Influence of two natural cross-linkers on microtensile bond strength durability ­ An in vitro study / Influência de dois reticuladores naturais na durabilidade da resistência de união à microtração ­ Um estudo in vitro

Objective: to investigate the effect of two natural cross-linkers on microtensile bond strength (µTBS) and evaluate their influence on the durability of the resin dentin bonds. Material and Methods: the Moringa oleifera and Centella asiatica plant extracts were qualitatively tested with high-performance thin layer chromatography (HPTLC) for the presence of phenols. The phenolic content ranged from 27 to 30 gallic acid equivalents (GAE), µg/mg of dry weight. After etching, two concentrations (5% and 1%) of these two extracts were prepared and used as pretreatment liners on dentin. They were applied for a min. After restoration with resin composite, dentin resin beams were prepared. The study groups were 5% Moringa, 1% Moringa 5% Centella 1% Centella, and control (without cross-linker application). For each group, half of the samples underwent µTBS testing after 24 hours, while the remaining half were immersed in artificial saliva to assess the bond's longevity after 6 months of ageing. Statistical analysis was performed using one-way ANOVA followed by Tukey's post hoc test. Results: both 5% and 1% Moringa showed a significant difference (p<0.05) compared to the other groups at both intervals. However, after ageing, the specimens in the control and 1% Centella groups resulted in a significant decrease in µTBS. Conclusion: overall, both concentrations of Moringa (5% and 1%) were effective in stabilising the bond during both intervals.(AU)

Objetivo: investigar o efeito de dois reticuladores naturais na resistência de união (µTBS) à microtração e avaliar sua influência na durabilidade da adesão da resina à dentina. Material e Métodos: extratos das plantas Moringa oleifera e Centella asiatica foram qualitativamente testados através de cromatografia em camada fina de alta performance (HPTLC) para a presença de fenóis. O conteúdo fenólico alcançou entre 27 a 30 equivalentes de ácido gálico (GAE), µg/mg de peso seco. Após o condicionamento, duas concentrações (5% e 1%) dos extratos foram preparadas e utilizadas como forros de pré-tratamento em dentina. Eles foram aplicados por um minuto. Após a restauração com resina composta, palitos de dentina e resina foram preparados. Os grupos foram 5% Moringa, 1% Moringa, 5% Centella, 1% Centella e controle (sem aplicação de reticulador). Para cada grupo, metade das amostras foram submetidas ao teste µTBS após 24 horas, enquanto a outra metade foi imersa em saliva artificial para avaliar a longevidade adesiva após 6 meses de envelhecimento. Foi realizada análise estatística através de ANOVA 1-fator, seguido do teste post hoc de Tukey. Resultados: ambas as concentrações de 5% e 1% de Moringa demonstraram diferença significativa (p<0.05) comparadas aos outros grupos em ambos os intervalos. No entanto, após o envelhecimento, os espécimes dos geupos controle e 1% de Centella resultaram em uma redução significativa de µTBS. Conclusão: no geral, ambas as concentrações de Moringa (5% e 1%) foram efetivas em estabelecer a adesão em ambos os intervalos (AU)

Discoloration of Resin Composites Induced by Coffee and Tomato Sauce and Subjected to Surface Polishing: An In Vitro Study.

BACKGROUND The purpose of this study is to evaluate and compare color stability of 3 resin based restorative materials when immersed into staining media at 0, 3, 30, 45, 60, and 75 days, and to assess the efficacy of surface polishing in reducing possible discoloration. MATERIAL AND METHODS Ninety composite discs were prepared in a custom-made mold (5 mm diameter and 2 mm thick) from 3 different light cured composites (Filtek™ Z250, Harmonize™, and G-aenial). Color differences of all specimens were measured by a spectrophotometer according to the CIE L*a*b* system. After baseline color measurements, 30 discs from each composite group were randomly divided into 3 subgroups of 10 specimens each. Subgroups (n=10) were immersed for 75 days into different staining solutions: coffee, tomato sauce, and distilled water (control). Solutions were changed every week and color measurements were repeated every 15 days. At day 75, color measurements of the specimens were performed before and after surface polishing with aluminum oxide discs. The experimental data were statistically evaluated using repeated measures one-way ANOVA test followed by Tukey's multiple pairwise comparison with a significance level of 5%. RESULTS Of the 3 composites, G-aenial reported the highest color change deviation when immersed into coffee (ΔE=8.674), and tomato sauce (ΔE=7.737) at day 75, followed by Harmonize that also exhibited a significant difference for coffee (ΔE=4.7) and tomato sauce (ΔE=3.8) when compared to distilled water. While Filtek™ Z250 did not show any significant difference between the 3 storage solutions (P>0.05). Only G-aenial had significant color change (P<0.05) after polishing with aluminum oxide discs for all tested samples, whereas Filtek™ Z250 and Harmonize presented no significant difference after surface polishing (P>0.05). CONCLUSIONS Under the tested experimental conditions, Filtek™ Z250, among the 3 resin-based composites, exhibited the highest color stability when subjected to coffee and tomato sauce as well. Whereas, G-aenial presented the highest color deviation when immersed in both staining media. Surface polishing effectively reduced coffee and tomato sauce discolorations for G-aenial's specimens and had no significant effect regarding Filtek™ Z250 and Harmonize.

Avaliação da alteração de cor da resina composta após imersão em diferentes soluções / Evaluation of color change of the composite resin after immersion in different solutions

Resinas compostas são materiais capazes de reproduzir as características ópticas próximas às do elemento dentário, além de possuírem propriedades mecânicas satisfatórias. Entretanto, elas apresentam instabilidade de cor em exposição prolongada a agentes corantes, tornando- -se um fator limitante, principalmente em áreas estéticas. O objetivo do presente trabalho foi avaliar a estabilidade de cor de duas resinas compostas, com partículas de carga diferentes, quando imersas em substâncias com potencial de manchamento. Foram confeccionadas 30 amostras da resina composta nano-particulada (Filtek Z350 XT, 3M ESPE, EUA) e 30 da resina micro-híbrida (Filtek Z250 XT, 3M ESPE, EUA). As amostras de cada resina foram divididas em 3 grupos (n=10) de acordo com as soluções utilizadas como meio de imersão: água destilada (controle), Cola-Cola® e café. A alteração de cor (ΔE) das amostras foram avaliadas através da diferença das tomadas de cor inicial e final (após 07 dias de imersão) por meio do espectrofotômetro. Os resultados mostraram que o meio de imersão influenciou significativamente no manchamento das resinas. A solução de café proporcionou os maiores valores de ΔE para ambas resinas testadas (nano-particulada = 20,07 +/- 0,67 e micro-híbrida = 17,24 +/- 0,53), e independente do meio de imersão, os maiores valores de ΔE foram encontrados na resina nano-particulada (p<0,05). Os resultados obtidos mostraram que o café é uma solução capaz de causar uma elevada alteração de cor nos compósitos e a resina nano-particulada Filtek Z350 XT é mais susceptível à alteração de cor do que a resina micro-híbrida Filtek Z250 XT (AU).

Composite resins are materials capable of reproducing optical characteristics close to the tooth and in addition have satisfactory mechanical properties. However, they present color instability in prolonged exposure to coloring agents, which becomes a limiting factor, mainly in aesthetic areas. The objective of this study was to evaluate the color stability of two composite resins with different charge particles when immersed in substances with staining potential. Thirty samples of nanoparticulated composite resin (Filtek Z350 XT, 3M ESPE, USA) and 30 of the micro-hybrid resin (Filtek Z250 XT, 3M ESPE, USA) were made. The samples of each resin were divided into 3 groups (n = 10) according to the solutions used as immersion medium: distilled water (control), Cola-Cola® and coffee. The color change (ΔE) of samples was evaluated using the difference of the initial and final color taken (after 07 days of immersion) through the spectrophotometer. The results showed that the immersion medium significantly influenced resin staining. The coffee solution provided the highest values of ΔE for both resins tested (nanoparticulated = 20,07 +/- 0,67 and micro-hybrid = 17,24 +/- 0,53), and independent of the immersion medium, higher values of ΔE were found in the nanoparticulated resin (p <0.05). The results showed that coffee is the solution capable of causing higher color change in the composites and Filtek Z350 XT nanoparticulated resin is more susceptible to color change than the Filtek Z250 XT micro-hybrid resin (AU).

Development of a composite resin disclosing agent based on the understanding of tooth staining mechanisms.

OBJECTIVES: To characterize the surface composition of dental enamel and composite resin, assess the ability of dyes with different affinities to stain these surfaces, and use this information to develop a disclosing agent that stains composite resin more than dental enamel. METHODS: One hundred and ten sound extracted teeth were collected and 60 discs of composite resin, 9 mm diameter and 3 mm thick, were prepared. X-ray photoelectron spectroscopy (XPS) was employed to determine the elemental composition on the different surfaces. A tooth shade spectrophotometer was used to assess the change in shade after staining the surfaces with different dyes. RESULTS: XPS analysis revealed that surfaces of both outer dental enamel and composite resin contained relatively high amounts of carbon, specifically hydrocarbons. Both dental enamel and composite surfaces were stainable with the hydrophobic dye (p<0.05); however, the composite resin was stained more than the dental enamel (p<0.05). CONCLUSIONS: The hydrophobic surface of dental enamel and composite resin might explain their high affinity to be stained by food and beverages containing hydrophobic molecules. The composite resin is more stainable by hydrophobic dyes than dental enamel. We used this information to develop an agent for disclosing composite resins that could be used to visualize composite resins that need to be removed. CLINICAL SIGNIFICANCE: Removal of composite resin can be problematic, time consuming and stressful to the dental practitioner. A composite disclosing agent would help the dental practitioner identify the composite resin and facilitate its removal without damaging the adjacent healthy tooth tissues.

Influencia de la fotopolimerización gradual en el estrés de contracción en restauraciones de resina compuesta / Influence of gradual polymerization contraction stress of composite restorations

Cuando el factor estética es primordial, las resinas compuestas continúan siendo la opción restauradora más utilizada. Sin embargo, a pesar de su constante evolución aún presentan algunos inconvenientes, tales como: desgaste, contracción de polimerización e infiltración marginal. Actualmente, nuevos conceptos relacionados a técnicas de fotopolimerización desarrollaron una mejor adaptación marginal asociada a la permanencia de sus propiedades mecánicas. La polimerización gradual, es decir, reducción inicial de la intensidad de luz, seguida por fotoactivación con mayor intensidad han demostrado ser una alternativa con buenos resultados clínicos. Este trabajo propone discutir las principales variables que pueden interferir en el proceso de fotopolimerización, con el objetivo de alertar a los odontólogos en cuanto a la necesidad de un constante control clínico, no solamente por la observación de la técnica incremental, sino principalmente, a través de la monitorización de la cantidad de energía luminosa empleada en el proceso de fotopolimerización. En este contexto, son presentados, mediante revisión de literatura, los principales factores relacionados a la contracción de polimerización y las técnicas de fotopolimerización disponibles para minimizar sus efectos

The composite resins are still the most used restorative option when the esthetic aspect is primordial. However, even their constant evolution they present some inconvenients like: wear, polymerization contraction and marginal leakage. Today, new concepts related to light curing have developed a better marginal adaptation associated to the permanency of their mechanical properties. The gradual polymerization, which means, initial reduction at the light intensity, followed by the photoactivation with more intensity has demonstrated to be an alternative with good clinical results. This paper proposes to discuss the principal variables that could interfere at the light curing process, with the aim to alert the dentists about the necessity of a constant clinical control, not just by the observation of the incremental technique, but principally, through monitoring the quantity of light energy used at the polymerization process. In this context, are presented, by a literature revision, the principal factors related to the polymerization contraction and the available light curing techniques to minimize their effects

Influence of pH and time on organic substance release from a model dental composite: a fluorescence spectrophotometry and gas chromatography/mass spectrometry analysis.

In this study we assessed the influence of pH and time on the degradation and elution of organic substances from the composite resin material, Z-100. To accomplish this, fluorescence spectrophotometry was evaluated as an appropriate technique for the identification of six organic substances (methacrylic acid, methyl methacrylate, hydroquinone, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate and 4,4'-isopropylidenediphenol) that were eluted from resin composite material stored for 24 h or 6 months at pH 4.0, 6.0 or 8.0. In addition, complementary analyses (solid-phase microextraction/gas chromatography/mass spectrometry) were carried out to identify and quantify the substances. The main substances leached from the resin composite were methacrylic acid, triethylene glycol dimethacrylate and hydroquinone. It was concluded that fluorescence spectrophotometry seems to be a suitable, non-destructive technique for the qualitative analysis of eluted organic components. Critical combinations of time and pH allowed the elution of several organic substances, predominantly methacrylic acid, triethylene glycol dimethacrylate and hydroquinone, from the model resin composite, Z-100.

Estudio comparativo in vitro de la filtración entre composite y dentina al polimerizar con luz halógena Vs con luz de plasma / In vitro comparative study of filtration between composite resin and dentin after polymerizing with halogen and plasma arc light

Introducción: Justificación y objetivos: existen estudios de polimerización realizados con lámparas de luz halógena en los que se valoran negativamente las altas intensidades de luz por la contracción rápida de la resina que podría provocar despegamientos. Según la información proporcionada por el fabricante de las lámparas de polimerización plasmática rápida, el curado con éstas origina una mayor rigidez del material que limita la contracción al evitar la redistribución cómoda de la estructura molecular. Material y método: se adhirieron 30 cilindros de composite a superficies dentarias lisas; 15 se polimerizaron con lámparas de luz halógena y 15 con lámparas de polimerización plasmática rápida, se sumergieron en azul de metileno y se midió la filtración con estereomicroscopio. Resultados: en el análisis de la varianza se obtuvo un grado de libertad que corresponde a una suma de cuadrados de 112,15, F=0,1403 y P=0,7113. No se han encontrado diferencias en cuanto a la filtración en función de que la polimerización se haya realizado con lámparas de luz halógena o con las de polimerización plasmática rápida (AU)

Filler particle leachability of experimental dental composites.

We studied the effect of matrix selection, filler composition, and filler silanization on filler leachability after storage in distilled water or artificial saliva. We evaluated 2 matrix systems, 2 filler systems and 2 silane treatment procedures, combined into 8 different dental composite materials. A total of 128 batches were made, and 2 specimens per batch were prepared. Of these 2 specimens per batch, one was stored in distilled water and the other in artificial saliva, both at 37 degrees C. We transferred the specimens each 30th day during a 3-yr period to new vials containing either freshly distilled water or newly mixed artificial saliva and analyzed the solutions the specimens had been stored in regarding Si, Ba and Al concentrations. The analyses revealed that storage solution, filler composition, and total time in the storage solution had strong effects on leachability. The average monthly leakage of the three elements was linear with time and higher in the artificial saliva. The Ba-containing filler leached Si faster in artificial saliva than in distilled water, and roughly twice as much as the quartz filler. The storage effect approached an order of magnitude, while the filler effect was roughly a factor of two. Filler leaching was linear over time.

Manchamento em resinas compostas híbridas - açäo dos agentes polidores / Stain in the hybrid composite resins - effects of the polishing agents

O propósito do presente trabalho foi avaliar os diferentes tipos de procedimentos sequenciais para acabamento e polimento na superfície de resinas compostas. O método de avaliaçäo inclui uma observaçäo macroscópica quanto ao manchamento ocasionado na resina composta, por dois corantes (café e vinho) e o estudo topográfico da superfície das restauraçöes através da microscopia eletrônica de varredura (M.E.V.), sendo possível uma visualizaçäo detalhada quanto à textura, lisura e formaçäo de porosidades

Residual monomer leaching from chemically cured and visible light-cured orthodontic adhesives.

The objective of this study was to quantify the amount of residual monomer leached from chemically cured and visible light-cured orthodontic adhesives based on Bis-GMA/TEGDMA monomers, when bonded to ceramic and stainless steel brackets. The residual TEGDMA and Bis-GMA monomer concentrations were determined by high performance liquid chromatographic (HPLC) analysis of the extracts after specimen immersion in ethanol/water solution for 15 days at 37 +/- 1 degree C. According to the results the highest monomer concentrations eluted were obtained from the chemically cured adhesive. Direct (through the bracket) irradiation of stainless steel brackets bonded to the visible light-cured adhesive showed high monomer elution as well. A polycarbonate base ceramic bracket manifested significantly greater amount of monomer release compared with ceramic brackets when combined with the visible light-cured adhesive. Indirect (from the incisal and cervical edges of the bracket) irradiation of the visible light-cured adhesive bonded to the stainless steel brackets resulted in lower residual monomer elution compared to that of directly (through the bracket) irradiated metallic brackets. No statistical difference was found between direct or indirect irradiation of the ceramic brackets tested, with respect to monomer elution from the light-cured adhesive.

Estudo da influência da retençäo de corantes na translucidez de resinas compostas: efeito de materiais, tempo e meios de imersäo / Dye retention influense in the composite resins translucence: effect of materials, time and immersion ways

Os autores investigaram "in vitro" a influência da retençäo de corantes na translucidez das resinas compostas Herculite X para Esmalte (M1), para Dentina (M2) e Silux Plus para Esmalte (M3) e para Dentina (M4). Os corpos de prova foram submedidos a quatro diferentes meios de imersäo: I1 - coca-cola; I2 - café; I3 - vinho tinto; I4 - nicotina. A medida da translucidez foi obtida em três tempos diferentes: P0 - 1 hora antes da imersäo; P1 - após 2 horas após imersäo e P2 - 24 horas após imersäo. Com base na metodologia os autores concluíram que: 1) o material M1 apresentou maiores níveis percentuais de translucidez quando comparado com o material M3; 2) o meio de imersäo I2 propiciou menor translucidez seguido em ordem crescente por I3 e I4 que se apresentaram semelhantes e menores que I1; 3) em relaçäo ao tempo, a translucidez apresentou-se decrescente caracterizando manchamento lento e gradual

Characterization of inorganic fillers in visible-light-cured dental composite resins.

Inorganic fillers in seven visible-light (VL)-cured dental composite resins were examined for their size, composition, phase and content, employing the following analytical instruments. SEM observations indicated that five samples could be classified into the hybrid type while the remaining two belonged to micro-filled and sub-micron types. EDX analyses revealed that five samples contained BaO while others lacked BaO. XRD analyses showed that three were in vitreous phase, two were in the crystalline phase and two were mixtures of both. DTG thermal analyses indicated that the hybrid type composites had the higher inorganic filler content (wt%) than the composites of two other types. In conclusion, wide varieties exist in the inorganic fillers in VL-cured dental composite resins currently utilized.

Estudo da rugosidade superficial da resina composta submetida à açäo do jato de bicarbonato de sódio: efeitos da velocidade de vazäo de água e materiais / Study of superficial rugosity of composite resins submitted to sodium bicarbonate irrigation: effect of waters flow velocity and materials

Foi realizado estudo comparativo da rugosidade superficial de cinco marcas diferentes de resinas compostas: Adaptic, Herculite, Estic-microfill, Silux e P-30, submetidas à acäo do jato de bicarbonato de sódio do aparelho Profident, nas velocidades da vazäo de água, mínima, média e máxima. Os corpos-de-prova foram confeccionados com auxílio de uma matriz circular, e as alteraçöes superficiais foram analisadas no aparelho Hommel Tester T.1000 para medir a rugosidade inicial e após o tratamento com o jato abrasivo. Os dados obtidos foram submetidos a tratamento estatístico que, após análise e discussäo, permitiram concluir que a aplicaçäo do jato de bircabonato de sódio altera a superfície das resinas compostas, deixando-a mais rugosa, e que os materiais estudados exerceram níveis diferentes de rugosidade. O Herculite apresentou a superfície mais lisa e o Adaptic a mais rugosa, ficando os materiais P-30, Silux e Estic-microfill numa posiçäo intermediária