Bond strengths of various resin cements to different ceramics

Abstract This study evaluates the shear bond strength (SBS) of various resin cements to different ceramics. Composite resin cylinders of Z100 were fabricated and cemented to disks of feldspathic ceramic (Creation), leucite-reinforced feldspathic ceramic (Empress I), and densely sintered aluminum oxide ceramic (Procera AllCeram) using five resin cements: Panavia F (PAN), RelyX ARC (ARC), RelyX Unicem (RXU), RelyX Veneer, and Variolink II. SBS was measured after three days of water storage (baseline) and after artificial aging (180 days of water storage along with 12,000 thermal cycles). Failure mode of fractured specimens also was evaluated. Data were analyzed with Kruskal-Wallis and Mann-Whitney tests (α=0.05). RXU showed 1) the lowest baseline median SBS to feldspathic ceramic, which was not statistically different from PAN; 2) the lowest median baseline SBS to leucite-reinforced feldspathic and densely sintered aluminum-oxide ceramics. All cements performed similarly after aging, except for ARC (median 0.0 MPa) and PAN (median 16.2 MPa) in the densely sintered aluminum-oxide ceramic group. Resin cements perform differently when bonded to different ceramic substrates. While all test resin cements worked similarly in the long-term to feldspathic and leucite-reinforced feldspathic ceramics, only the MDP-containing resin cement provided durable bonds to densely sintered aluminum-oxide ceramic.

Género y trayectorias profesionales de las médicas de familia en Andalucía, España, a comienzos del siglo XXI / Gender and career paths of female primary care physicians in Andalusia, Spain, at the beginning of 21st century

El objetivo de este trabajo es estudiar, desde una perspectiva feminista, la diversidad y homogeneidad en las trayectorias profesionales de las médicas de familia que ejercían en Andalucía a comienzos del siglo XXI, a través del análisis de los significados que ellas mismas confieren a su desarrollo profesional y de la influencia de los factores personales, familiares y laborales. Realizamos un estudio cualitativo con seis grupos de discusión. Participaron 32 médicas de familia que se encontraban trabajando en los centros de salud urbanos de la red sanitaria pública de Andalucía. El análisis del discurso revela que la mayoría de las médicas no planifican sus metas profesionales y que, cuando lo hacen, las van entrelazando con las necesidades familiares. Esto se traduce en que sus trayectorias profesionales sean discontinuas. Por el contrario, las trayectorias orientadas al desarrollo profesional y a la planificación consciente de metas son más frecuentes entre las médicas que ocupan cargos de dirección en centros de salud.

The purpose of this article was to study, from a feminist perspective, the diversity and homogeneity in the career paths of female primary care physicians from Andalusia, Spain in the early 21st century, by analyzing the meanings they give to their careers and the influence of personal, family and professional factors. We conducted a qualitative study with six discussion groups. Thirty-two female primary care physicians working in urban health centers of the public health system of Andalusia participated in the study. The discourse analysis revealed that most of the female physicians did not plan for professional goals and, when they did plan for them, the goals were intertwined with family needs. Consequently, their career paths were discontinuous. In contrast, career paths oriented towards professional development and the conscious planning of goals were more common among the female doctors acting as directors of health care centers.

Fluoride and aluminum release from restorative materials using ion chromatography

OBJECTIVE: The aim of this study was to determine the amounts of fluoride and aluminum released from different restorative materials stored in artificial saliva and double-distilled water. Material and METHODS: Cylindrical specimens (10 x 1 mm) were prepared from 4 different restorative materials (Kavitan Plus, Vitremer, Dyract Extra, and Surefil). For each material, 20 specimens were prepared, 10 of which were stored in 5 mL artificial saliva and 10 of which were stored in 5 mL of double-distilled water. Concentrations of fluoride and aluminum in the solutions were measured using ion chromatography. Measurements were taken daily for one week and then weekly for two additional weeks. Data were analyzed using two-way ANOVA and Duncan's multiple range tests (p<0.05). RESULTS: The highest amounts of both fluoride and aluminum were released by the resin-modified glass ionomer cement Vitremer in double-distilled water (p<0.05). All materials released significantly more fluoride in double-distilled water than in artificial saliva (p<0.05). In artificial saliva, none of the materials were observed to release aluminum. CONCLUSION: It was concluded that storage media and method of analysis should be taken into account when the fluoride and aluminum release from dental materials is assessed.

Radiodensity evaluation of dental impression materials in comparison to tooth structures

In the most recent decades, several developments have been made on impression materials' composition, but there are very few radiodensity studies in the literature. It is expected that an acceptable degree of radiodensity would enable the detection of small fragments left inside gingival sulcus or root canals. OBJECTIVE: The aim of this study was to determine the radiodensity of different impression materials, and to compare them to human and bovine enamel and dentin. MATERIAL AND METHODS: Twenty-five impression materials, from 5 classes, were studied: addition and condensation silicones, polyether, polysulfides and alginates. Five 1-mm-thick samples of each material and tooth structure were produced. Each sample was evaluated 3 times (N=15), being exposed to x-ray over a phosphor plate of Digora digital system, and radiodensity was obtained by the software Digora for Windows 2.5 Rev 0. An aluminum stepwedge served as a control. Data were subjected to Kruskal-Wallis and Dunn's method (α=0.05). RESULTS: Different materials and respective classes had a different behavior with respect to radiodensity. Polysulfides showed high values of radiodensity, comparable to human enamel (p>0.05), but not to bovine enamel (p<0.05). Human dentin was similar only to a heavy-body addition silicon material, but bovine dentin was similar to several materials. Generally, heavy-body materials showed higher radiodensity than light-body ones (p<0.05). CONCLUSION: Impression materials' radiodensity are influenced by composition, and almost all of them would present a difficult detection against enamel or dentin background in radiographic examinations.

Construction of a copper stepwedge with aluminum equivalent mean gray values

OBJECTIVES: To produce a copper (Cu) stepwedge with aluminum (Al) equivalent mean gray values (MGV). MATERIAL AND METHODS: The thicknesses of Cu steps that were equivalent to those of the Al were formulated using the X-ray attenuation properties of the materials. The Al and fabricated Cu stepwedges were radiographed, but the MGVs of the Cu stepwedge were mismatching to those of the Al. Using a mathematical function to adjust the pixel MGV of Cu stepwedge to those of the Al, new Cu stepwedges were created. In vitro iterations were performed until best approximation to Al was reached. RESULTS: The MGV of the Cu stepwedges fabricated by formularization were different than those of Al (p=0.001). Iteration method led to MGV similar to those of the Al stepwedge (p=0.207). CONCLUSIONS: Construction of a Cu stepwedge according to the basic rules of radiophysic failed to result in a stepwedge with similar radiodensity values to those of Al stepwedge. Further studies may use the formularization method only for prototype Cu wedge production, but consecutive iterations shall be compassed to obtain the best approximation to Al MGV.

Radiopacity evaluation of root-end filling materials by digitization of images

The purpose of this study was to evaluate the radiopacity of 5 root-end filling materials (white MTA-Angelus, grey MTA-Angelus, IRM, Super EBA and Sealer 26). Five specimens (10 mm diameter X 1 mm thickness) were made from each material and radiographed next to an aluminum stepwedge varying in thickness from 2 to 16 mm. Radiographs were digitized and the radiopacity of the materials was compared to that of the aluminum stepwedge using VIXWIN 2000 software in millimeters of aluminum (mm Al). Data were analyzed statistically by ANOVA and Tukey's test at 5% significance level. Radiopacity values varied from 3 mm Al to 5.9 mm Al. Sealer 26 and IRM presented the highest radiopacity values (p<0.05), while white/grey MTA and Super EBA presented the lowest radiopacity values (p<0.05). The tested root-end filling materials presented different radiopacities, white/grey MTA and Super EBA being the least radiopaque materials.

Influence of physico-chemical factors on leaching of chemical additives from aluminium foils used for packaging of food materials.

In recent years, the use of aluminium foils to wrap foodstuff and commodities has been increased to a great extent. Aluminium was found to leach out from the foil in different simulants particularly in distilled water, acidic and alkaline medium at 60 +/- 2 degrees C for 2 hours and 40 +/- 2 degrees C for 24 hours. The migration was found to be above the permissible limit as laid down by WHO guidelines, that is of 0.2 mg/L of water. The protocol used for this study was based on the recommendation of Bureau of Indian Standard regarding the migration of chemical additives from packaging materials used to pack food items. Migration of the aluminium metal was found significantly higher in acidic and aqueous medium in comparison to alcoholic and saline medium. Higher temperature conditions also enhanced the rate of migration of aluminium in acidic and aqueous medium. Leaching of aluminium metal occurred in double distilled water, acetic acid 3%, normal saline and sodium carbonate, except ethanol 8%, in which aluminium migration was below the detection limit of the instrument where three brands of the aluminium foil samples studied.

Cu redeposition and surface enrichment during the dissolution of Al-Cu Alloy in 0.1 M HCI

The enrichment of Cu on the surface of Al - 3.84% Cu alloy during the dissolution in 0.1 M HCI has been examined using open circuit potential [OCP] accompanied by scanning electron microscopy [SEM], Auger electron spectroscopy [AES] and X-ray photoelectron spectroscopy [XPS]. Results obtained during this study show that there are two types of Cu enrichment, one of them is in the form of Cu clusters, which is formed due to the outer diffusion or segregation of Cu to the alloy surface. The second type is more uniform deposition as a result of copper redeposition from solution, this data is confirmed by the AES survey point analysis, which show that the detection of Cu peak beside the disappearance of Al peak occurred at the whole surface. It is also indicated that the Cu released from the alloy surface is due to two different sources. The first occurred due to the severe galvanic attack, around the breifery of the clusters. This attack can be extended under the cluster and released. The other was attributed to the uniform redeposition of Cu on pure Al, where the disproportionation reaction of Cu[+] ions takes place on the surface, which can produce Cu[++] ions to the solution. The higher resolution multiplex of Cu using XPS analysis shows that the appearance of three peaks corresponding to Cu[°] [metallic copper], CuCI, CuCI[2] and devoid of any Al species. Accordingly the redeposit Cu on pure Al can behaves as Cu metal and dissolves also as dichlorocoprate [CuCI[2]] soluble complex beside CuCI[2]

Odontologic use of copper/aluminum alloys: mitochondrial respiration as sensitive parameter of biocompatibility

Copper/aluminum alloys are largely utilized in odontological restorations because they are less expensive than gold or platinum. However, tarnishing and important corrosion in intrabuccal prostheses made with copper/aluminum alloys after 28 days of use have been reported. Several kinds of food and beverage may attack and corrode these alloys. Copper is an essential component of several important enzymes directly involved in mitochondrial respiratory metabolism. Aluminum, in contrast, is very toxic and, when absorbed, plasma values as small as 1.65 to 21.55 µg/dl can cause severe lesions to the nervous system, kidneys, and bone marrow. Because mitochondria are extremely sensitive to minimal variation of cellular physiology, the direct relationship between the mitocondrial respiratory chain and cell lesions has been used as a sensitive parameter to evaluate cellular aggression by external agents. This work consisted in the polarographic study of mitochondrial respiratory metabolism of livers and kidneys of rabbits with femoral implants of titanium or copper/aluminum alloy screws. The experimental results obtained did not show physiological modifications of hepatic or renal mitochondria isolated from animals of the three experimental groups, which indicate good biocompatibility of copper/aluminum alloys and suggest their odontological use

Cytotoxicity of yellow sand in lung epithelial cells.

The present study was carried out to observe the cytotoxicity of yellow sand in comparison with silica and titanium dioxide in a rat alveolar type II cell line (RLE-6TN). Yellow sand (China Loess) was obtained from the loess layer in the Gunsu Province of China. The mean particle diameter of yellow sand was about 0.003 +/- 0.001 mm. Major elements of yellow sand were Si(27.7 +/- 0.6%), Al(6.01 +/- 0.17%), and Ca(5.83 +/- 0.23%) in that order. Silica and yellow sand significantly decreased cell viability and increased [Ca2+]i. All three particles increased the generation of H2O2. TiO2 did not change Fenton activity, while silica induced a slight increase of Fenton activity. In contrast, yellow sand induced a significant increase of Fenton activity. Silica, yellow sand and TiO2 induced significant nitrite formations in RLE-6TN cells. Silica showed the highest increase in nitrite formation, while yellow sand induced the least formation of nitrite. Silica and yellow sand increased the release of TNF-a. Based on these results, we suggest that yellow sand can induce cytotoxicity in RLE-6TN cells and reactive oxygen species, Fenton activity and reactive nitrogen species might be involved in this toxicity.

Lasers en odontología / Lasers in dentistry

El uso del rayo láser en odontología inició en la década de ;ps 80, principalmente el CO2 y el Nd/YAG (Neodimium/Ytrium-Aluminium-Garnet); su principal uso es en los tejidos blandos en la cavidad bucal, por ejemplo en tratamientos periodontales, en excisión de fibromas, etc., así como también el Er/YAG que se utiliza hoy en día para remover caries y perforar estructura dentaria. El uso de láser en odontología tiene sus limitaciones, ventajas y desventajas, así como cualquier otra técnica quirúrgica/operatoria. El entendimiento de las bases de la óptica láser y las reacciones de los tejidos son esenciales. Aún así el operador debe tener conocimiento de las diferentes aplicaciones para tratamiento

Rayo láser en periodoncia / Laser in periodontics

Este trabajo tiene la finalidad de promover el conocimiento del uso del láser en periodoncia, sus propiedades físicas, tipos de rayos láser actualmente disponibles y sus efectos de accón sobre tejidos orales y posibilidades de aplicación clínica. Los rayos láser más usados en odontología son el de dióxido de carbono (CO2) y el de neodymium:yttrium-aluminium-garnet (Nd:YAG), para una amplia variedad de procedimientos quirúrgicos, control de la microflora subgingival sobre la superficie radicular, donde se demostró efectos significativos

Almacenamiento y uso de antioxidantes en barras de cereales y maní / Storage and use of antioxidants in cereal and peanut bars

La utilización de materias grasas en las barras de cereales les da un adecuado valor energético pero también las expone al desarrollo de rancidez oxidativa, la cual puede afectar su aceptabilidad y calidad nutricional. De acuerdo a esto, el objetivo del presente trabajo fue: determinar la estabilidad en almacenamiento y el efecto de antioxidantes en tres tipos de barras de cereales y maní. Para ello se elaboraron barras de cereales con 18 por ciento de maní, con y sin antioxidantes (BHA+BHT; 100 ppm). Las barras se envasaron en bolsas de polipropileno -aluminio- polietileno y se almacenaron por 90 días a temperatura ambiente (18-20 grados Celsius). Cada 30 días se realizaron análisis de: Actividad de agua (Aw); Humedad; Indice de peróxido y Evaluación sensorial para determinar su calidad (aroma, sabor y apariencia) y aceptabilidad. El contenido de humedad fue similar en todas las barras (7,6-9,5 por ciento) en tanto que Aw fue superior en las barras con amaranto dilatado y antioxidante. El índice de peróxidos a los 60 días de almacenamiento fue menor que las barras con antioxidantes, presentando diferencias significativas solo la barra con amaranto dilatado (16,4 meq/Kg para la barra con antioxidante y 25,7 meq/Kg para la barrra testigo). En cuanto a la calidad sensorial los valores de los tres parámetros se mantuvieron dentro de los rangos normales, sin diferencias entre las barrras testigo y las barras con antioxidante y sin variaciones durante el período de almacenamiento. La vida útil de las barras CM1 y CM2 es al menos de 60 días cuando son conservadas a 18-20 grados Celsius.

Estudo comparativo da dureza superficial, resistência à corrosäo e rugosidade superficial de ligas metálicas alternativas / Comparative study of the superficial hardness, resistence to corrosion and superficial roughness of experimental metallic alloys

Há muitos anos, as restauraçöes metálicas fundidas com ligas de ouro vêm desempenhando grande funçäo nos trabalhos restauradores em odontologia, porém, a necessidade de substituiçäo das ligas, à base de ouro, em funçäo do seu alto custo, fez surgir no comércio odontológico uma grande quantidade de ligas metálicas alternativas. Os processos de fundiçäo e manipulaçäo dessas ligas, dispondo hoje de recursos vários, para obtençäo de restauraçöes mais precisas, vêm evoluindo rapidamente. Quanto aos conhecimentos a respeito das propriedades físicas, químicas, mecânicas e biológicas das ligas metálicas alternativas, parece näo haver um consenso entre os pesquisadores, näo existindo ainda uma liga alternativa que possa ser considerada como uma liga sucedânea das ligas de ouro. Por esse motivo, propusemo-nos verificar algumas propriedades físicas de: dureza supercial (Vickers), resistência à corrosäo pela perda ou ganho de peso e pela modificaçäo da rugosidade superficial em funçäo do tratamento térmico aplicado a algumas ligas metálicas experimentais (MID, Q, C2, C13) e comerciais (INOX GOLD e OURO SINTÉTICO), à base de cobre e níquel. Após obtidos os corpos de prova, estes foram submetidos a três tipos de tratamentos térmicos, a saber...

Spectrophotometric studies of Al [III] complexes with 4- [arylazo] -1-hydroxy-2-naphtoic acid dyes

The optimum conditions favoring the formation of Al [III] complexes with 4-arylazo-1-hydroxy-2-naphthoic acid dyes [Ia-h] are extensively investigated. The molecular structure of the complexes and their obedience to Beer's law and Ringbom ranges, as well as, their stabilities are studied. Methods for the spectrophotometric determination of Al [III] and spectrophotometric titration using EDTA and CDTA were reported. The interference effect of several ions was checked. The stoichiometry of Al [III] with [Ia-h] dyes was investigated by conductometric titrations. The study was extended to the determination of Al in pure Al metal and in Si-Al master alloy. A new rapid and accurate method for the spectrophotometric microdetermination of Al [III] using 4-[arylazo]-1-hydroxy-2-naphthoic acid dyes [Ia-h] is given

Avaliaçäo objetiva (espectrofotometria) e subjetiva (visual) das alteraçöes no brilho de quatro ligas metálicas odontológicas (ouro, níquel-cromo, cobre-alumínio e amálgama), mantidas no meio bucal por 6 meses / Objective evaluation (spectrophotometry) and subjective (visual) of luster alterations of four dental metalic alloys (gold, nickel-chromium, cooper aluminum and amalgam), maintened in the mouth for 6 months

Neste estudo foram utilizadas quatro ligas metálicas, sendo uma liga de ouro tipo IV que serviu como controle, uma liga de cobre-alumínio, uma liga de níquel-cromo e uma liga para amálgama. Padröes em forma de discos com 6 mm de diâmetro e 2 mm de espessura foram fundidas e sofreram acabamento pelos métodos convencionais após inclusäo em blocos de resina acrílica. O aspecto das peças foi avaliado clinicamente em uma escala de 0 a 3, quanto a ocorrência de manchas, brilho e descoloraçäo, sendo posteriormente avaliadas em um espectrofotômetro utilizando-se mudanças cromáticas na luz a fim de quantificar a refletância superficial. As peças foram fixadas na regiäo posterior da face vestibular de dentaduras superiores de pacientes, tendo suas características superficiais novamente analisadas depois de um, três e seis meses, com o propósito de observar o comportamento clínico das ligas. As peças foram combinadas entre si da seguinte maneira: 5 peças de ouro com 5 de cobre-alumínio, 5 de ouro com 5 de níquel-cromo, 5 de Sybraloy com 5 de cobre-alumínio, 5 de Sybraloy com 5 de níquel-cromo, 5 de cobre-alumínio com 5 de cobre-alumínio, 5 de cobre-alumínio com 5 de níquel-cromo, 5 de níquel-cromo com 5 de níquel-cromo. Em cada dentadura foram colocadas no máximo quatro peças, sendo duas de cada lado, respeitando a combinaçäo acima. Os resultados e conclusöes foram: A - Avaliaçäo objetiva: 1 - as ligas metálicas, quando testadas com outras ligas mo meio oral, em funçäo do tempo, apresentaram alteraçäo de cor; 2 - em funçäo do tempo, a liga que teve menor alteraçäo de cor foi a de Ni-Cr, as outras três näo mostraram diferenças significantes entre si. B - Avaliaçäo subjetiva: 1 - resistência à oxidaçäo: liga de ouro apresentou melhores resultados enquanto o amálgama e a liga de cobre-alumínio apresentaram os piores resultados; 2 - resistência à descoloraçäo: ao longo do tempo e em ordem decrescente as ligas que apresentaram os melhores resultados foram ouro, níquel-cromo, cobre-alumínio e amálgama; 3 - perda de brilho: em funçäo do tempo todas as ligas perderam brilho de forma semelhante, embora o amálgama tenha mostrado os piores resultados