Analysis of sealing vs tensile bond strength of eight adheisve restorative material systems

Purpose: Using a simulated perfusion system, the intent was to determine: 1) the sealing ability of eight restorative materials (five composite resins and three compomers) used together with their corresponding dentin bonding systems, 2) their tensile bond strength, and 3) the correlation (if any) between both parameters. Materials and Methods: Permeability in crown segments from sound human third molars (n = 140) subjected to simulated perfusion (32 cm of distilled water) was measured before and after restoring with each material, and the percentage of decrease in permeability ((PPD) was recorded. Specimens were tater subjected to tensile tests to determine the tensile bond strength (TBS) of the interface. Finally, parameters were analyzed for correlation. Results: For the eight adhesive systems, the percentage of reduction in permeability was relatively hlgh [mean in %, (SD)]: F2000 93.6 (5.7),S B188.6 (11.31,S SC 86.0 (5.7), PB20 81.1 (15.9)C,O M 77.5 (10.8), OPTS 75.3 (20.6)D,Y R 73.7 (12.7)S,S PR 65.5 (19.8)T.B S values were relatively low [mean (SD)], in MPa: F2000 1.8 (0.71, SB1 4.9 (1.4)S,S C 2.6 (1.4), PB20 4.3 (1.21,C OM 2.4 {1.1),O PTS 4.5 (1.7)D,Y R L6 (0.6), SSPR.4.2 (1.5). We could not demonstrate any statistically significant correlation between both parameters for these results (maximum significance [F20001: r = 0.39, p = 0.206). Conclusion: No material completely ceased to filtrate through the interface. The low TBS values were probably due to the large size of adhesive areas. No significant correlation was found between PPD and TBS for the materials tested. There was a statistically significant relationship (r2 = 0.063, p = 0.018) between TBS and TEA (total bonded area), described by the equation TBS = 5.9 - 0.03'TBA

Estudio in vitro de las variaciones de la permeabilidad dentinaria tras la obturación mediante cementos de vidrio ionómero fotopolimerizables

La presencia constante de fluido dentinario en la superficie adhesiva condiciona la unión diente/material restaurador. Por otra parte, al sellarse la interfase diente/material el comportamiento de dicho fluido dentinario debería cambiar. Esto es lo que hemos estudiado en nuestro trabajo, para tres cementos de vidrio ionómero fotopolimeralizables (Photac Fil, Viltremen y Dyract), utilizando un sistema derivado del descrito por Derkson, Pashley y Derkson, que mide, en microlitros, las pérdidas que se producen a través de la dentina cortada de coronas de molares humanos extraídos. El área de pérdidas se mide mediante análisis computarizado de imágenes y se utiliza como patrón el comportamiento de casos sin restaurar, comparándolos con casos restaurados con los tres tipos de materiales citados. Los resultados parecen indicar que no se produce la detención esperada del movimiento hacia fuera del fluido, lo que nos sugiere nuevas modificaciones del sistema de medición, como la utilización de discos de dentina, y de la preparación de los especímenes.// The constant presence of dentinary fluid in the adhesive surface conditions the tooth/restorative material interaction. In the other hand, when the interfase is properly sealed, the behaviour of that dentinary fluid should change. This possible change is studied in this work, for three light-cured glass ionomer cements (Photac Fil, Vitremen and Dyract), using a system derived of the one described by Derkson, Pashley and Derkson, able to measure, in microliters, the dentinary fluid outward movement through the cut dentin of crowns of human molars. The exposed area is measured by computerized image analysis, The loss of unrestored specimens is used as a control and compared with three types of above said materials. Results denote that expected halt of outward movement of the fluid does not take place. This suggests us further modifications of the system, as the utilization of dentin disc and different specimen holders

Sealing and dentin bond strength of adhesive systems in selected areas of perfused teeth

Objectives: (1) Test the sealing capacity and tensile strength of various adhesive systems: Scotch Bond 1 (Single Bond in USA)(SB1) + Z100, Syntac Sprint (SYN) + Tetric Ceram, Prime and Bond 2.1 (PB21) + TPH Spectrum, F2000 (Adhesive 1 Compomer) (F2000) and Optibond Solo (OPT) + Prodigy, to perfused teeth (30 cm distilled H2O), in select areas. (2) Determine the relationship between sealing ability and size of adhesive area (BA) with tensile strength (TS). Methods: Segments of human third molars (n=67) sealed with amalgam on their coronal side were connected to a perfusion system (30 cm distilled H2O), to measure the basal permeability. Access cavities were drilled through the amalgam to expose dentin (area range: 8.7±20.8 mm2) and measure the permeability of that area. Cavities were sealed with one of the test materials and permeability measured prior to tensile testing. The percentage of decrease in permeability (PPD) that occurred with the different combinations of materials was also measured. Results. Tensile strength: there were no statistically signi®cant differences among groups. Permeability: ANOVA showed that there were statistically signi®cant differences in the mean % decrease in permeability (PPD) among groups (p= 0:018): Student-Newman-Keuls test (p=0:05) detected that the mean PPD of F2000 ranked statistically higher than that of SB1. Relationship among variables: a linear correlation was found defined by the formula TS= 7:47+ 0:008·PPD - 0:23·BA; with a significance of the model p=0.0097. Significance: None of the materials studied reduced permeability up to 100%. They all produced low tensile bond strengths (maximum mean value of groups: 5.51 MPa (OPT))

Permeabilidad dentinaria. Relación entre los distintos parámetros que la definen

Mediante un sistema simulado de perfusión, se mide la permeabilidad de discos de dentina. Se estudia la relación entre el área y el espesor de la dentina a través de la cual se perfunde, y la magnitud del gasto (volúmen/tiempo). Debido principalmente a la variabilidad anatómica, no es posible establecer una relación estadísticamente significativa entre dichos parámetros. El radio efectivo medio calculado (p<0.001) de los túbulos varía entre 0,13±0.024 µm y 0.08 ± 0.0015 µm, supuestas unas densidades tubulares respectivas de 20.000 y 50.000 túbulos/mm². // We measure of permeability of dentin by means of a simulated perfusion system. We study the relation between the area, the thickness and the volume/time magnitude. We could not establish an statistical relationship between the cited factors, because of anatomical variations. The median effective radius calculated (p<0.001) was between 0.13±0.024 µm and 0.08±0.0015 µm, suposed a density of 20.000 or 50.000 tubuli/mm², respectively.Depto. de Odontología Conservadora y PrótesisFac. de OdontologíaTRUEpu

Nonlinear thermoelectric response of quantum dots: renormalized dual fermions out of equilibrium

The thermoelectric transport properties of nanostructured devices continue to attract attention from theorists and experimentalist alike as the spatial confinement allows for a controlled approach to transport properties of correlated matter. Most of the existing work, however, focuses on thermoelectric transport in the linear regime despite the fact that the nonlinear conductance of correlated quantum dots has been studied in some detail throughout the last decade. Here, we review our recent work on the effect of particle-hole asymmetry on the nonlinear transport properties in the vicinity of the strong coupling limit of Kondo-correlated quantum dots and extend the underlying method, a renormalized superperturbation theory on the Keldysh contour, to the thermal conductance in the nonlinear regime. We determine the charge, energy, and heat current through the nanostructure and study the nonlinear transport coefficients, the entropy production, and the fate of the Wiedemann-Franz law in the non-thermal steady-state. Our approach is based on a renormalized perturbation theory in terms of dual fermions around the particle-hole symmetric strong-coupling limit.Comment: chapter contributed to 'New Materials for Thermoelectric Applications: Theory and Experiment' Springer Series: NATO Science for Peace and Security Series - B: Physics and Biophysics, Veljko Zlatic (Editor), Alex Hewson (Editor). ISBN: 978-9400749863 (2012

Budget impact analysis of medicines : updated systematic review and implications

This evaluation determines whether published studies to date meet the key characteristics identified for budget impact analyses (BIA) for medicines, accomplished through a systematic review and assessment against identified key characteristics. Studies from 2001 to 2015 on "budget impact analysis" with "drug" interventions were assessed, selected based on their titles/abstracts and full texts, with their characteristics checked according to key criteria. Out of 1984 studies, 92 were identified. Of these, 95% were published in Europe and the USA. 2012 saw the largest number of publications (16%) with a decline thereafter. 48% met up to 6 or 7 out of the 9 key characteristics. Only 22% stated no conflict of interest. The results indicate low adherence to the key characteristics that should be considered for BIAs and strong conflict of interest. This is an issue since BIAs can be of fundamental importance in managing the entry of new medicines including reimbursement decisions

Anthropogenic noise is associated with changes in acoustic but not visual signals in red-winged blackbirds

Some birds in noisy areas produce songs with higher frequency and/or amplitude and altered timing compared to individuals in quiet areas. These changes may function to increase the efficacy of acoustic signals by reducing masking by noise. We collected audio recordings of red-winged blackbirds and measured noise levels. We found that males in noisier places produced songs with fewer syllables and slower repeat rate of elements in some components (rattles). Birds may also improve the efficacy of communication in noise by increasing usage of other signaling modalities. Red-winged blackbirds also perform a visual display in different intensities while singing. We also tested whether this species performs the visual display in different intensities according to current noise levels, and predicted that if the efficacy of songs is impaired in noisy places, males would compensate by performing a more intense visual display. For this, we also collected visual recordings from the same males from which we obtained acoustic recordings. We found no association between acoustic noise and the intensity of the visual display; thus, our results do not support the idea that males are using the visual display as a backup signal to communicate under acoustic noise. We discuss some possible explanations of this negative finding and for the observed noise-related changes in song length and rattle rate in the context of communication under noise

Sealing and Dentin Bond Strengths of Adhesive Systems

The objectives of this research were (1) to analyze the variations of the permeability of dentin after restoration with two polyacid-modified resin composites (Compoglass, Dyract) and four single-bottle adhesives (Prime & BOnd 2.0, Syntac Single Component, OptiBond Solo, and Single Bond -Scotch Bond 1 in Europe- immediately (approximately 1 hour) after insertion. A perfusion system with distilled water was used at a pressure of 32.5 cm of water; (2) to study the bond strength of their interfaces; and (3) to find the correlation, if any, between both parameters. None of the materials used produces a complete cessation in fluid filtration. Tensile strengths were very low (maximum: P&B=3.96MPa) probably because of the very large bonding surfaces used (mean bonded surface area = 88.8mm²). No significant correlation was found between tensile bond strength and the sealing ability for any material