El material restaurador ideal en la era de la odontología de invasión mínima. Rescatando al oro directo / The ideal restorative material at the minimal invasive dentistry era. Rescuing direct gold

Los logros de los avances obtenidos en el manejo actual de la caries han dado la oportunidad a los odontólogos de detectar lesiones de caries en sus estadios incipientes. A pesar de la existencia de una gran variedad de materiales restauradores directos disponibles en el mercado actual y que pueden utilizarse para restaurar lesiones pequeñas de caries, el material que tiene más posibilidades de éxito para este tipo de lesiones es sin duda alguna el oro cohesivo, también conocido como oro directo (AU)

The goals obtained with the current management of dental caries has given the dentists the opportunity to detect incipient caries lesions in early stages. Although, the current existence of a great variety of direct restorative materials available in the market to restore small caries lesions, the material that may show better success for these type of lesions, is without any doubt: the gold foil or direct gold (AU)

Concentración de aluminio en carne cocida almacenada en bandejas de aluminio descartables / Aluminum concentration in cooked beef stored in disposable aluminum trays

El aluminio puede ser consumido por personas a través de la contaminación de alimentos y el agua. Los metales pesa­dos en alimentos de origen animal son un riesgo potencial para la salud de los consumidores. En algunos países, es una práctica habitual que las comidas cocinadas listas para el consumo se presenten y mantengan calientes en bandejas de aluminio en tiendas minoristas, como locales de comida rápida y supermercados. No hay información disponible sobre el desprendimiento de metal en este tipo de recipiente de conservación de alimentos. El objetivo de este estudio fue determinar la concentración de aluminio en la carne y en los líquidos de cocción almacenados en bandejas de aluminio descartables. El diseño del estudio incluyó carne bovina cocida almacenada sola, en una salsa acuosa de hierbas a pH 7, y en una salsa acuosa cítrica (a base de limón) a pH 4, para simular condiciones encontradas en la práctica minorista. El Comité Mixto FAO / OMS de Expertos en Aditivos Alimentarios estableció una ingesta semanal tolerable provisional de 2 mg Al kg-1 de peso corporal. Una sola porción de 250 g de carne en salsa ácida almace­nada en una bandeja de aluminio calentada durante 1, 2, 4 u 8 horas contribuiría con 0,9%, 3,4%, 6,9% y 19,8% respectivamente de acuerdo al límite tolerable. Aunque la carne se mantiene caliente durante largos períodos en bandejas de aluminio descartable, el contenido de aluminio no se acerca a los límites actualmente recomendados. Este estudio proporciona datos que sugieren que puede ser prudente limitar el consumo de este tipo de comidas a base de carne con salsas ácidas almacenadas calientes por tiem­pos extendidos en contenedores de aluminio.

Aluminium can be consumed by people through contamination of foods and in water. Heavy metals in foods of animal origin are a potential risk to the health of consumers. It is common practice in some countries that ready-to-eat cooked meals are often presented and maintained hot in aluminium trays in retail outlets such as fast food take-out stores and supermarkets. There are not available information about the detachment of metal in this kind of container food preservation. The objective of this study was to determine the concentration of aluminium in meat and cooking liquids stored in disposable aluminium trays. The design of the study included cooked beef meat stored either alone, or in an aqueous sauce of herbs at pH 7, or in a citric (base of lemon) aqueous sauce at pH 4, to simulate a range of conditions found in retail practice. The Joint FAO/WHO Expert Committee on Food Additives established a provisional tolerable weekly intake of 2 mg Al kg body weight-1. A single 250 g portion of meat in acid sauce stored in a heated aluminium tray for 1, 2, 4, or 8 hours would contribute 0.9%, 3.4%, 6.9% or 19.8% towards this tolerable limit, respectively. Although the aluminium content in meat held warm for long periods in aluminium foil trays does not approach the consumption limits currently recommended, this study provides data that suggest that is may be prudent to limit consumption of ready-to eat meat-based meals with acid sauces stored warm in aluminium containers for extended times.

Accuracy of a separating foil impression using a novel polyolefin foil compared to a custom tray and a stock tray technique

PURPOSE: To compare the dimensional accuracy of three impression techniques- a separating foil impression, a custom tray impression, and a stock tray impression. MATERIALS AND METHODS: A machined mandibular complete-arch metal model with special modifications served as a master cast. Three different impression techniques (n = 6 in each group) were performed with addition-cured silicon materials: i) putty-wash technique with a prefabricated metal tray (MET) using putty and regular body, ii) single-phase impression with custom tray (CUS) using regular body material, and iii) two-stage technique with stock metal tray (SEP) using putty with a separating foil and regular body material. All impressions were poured with epoxy resin. Six different distances (four intra-abutment and two inter-abutment distances) were gauged on the metal master model and on the casts with a microscope in combination with calibrated measuring software. The differences of the evaluated distances between the reference and the three test groups were calculated and expressed as mean (± SD). Additionally, the 95% confidence intervals were calculated and significant differences between the experimental groups were assumed when confidence intervals did not overlap. RESULTS: Dimensional changes compared to reference values varied between -74.01 and 32.57 µm (MET), -78.86 and 30.84 (CUS), and between -92.20 and 30.98 (SEP). For the intra-abutment distances, no significant differences among the experimental groups were detected. CUS showed a significantly higher dimensional accuracy for the inter-abutment distances with -0.02 and -0.08 percentage deviation compared to MET and SEP. CONCLUSION: The separation foil technique is a simple alternative to the custom tray technique for single tooth restorations, while limitations may exist for extended restorations with multiple abutment teeth.

An Old Wine In A New Bottle- Liquid Supported Denture For Atrophic Residual Ridge.

Liquid supported denture can be a permanent solution in edentulous patients with atrophied ridge. A complete denture is designed so that the base is covered with a pre-shaped, close fitting flexible foil containing a thin film of high viscosity liquid. Liquid-supported dentures will have optimal stress distribution during masticatory function. It will act as a continuous reliner for the denture and thus has an advantage over the conventional denture.

An investigation on the influence of tin foil substitute contamination on bond strength between resin denture teeth and the denture base: An in vitro study.

Statement of Problem: The problem of acrylic resin denture teeth separating from their denture base remains a major problem in prosthodontic practice and is frustrating to the patients as well as the dentists. Purpose: This study investigated the influence of tin foil substitute contamination on bond strength between acrylic resin denture teeth and their denture base. Materials and Methods: A total of 80 modified acrylic resin maxillary left central incisors were processed to their denture base material. The 80 specimens were divided into two groups of 40 specimens each: the experimental group and the control group. The experimental group had the denture tooth ridge lap area contaminated with tin foil substitute.The 40 specimens in the control group were not contaminated. After 7 days of storage at room temperature, the bond strengths of the two groups were tested with a universal testing machine.The nature of failure was noted as adhesive (interface) or cohesive (in tooth or denture base material). The Welch test and z-test were performed to identify significant differences. Results: The uncontaminated specimens (group I) showed superior bond strength as compared to the contaminated specimens (group II); the difference in bond strength between the groups was highly significant (P<0.0001). Also the contaminated specimens exhibited predominantly adhesive failure (89.74%), whereas the uncontaminated specimens exhibited 55% adhesive failure and 45% cohesive failure. Conclusion: Tin foil substitute contamination of the ridge laps of acrylic resin denture teeth greatly reduced the bond strength.

Evaluación del destino dado a los residuos de materiales radiográficos por parte de los dentistas de la ciudad Juiz de Fora Minas Gerais, Brasil

El objetivo de este estudio fue evaluar el destino que los dentistas de la ciudad de Juiz de Fora (Minas Gerais, Brasil) les dan a los residuos radiográficos que producen. Setenta y cuatro profesionales respondieron un cuestionario, con preguntas objetivas sobre el desecho de las soluciones reveladora y fijadora, de radiografías insatisfactorias para diagnóstico y de las láminas de plomo de los embalajes de películas intrabucales. El cuestionario también verificó el conocimiento sobre la resolución RDC 306/2004 de la ANVISA. Aproximadamente un 50% de los participantes relató que hace el desecho de las soluciones procesadoras en desagüe común y sin dilución, además de tirar las radiografías insatisfactorias en la basura común. Cerca de un 30% desecha las láminas de plomo de las películas intrabucales en el basurero hospitalario. Cincuenta y tres por ciento desconoce totalmente la Resolución RDC nº 306/2004 y un 20% desconoce totalmente lo que es el Plan de Gestión de Residuos de Salud. Aproximadamente un 75% de los dentistas nunca había recibido orientaciones o advertencias sobre el destino dado a los residuos de materiales radiográficos en su consultorio y un 90% dijo que le gustaría recibir informaciones sobre el asunto. Se llegó a la conclusión que la gran mayoría de los dentistas no tiene conocimiento del correcto desecho de residuos de materiales radiográficos, pero, demostraron que se preocupan con eso, ya que destacaron la necesidad de recibir informaciones

The objective of this study was to evaluate the destination of radiograph residue produced by dentists of the city of Juiz de Fora (Minas Gerais, Brazil). Seventy-four professionals answered a questionnaire with objective questions about the disposal of developer and fixer solutions, of unsatisfactory radiographs for diagnosis and of the lead foil in intraoral film. The questionnaire verified their knowledge of the ANVISA RDC 306/2004 resolution as well. Approximately 50% of the participants revealed they dispose of the processing solutions in the common sewer system with no dilution, in addition to disposing of unsatisfactory radiographs in normal trash. Approximately 30% dispose of lead foil in intraoral film as hospital waste. Fifty-three percent never heard of Resolution RDC 306/2004 and 20% have no knowledge of the Health Residue Management Plan. Approximately 75% of the dentists had never received guidance or warnings about the destination given to radiograph material residue in their offices and 90% said they would like to receive information on the matter. In conclusion, most of the dentists have no knowledge of the correct disposal of radiograph material residue; however, they demonstrated concern highlighting the need to receive information

A comparison of marginal fit of glass infiltrated alumina copings fabricated using two different techniques and the effect of firing cycles over them

PURPOSE: This study evaluated marginal fit of glass infiltrated alumina cores fabricated using two techniques and their marginal stability after firing cycles of veneering porcelain. MATERIALS AND METHODS: Fifteen standardized all-ceramic crowns were fabricated on a metal die using each technique: slip cast technique of VITA In-Ceram sprint Alumina (Group A as control) and plastic foil matrix technique of Turkom-Cera fused alumina core system (Group B). Copings were compared between groups and within groups at coping stage and after firing each layer of veneering porcelain. A device was used to standardize seating of copings on the metal die and positioning of the specimens under the microscope after each stage of fabrication. The specimens were not cemented and marginal gap was measured using an image analyzing software (Imagepro Express) on the photographs captured under an optical microscope. Two tailed unpaired 't test' was used to compare marginal gaps in two groups and one way ANOVA was used to analyze marginal distortion within each group at 95% confidence interval. RESULTS: The marginal gap was smaller at the coping stage in group B (60 + 30 microm) than group A (81 + 21 microm) with statistical significance. After firing of veneering porcelain the difference was insignificant. At the final stage, both groups exhibited lower mean marginal gaps than at the initial coping stage with the difference of 11.75 microm for group A and 11.94 microm for group B, but it was statistically insignificant due to high value of standard deviation. CONCLUSION: Within the limitations of this study, it was concluded that both techniques produced copings with comparable and acceptable marginal fit and marginal stability on firing veneering porcelain.

The Effect of the Consumption Monitoring Inaccuracy by Vision on Kimbab Intake and Satiety Rate / 대한지역사회영양학회지

It was examined whether altering vision would influence food intake through consumption monitoring and whether this would be reflected in consumption estimate and satiety. The experiment was designed in two visibility levels: 1) an accurate visual cue (bowl covered with wrap) vs 2) a biased visual cue (bowl covered with foil). Thirty three female college students participated in this study. The subjects ate Kimbab in the lab once a week for 2 weeks. They were served 24 pieces of Kimbab in a bowl covered either with wrap or foil. The results showed that the actual Kimbab intake from the bowl covered with foil was significantly lower than the test using wrap (13.4 +/- 3.3 pieces vs 15.0 +/- 3.8 pieces, p < 0.05). And there were no significant differences from the cognitive Kimbab intake between the tests with foil and wrap. However, the satiety rate of Kimbab in a bowl covered with foil was significantly higher than that with wrap at 1 hour and 2 hour after the Kimbab eaten (p < 0.05). Less consumed cases were recognized by subjects due to the inaccuracy during the consumption monitoring process. This result revealed that vision influences not only eating behavior but also subjective feelings of satiety after meal. In conclusion, the consumption monitoring by visual cues can play an important role in food intake and satiety rate.

Study on lift-up speed of aerodynamic compliant foil thrust bearings / 药物分析学报

Objective The experimental study on the lift-up speed of a new kind of compliant aerodynamic foil thrust bearings was performed on the multifunctional test rig established for testing the performances of foil gas bearings. Methods The lift-up speed of foil gas thrust bearing under given axial load was analyzed through the spectrum of axial displacement response in frequency domain. Results The test results indicated that the difference in the spectrum of axial displacement responses before and after lifting up of the rotor was obvious. After lifting up of the rotor, there were only larger components of rotation frequency and lower harmanic frequencies. If the rotor wasn't lift-up, there were also larger components of other frequencies in the spectrum. Conclusion So by analyzing the spectrum of axial displacement response, the results showed that the lift-up speed was about 1 860 rpm when the axial load was 31N.