saliva artificial (2 h/37°C). Após os ciclos diários, os espécimes também foram armazenados em saliva artificial a 37ºC. Foram realizadas leituras finais de cor, microdureza e rugosidade superficial. Os dados de cor e microdureza foram analisados ​​por ANOVA de uma via, teste de Tukey; e dados de rugosidade superficial, por ANOVA de duas vias, teste de Tukey (p<.05). A maior ΔE ocorreu em Saliva+DE (p<.05). Grupos tratados com PHS apresentaram menor alteração de cor do que Saliva+DE (p<.05). Biosilicate+DE demonstrou valores intermediários, similar (p>.05) aos outros grupos, exceto Saliva+DE. Todos os grupos presentaram média acima dos limites 50:50% de perceptibilidade (50:50%LP) e aceitabilidade (50:50%LA) exceto o controle que demonstrou média acima do 50:50%LA mas abaixo do 50:50%LP. Biosilicate+DE mostrou maior microdureza realativa do que Saliva+DE (p<.05), mas similar a PHS+DE e PHS+Biosilicato+DE. A rugosidade de superfície do esmalte aumentou para todos os grupos, exceto para o controle que presentou a menor alteração (p<.05). O Biosilicato apode prevenir perda mineral do esmalte indizido pela erosão melhor que a saliva. O PHS associado ou não ao Biosilicato demonstrou melhor estabilidade de cor que a saliva.

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OBJECTIVE: To evaluate the effect of delayed light-curing of dual-cure bulk-fill composites on internal adaptation and microhardness (KHN) in depth. MATERIALS AND METHODS: Bulk-fill composites were placed in 35 box-shaped preparations and cured according to the following protocols (n = 5): Filtek Bulk-Fill light-cured immediately after insertion (FBF); Bulk-EZ light-cured immediately after insertion (BEZ-I); Bulk-EZ light-cured 90 s after insertion (BEZ-DP); Bulk-EZ self-cured (BEZ-SC); HyperFIL light-cured immediately after insertion (HF-I); HyperFIL light-cured 90 s after insertion (HF-DP); HyperFIL self-cured (HF-SC). After 24 h, the samples were axially sectioned, and the internal adaptation was evaluated using replicas under a scanning electron microscope. The KHN was evaluated at six depths (0.3 mm, 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm). The statistical analysis was performed using α = 0.05. RESULTS: The KHN significantly decreased with depth, except in self-curing mode, when it was similar at all depths. Delayed light-curing significantly increased the KHN at higher depths. The internal adaptation was material-dependent. Light-curing did not influence the internal adaptation of HyperFIL, whereas delayed light-curing significantly reduced the internal gaps (%) of Bulk-EZ. CONCLUSION: Delayed light-curing improved the depth of cure of dual-cure resin composites. Light-curing did not influence the internal adaptation of HyperFIL, but delayed light-curing improved the internal adaptation of Bulk-EZ. CLINICAL SIGNIFICANCE: Light-curing is fundamental for improving the mechanical properties of dual-cure resin composites. Moreover, depending on the dual-cure resin composite, the delay in light-curing can reduce the internal gaps.

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OBJECTIVE: The aim of this scoping review was to analyze the available evidence on the preheating process and its effects on physicochemical properties of composite resins. MATERIALS AND METHODS: A systematic search was performed in August 2021 using PubMed/Medline, Embase, Scopus, and ISI Web of Science databases and gray literature without language or date restriction. Inclusion criteria were in vitro studies that assessed the physicochemical properties and marginal adaptation of preheated composite. Exclusion criteria were studies with experimental composite, literature reviews, clinical studies. Data from selected studies were qualitatively analyzed. RESULTS: In total, 104 studies were found from which 39 were included. The most used composite resin was Filtek Z350 XT (3 M/ESPE), preheated at 68°C in a Calset device (AdDent Inc., Danbury, CT, USA) for 5 or 15 min. Most studies showed decreased viscosity, increased conversion degree and microhardness of composite resins, and better marginal adaptation of direct and indirect restorations. Also, flexural strength was not affected, and data about bond strength were inconclusive due to heterogeneity among studies. CONCLUSION: The parameters used for preheating composite resins are heterogeneous. Preheating decreased viscosity, increased the conversion degree and microhardness of composite resins, and improved the marginal adaptation of direct and indirect restorations. CLINICAL SIGNIFICANCE: The analysis of evidence showed a high heterogeneity among preheating protocols. Preheating may benefit the handling and physicochemical properties of composite resins.

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OBJECTIVE: This study evaluated the in vitro and in situ effects of phytosphingosine (PHS) associated with tooth brushing on color stability, surface roughness, and microhardness of dental enamel. METHODS: Sixty-four specimens of bovine teeth (6 × 6 × 2 mm) were separated into 8 groups (n = 8): S + TB: PHS (spray) + tooth brushing; TB + S: tooth brushing + PHS (spray); I + TB: PHS (immersion) + tooth brushing; TB + I: tooth brushing + PHS (immersion); TB: tooth brushing; S: PHS spray; I: immersion in PHS solution, and Saliva: immersion in saliva. Tooth brushing simulation (Mavtec, Brazil) was performed (356 rpm on 3.8 cm area by the toothbrush - Soft Tek) for 1, 7, 15, and 30 days. PHS remained in contact with specimens for 15 min. The specimens were evaluated before and after tooth brushing for color alteration (Easy Shade, VITA), and surface roughness (Model SJ-201P Mitutoyo), and Knoop microhardness (HMV-2, Shimadzu Corporation). For the in situ analyses, 8 participants were recruited and received an intraoral device with 6 fragments of bovine enamel (6 × 6 × 2 mm). The properties evaluated were the same as those of the in vitro study. Participants were randomized following best results of in vitro tested protocols, for 15 days: TB, TB + S, I + TB. Data obtained by in vitro (two-way ANOVA, Tukey, p < .05) and in situ (one-way ANOVA, Tukey, p < .05) studies were analyzed. RESULTS: The in vitro study showed that greater color change was found after 30 days. The greatest differences in surface roughness occurred between the initial value and after 1 day. Regarding microhardness, the highest values occurred after 15 and 30 days, which showed similar results. The in situ study showed greater color changes for the TB and I + TB, and greater surface roughness changes for TB as well as a similar increase in microhardness for the PHS protocols, which were higher than TB. CONCLUSIONS: Phytosphingosine leads to an increase in performance regarding color stability, surface roughness, and microhardness when applied. In general, the application of PHS after brushing showed a positive impact on its performance. CLINICAL RELEVANCE: Phytosphingosine proved to be interesting for compound prevention formulations in the dentistry field.

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AIM: It has been reported that resin composites may experience alterations in their mechanical properties when they come into contact with glove powder. Therefore, the present study aimed to compare the surface microhardness of 3 bulk-fill resin composites handled with latex and nitrile gloves prior to light curing. METHODS: This in vitro experimental study consisted of 90 resin composite specimens with a 6-mm diameter and a 4-mm height divided equally and randomly into 9 groups. Prior to light curing, the resin composites were handled with latex gloves, nitrile gloves, or only a spatula (control). Subsequently, the surface microhardness was measured with an Electronic Vickers Hardness Tester. The Kruskal-Wallis nonparametric H test with Bonferroni correction was used for comparisons. A significance level of 5% (P < .05) was considered. RESULTS: When comparing surface microhardness of each resin composite according to type of handling received, significant differences were observed in Filtek One Bulk Fill (P < .001) and Opus Bulk Fill (P < .001). In addition, these resin composites presented significantly higher surface microhardness than Tetric N-Ceram Bulk Fill resin (P < .05) when handled with latex gloves, nitrile gloves, and only a spatula. Finally, Filtek Bulk Fill resin presented significantly higher surface microhardness compared to Opus Bulk Fill resin when handled with nitrile gloves (P = .038) and a spatula only (P = .033). CONCLUSIONS: The surface microhardness of Filtek One Bulk Fill and Opus Bulk Fill resin composites decreased significantly when handled with latex or nitrile gloves, showing no variation in Tetric N-Ceram Bulk Fill resin composite. In addition, Filtek One Bulk Fill resin composite showed significantly higher surface microhardness than Opus Bulk Fill and Tetric N-Ceram Bulk Fill resin composites when handled with nitrile gloves. It is recommended that bulk-fill resin composites be handled with a spatula, because the use of latex or nitrile gloves could adversely affect their clinical performance.

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To try to reduce the deleterious effects of tooth whitening, bioactive materials have been used. Forty enamel/dentin blocks were stained on dark tea and randomly assigned into four groups (n=10): control group (unbleached), HP35 % (35 % hydrogen peroxide), BG45S5 (Bioglass 45S5® incorporated into HP35 %), and BIO (Biosilicate® incorporated into HP35 %). Colorimetric analysis and microhardness evaluation was performed at baseline, 24 hours and 7 days after the final whitening session. Two-way ANOVA for repeated measures and Bonferroni test was used at a significance level of 5 %. All the coordinates (ΔL*, Δa*, Δb*, ΔE00 and WID) showed a difference between the control group and the experimental ones (p0.05), which suggest a color stability over a week. In contrast, after 7 days, the WID showed that control and PH35 % were different than the other groups (p 0.05). The microhardness did not change over time (p>0.05), except for 35 % HP. In conclusion Bioglass 45S5® and Biosilicate® prevented enamel damage without negatively affect the whitening efficacy.

Para intentar reducir los efectos nocivos del aclaramiento dental, se han usado materiales bioactivos. Cuarenta bloques de esmalte/dentina se tiñeron con té oscuro y se asignaron al azar en cuatro grupos (n=10): grupo de control (sin blanquear), HP35% (peróxido de hidrógeno al 35 %), BG45S5 (Bioglass 45S5® incorporado en HP35%) y BIO (Biosilicato® incorporado a HP35%). El análisis colorimétrico y la evaluación de la microdureza se realizaron al inicio del estudio, 24 horas y 7 días después de la última sesión de blanqueamiento. Se utilizó ANOVA de dos vías para medidas repetidas y la prueba de Bonferroni a un nivel de significancia del 5 %. Todas las coordenadas (ΔL*, Δa*, Δb*, ΔE00 y WID) mostraron diferencia entre el grupo control y el experimental (p0.05), lo que sugiere una estabilidad del color durante una semana. En cambio, a los 7 días, el WID mostró que el control y el PH35 % eran diferentes a los demás grupos (p 0.05). La microdureza no cambió con el tiempo (p>0.05), excepto para 35 % HP. En conclusión Bioglass 45S5® y Biosilicate® previnieron el daño del esmalte sin afectar negativamente la eficacia del blanqueamiento.

RESUMO

Abstract This study evaluates the effect of curing modes and times on the mechanical properties of nanocomposites. Two nanocomposite resins were investigated: suprananohybrid (Estelite Posterior Quick; EP) and nanohybrid (Solare X; SX). They were polymerized with a light-emitting diode light-curing units (LED LCU, Valo) as follows: standard mode for 20s (ST20), high power mode for 12s (HP12), high power mode for 20s (HP20), extra power mode for 6s (XP6), and extra power mode for 20s (XP20). For Vickers microhardness (HV), disc-shaped specimens were fabricated (n=10). For the three-point bending test, bar-shaped specimens were fabricated (n=10). Flexural strength and resilience modulus were calculated. The fractured surfaces and specimen surfaces of composites were observed using scanning electron microscopy. The data were analyzed with repeated measures ANOVA, two-way variance, and Bonferroni tests (p<0.05). On the top and bottom surfaces of the EP nanocomposite resin, ST20 and HP12 revealed statistically higher HV than with XP6. Moreover, HP20 and XP20 had statistically higher HV than HP12 and XP6. For the SX nanocomposite resin, HP20 had statistically higher HV than HP12. For EP and SX, there were no significant differences in flexural strength and resilience modulus regarding the curing modes and times. Furthermore, SX demonstrated lower mechanical properties than EP. Scanning electron microscopy indicated that both nanocomposites had similar surface appearances. However, with all curing modes and times, SX exhibited layered fractures and more crack formations than EP. Different curing modes and times could influence the microhardness of nanocomposites.

Resumen Este estudio evalúa el efecto del modo y tiempo de fotocurado sobre las propiedades mecánicas de los nanocompuestos. Se investigaron dos resinas nanocompuestas: supra-nanohíbrida (Estelite Posterior Quick; EP) y nanohíbrida (Solare X; SX). Se polimerizaron con unidades de fotopolimerización de diodos emisores de luz (LED LCU, Valo) de la siguiente manera: modo estándar durante 20s (ST20), modo de alta potencia durante 12s (HP12), modo de alta potencia durante 20s (HP20) , modo extra power durante 6s (XP6) y modo extra power durante 20s (XP20). Para la microdureza Vickers (HV), se fabricaron especímenes en forma de disco (n=10). Para el ensayo de flexión de tres puntos, se fabricaron probetas en forma de barra (n=10). Se calcularon la resistencia a la flexión y el módulo de resistencia. Las superficies fracturadas se observaron mediante microscopía electrónica de barrido. Los datos se analizaron con ANOVA varianza de dos vías y pruebas de Bonferroni (p<0,05). En las superficies superior e inferior de la resina nanocompuesta EP, ST20 y HP12 revelaron un HV estadísticamente mayor que con XP6. Además, HP20 y XP20 tenían un HV estadísticamente más alto que HP12 y XP6. Para la resina nanocompuesta SX, HP20 tenía un HV estadísticamente más alto que HP12. Para EP y SX, no hubo diferencias significativas en la resistencia a la flexión y el módulo de resistencia con respecto al modo y tiempo de fotocurado. Además, SX demostró propiedades mecánicas inferiores que EP. La microscopía electrónica de barrido indicó que ambos nanocompuestos son similares en la superficie. Sin embargo, SX exhibió fracturas en capas y más formaciones de grietas que EP. Diferentes modos y tiempos de fotocurado podrían influir en la microdureza de los nanocompuestos.

Assuntos

RESUMO

Recently, several studies have introduced nanotechnology into the area of dental materials with the aim of improving their properties. The objective of this study is to determine the antibacterial and mechanical properties of type I glass ionomers reinforced with halloysite nanotubes modified with 2% chlorhexidine at concentrations of 5% and 10% relative to the total weight of the powder used to construct each sample. Regarding antibacterial effect, 200 samples were established and distributed into four experimental groups and six control groups (4 +ve and 2 -ve), with 20 samples each. The mechanical properties were evaluated in 270 samples, assessing microhardness (30 samples), compressive strength (120 samples), and setting time (120 samples). The groups were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy, and the antibacterial activity of the ionomers was evaluated on Streptococcus mutans for 24 h. The control and positive control groups showed no antibacterial effect, while the experimental group with 5% concentration showed a zone of growth inhibition between 11.35 mm and 11.45 mm, and the group with 10% concentration showed a zone of growth inhibition between 12.50 mm and 13.20 mm. Statistical differences were observed between the experimental groups with 5% and 10% nanotubes. Regarding the mechanical properties, microhardness, and setting time, no statistical difference was found when compared with control groups, while compressive strength showed higher significant values, with ionomers modified with 10% concentration of nanotubes resulting in better compressive strength values. The incorporation of nanotubes at concentrations of 5% and 10% effectively inhibited the presence of S. mutans, particularly when the dose-response relationship was taken into account, with the advantage of maintaining and improving their mechanical properties.

RESUMO

ABSTRACT: Bioactive materials have shown positive results in reducing the deleterious effects of tooth whitening. However, their effects on whitening efficacy is still uncertain. Therefore, the aim of this study was to evaluate the effects of F- 18 bioactive glass incorporation into a bleaching gel on color and microhardness of enamel after tooth whitening. Thirty bovine enamel-stained specimens were randomly divided into three groups (n=10) according to the whitening protocol: control group (unbleached), HP35 % (35 % hydrogen peroxide) and F-18 (F-18 bioactive glass incorporated into HP35 %). pH, color change and microhardness analyzes were performed at baseline, 24 hours and 7 days after tooth whitening. Color evaluation showed that experimental groups were different than control group for all coordinates (p 0.05). No differences in enamel microhardness were found among the groups within the same evaluation time (p > 0.118). Regarding the intragroup comparisons, no differences were observed for control and F-18 groups (p > 0.129). It was concluded that F-18 bioactive glass incorporation did not affect the whitening efficacy and the enamel microhardness.

RESUMEN: Los materiales bioactivos han mostrado resultados positivos en la reducción de efectos nocivos del aclaramiento dental. Sin embargo, sus efectos sobre la eficacia del aclaramiento aún son inciertos. Por lo tanto, el objetivo de este estudio fue evaluar los efectos de la incorporación de vidrio bioactivo F-18 en un gel aclarador sobre el color y la microdureza del esmalte después del aclariamiento dental. Treinta especímenes bovinos teñidos con esmalte se dividieron aleatoriamente en tres grupos (n=10) de acuerdo con el protocolo de aclaramiento: grupo control (sin aclaramiento), HP35 % (peróxido de hidrógeno al 35 %) y F-18 (vidrio bioactivo F-18 incorporado en HP35 %). Se realizaron análisis de pH, cambio de color y microdureza al inicio del estudio, 24 horas y 7 días después del aclaramiento dental. La evaluación del color mostró que los grupos experimentales eran diferentes al grupo de control en todas las coordenadas (p 0,05). No se encontraron diferencias en la microdureza del esmalte entre los grupos dentro del mismo periodo de evaluación (p > 0,118). En cuanto a las comparaciones intragrupos, no se observaron diferencias para los grupos control y F-18 (p > 0,129). Se concluyó que la incorporación de vidrio bioactivo F-18 no afectó la eficacia de aclaramiento ni la microdureza del esmalte.

RESUMO

Abstract The objective of this study was to evaluate the effect of natural bleaching products on the color, whiteness, and superficial properties of dental enamel. Seventy fragments of bovine teeth were obtained (6mm x 6mm x 2mm). Initial surface roughness (Surfcorder SE1700, Kosakalab), microhardness (HMV-2, Shimadzu), color (EasyShade, VITA), and surface gloss (Micro-Gloss 45º BYK, Gardner) readings were done. Samples were separated into five groups (n=14) according to the treatments used: CT-conventional toothpaste (negative control); CH-charcoal; TU-turmeric; BP-banana peel, and CP16%-16% carbamide peroxide gel (positive control, 4 h/day for 14 days), and then brushed for 560 cycles (T1) and 1200 cycles (T2), equivalent to 14 and 30 days of brushing. New measurements were performed after T1 and T2. The whiteness index for dentistry change (∆WID) and Weight loss (Wl) were calculated. CP16% demonstrated the highest (p<.05) color change (ΔE00) and ∆WID (2-way ANOVA, Bonferroni, p<.05). Surface gloss alterations were lower for TU, CP16%, and BP. CT and CH increased surface roughness (p<.05). CP16% decreased enamel microhardness. CH presented medium abrasiveness, and CT and TU, low abrasiveness. The popular bleaching products were not efficient for tooth whitening. Furthermore, brushing with charcoal increased the enamel surface roughness, and CP16% decreased enamel microhardness over time

Resumo O objetivo deste estudo foi avaliar o efeito de produtos clareadores naturais na cor, efeito clareador e propriedades superficiais do esmalte dentário. Setenta fragmentos de dente bovino foram obtidos (6mm x 6mm x 2mm). Foram realizadas leituras iniciais de rugosidade de superfície (Surfcorder SE1700, Kosakalab), microdureza (HMV-2, Shimadzu), cor (EasyShade, VITA) e brilho (Micro-Gloss 45º BYK, Gardner). As amostras foram separadas em cinco grupos (n=14), de acordo com os tratamentos utilizados: DC - dentifrício convencional (controle negativo); CA - carvão ativado; CM - cúrcuma; CB - casca de banana e PC16% - gel de peróxido de carbamida a 16% (controle positivo, 4h/dia por 14 dias), foram então escovadas por 560 ciclos (T1) e 1200 ciclos (T2), equivalente a 14 e 30 dias de escovação. Novas leituras foram realizadas após T1 e T2. A alteração do whiteness index for dentistry (∆WID) e perda de massa (Pm) foram calculadas. PC16% demonstrou a maior (p<0,05) alteração de cor (ΔE00) e ∆WID (2-way ANOVA, Bonferroni, p<0,05). A alteração de brilho foi menor para CM, PC16% e CB. DC e CA aumentaram a rugosidade de superfície (p<0,05). PC16% diminuiu a microdureza do esmalte. CA apresentou abrasividade média, e DC e CM, baixa abrasividade. Os produtos clareadores populares não foram eficientes para clareamento dental. Ademais, a escovação com carvão ativado aumentou a rugosidade de superfície do esmalte dentário, e com maior tempo PC16% diminuiu a microdureza do esmalte.

RESUMO

The aim of this study was to assess the microhardness and surface roughness of bulk-fill resin composites treated with and without the application of an oxygen-inhibited layer (OIL) and a polishing system. This in vitro experimental study consisted of 72 resin composite blocks divided into three groups: Tetric N-Ceram Bulk Fill, Opus Bulk Fill APS, and Filtek Bulk Fill. Each resin composite group was further divided into two subgroups: with and without OIL control. Subsequently, surface roughness and microhardness were measured before and after polishing. A t-test was used to compare independent and related measures. For the intergroup comparison of variation before and after polishing, the Kruskal−Wallis test with Bonferroni post hoc was used considering a significance level of p < 0.05. When comparing surface roughness, significant differences were observed between Opus Bulk Fill resin composite with and without OIL control (p = 0.003) before polishing. The same occurred when comparing Tetric N-Ceram resin composite with and without OIL control (p = 0.039) after polishing. In addition, the surface roughness of Filtek Bulk Fill, Opus Bulk Fill, and Tetric N-Ceram Bulk Fill resin composites, with and without OIL control, decreased significantly after polishing (p < 0.001), while surface microhardness significantly increased (p < 0.05), with the exception of Opus Bulk Fill resin with OIL control (p = 0.413). In conclusion, OIL control and polishing significantly improved the surface roughness and surface microhardness of Filtek Bulk Fill and Tetric N-Ceram Bulk Fill resin composites. However, in the case of Opus Bulk Fill resin composite, only its surface roughness was significantly improved.