Effect of Water and Chlorhexidine with Different Pressures of Oral Irrigation Device on the Surface Roughness and Topography of Giomer

Abstract Objective: To evaluate the effect of different pressures of an oral irrigation device (OID) and the irrigation solution type on the surface roughness of the giomer restorative material. Material and Methods: In this in vitro study, disk-shaped giomer samples were fabricated and assigned to 5 groups (n=23): Group 1, storage in distilled water (control); Group 2, OID #7 pressure/ water; Group 3, OID #10 pressure/ water; Group 4, OID #7 pressure/ 0.05% CHX; Group 5, OID #10 pressure/ 0.05% CHX. The samples' treatment simulated a one-year application of OID. Surface roughness (Ra) and topography of the giomer were evaluated using profilometry and scanning electron microscopy. The data were analyzed with Paired t-test, Tukey, and ANOVA tests (α=0.05). Results: The Ra of the samples increased significantly after treatment with OID (p<0.001). The roughness increase in groups with a pressure of 10 was higher than those with a pressure of 7 (p<0.001). The effect of pressure on surface changes was significant (p<0.001). However, the solution type and the cumulative effect of these two factors were insignificant (p=0.08 and p=0.43, respectively). Conclusion: Oral irrigation device with both solutions significantly increased the surface roughness and topographic changes of the giomer. The severity of these changes was related to the device's pressure.

The influence of general knowledge test performance on self-ratings of and perceived relationships between intelligence, knowledge, and memory.

The present study examined how taking a general knowledge (GK) test affects perceptions of one's intelligence, memory, and knowledge and the relationship between these three constructs. Participants rated their abilities on each construct and the strength of the relationships between them before and after completing an easy or hard GK test or control task. In Experiment 1, participants were (mis)informed that GK questions were correctly answered by 50% of the population; in Experiment 2, no such information was provided. Regardless of (mis)information about others' performance, participants in the Hard condition believed they had a worse memory, were less knowledgeable, and were less intelligent post-task. However, the strength of the perceived relationship between GK and intelligence decreased only when participants were misled. Judgments of one's intelligence, memory, and knowledge can be manipulated by taking a GK test, and individuals engage in self-protective behavior to reduce the potential threat to one's self-concept.

Comparison between different fracture toughness techniques in zirconia dental ceramics.

Vickers indentation (IF) and single-edge-V-notched beam (SEVNB), to measure the fracture toughness (KIC ) of zirconia-based dental ceramics and mathematical models were proposed to establish a correlation between both. Zirconia (ZrO2 ) stabilized with 3 mol. % of Y2 O3 (3Y-TZP) and 5 mol% of Y2 O3 (5Y-PSZ) were compacted (n = 42) and sintered for 2 h at different temperatures (1475°C, 1500°C, 1550°C, or 1600°C). After sintering, they were characterized by relative density using the ASTM C373-88 standard, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The average grain size was measured according to the ASTM E1382-97 standard. The fracture toughness (KIC ) was determined using two methods: Vickers indentation fracture toughness (KIC-IF ): method based on mathematical modeling that considers the parameters used for the Vickers hardness test and Fracture toughness by the single-edge-V-notch-beam (KIC-SEVNB ): method proposed by ISO 23146:08. The main phases of the 3Y-TZP and 5Y-PSZ ceramics were ZrO2 -tetragonal and ZrO2 -cubic, respectively. The 3Y-TZP specimens showed equiaxed grains with average grain sizes ranging from 0.55 to 0.79 µm. The grain sizes of 5Y-PSZ of specimens sintered at 1475°C and 1600°C were 0.62 and 2.32 µm, respectively. For all ceramics the crack size ratio was c/a < 2.5, suggesting a Palmqvist-type crack system. The fracture toughness measured by the Vickers indentation method (KIC-IF ) and by the SEVNB method (KIC-SEVNB ) was the same when the experimental data were fit to a mathematical model.

Effects of black tea tooth staining previously to 35% hydrogen peroxide bleaching

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

Flexural strength and Vickers hardness of milled and 3D-printed resins for provisional dental restorations

Various forms of temporary resins are offered on the market; however, the properties of temporary resins obtained by milling and 3D printing have not been fully examined. This study aimed to compare the flexural strength and Vickers hardness of milled and 3D-printed resins. Methods: Three resins were tested: Evolux PMMA (milled resin), Cosmos Temp (3D-printed resin), and Structur 2 SC (bis-acrylic resin, group control). Specimens were prepared with rectangular shapes (n = 12) for flexural strength measurements and disc shapes (n = 9) for Vickers hardness tests. Flexural strength tests were performed at a crosshead speed of 0.75 mm/min, and the Vickers hardness was measured under a load of 20 N for 10 s. The obtained data were subjected to the Kruskal­Wallis test. Results: A significant difference (p < 0.05) in flexural strength was observed among the three sample groups: Evolux PMMA (111.76 MPa), Structur 2 SC (87.34 MPa), and Cosmos Temp (56.83 MPa). No significant difference (p < 0.05) was observed between the Vickers hardness values of Structur 2 SC (33.37 VHN) and Evolux PMMA (29.11 VHN); however, both materials were statistically superior to Cosmos Temp (10.90 VHN). Conclusion: While the mechanical properties of the milled resin were superior or similar to those of the bisacrylic resin, the 3D-printed resin was statistically inferior to both the milled and bis-acrylic resins

Avaliação in vitro da razão base/topo de dureza e da resistência de união push-out entre uma resina composta contendo diatomita e uma resina composta bulk-fill / In vitro evaluation of the base/top hardness ratio and push-out bond strength between a diatomite-containing composite resin and a bulk-fill composite resin

A escassez de dados científicos que validem os benefícios da diatomita para as propriedades físicas da resina composta Zirconfill® torna imperioso a realização de novos estudos, principalmente no tocante a utilização dessa resina contendo diatomita em restaurações semidiretas. Objetivo: Avaliar in vitro a polimerização e resistência de união entre uma resina composta contendo diatomita e de uma resina composta bulk-fill após 24 horas e após 06 meses de envelhecimento em água. Materiais e métodos: Foram utilizados 28 incisivos bovinos para produzir cavidades dentinárias cônicas (4,8 mm de diâmetro maior x 2,8 mm de diâmetro menor x 4 mm de espessura) e fator C de magnitude 3,1. Esses preparos cavitários (n=28) foram restaurados com as resinas compostas Filtek™ One Bulk-fill (BF) (3M ESPE) ou Zirconfill ® (ZF) (BM4), através da técnica semidireta, utilizando o sistema adesivo Single Bond Universal (3M ESPE) e o cimento resino dual Relyx™ Ultimate (3M ESPE). A análise da polimerização foi realizada através da razão base/topo (B/T) de dureza Vickers. E a resistência de união RU foi realizada através do teste de extrusão push-out em máquina de ensaio universal. As amostras foram armazenadas em água destilada a 37 ºC por 24 horas ou 06 meses, mas apenas a RU avaliou as amostras após 06 meses de envelhecimento. Os dados da B/T e da RU foram submetidos à análise de variância (ANOVA) a um e a dois critérios, respectivamente, com pós-teste de Tukey (p <0.05). Resultados: Não houve diferença estatisticamente significativa entre as resinas compostas na B/T. Para a RU, a resina composta ZF mostrou valores maiores do que a resina BF em ambos os tempos avaliados. Não houve diferença estatisticamente significativa de nenhuma resina na avaliação ao longo do tempo. Conclusão: A resina composta contendo diatomita mostrou-se promissora quando utilizada em restaurações semidiretas, visto que obteve resultados similar e até superior a resina composta bulk-fill (AU).

The scarcity of data validating scientific diatomite benefits for physical properties of Zirconfill® resin composite makes essential to develop new studies, especially regarding the use of this resin composite containing diatomite in semi-direct restorations. Aim: To evaluate in vitro the cure and bond strength between a resin composite containing diatomite and a bulk-fill resin composite after 24 hours and after 06 months of water storage. Materials and methods: Twenty-eight bovine incisors (n=28) were used to produce conical dentinal cavities (4,8 mm of larger diameter x 2,8 mm of smaller diameter x 4 mm of thickness) and C-factor of magnitude 3.1. These cavities were restored with Filtek™ One Bulk-Fill (BF) (3M ESPE) or Zirconfill® (ZF) (BM4) resin composites, through the semi-direct technique, using Scotchbond™ Universal (3M ESPE) adhesive system and Relyx™ Ultimate (3M ESPE) dual resin cement. The cure analysis was performed through bottom-to-top (B/T) ratio of vickers hardness, while bond strength (RU) was performed through the push-out test in a universal testing machine. The specimens were stored in distilled water at 37 ºC for 24 hours or 06 months, but only RU analyzed the specimens after 06 months aging. B/T and RU data were, respectively, submitted to one-way and two-way analysis of variance (ANOVA) with Tukey's post-test (p <0.05). Results: There was no statistically significant difference between the composite resins in B/T. For RU, the ZF composite resin showed higher values than the BF resin at both evaluated times. However, there was no statistically significant difference in resin composites over time. Conclusion: The resin composite containing diatomite showed promise when used in semi-direct restorations since it obtained similar or even superior results to bulk-fill resin composite (AU).

Influência do clareamento dentário de consultório na dureza superficial de resinas compostas: um estudo in vitro / Influence of in-office tooth whitening on the surface hardness of composite resins: An In Vitro Study

O estudo objetivou avaliar a dureza superficial de três resinas compostas (Filtek Z350 - 3M ESPE, Zirconfil - TECHNEW, Vitra ­ FGM), após processo de clareamento dental de consultório a base de peróxido de Hidrogênio a 40%. Foram confeccionados 60 corpos de prova, com espessuras de 6,0 x 2,0 mm, sendo 20 corpos de cada material restaurador (n=20). Após processo de acabamento e polimento, os espécimes foram divididos aleatoriamente em dois grupos para cada material restaurador (n=10), onde o grupo controle G1-C, foi mantido em saliva artificial e o grupo experimental G2-E, foi submetido ao gel clareador de consultório a base de peróxido de hidrogênio a 40% de acordo com a indicação do fabricante. O teste de dureza utilizado foi o de Vickers. Para cada corpo de prova, foram realizadas quatro leituras consecutivas e equidistantes, com uma carga de 300g de força durante 15s. Os valores de dureza para resinas testadas foram estatisticamente mais elevadas no grupo controle, do que no grupo teste. Sendo que a maior diferença nos valores das médias entre os grupos ocorreu na resina Z350XT e para a margem de erro fixada (5%) se comprova diferença significativa (p < 0,05) entre os grupos teste e controle para cada resina. O uso do peróxido de hidrogênio 40% pela técnica de consultório, promoveu mudanças significativas na dureza superficial das resinas testadas. Além disso, a resina Z350XT apresentou dureza superior as demais resinas, porém foi a mais afetada pelo agente clareador (AU).

The study aimed to evaluate the surface hardness of three composite resins (Filtek Z350 - 3M ESPE, Zirconfil - TECHNEW, Vitra - FGM), after an in-office tooth whitening process using 40% hydrogen peroxide. Sixty specimens were made, with thicknesses of 6.0 x 2.0 mm, with 20 specimens of each restorative material (n=20). After finishing and polishing, the specimens were randomly divided into two groups for each restorative material (n=10), where the control group G1-C was maintained in artificial saliva and the experimental group G2-E was subjected to gel in-office bleaching agent based on 40% hydrogen peroxide, according to the manufacturer's instructions. The hardness test used was the Vickers hardness test and for each specimen, four consecutive and equidistant readings were performed, with a load of 300g of force for 15s. Hardness values for tested resins were statistically higher in the control group than in the test group. The greatest difference in mean values between the groups occurred in the Z350XT resin and for the fixed margin of error (5%) there is a significant difference (p < 0.05) between the test and control groups for each resin. The use of 40% hydrogen peroxide by the in-office technique promoted significant changes in the surface hardness of the tested resins. In addition, the Z350XT resin presented higher hardness than the other resins, but was the most affected by the bleaching agent (AU).

Comparative evaluation of fiber-reinforced, bulk-fill and conventional dental composites: Physical characteristics and polymerization properties.

BACKGROUND: Resin composites have various applications. At the same time, they have some drawbacks, such as polymerization shrinkage. Conventional composites are polymerized in 2-mm thick layers. However, in posterior restoration, the 2-mm depth of cure is not satisfactory. To find a solution, resin composites have been vastly improved in terms of fillers, matrix and initiators. OBJECTIVES: To evaluate polymerization properties and physical characteristics of fiber-reinforced composites and compare them with bulk-fill composites that are designed for large posterior restorations. MATERIAL AND METHODS: Samples were prepared from each resin composite. The 3-point bending test was performed to evaluate the flexural strength of all composites. The depth of cure of the composite from 1 mm to 4 mm of depth was analyzed using Vickers hardness test (VHN). To analyze the degree of conversion, Fourier-transform infrared spectroscopy (FTIR) of the top and bottom surfaces of the samples with 4-mm thickness was calculated. The data were analyzed using one-way analysis of variance (ANOVA) test followed by post hoc test (95% confidence interval (95% CI)). RESULTS: The Filtek showed the highest flexural strength followed by everX and X-tra fil. At 1-mm depth, X-tra fil had the highest and Gradia had the lowest microhardness. At the 4-mm depth, the microhardness trend was as follows: everX > Filtek > X-tra fil > Gradia > Beautifil. The everX composite had the lowest reduction of the degree of conversion at 4-mm thickness, which showed a significant difference in comparison with Filtek, Gradia and X-tra fil composites. CONCLUSIONS: Based on the results of our study, it can be concluded that the fiber-reinforced composite everX showed more favorable results regarding polymerization properties, such as the degree of conversion and the depth of cure. However, the flexural strength results in Filtek were better than those in everX.

Preparation of medical Mg-Zn alloys and the effect of different zinc contents on the alloy.

In recent years, along with the development and application of magnesium alloys, magnesium alloys have been widely used in automotive, aerospace, medicine, sports, and other fields. In the field of medical materials, magnesium not only has the advantage of light weight, high strength, and a density similar to that of human bone, but also has good biocompatibility and promotes the growth of human bone. However, the mechanical properties and corrosion resistance of magnesium alloys need to be further improved to meet the requirements for human biodegradable implants. In this study, three alloys (mass fractions: Mg-10Zn, Mg-20Zn, and Mg-30Zn (wt.%)) were prepared using powder metallurgy by homogeneously mixing powders of the above materials in a certain amount with magnesium as the substrate through the addition of zinc elements, which also have good biocompatibility. The effect of zinc on the microstructure, mechanical properties, wear performance, and corrosion resistance of magnesium-zinc alloys was studied when the zinc content was different. The results show that compared with the traditional magnesium alloy using powder metallurgy, prepared magnesium alloy has good resistance to compression and bending, its maximum compressive stress can reach up to 318.96 MPa, the maximum bending strength reached 189.41 MPa, and can meet the mechanical properties of the alloy as a human bone-plate requirements. On the polarization curve, the maximum positive shift of corrosion potential of the specimens was 73 mv and the maximum decrease of corrosion-current density was 53.2%. From the comparison of the above properties, it was concluded that the three prepared alloys of which Mg-20% Zn had the best overall performance. Its maximum compressive stress, maximum bending strength, and corrosion-current density reached 318.96 MPa, 189.41 MPa and 2.08 × 10-5 A·cm-2 respectively, which are more suitable for use as human implant bone splints in human-body fluid environment. The mechanical properties of the sintered Mg-Zn alloys were analyzed using powder-metallurgy techniques, and their microstructure, micromotion wear properties, electrochemical corrosion properties and composition of the physical phases were analyzed and discussed.

Cyclic Fatigue Resistance and Surface Roughness of Rotary NiTi Instruments after Simulated Clinical Use in Curved Root Canals - An Atomic Force Microscopy Study

Abstract Objective: To examine the cyclic fatigue resistance and surface topography of TruNatomy and ProTaper Gold nickel-titanium rotary files and evaluate the presence of alterations to surface topography following instrumentation in simulated curved canals. Material and Methods: Twenty-four nickel-titanium instruments, twelve each of TN and PTG file systems, were evaluated for cyclic fatigue resistance. The rotary files were rotated in a simulated root canal with standardized diameter, angle of curvature, and radius of curvature in a custom-made cyclic fatigue testing device until the instrument fracture occurred. The time to fracture for each instrument was recorded with a stopwatch; in seconds in each group. Fractured instruments were subjected to atomic force microscopy analysis measuring the average roughness and the root mean square values to investigate surface features of endodontic files. Mean values and standard deviation were calculated. Data were analyzed using the Mann-Whitney U test. Results: Time to fracture was marginally higher in PTG instruments than in the TN file systems. PTG files exhibited higher surface roughness when compared with TN files (p<0.05). Conclusion: TN file system had a higher cyclic fatigue resistance than PTG. Cyclic fatigue causing file breakage did affect the surface topography of the files. PTG files showed a higher surface porosity value than the TN files (AU).

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.

O método de fotopolimerização é capaz de influenciar nos valores de microdureza das resinas compostas? Um estudo in vitro / Is the photopolimerization method able to influence on the microhardness values of composite resins? An in vitro study

Introdução: a inovação dos métodos de fotopolimerização foi proposta na tentativa de diminuir o estresse de contração de polimerização das resinas compostas e proporcionar maior conforto ao paciente, reduzindo o tempo de atendimento odontológico. Objetivo: avaliar a microdureza de duas resinas compostas nanoparticuladas submetidas a diferentes técnicas de polimerização. Material e método: quarenta espécimes foram divididos em quatro grupos (n=10) da seguinte forma: Filtek Z350 XT® + técnica imediata (GI); Filtek One Bulkfill® + técnica imediata (GII); Filtek Z350 XT® + técnica de pulso tardio (GIII); Filtek One Bulkfill® + técnica de pulso tardio (GIV). Após o armazenamento em água destilada à temperatura ambiente, os corpos de prova foram direcionados para a medição de microdureza. Utilizou-se teste T para comparação de técnicas e teste Two-Way ANOVA para calcular os efeitos das resinas compostas, técnicas de polimerização e interações referentes à variável dependente (p ≤0,05). Resultado: a resina Filtek Z350 XT® apresentou maior dureza na técnica imediata (GI - 312,45 ± 64,37) e pulso tardio (GIII - 244,50 ± 75,63) comparado à resina Filtek One Bulkfill®, em ambas as técnicas. Observaram-se maiores valores de dureza referentes à técnica imediata, com diferença estatística significativa em relação à resina testada (p = 0,04 - Filtek Z350 XT®; p = 0,03 - Filtek One Bulkfill®). Ambos os fatores isolados (resina e técnicas) apresentaram efeito nos valores de microdureza (p = 0,02 e p < 0,01, respectivamente). Conclusão: a técnica convencional demonstrou atingir maiores valores de dureza quando comparada à técnica de polimerização alternativa.

Introduction: the innovation of photopolymerization methods was proposed in an attempt to reduce the polymerization shrinkage stress of composite resins and also provide more comfort to patient reducing the chair time. The aim of this in vitro study was to assess the microhardness of two nanofilled composite resins subject to different curing techniques. Objective: assess the microhardness of two nanofilled composite resins subject to different curing techniques. Material and method: forty specimens were divided into four groups (N=10) as follows: Filtek Z350 XT® + immediate technique (GI); Filtek One Bulkfill® + immediate technique (GII); Filtek Z350 XT® + delayed pulse technique (GIII); Filtek One Bulkfill® + delayed pulse technique (GIV). After storage in distilled water at room temperature the specimens were assessed for microhardness measurement. T-test was used for comparison of techniques and two-way ANOVA used to calculate the effects of composite resins, curing techniques and their interactions on dependent variable (p set at 0.05). Result: Filtek Z350 XT® resin presented greater hardness on immediate technique (GI - 312,45 ± 64.37) and delayed pulse (GIII - 244,50 ± 75.63) compared to Filtek One Bulkfill® under both techniques. Overall, it was observed greater hardness values under immediate technique with a significant statistical difference apart of tested resin (p = 0.04 - Filtek Z350 XT®; p = 0.03 - Filtek One Bulkfill®). Both isolated factors (resin and techniques) presented effect on microhardness values (p = 0.02 and p < 0.01, respectively). Conclusion: the conventional technique demonstrated to reach higher hardness values when compared to the alternative polymerization technique

Influence of fluoride-releasing materials in the inhibition of enamel and dentin demineralization around restorations / Influência de materiais liberadores de flúor na inibição da desmineralização do esmalte e da dentina ao redor de restaurações

Objective: The aim was to evaluate the influence of fluoride-releasing restorative materials in enamel and dentin microhardness. Material and Methods: 40 blocks (5x5x3 mm) from cervical third of human molars received a cavity preparation between the enamel and dentin, and the restorations were subjected to in vitro caries model. Specimens were randomly restored with (n=10): conventional glass ionomer cement (Ketac Cem, 3M ESPE); polyacid-modified composite resin (Ionoseal, VOCO); resin-modified glass ionomer cement (Ionofast, Biodinâmica); or microhybrid composite resin (Filtek Z250, 3M ESPE). The specimens were sectioned longitudinally and enamel and dentin Knoop microhardness were determined at different distances from the restorative material (100, 200 and 300 µm) and depth of surface (20, 40 and 60 µm). The data were submitted to three-way repeated measures ANOVA and Tukey ́s test ( α =0.05). Results: For enamel, the double interactions between material x distance and material x depth were statistically significant. In all depths and distances, the highest values of enamel microhardness were observed for Ketac Cem. In dentin, the materials differed statistically from each other, and Ionoseal obtained higher microhardness values than those found in Ionofast. Conclusion: Conventional glass ionomer cement is more effective in preventing enamel demineralization around restoration followed by the polyacid-modified composite resin. In dentin, the polyacid-modified composite resin obtained better performance than resin-modified glass ionomer cement. (AU)

Objetivo: O objetivo foi avaliar a influência de materiais restauradores liberadores de flúor na microdureza do esmalte e da dentina. Material e Métodos: 40 blocos (5x5x3 mm) do terço cervical de molares humanos receberam preparo cavitário entre esmalte e dentina, e após a restauração foram submetidas a um modelo in vitro de cárie. As amostras foram restauradas aleatoriamente com (n=10): cimento de ionômero de vidro convencional (Ketac Cem, 3M ESPE); resina composta modificada por poliácidos (Ionoseal, VOCO); cimento de ionômero de vidro modificado por resina (Ionofast, Biodinâmica); ou resina composta microhíbrida (Filtek Z250, 3M ESPE). As amostras foram seccionadas longitudinalmente e a microdureza Knoop de esmalte e dentina foi determinada em diferentes distâncias do material restaurador (100, 200 e 300 µm) e profundidade de superfície (20, 40 e 60 µm). Os dados foram submetidos à ANOVA para medidas repetidas de três fatores e teste de Tukey (α =0,05). Resultados: Para o esmalte, as duplas interações entre material x distância e material x profundidade foram estatisticamente significativas. Em todas as profundidades e distâncias, os maiores valores de microdureza do esmalte foram observados para o Ketac Cem. Na dentina, Ionoseal obteve valores de microdureza superiores aos encontrados no Ionofast. Conclusão:O cimento de ionômero de vidro convencional é mais eficaz na prevenção da desmineralização do esmalte ao redor da restauração, seguido pela resina composta modificada por poliácidos. Na dentina, a resina composta modificada por poliácidos obteve melhor desempenho que o cimento de ionômero de vidro modificado por resina. (AU)

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

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

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

Prediction of quality attributes (mechanical strength, disintegration behavior and drug release) of tablets on the basis of characteristics of granules prepared by high shear wet granulation.

High shear wet granulation is commonly applied technique for commercial manufacturing of tablets. Granulation process for tablets manufacturing is generally optimized by hit and trial which involves preparation of granules under different processing parameters, compression of granules and evaluation of the resultant tablets; and adjustment is made in granulation process on the basis of characteristics of tablets. Objective of the study was to optimize the process of high shear wet granulation and prediction of characteristics of tablets on the basis of properties of granules. Atenolol granules were prepared by high shear wet granulation method, using aqueous solution of polyvinyl pyrrolidone (PVP k-30) as binder. Concentration of binder solution and granulation time were taken as process variables, both studied at three levels. Different combinations of process variables were determined by Design Expert software. Granules were evaluated for different parameters on the basis of SeDeM-ODT (Sediment Delivery Model-Oro Dispersible Tablets) expert system. Granules from all the trials were compressed using round (10.5 mm) flat faced punches at compression weight of 250 mg/tablet. Tablets were evaluated of different quality control parameters as per USP. Results showed that both the process variables had positive effect on mechanical strength of tablets and negative effect on disintegration and dissolution rate. Granule prepared with highest level of binder concentration (15%) and highest granulation time (60 sec) resulted in tablets with highest crushing strength (11.8 kg), specific crushing strength (0.328 kg/mm2), tensile strength (0.208 kg/mm2), lowest value of friability (0.19%) and highest disintegration time (10.9 min), as predicted from granules characteristics on the basis of SeDeM-ODT expert system. Drug release from Trial-13 (processed under highest level of both process parameters) was also lower than rest of the trials. It is concluded from the study that quality characteristics of tablets can be predicted from granules characteristics using SeDeM-ODT expert system. Furthermore, SeDeM-ODT expert system can also be used for optimization of the process of high shear wet granulation.

Application of Er,Cr:YSGG laser versus photopolymerization after silver diamine fluoride in primary teeth.

Examine the effect of dental curing light and laser treatments applied after Silver Diamine Fluoride (SDF) on dentin hardness in carious primary molars. This in-vitro study consisted of 30 extracted primary molars with caries extending into dentin without pulpal involvement. The collected teeth were randomly divided into three groups: group 1: received SDF then Sub-ablative low-energy of Er,Cr:YSGG laser, group 2: received SDF followed by application of curing light for 40 s, group 3: had SDF treatment only. In all groups, 38% Ag (NH3)2F SDF was used. Vickers hardness test was performed on sound dentin below carious lesion. Kruskal-Wallis Test was used to determine the mean difference in dentin hardness of the groups at 5% Significance level using SPSS software. Surface hardness of sound dentin below the carious lesion was statistically significantly higher in the laser + SDF group (891.24 ± 37.33 kgf/mm2) versus the two other groups (Light cure + SDF = 266.65 ± 90.81 kgf/mm2 and SDF only = 117.91 ± 19.19 kgf/mm2) with p-value ≤ 0.001. Although Photopolymerization of SDF increases the surface hardness of sound dentin below the carious lesion, applying laser after SDF has the highest surface hardness due to the laser's sub-ablation of dentin.

Biomechanical Properties and Biocompatibility of Implant-Supported Full Arch Fixed Prosthesis Substructural Materials.

OBJECTIVES: The purpose of this study was to investigate the fracture resistance, biocompatibility, hardness, and transverse strength of non-precious metal alloy (chromium-cobalt; Cr-Co), titanium (Ti), zirconia (Zr), polymethylmethacrylate (PMMA), and polyetheretherketone (PEEK) when employed as substructure materials according to the implant supported full arch fixed prosthesis treatment concept. MATERIALS AND METHODS: In total, 150 Cr-Co, Ti, Zr, PMMA, and PEEK samples (n = 30 per material) measuring 25 × 2 × 2 mm in size were produced. Of the samples, 50 (n = 10 for each material, all having dimensions of 6 × 3 mm) were subjected to biocompatibility tests. The Vickers hardness test and three-point bending test were performed; fracture resistance measurements were taken and the biocompatibility of the samples was evaluated by the XTT assay. RESULTS: Vickers hardness was highest for Zr (p < 0.05). PEEK and PMMA had the lowest (and similar) fracture resistance values (p < 0.05). Cell proliferation on the surfaces of the materials was similar between PEEK and Zr (p > 0.05), which were the most biocompatible materials. CONCLUSIONS: Within the limitations of this study, the most favorable materials in terms of biocompatibility were found as PEEK and Zr. When biomechanical properties are evaluated, the most durable materials can be specified as Cr-Co and Zr. Also, further studies are needed to improve material stability.

Effect of Surface Wetting Resin on the Color Stability and Microhardness of Esthetic Composites / Efecto de la resina humectante de superficies sobre la estabilidad del color y la microdureza de resinas compuestas estéticas

ABSTRACT: Objective: The aim of this study was to evaluate and compare the effects of the superficial application of two different modeling resins on the surface microhardness and discoloration of composite resins. Material and Methods: The present study used two different composites and modeling resins. The composites were placed in plastic molds. Subsequently, the modeling resins were applied on the surface of the two composite groups. The microhardness and color pertaining to all the groups were evaluated. The current study used the One-Way ANOVA and Kruskal Wallis tests, in order to perform the statistical evaluation (p<0.05). Results: The present study compared the microhardness pertaining to the groups and the highest microhardness values were observed in the Estelite Asteria group (none), whereas the lowest values were observed in the GC Essentia group (Ultradent). Moreover, the current study evaluated the color stability and the greatest discoloration was observed in the control group of the GC Essentia group, whereas the least discoloration was observed in the Estelite Asteria group that included the samples prepared using Ultradent Wetting Resin. Conclusions: The results of the present study demonstrated that the use of modeling resins, which facilitate the placement of composite resins, reduced the microhardness and discoloration of composite resins. The aforementioned effect can be attributed to the variations in the structure of the filling. However, further studies are warranted to support and verify the results of the current study.

RESUMEN: Objetivo: El objetivo del presente estudio fue evaluar y comparar los efectos de la aplicación superficial de dos resinas humectantes sobre la microdureza superficial y la decoloración de las resinas compuestas. Material y métodos: El presente estudio utilizó dos resinas humectantes y resinas de modelado diferentes. Las resinas compuestas se colocaron en moldes de plástico. Posteriormente, se aplicaron las resinas humectantes sobre la superficie de los dos grupos. Se evaluó la microdureza y el color de todos los grupos. El presente estudio utilizó las pruebas One-Way ANOVA y Kruskal Wallis, para realizar la evaluación estadística (p<0.05). Resultados: Los valores más altos de microdureza se observaron en el grupo Estelite Asteria, mientras que los menores valores se observaron en el grupo GC Essentia (Ultradent). La mayor decoloración se observó en el grupo control o el grupo GC Essentia, mientras que la menor decoloración se observó en el grupo Estelite Asteria con Ultradent Wetting Resin. Conclusiones: Los resultados del presente estudio demostraron que el uso de resinas humectantes, que facilitan la colocación de resinas compuestas, redujo la microdureza y decoloración de las resinas compuestas. El efecto mencionado anteriormente se puede atribuir a las variaciones en la estructura del relleno. Sin embargo, se necesitan más estudios para respaldar y verificar los resultados del presente estudio.

Microdureza de dos materiales endodónticos a base de silicato de calcio. Un ensayo ex vivo / Surface microhardness of two calcium silicate-based endodontic materials. An ex vivo assay

esumen Objetivo: Comparar la microdureza de dos materiales endodónticos a base de silicato de calcio: MTA Densell Endo Sealer y TotalFill BC Sealer. Materiales y métodos: Se evaluó la microdureza de los selladores MTA Densell Endo Sealer (Grupo 1, n=5) y To- talFill BC Sealer (Grupo 2, n=5) contenidos en cilindros de dentina de vacuno a los 14 días posteriores a su fraguado. La medición se realizó a temperatura ambiente mediante la prue- ba de indentación Vickers. Se realizaron cinco indentaciones por probeta con una carga de 100 g durante 10 s cada una. Las mediciones se convirtieron a valores de dureza Vickers (HV) y los promedios de los valores HV de cada grupo se compararon por medio de la prueba t de Student con un nivel de significación de P <0,05. Resultados: A los 14 días, luego del fraguado, la mi- crodureza de MTA Densell Endo Sealer fue significativamen- te mayor (P=0,001) que la de TotalFill BC Sealer. Conclusiones: Los resultados sugieren que a causa de su dureza la remoción de MTA Densell Endo Sealer puede resultar dificultosa cuando está indicado un retratamiento (AU)

Aim: To compare the microhardness of two silicate-based endodontic materials: MTA Densell Endo Sealer and Total Fill BC Sealer. Materials and methods: Samples of MTA Densell Endo Sealer (Group 1, n=5) and Total Fill BC Sealer (Group 2, n=5) contained into cow dentine cylinders were subjected to the Vickers Microhardness Indentation test at room temper- ature and 14 days after setting. Five indentations per sample were performed under a load of 100 g for 10 s. The indenta- tion measurements were converted into hardness values (HV). Mean HV values of each group were compared using the Stu- dent t test at a significance level of P <0,05. Results: 14 days after setting, the microhardness of MTA Densell Endo Sealer was significantly greater (P=0,001) than that of Total Fill BC Sealer. Conclusions: The results of this study suggest that due to its hardness the removal of MTA Densell Endo Sealer could be difficult to perform when a root canal retreatment is indicated (AU)

El esmalte dental bovino como modelo experimental para la investigación en odontología: una revisión de la literatura / Bovine dental enamel as experimental model for research in dentistry. A literature review

El propósito de esta revisión bibliográfica es aportar información actualizada acerca de las características de los dientes bovinos en relación con su uso como sustitutos de dientes humanos en trabajos de investigación. De acuerdo con la información registrada, los dientes bovinos serían excelentes sustitutos de la dentición humana para la realización de ensayos de laboratorio con el esmalte dental como modelo experimental (AU)

The purpose of this bibliographic review is to provide updated information about the characteristics of bovine teeth to be used as substitutes for human teeth in dental research. According to the information recorded, bovine teeth appear to be excellent substitutes for human dentition for conducting laboratory tests, using dental enamel as an experimental model (AU)