Surface Roughness of Composite Resins Subjected to Hydrochloric Acid

The purpose of this study was to determine the influence of hydrochloric acid on surface roughness of composite resins subjected to brushing. Sixty samples measuring 2 mm thick x 6 mm diameter were prepared and used as experimental units. The study presented a 3x2 factorial design, in which the factors were composite resin (n=20), at 3 levels: microhybrid composite (Z100), nanofilled composite (FiltekTM Supreme), nanohybrid composite (Ice), and acid challenge (n=10) at 2 levels: absence and presence. Acid challenge was performed by immersion of specimens in hydrochloric acid (pH 1.2) for 1 min, 4 times per day for 7 days. The specimens not subjected to acid challenge were stored in 15 mL of artificial saliva at 37 oC. Afterwards, all specimens were submitted to abrasive challenge by a brushing cycle performed with a 200 g weight at a speed of 356 rpm, totaling 17.8 cycles. Surface roughness measurements (Ra) were performed and analyzed by ANOVA and Tukey test (p≤0.05). Surface roughness values were higher in the presence (1.07±0.24) as compared with the absence of hydrochloric acid (0.72±0.04). Surface roughness values were higher for microhybrid (1.01±0.27) compared with nanofilled (0.68 ±0.09) and nanohybrid (0.48±0.15) composites when the specimens were not subjects to acid challenge. In the presence of hydrochloric acid, microhybrid (1.26±0.28) and nanofilled (1.18±0,30) composites presents higher surface roughness values compared with nanohybrid (0.77±0.15). The hydrochloric acid affected the surface roughness of composite resin subjected to brushing.

Este estudo avaliou a influencia do ácido clorídrico na rugosidade superficial de resinas compostas submetidas a escovação. Sessenta corpos de prova medindo 2 mm de espessura x 6 mm de diâmetro foram confeccionados e utilizados como unidades experimentais. O presente estudo envolve uma análise fatorial 3x2, onde os fatores foram resina composta (n=20), com 3 níveis: resina composta microhíbrida (Z100), nanoparticulada (Filtek TM Supreme) e nanohíbrida (Ice); e desafio ácido (n=10), com 2 níveis: ausência e presença. O desafio ácido foi realizado por meio da imersão em ácido clorídrico (pH 1,2) por 4 h diárias, 1 min cada imersão, durante 7 dias. Os espécimes que não foram submetidos ao desafio ácido foram armazenados em 15 mL de saliva artificial a 37 °C. Todos os espécimes foram submetidos ao desafio abrasivo. O processo de escovação foi realizado com 200 g de peso, com velocidade de 356 rpm, totalizando 17,8 ciclos. As medidas de rugosidade superficial (Ra) foram realizadas e analisadas por meio da ANOVA e teste de Tukey (p<0,05). Os valores de rugosidade superficial foram maiores na presença (1,07±0,24)quando comparado com a ausencia do ácido hidroclorídrico (0,72±0,04). A resina microhíbrida (1,01±0,27) apresentou maior rugosidade superficial que as resinas nanoparticulada (0,68±0,09) e nanohíbrida (0,48±0,15) quando os espécimes não foram submetidos ao desafio ácido. Na presença do ácido hidroclorídrico, a resina microhíbrida (1,26±0,28) e a resina nanoparticulada (1,18±0,30) apresentou maior valor de rugosidade superficia comparado com a resina nanohíbrida (0.77±0.15). O ácido hidroclorídrico influenciou a rugosidade superficial da resina composta submetida a escovação.

Microabrasión de esmalte dentario en odontología restauradora / Dental enamel microabrasion in restorative dentistry

La estética es el paradigma de la odontología restauradora. En la actualidad, se utilizan procedimientos combinados, por la exigencia sostenida de los pacientes por tener piezas dentarias blancas y brillantes. Es así que, para cumplir con esas expectativas, clínicas, en algunos casos se utilizan técnicas de blanqueamiento dentario, mientras que en otros se necesitan procedimientos como los de microabrasión o micro-macro abrasión, para remover manchas oscuras o blancas del esmalte dentario, buscando de esta manera, la satisfacción en lo que a estética se refiere. La microabrasión es un procedimiento muy utilizado en la actualidad por los profesionales odontólogos, por lo anteriormente expuesto o como técnica previa al uso de sistemas adhesivos. Por ello, se pretende con este documento, presentar una revisión sobre conceptos actuales, como así también los condicionantes al momento de seleccionar materiales o realizar el procedimiento de microabrasión.

Effect of foods and drinks on primary tooth enamel after erosive challenge with hydrochloric acid

The aim of this study was to evaluate the effect of industrialised foods and drinks on primary tooth enamel previously eroded with hydrochloric acid (HCl). The crowns of one hundred two specimens were subjected to an erosive challenge with HCl and randomly divided into six groups (n = 17): Chocolate Milk (Toddynho® - Pepsico) - negative control; Petit Suisse Yogurt (Danoninho® - Danone); Strawberry Yogurt (Vigor); Apple puree (Nestlé); Fermented Milk (Yakult® - Yakult); and Home Squeezed Style Orange Juice (del Valle) - positive control. The 28-day immersion cycles for the test products were performed twice daily and were interspersed with exposure of the test substrate to artificial saliva. Measurements of enamel surface microhardness (SMH) were performed initially, after immersion in HCl and at 7, 14, 21 and 28 days of experimentation. A two-way ANOVA, according to a split-plot design, followed by the sum of squares decomposition and Tukey’s test, revealed a significant effect for the interaction between Foods and Drinks and Length of Exposure (p < 0.00001). Orange juice resulted in greater mineral loss of enamel after 28 days. None of the test products was associated with recovery of tooth enamel microhardness.

Physicochemical properties of enamel after microabrasion technique

AIM: This study aimed to evaluate the enamel microhardness, surface roughness, and chemical composition after microabrasion technique, followed by polishing and different immersion times in artificial saliva. Materials and methods: Ninety enamel blocks (25mm2) from bovine incisors were divided into two groups (G1 and G2), and then subdivided in five subgroups (n = 9) according to their microabrasion treatment and polishing with a diamond paste: 35% phosphoric acid and pumice (H3PO4+Pum) and polishing; just H3PO4+Pum; 6.6% hydrochloric acid and silica (HCl+Sil) and polishing; just HCl+Sil; and control (no treatment). For G1, roughness and microhardness analyses were performed before (L1) and after (L2) microabrasion. After 15 (L3) and 30 (L4) days of immersion in artificial saliva, microhardness analysis was also performed. After (L4) analysis, the specimens were subjected to SEM analysis. G2 was used for the chemical analysis using energy dispersion testing (EDS). The data was subjected to statistical analysis (α = 5%). For roughness, L2 presented higher values than L1, except for the polished groups. For microhardness, L2 presented higher values than L1, except for unpolished groups. The L3 and L4 did not differ and were higher than L1. RESULTS: No changes were observed in the phosphorus concentrations of the microabrasioned enamel. However, the specimens treated with HCl+Sil were observed as having decreased calcium and increased chlorine and silica on the EDS test. Conclusion: Microabrasion followed by polishing and immersion in artificial saliva for 15 days is enough to increase the microhardness of microabrasioned enamel surfaces, although the microabrasion procedure can alter the mineral content of the enamel.

Characterization and in vitro cytocompatibility of an acid-etched titanium surface

The aims of this study were to characterize the microstructure of a commercially pure titanium (cpTi) surface etched with HCl/H2SO4 (AE-cpTi) and to investigate its in vitro cytocompatibility compared to turned cpTi (T-cpTi). T-cpTi showed a grooved surface and AE-cpTi revealed a surface characterized by the presence of micropits. Surface parameters indicated that the AE-cpTi surface is more isotropic and present a greater area compared to T-cpTi. The oxide film thickness was similar between both surfaces; however, AE-cpTi presented more Ti and O and less C. Osteoblastic cell proliferation, alkaline phosphatase activity, and bone-like nodule formation were greater on T-cpTi than on AE-cpTi. These results show that acid etching treatment produced a surface with different topographical and chemical features compared to the turned one, and such surface modification affected negatively the in vitro cytocompatibility of cpTi as demonstrated by decreasing culture growth and expression of osteoblastic phenotype.

O objetivo deste estudo foi caracterizar a microestrutura de uma superfície de titânio comercialmente puro (cpTi) condicionada com HCl/H2SO4 (acid etched) (AE-cpTi) e investigar sua citocompatibilidade in vitro, comparada à do cpTi usinado (turned) (T-cpTi). O T-cpTi apresentou uma superfície com sulcos e o AE-cpTi exibiu uma superfície caracterizada pela presença de micro-vales. Os parâmetros de superfície indicaram que a superfície AE-cpTi é mais isotrópica e apresenta uma área maior quando comparada à superfície T-cpTi. A espessura da camada de óxido foi similar para as duas superfícies; no entanto, a AE-cpTi apresentou maiores quantidades de Ti e O e menor, de C. A proliferação de células osteoblásticas, a atividade de fosfatase alcalina e a formação de matriz mineralizada foram maiores na superfície T-cpTi que na AE-cpTi. Esses resultados mostram que o condicionamento ácido produziu uma superfície com características topográficas e químicas diferentes quando comparadas às da superfície usinada. Além disso, observou-se que essas modificações de superfície afetaram de forma negativa a citocompatibilidade in vitro do cpTi como demonstrado pela inibição da proliferação celular e da expressão do fenótipo osteoblástico.

Evaluation of change in water quality with strong acid exchanger effluent conductivity.

Koradi Thermal Power Station requires 1-1.2 lakh m3 of water per day and pond No. 3 is the source of water supply of Koradi Thermal Power Station. This Pond No. 3 is being replenished by Pench Canal water, but water undergoes significant changes in quality after entering Pond No. 3 and hence this aspect may be crucial for raw water intake at Water Treatment Plant Stg-II of Koradi Thermal Power Station. Therefore, an attempt has been made to evaluate the change in water quality on the basis of Strong Acid Cation Exchanger Effluent Conductivity and its impact on demineralised water treatment plant.

Fluorosis: tratamiento mediante microabrasión del esmalte / Fluorosis: treatment by means of enamel microabrasion

A partir del advenimiento de las técnicas de blanqueamiento, dada la complejidad de las distintas pigmentaciones y orígenes, surgieron diversas modalidades de tratamiento. La microabrasión, técnica experimentada por Kane en 1916, surgió con la idea de tratar zonas puntuales de coloración en tejido adamantino, resistente a otros tipos de tratamiento para clareamiento dental. En el presente trabajo se demuestran los resultados de dichas técnicas aplicadas a seis casos clínicos

A study of effects of acid activated saw dust on the removal of different dissolved tannery dyes (acid dye) from aqueous solutions.

The effectiveness of acid activated sawdust in absorbing D-Brown EGP and Lurazol Brown PM dyes from aqueous solutions was studied as a function of agitation time and initial dye concentration. The experimental data were fitted to Langmuir and Freundlich isotherm and found that adsorption process follows both the isotherms. The values of Langmuir and Freundlich constants indicate favorable and beneficial adsorption. Saw dust is an excellent low cost adsorbent of colored organic anions and may have significant potential as a color removal from tannery wastewater.

Implantes de cara al 2000 / Implants facing the year 2000

Ante la creciente oferta de sistemas y marcas comerciales existentes actualmente en plaza, cada vez resulta más imprescindible la selección profesional jerarquizada para cada caso clínico en particular. Hay innumerable cantidad de clonaciones que muchas veces nada nuevo aportan y confunden cada día más el mercado. Calidad y servicio son factores a tener en cuenta en el momento de la elección. Resulta indudable que son las empresas que más aportan en investigación, las que marcan pautas a nivel mundial y ofrecen profuctos de avanzada. Ciertos parámetros a tener en cuenta en el momento de decidir qué implante colocar son: - Los hexágonos externos presentan excelentes soluciones estéticas y permiten una adecuada corrección de las angulaciones. Su mayor limitación suele ser el sistema de conexión y cierta tendencia al aflojamiento o pérdida de los tornillos, sobre todo en restauraciones unitarias. El uso de tornillos de oro y torque adecuada minimizan dicho problema. - Los de hexágono interno y cono tornillo presentan mayor estabilidad en el encastre y una adecuada solución cosmética aunque menos versátil. En estos últimos, implantes preangulados contribuyen a tal fin en casos clínicos que así lo requieran. - Los implantes de superficie tratada con ácido se indican expecialmente en huesos de baja y mala calidad por los excelentes reportes clínicos que auguran un índice de éxito a largo plazo, significativamente mayor. Sin embargo, es necesario un seguimiento durante lapsos más prolongados para corroborar lo expuesto. De la misma manera, en huesos de buena calidad se podrían acortar los tiempos de espera para la carga. - En huesos de poco espesor y/o calidad pobre sería de elección el implante de una sola fase quirúrgica y de superficie tratada para optimizar los resultados

Resistencia a la tracción que ofrece un grabado electrolítico y un grabado por calor en medio ácido sobre estructuras metálicas coladas / Tensile strength of an electrolytic etching and a heat etching in acid medium, on cast metal structures

En el presente estudio se realizó un análisis comparativo del comportamiento de un grabado electrolítico y un grabado por calor en medio ácido sobre estructuras metálicas coladas. Se hicieron determinaciones para analizar el factor de retención que produjo cada conjunto metal-metal cementado utilizando para ello cemento de resina compuesta BIS-GMA (Comspan26). Durante el curso de la investigación fue obtenida una información con respecto al procedimiento de grabado utilizado, muestra control y análisis al microscopio electrónico de barrido usados a través del experimento. El análisis de los datos reveló diferencias en la resistencia al despegue que ofrecieron las muestras metálicas cementadas con respecto a los procedimientos utilizados en el desarrollo de la investigación, lo que estuvo en concordancia con las muestras metálicas estudiadas en el microscopio electrónico de barrido.

Chemical durability of some glasses in hydrochloric acid solution

Chemical durability of some sodium silicate and sodium boro-silicate glasses in 0.1 M hydrochloric acid solution was studied. The raw materials used were all of chemically pure grade and were finely pulverized. All melts were made in Pt-2% Rh crucibles in electric furnaces. The temperature of melting ranged from 1400 to 1500 degree for 4 hours. After complete melting, the molten glass was annealed at the appropriate temperature, and then the glass was crushed using an agate mortar. All the measurements of the chemical durability of the glass grains [0.3-0.6 mm] for each glass sample, was carried out by the grain method using 0.1 M HCl solution as the immersion solution. The experimental results obtained revealed that the change in the weight loss with the gradual increase of the soda content was attributed to the accepted ionic diffusion mechanism for acidic solution in such glasses. Also, the mixed alkali effect on such behavior was discussed

Hydrochloric acid-activation of some Egyptian bentonite

Acid activation of nine egyptian bentonite samples in addition to an equally blend samples, was performed using hydrochloric acid. The efficiency of activation was examined by measuring their bleaching capacity, for crude cotton seed oil, and changes in their surface areas. The acid treatment resulted in more than 4-fold increase in the activity of the pretreated bentonite specimens. The extend of activation was found to be pronounced after the first 30 min of acid treatment