Physicochemical properties of flowable composites using isobornyl methacrylate as diluent monomer

Abstract Objective this study sought to evaluate the effect of isobornyl methacrylate (IBOMA) as a diluent monomer on the physicochemical properties of experimental flowable resin composites. Methodology the organic resin matrix of a modal flowable resin composite was formulated with 50 wt.% of bisphenol-A-glycidyl methacrylate (Bis-GMA) and 50 wt.% of a diluent monomer, in which IBOMA was used as a combining or substituent diluent monomer to triethylene glycol dimethacrylate (TEGDMA). The resin matrices were filled with 55 wt.% particles, of which 10 wt.% was 0.05-μm fumed silica, and 45 wt.% was 0.7-μm BaBSiO2 glass. Polymerization shrinkage stress (PSS; n=10), degree of conversion (DC; n=3), maximum rate of polymerization (Rpmax; n=3), film thickness (FT; n=10), sorption (Wsp; n=10), solubility (Wsl; n=10), flexural strength (FS; n=10), flexural modulus (FM; n=10), Knoop microhardness (KH; n=10), and microhardness reduction after chemical softening (HR; n=10) were evaluated. Data were analyzed using one-way ANOVA, followed by Tukey's test (α=0.05; β=0.2). Results the results showed that the substitution or addition of IBOMA reduced FT (p=0.001), PSS (p=0.013), Rpmax (p=0.001), DC (p=0.001), FM (p=0.006) Wsp (p=0.032), and Wsl (p=0.021). However, when used as a complete substituent, IBOMA demonstrated significantly lower FS (p=0.017) and KH (p=0.008), while TEGDMA demonstrated significantly lower HR (p=0.022). Conclusion the flowable composite containing IBOMA combined with TEGDMA showed no effect in KH and FS and effectively reduced the PSS, RP, FT, Wsp, and Wsl. However, it showed a reduction in DC, FS, and an increase in HR.

Bond strength comparison among 10-MDP-containing and non-10-MDP-Containing adhesives in different degrees of dental fluorosis / Comparación de fuerza de unión entre adhesivos que contienen y no contienen 10-MDP en diferentes grados de fluorosis dental

Dental fluorosis can cause changes in the enamel surface, conditioning its functionality and esthetics. The application of dental adhesives is a treatment option; however, their use on fluorotic teeth can result in limitations. The aim of this study was to compare the shear bond strength of two different adhesives, one with 10-MDP and one without 10-MDP, in different degrees of dental fluorosis.This is an in vitro study on dental enamel samples, a total of 180 samples with the inclusion criteria were treated, randomly divided into two groups of 90, according to the type of dental adhesive, where each group was again divided into three groups of 30 samples, representing different degrees of dental fluorosis according to the Thylstrup-Fejerskov index (Group I: TF1 and TF2; Group II: TF3; Group III: TF4). Normality tests, two-factor ANOVA, and post-hoc tests were used to determine differences between the groups, with a significance level of 95%. As results, a statistically significant difference was shown between the use of dental adhesive with 10-MDP and the three groups of dental fluorosis (p=0.011), in addition, a Tukey post-hoc test on the groups treated with 10-MDP adhesive revealed a statistically significant difference between group I versus group II, and group I versus group III, (p=<0.05). It is concluded that the use of adhesive systems with 10-MDP presents a better shear bond strength on enamel with dental fluorosis grades I and II in the Thylstrup-Fejerskov index.

La fluorosis dental puede ocasionar cambios en la superficie del esmalte, condicionando su funcionalidad y estética, la aplicación de adhesivos dentales es una opción de tratamiento, sin embargo, su uso en dientes fluoroticos puede resultar en limitaciones. El objetivo de este estudio consistió en comparar la fuerza de adhesión a la cizalladura de dos diferentes adhesivos, uno con 10-MDP y otro sin 10-MDP, en diferentes grados de fluorosis dental. Se trata de un estudio in vitro en muestras de esmalte dental, un total de 180 muestras con los criterios de inclusión fueron tratadas, aleatoriamente divididas en dos grupos de 90, de acuerdo al tipo de adhesivo dental, donde cada grupo fue dividido nuevamente en tres grupos de 30 muestras, representando diferentes grados de fluorosis dental según el índice de Thylstrup- Fejerskov (Grupo I: TF1 y TF2; Grupo II: TF3; Grupo III: TF4). Para determinar diferencias entre los grupos se utilizaron pruebas de normalidad, ANOVA de dos factores, y pruebas post-hoc, con un nivel de significancia de 95%. Como resultados, se mostró una diferencia estadísticamente significativa entre el uso de adhesivo dental con 10- MDP y los tres grupos de fluorosis dental (p=0.011), además, una prueba post hoc de Tukey sobre los grupos tratados con adhesivo 10-MDP revelaron una diferencia estadísticamente significativa entre el grupo I frente al grupo II, y el grupo I frente al grupo III, (p=<0.05) Se concluye que el uso de sistemas adhesivos con 10-MDP presentan una mejor resistencia de adhesión al cizallamiento en esmalte con grados de fluorosis dental I y II en el índice de Thylstrup-Fejerskov

Research progress of dental self-healing microcapsule materials / 口腔医学

@#The self-healing microcapsule material is one of the smart materials that can self-identify and self-heal microcracks. Adding microcapsules to dental resin composites can resist generation of microcracks and prolong service life of resin restorations. In this literature, the overview of self-healing microcapsule materials, the combined application of self-healing microcapsule materials and other modified materials, the silanization treatment of dental self-healing microcapsules, the dynamic mechanics, fatigue and aging studies on self-healing dental resins were comprehensively presented and reviewed. In addition, prospects of dental self-healing microcapsule materials were also discussed.

Rehabilitación estética mínimamente invasiva en diente anterior afectado por hipoplasia de esmalte: Reporte de caso clínico / Minimally Invasive Restoration in Anterior Teeth Affected by Enamel Hypoplasia: Clinical Case Report

RESUMEN La preservación de tejido dental sano contribuye a la práctica de una Odontología conservadora, permitiendo la aplicación de los principios biológicos y mecánicos de una forma más predecible. Las preparaciones cavitarias mínimamente invasivas son el complemento de la correcta selección de materiales adhesivos y de resina compuesta. La correcta aplicación de un protocolo adhesivo nos proporcionará resultados estéticos imperceptibles y un longevo desempeño clínico.

ABSTRACT The preservation of healthy dental structures contributes to the practice of a conservative dentistry. This concept involves the implementation of biological and mechanical principles in a more predictable manner. Minimally invasive cavity preparations are the complement to the selection of adhesive and composite resin materials. The correct application of an adhesive protocol will provide imperceptible aesthetic restorations and adequate clinical performance.

Interfacial properties and bottom/top hardness ratio produced by bulk fill composites in dentin cavities

Abstract The aim of this study was to evaluate the bond strength, bottom/top hardness ratio, marginal adaptation, and interfacial nanoleakage of regular viscosity bulk fill composites (RVBFC) and regular viscosity traditional composites (RVTC). Two RVBFC (Filtek Bulk Fill and Aura Bulk Fill) and two RVTC (Filtek Z250XT and Aura) were assessed. Forty conical cavities (4.8×2.8×4.0) were prepared in bovine dentin and restored with composites (n=10). After 24h in water, marginal adaptation was evaluated by staining with a caries detector. The top and bottom surfaces of the conical restorations were stained for five seconds and the gap percentage in the composite/dentin interface was determined using digital images on a measurement program (ImageTool). The Vickers microhardness was measured and the bottom/top microhardness ratio (B/T) was determined. Push-out bond strength test was performed in a universal testing machine (0.5mm/min) and failure modes were evaluated in a stereomicroscope (20×). Other specimens (n=3) were produced for interfacial nanoleakage evaluation. Data were analyzed using one and two-way ANOVA and Tukey's test (α=0.05). The gap percentage was higher in the bottom compared to the top. The B/T ratio of the Aura Bulk Fill was statistically lower than other composites. Push-out bond strength were similar among composites. The RVBFC presented lower nanoleakage than the RVTC in the bottom of the conical restoration and there was no difference among the materials in the top surfaces. In conclusion, Filtek Bulk Fill performed better than Aura Bulk Fill regarding the analyzed properties.

Resumo O objetivo deste estudo foi avaliar a resistência de união, razão base/topo de microdureza, adaptação marginal e nanoinfiltração interfacial de resinas compostas bulk fill (BF) e tradicional (RT) de viscosidade regular.: Duas BF (Filtek Bulk Fill e Aura Bulk Fill) e duas RT (Filtek Z250XT e Aura) foram testados. Quarenta cavidades cônicas (4,8×2,8×4,0) foram preparadas em dentina bovina e restauradas com os compósitos (n=10). Depois de 24 h em água, a adaptação marginal foi avaliada por meio do corante com detector de cárie. As faces de topo e base das restaurações cônicas foram coradas por cinco segundos e a porcentagem de fendas na interface compósito/dentina foi determinada utilizando-se imagens analisadas num programa (ImageTool). A microdureza Vickers foi mensurada e a razção base/topo de microdureza (B/T) foi determinada. A resistência de união por push-out foi executada numa máquina de ensaios universal (0,5mm/min) e o padrão de fratura avaliado num estereomicroscópio (20x). Espécimes adicionais (n=3) foram confeccionados para avaliação da nanoinfiltração interfacial. Os dados foram analisados por meio de ANOVA a dois fatores e teste de Tukey (a=0,05). A porcentagem de fendas foi maior na base que no topo. A B/T da Aura Bulk Fill foi estatisticamente menor que os demais compósitos. A resistência de união por push-out foi similar entre os compósitos. As BF apresentaram menos nanoinfiltração que as RT na base das restaurações cônicas e não houve diferenças entre os materiais no topo. Conclui-se que a Filtek Bulk Fill comportou-se melhor que a Aura Bulk Fill considerando-se as propriedades analisadas.

Solvent degradation and polymerization shrinkage reduction of resin composites using isobornyl methacrylate

Abstract The aim of this study was to use the isobornyl methacrylate (IBOMA) as a combining or substituent diluent monomer in the resin matrix of dental resin composites. Thus, the resin matrix was formulated with 60 wt% of BisGMA and 40 wt% of diluent monomers. TEGDMA as the only diluent monomer was used as control with 40 wt%, while total substitution of TEGDMA was done with 40 wt% of IBOMA. The combination of IBOMA and TEGDMA was done with 20 wt% of each monomer. To the resin matrix, 65 wt% of filler particles was added. Degree of conversion (DC) using FT-IR, flexural strength (FS), flexural modulus (FM), polymerization shrinkage by gap formation (GF), Knoop hardness (KH) and solvent degradation (SD) were evaluated. Data were analyzed using ANOVA and Tukey's test (α=0.05; b=0.2). The results showed that reducing or substituting TEGDMA using IBOMA did not affect the DC (0.085), FS (p=0.886) or FM (p=0.414). Also, when IBOMA was used, lower GF was found in comparison to the control containing only TEGDMA as the diluent monomer (p=0.032). However, even though all composites presented reduction in KH during the SD test, the combination of IBOMA and TEGDMA showed similar reduction in KHN in comparison to the control group (p=0.001), while the total substitution of TEGDMA with IBOMA decreased KHN after SD (p=0.041). Thus, the combination of IBOMA and TEGDMA seem to reduce SD and GF without affecting the properties of resin composites.

Resumo O objetivo nesse estudo foi utilizar o isobornil metacrilato (IBOMA) como monômero combinante ou substituinte na matriz resinosa de resinas compostas odontológicas. Para tanto, a matriz resinosa foi formulada com 60 % em peso de BisGMA e 40 % em peso de monômero diluente. O TEGDMA foi utilizado como único monômero diluente para o grupo controle com 40 % em peso, enquanto a substituição total de TEGDMA foi feita com 40 % em peso de IBOMA. Na combinação de IBOMA e TEGDMA foram utilizados 20 % em peso de cada monômero. Na matriz resinosa, 65 % em peso de partículas de carga foi adicionado. O grau de conversão (GC) utilizando FT-IR, a resistência flexural (RF), o módulo flexural (MF), a contração de polimerização por formação de gap (FG) utilizando Microscopia Confocal à Laser, a Dureza Knoop (DK) e a degradação em solvente (DS) foram avaliados. Todos os dados foram analisados utilizando ANOVA e teste de Tukey (α=0.05; b=0.2). Os resultados demonstraram que reduzindo ou substituindo o TEGDMA utilizando o IBOMA não afetou o GC (p=0.085), a RF (p=0.886) ou o MF (p=0.414). Ainda, quando o IBOMA foi utilizado como um monômero combinante ou substituinte, menor FG foi observada em comparação ao controle contendo apenas TEGDMA como monômero diluente (p=0.032). Contudo, apesar de todos os compósitos terem apresentados redução na DK durante o teste de DS, a combinação de IBOMA e TEGDMA demonstrou uma redução na DK similar ao grupo (p=0.001), enquanto a substituição total de TEGDMA com IBOMA reduziu a DK após DS (p=0.041). Dessa forma, a combinação do IBOMA e TEGDMA parece reduzir DS e a FG sem afetar as propriedades de resinas compostas.

Influence of different types of light curing units and photoinitiators in microhardness and color of composite resins after immersion in wine / Influencia dos diferentes tipos de unidade fotoativadoras e fotoiniciadores na microdureza e cor de resinas compostas após imersão em vinho

Objective: the aim of this study is to evaluate the microhardness and color change (∆E) of composite resins, that were light-cured with different LEDs, after being immersed in a staining drink. Material and Methods: Two composite resins with Lucerin-TPO (Tetric N-Ceram/ Vit-l-escence) and camphorquinone (Filtek Z350) were selected. The specimens (n=120) were prepared and lightcured with LED of monowave or polywave lightemitting diode (LED) devices. Microhardness and color evaluations were measured before and after immersion in staining drink. Microhardness data were evaluated by Kruskal-Wallis test, MannWhitney and Wilcoxon tests. Color changes were evaluated by two-way analysis of variance (ANOVA) and Tukey test (p ≤ 0.05). Results: No statistically significant difference between the two generations of LEDs was found for microhardness data. Regarding the ∆E, a statistical difference between the two LEDs was observed for Tetric NCeram and Filtek Z350. Conclusion: The compostion of composites appears to have more influence on analyses than the type of LEDs used. A decreased microhardness occurred to Vit-lescence for monowave and to Filtek Z350 for both LED devices. A clinically perceptible color change was observed for Tetric-N Ceram and Filtek Z350 when polywave LED were used. (AU)

Objetivo: o objetivo deste estudo foi aviliar a microdureza e alteração de cor (∆E) de resinas compostas, fotoativadas com diferentes LEDs, imergidas em bebidas pigmetadas. Material e métodos: Duas resinas compostas com Lucerina-TPO (Tetric N-Ceram/ VIt-l-essence) e canforoquinona (Filtek Z350) foram selecionadas. Os espécimes (n=120) foram preparados. Os mesmos foram fotopolimerizados com LED monowave ou polywave. Microdureza e cor foram avaliadas antes e após a imersão em bebidas pigmentadas. Os dados de microdureza foram avaliados pelos testes de Kruskal-Wallis, Mann-Whitney e Wilcoxon. As alterações de cor foram avaliadas por análise de variância a dois critérios (ANOVA) e Tukey (p ≤ 0,05). Resultados: Não foi encontrada diferença estatística entre as duas gerações de LEDs, para os dados da microdureza. Quanto ao ∆E, foi encontrada diferença estatisticamente significante entre os dois LEDs, sendo observadas na Tetric N-Ceram na FIltek Z350. Conclusão: A composição das resinas compostas parece ter mais influencia nas análises do que o tipo de LEDs. Uma redução na microdureza ocorreu para Vit-lescence para monowave e para Filtek Z350 para ambos os dispositivos LED. Uma mudança de cor clinicamente perceptível foi observada em Tetric-N Ceram para polywave e Filtek Z350 para ambos os dispositivos LED. (AU)

Color changes caused by reduction on the dentin shade composite thickness

Resumo Este estudo objetivou determinar o limiar de redução na espessura do compósito de cor da dentina necessário para resultar em mudanças de cor perceptíveis e aceitáveis em restaurações simuladas. Três sistemas de compósitos (Charisma Diamond, IPS Empress Direct e Filtek Z350 XT) foram avaliados utilizando corpos-de-prova cilíndricos construídos com cores de dentina e esmalte. A opacidade dos compósitos foi avaliada usando cilindros de 1,0 mm de espessura sobre fundo preto e branco. Uma cor inicial padrão foi estabelecida para cada sistema pela combinação de esmalte de 1,0 mm de espessura com 3,0 mm de cilindros de resina na cor de dentina sobre um fundo escuro (n = 9). Em seguida, foram calculadas as alterações de cor (∆E00) causadas por reduções sequenciais de 0,1 mm nos cilindros de resina na cor de dentina. Mudanças de opacidade em cilindros na cor de dentina e cilindros combinados de esmalte e dentina foram também avaliadas após cada redução de espessura. Regressão polinomial foi realizada com médias de ∆E00 em função da espessura dos cilindros na cor de dentina; e os limiares de aceitabilidade (∆E00 = 1,77) e perceptibilidade (∆E00 = 0,81) foram calculados. Regressões lineares também foram realizadas para ∆E00 em função da opacidade dos cilindros na cor de dentina e do par combinado de cilindros de esmalte-dentina. Com exceção da Charisma, os compósitos de esmalte apresentaram menor opacidade do que os de dentina. Alterações de cor perceptíveis e aceitáveis foram observadas quando os cilindros na cor de dentina foram mais finos que 2,0-2,4 mm e 1,1-1,4 mm, respectivamente. Nenhuma diferença entre os sistemas compostos foi observada. Em conclusão, reduções no compósito de dentina menor que 0,6 mm não produziu mudanças de cor perceptíveis, e mudanças de cor clinicamente significantes apenas foram observadas com reduções maiores que 1,6 mm.

Abstract This study determined the reduction threshold in thickness of the dentin shade composite necessary to result in perceptible and acceptable color changes on simulated restorations. Three composite systems (Charisma Diamond, IPS Empress Direct, and Filtek Z350 XT) were evaluated using cylinder-shaped specimens built-up with dentin and enamel shades. The opacity of the composites was assessed using 1.0 mm thick specimens over black and white backgrounds. A baseline color was established for each system by combining 1.0 mm thick enamel shade with 3.0 mm of dentin shade cylinders over a dark background (n = 9). Then, the color changes (∆E00) caused by sequential 0.1 mm reductions on dentin shade cylinders were calculated. Opacity changes on dentin shade cylinders and combined enamel-dentin pair cylinders were also assessed after each thickness reduction. Polynomial regression was performed with averages of ∆E00 as a function of thickness of dentin shade cylinders; and acceptability (∆E = 1.77) and perceptibility (∆E = 0.81) thresholds were calculated. Linear regressions were also performed for ∆E00 as function of opacity of dentin shade cylinders and combined enamel-dentin pair of cylinders. Except for Charisma, enamel shades presented the lowest opacity than dentin one. Perceptible and acceptable color changes were observed for dentin shade cylinders thinner than 2.0-2.4 mm and 1.1-1.4 mm, respectively, were used. No difference among the composite systems was observed. In conclusion, reductions on dentin shade composite lower than 0.6-mm did not yield perceptible color changes, and clinically significant color changes only were observed within reductions higher than 1.6-mm.

Alteração de cor em simulação de dente escurecido, utilizando duas resinas compostas de mesma cor com diferentes opacidades / Colour change in a simulation of discolored tooth using two composite resins of the same colour but different opacities

Introdução: o tratamento estético de dentes escurecidos é desafiador, especialmente quando o escurecimento ocorre de maneira pontual. Para alcançar bons resultados, é imprescindível, além do domínio da técnica restauradora, o conhecimento sobre a composição e características ópticas dos materiais restauradores. Objetivo: avaliar a cor resultante da sobreposição de duas resinas compostas, quando utilizadas sobre um substrato escurecido. Metodologia: na confecção dos corpos de prova, foram utilizadas duas matrizes metálicas e as resinas compostas Charisma A2 e OA2 e Opallis DA4 (simulando o substrato escurecido), perfazendo um total de 30 corpos de prova. As mensurações de cor foram realizadas em espectrofotômetro de reflexão (UV-2600; Shimadzu) e as leituras colorimétricas foram realizadas no programa Color Analysis, seguindo os parâmetros do sistema CIEL*a*b*. A análise estatística inferencial foi realizada pela ANOVA 1-critério. Para as comparações múltiplas, utilizou-se o teste Tukey (significância de 5%). Resultados: entre as três variáveis, apenas na variável a* houve diferença estatística (p<0,0001). Conclusão: os resultados permitiram a observação de alteração colorimétrica após o uso de ambas as resinas, porém com melhores resultados para o grupo da resina AO2, quando em comparação com o grupo da A2.

Introduction: the aesthetic treatment of darkened teeth is challenging, especially when darkening occurs in a timely manner. Besides mastering the restorative technique, knowledge about the composition and optical characteristics of restorative materials are essential in order to achieve good results. Objective: to evaluate the colour resulting from the overlapping of two composite resins when used on a darkened substrate. In the preparation of the test specimens, two metal matrices and the Charisma A2 and OA2 and Opallis DA4 composite resins (simulating the darkened substrate) were used, making a total of 30 specimens. The color measurements were performed in a spectrophotometer (UV-2600; Shimadzu) and the colorimetric readings were performed in the Color Analysis program, following the CIEL * a * b * system parameters. Inferential statistical analysis was carried out by ANOVA 1-criterion. The Tukey test (5% significance) was used for the multiple comparisons. Results: among the three variables, only in variable a * there was a statistical difference (p <0.0001). Conclusion: the results allowed the observation of colorimetric alteration after the use of both resins, but with better results for the AO2 resin group in comparison to the A2 group.

Surface roughness, gloss and color change of different composites after exposure to ultimate challenges

Aim: The study aimed to investigate the effect of the association of chemical and mechanical degradation on the surface roughness, gloss and color of nano and microfilled composites. Method: Disc-shaped specimens (n=10) were prepared for three nanocomposites (Filtek Z350XT, IPS Empress Direct, Charisma Diamond) and three microfilled composites (Estelite Σ Quick, Durafill VS, Renamel). After polishing, baseline surface roughness, gloss and color measurements were obtained. Specimens were submitted subsequently to the following challenges: chemical for 1 week (Hydrochloric acid, Coca-Cola and Red Wine) and mechanical (Toothbrushing). Surface roughness and gloss data were analyzed by Kruskal-Wallis followed by Dunn's test. Color difference (ΔE) was analyzed by one-way ANOVA and Tukey test. Results: The initial data were compared with those after challenges using the Wilcoxon test (p<0.05). All composites showed a significant increase (p<0.05) of surface roughness, after overstress. Filtek Z350 XT and Renamel had the lowest final surface roughness values and roughness increase (p<0.05). The comparative analysis revealed that Estelite Σ Quick and Renamel did not significantly change the gloss after challenges (p=0.185). Filtek Z350 XT and IPS Empress Direct had higher color variations, after the challenges than the other resins (p<0.05). Conclusion: Chemical and mechanical challenges influence on characteristics of all composites, except for gloss on Estelite Σ Quick and Renamel composites (AU)

Influence of Different Concentration and Ratio of a Photoinitiator System on the Properties of Experimental Resin Composites

Abstract The aim in this study was to evaluate the influence of different ratio of camphorquinone/tertiary amine concentration on the flexural strength (FS), elastic modulus (EM), degree of conversion (DC), yellowing (YL), water sorption (WS) and water solubility (WSL) of experimental composites. Thus, acrylate blends were prepared with different camphorquinone (CQ) and amine (DABE) concentrations and ratios by weight: (CQ/DABE%): 0.4/0.4% (C1), 0.4/0.8% (C2), 0.6/0.6% (C3), 0.6/1.2% (C4), 0.8/0.8% (C5), 0.8/1.6% (C6), 1.0/1.0% (C7), 1.0/2.0% (C8), 1.5/1.5% (C9), 1.5/3.0% (C10). For the FS and EM, rectangular specimens (7x2x1 mm, n=10) were photo-activated by single-peak LED for 20 s and tested at Instron (0.5 mm/min). Then, the same specimens were evaluated by FTIR for DC measurement. For YL, disks (5x2 mm, n=10) were prepared, light-cured for 20 s and evaluated in spectrophotometer using the b aspect of the CIEL*a*b* system. For WS and WSL, the volume of the samples was calculated (mm³). For WS and WSL, composites disks (5x0.5 mm, n=5) were prepared. After desiccation, the specimens were stored in distilled water for 7 days and again desiccated, in order to measure the WS and WSL. Data were submitted to one-way ANOVA and Tukey's test (5%). The groups C8, C9 and C10 showed higher DC, EM and YL means, compared to other composites. Therefore, the FS and WS values were similar among all groups. Also, C1, C2 and C3 presented higher WSL in 7 days, compared to other composites. In general, higher concentrations of camphorquinone promoted higher physical-mechanical properties; however, inducing higher yellowing effect for the experimental composites

Resumo O objetivo foi avaliar a influência da concentração e proporção de canforoquinona (CQ)/amina terciária (DABE) na resistência à flexão (RF), módulo flexural (MF), grau de conversão (GC), amarelamento (AM), sorpção (SA) e solubilidade em água (SL) de compósitos experimentais. Blendas acrilatas foram preparadas com diferentes concentrações e proporções de CQ/DABE em peso, como segue: (CQ/DABE%): 0,4/0,4% (C1); 0,4/0,8% (C2); 0,6/0,6% (C3); 0,6/1,2% (C4); 0,8/0,8% (C5); 0,8/1,6% (C6); 1,0/1,0% (C7); 1,0/2,0% (C8); 1,5/1,5% (C9); 1,5/3,0% (C10). Para RF e MF, espécimes retangulares (7x2x1 mm, n=10) foram fotoativados com LED de pico único (Radii Cal) por 20 s e testados em máquina Instron (0,5 mm/min). Após, o GC dos mesmos espécimes (fragmentos) foi mensurado por FTIR. Para AM, discos de compósito (5x2 mm, n=10) foram preparados, fotoativados por 20 s e imediatamente avaliados em espectrofotômetro, considerando o aspecto b do sistema CIEL*a*b*. Para SA e SL, discos de compósito (5x0,5 mm, n=5) foram preparados e seus volumes calculados (mm³). Após desidratação, as amostras foram pesadas e armazenadas em água destilada por 7 dias, pesadas e novamente desidratadas e pesadas, para se calcular o SA e SL. Os dados foram submetidos a one-way ANOVA e teste de Tukey (5%). Os grupos C8, C9 e C10 mostraram maior GC, MF e AM, comparado aos outros grupos. No entanto, RF e SA foram similares entre todos os grupos. Ainda, C1, C2 e C3 apresentaram maior SL em 7 dias comparado aos outros grupos. Em geral, maiores concentrações de CQ promoveram melhores propriedades físico-mecânicas; no entanto, levaram ao maior amarelamento dos compósitos.

Abordaje conservador y mínimamente invasivo de la Hipomineralización Molar-Incisivo (HMI) -Relato de casos clínicos / Minimally invasive treatment for esthetic management of Molar-Incisor Hypomineralization (MIH) -A case report

La Hipomineralización Molar-Incisivo (HMI) es un defecto de esmalte de origen sistèmico que afecta uno o varios molares permanentes, asociado en algunos casos a los incisivos permanentes. Defectos de esmalte, como la HMI pueden influenciar negativamente la calidad de vida, percepción estètica y autoestima de niños y adolescentes. Las opciones de tratamiento para este tipo de alteración, incluye desde medidas preventivas y procedimientos restauradores hasta la extracción dental. Factores como la edad y expectativas del paciente, severidad de la alteración y materiales deben ser considerados en el plan de tratamiento del paciente con HMI. La utilización de resinas compuestas para la restauración de molares e incisivos ha mostrado buenos resultados relacionados a la durabilidad y estètica. Este artículo presenta dos casos clínicos sobre el abordaje de la HMI en dientes anteriores, realizando preparos cavitários conservadores por medio de puntas ultrasónicas adaptadas a un sistema de ultrasonido y restauración con resina compuesta, obteniendo resultados estéticos favorables con un año de acompañamiento.

Molar-Incisor Hypomineralization (MIH) is a qualitative developmental enamel defect that affects one to four permanent first molars, with or without involvement of permanent incisors. Enamel defects may produce many symptoms that have physical, social and psychological effects and influence day-to-day living or quality of life. The available treatment modalities for teeth with MIH are extensive, ranging from prevention, restoration, to extraction. Factors such as age, patient expectations, severity of the lesion and materials should be considered in the treatment of the patient with MIH. Restoration with composite resin is an alternative choice for posterior and anterior MIH defective teeth and its use has been show acceptable results. This article describes two clinical cases involving pediatric patients with MIH whose procedure of cavity preparation was based on the use of CVD ultrasound diamond tips and restored using composite resin obtaining favorable esthetics results after a 1 year follow-up.

Rehabilitación dental y trastornos temporomandibulares en adolescentes de Puebla, México / Temporomandibular dental rehabilitation and adolescent disorders of Puebla, México

OBJETIVO: determinar el factor de riesgo para desarrollar trastornos temporomandibulares en adolescentes (TTM). METODOLOGIA: cohorte prospectiva realizada en 153 adolescentes, (52,9% mujeres y 47% hombres) libres de TTM. Para diagnosticar los TTM se utilizaron los Criterios Diagnósticos para la Investigación de los TTM (CDI/TTM), para determinar caries se aplicó el índice CPOD. Se formaron dos grupos, el grupo expuesto a rehabilitación dental (74), y el grupo no expuesto (79). Se realizaron seguimientos a las dos semanas, tres y seis meses de la rehabilitación dental. Se utilizó estadística descriptiva y se calculó el riesgo relativo con intervalos de confianza al 95%. Para el grupo de los expuestos, se incluyeron adolescentes libres de TTM en los que fue necesario realizar tratamiento de rehabilitación dental en órganos posteriores con caries en esmalte y dentina en fosas y fisuras. Para el grupo no expuesto, se incluyeron adolescentes pareados por edad y sexo con los expuestos, libres de TTM sin necesidades de rehabilitación dental. RESULTADOS : la incidencia de TTM a los quince días de los expuestos (18,9%) fue superior en contraste con los no expuestos (5,0%). El riesgo relativo de desarrollar TTM en los adolescentes rehabilitados con resina a las dos semanas posteriores a la rehabilitación fue de 2.412 (I.C. 95% 1.001-5,81) veces más que en aquellos que no fueron sometidos a la rehabilitación. CONCLUSION:la rehabilitación dental es un factor de riesgo mínimo para desarrollar TTM a corto plazo (15 días) de realizado el procedimiento, dicho padecimiento inducido por la rehabilitación dental es agudo y auto limitante.

OBJECTIVE: Determine the risk factor involved with developing temporomandibular disorders (TMD) in adolescents. METHODOLOGY: Prospective cohort study carried out on 153 TMD-free adolescents (52.9% women and 47% women). In order to diagnose TMDs the Diagnostic Criteria for Research into TMDs (CDI/TMD), and the CPOD index was used to determine cavities. Two groups were formed: one exposed to dental rehabilitation (74) and one group unexposed (79). Follow-ups were performed two weeks, three months and six months after dental rehabilitation. Descriptive statistics were used and the relative risk was calculated with confidence intervals at 95%. Included in the exposed group were TMDfree adolescents in whom it was necessary to carry out dental rehabilitation treatment on rear teeth with cavities using enamel and dentin to fill in pits and fissures. Included in the unexposed group were adolescents paired with the exposed group based on age and sex, TMD-free and without the need for dental rehabilitation. RESULTS :The incidence of TMD two weeks subsequently in the exposed group (18.9%) was greater in contrast with the unexposed group (5.0%). The relative risk of carrying out TMD on adolescents rehabilitated with resin two weeks after rehabilitation was 2.412 (C.I. 95% 1.001-5.81) times more than in those that did not undergo rehabilitation. CONCLUSION:Dental rehabilitation is a minimum risk factor for carrying out TMD in the short term (two weeks) after the procedure, as this disease induced by rehabilitation is acute and self-limiting.

Effect of water storage on the fracture toughness of dental resin cement used for zirconia restoration / 대한치과보철학회지

PURPOSE: The aim of this study was to compare the fracture toughness of currently available resin cements for zirconia restorations and evaluate the effect of water storage on fracture toughness of those resin cements. MATERIALS AND METHODS: Single-edge notched specimens (3 mm x 6 mm x 25 mm) were prepared from three currently available dual cure resin cements for zirconia restorations (Panavia F 2.0, Clearfil SA luting and Zirconite). Each resin cement was divided into four groups: immersed in distilled water at 37degrees C for 1 (Control group), 30, 90, or 180 days (n=5). Specimens were loaded in three point bending at a cross-head speed of 0.1 mm/s. The maximum load at specimen failure was recorded and the fracture toughness (K(IC)) was calculated. Data were analyzed using one-way ANOVA and multiple comparison Scheffe test (alpha=.05). RESULTS: In control group, the mean KIC was 3.41 +/- 0.64 MN.m(-1.5) for Panavia F, 2.0, 3.07 +/- 0.41 MN.m(-1.5) for Zirconite, 2.58 +/- 0.30 MN.m(-1.5) for Clearfil SA luting respectively, but statistical analysis revealed no significant difference between them. Although a gradual decrease of K(IC) in Panavia F 2.0 and gradual increases of KIC in Clearfil SA luting and Zirconite were observed with storage time, there were no significant differences between immersion time for each cement. CONCLUSION: The resin cements for zirconia restorations exhibit much higher K(IC) values than conventional resin cements. The fracture toughness of resin cement for zirconia restoration would not be affected by water storage.

Rheological properties of dental resin cements during polymerization / 대한치과보철학회지

PURPOSE: The purpose of this study was to observe the change of viscoelastic properties of dental resin cements during polymerization. MATERIALS AND METHODS: Six commercially available resin cement materials (Clearfil SA luting, Panavia F 2.0, Zirconite, Variolink N, RelyX Unicem clicker, RelyX U200) were investigated in this study. A dynamic oscillation-time sweep test was performed with AR1500 stress controlled rheometer at 32degrees C. The changes in shear storage modulus (G'), shear loss modulus (G"), loss tangent (tan delta) and displacement were measured for twenty minutes and repeated three times for each material. The data were analyzed using one-way ANOVA and Tukey's post hoc test (alpha=0.05). RESULTS: After mixing, all materials demonstrated an increase in G' with time, reaching the plateau in the end. RelyX U200 demonstrated the highest G' value, while RelyX Unicem (clicker type) and Variolink N demonstrated the lowest G' value at the end of experimental time. Tan delta was maintained at some level and reached the zero at the starting point where G' began to increase. The tan delta and displacement of the tested materials showed similar pattern in the graph within change of time. The displacement of all 6 materials approached to zero within 6 minutes. CONCLUSION: Compared to other resin cements used in this study, RelyX U200 maintained plastic property for a longer period of time. When it completed the curing process, RelyX U200 had the highest stiffness. It is convenient for clinicians to cement multiple units of dental prostheses simultaneously.

Analysis of flexural strength of a self cured acrylic resin used for fabricating provisional restorations with three different types of reinforcements / Análise da resistência à flexão de uma resina acrílica de ativação química utilizada para confecção de restaurações provisórias utilizando-se de três diferentes tipos de reforços

Objetivo: Avaliar o efeito de três diferentes tipos de reforços na resistência à flexão de uma resina acrílica quimicamente ativada. Material e Métodos: A máquina de teste universal EMIC 2000 foi utilizada a uma velocidade de 5 mm/min, para avaliar a resistência à flexão de 40 espécimes de ensaio (65 x 10mm x 2,5 mm) fabricados em resina acrílica quimicamente ativada, distribuídos em quatro grupos: (1) controle - sem reforço; (2) reforçado com 0,7 mm de aço inoxidável- fio ortodôntico; (3) reforçado com Fibrex-lab ® fibra de vidro e, (4) Perma-reforçado com fibra de vidro ®. Resultados: Os valores de resistência à flexão obtidos foram: Grupo 1- 80,60 MPa; Grupo 2- 95,96 MPa; Grupo 3- 105,70 MPa e Grupo 4-108,70 MPa. A análise de variância (p < 0,05) mostrou diferença significativa entre os grupos, e o teste de Tukey que o grupo de controle apresentou o pior comportamento, seguido do grupo de reforço com fios de metal, que mostrou resultados estatisticamente semelhantes aos do Grupo 3. Não houve diferença estatística entre os grupos de fibras. Conclusão: O reforço com fibras de vidro apresentam uma melhor resistência à flexão, em comparação com os outros métodos.

Objective: To evaluate the effect of three different types of reinforcements on the flexural strength of a chemically activated acrylic resin. Material and Methods: A Universal test machine EMIC 2000 was used at a speed of 5mm/min., to evaluate the flexural strength of 40 test specimens (65 mm x 10 mm x 2.5 mm) fabricated of self cured activated acrylic resin, distributed into the following 4 groups: (1) control – without reinforcement; (2) reinforced with 0.7 mm stainless steel orthodontic wire; (3) reinforced with Fibrex-lab® glass fiber and; (4) reinforced with Perma-Fiber®glass fiber. Results: The following flexural strength values were obtained: Group 1 – 80.60 MPa; Group 2 – 95.96 MPa; Group 3 – 105.70 MPa; and Group 4 – 108.70 MPa. The analysis of variance (p < 0.05) showed significant difference among the groups and the Tukey test showed that the control group presented the worst behavior, followed by reinforcement with metal wire, which showed statistically similar results to those of Group 3, with no difference shown between the fiber groups. Conclusion: Reinforcement with glass fibers present better flexural strength in comparison with the other methods.

Repair of amalgam restorations with composite resin and bonded amalgam: A microleakage study.

Background: Total replacement is the most common technique for defective amalgam restorations, and it represents a major part of restorative dental treatment. Repair is an alternative option for amalgam restorations with localized defects. Aims: This study compared microleakage of amalgam restorations repaired by bonded amalgam or composite resin. Materials and Methods: Thirty extracted human pre-molars were prepared and restored with class I amalgam. A simulated defect was prepared that included the cavosurface margin on restorations, and the pre-molars were assigned to two treatment groups (n=15): In group 1, premolars were treated by composite resin (34% Tooth Conditioner Gel + Adper Single Bond 2 + Z100) and in group 2, premolars were repaired by bonded amalgam (34% Tooth Conditioner Gel + Prime and Bond 2.1 + Permite C). The teeth were immersed in a 50% silver nitrate solution, thermocycled, sectioned longitudinally and then observed by three examiners using a stereomicroscope. Microleakage was evaluated using a 0-4 scale for dye penetration, and data was analyzed by Kruskal Wallis and Dunn tests. Results: Neither of the two methods eliminated microleakage completely. Composite resin was significantly the most effective for repair/tooth interface sealing (score 0 = 80.0%; P=0.0317). For the repair/restoration interface, composite resin was also statistically more effective as a sealant (score 0=66%; P=0.0005) when compared to the bonded amalgam technique (score 0=13%; P=0.0005). Conclusions: The use of adhesive systems significantly affected the ability to seal the repair/ tooth interface. However, at the level of the repair/restoration interface, the bonded amalgam technique may increase microleakage.