Calcium hydroxide and a corticosteroid-antibiotic association as dressings in cases of biopulpectomy. A comparative study in dogs' teeth.

The subject of this paper was to study the behavior of the periapical tissues of dogs' teeth after biopulpectomy and dressing with calcium hydroxide or a corticosteroid-antibiotic association, before root canal filling with zinc oxide eugenol (ZOE) or Sealapex sealers. The teeth were overinstrumented and dressed for 7 days before the root canal filling. The animals were sacrificed 180 days after treatment and the specimens were prepared for morphological analysis. Specimens treated with Sealapex presented a higher number of cases with biological closure than ZOE. When the root canals were filled with ZOE, better results were observed with the use of the Ca(OH)2 dressing.

Sistemas para liberação colônica: Uma alternativa para a veiculação de fármacos para efeito local ou sistêmico

Problems related to the systemic administration of drugs, such as biodistribution, difficulty of targeting, necessity of high doses to achieve adequate levels of the drug in specific sites, toxicity, and undesirable side effects have lead to the development of systems able to direct the drug to specific sites in the body. Among the possible organs to the targeting of drugs, the colon can be used for local and systemic therapies. By developing such systems some models have been tested, using pH dependent release, release controlled by enzymatic degradation, time controlled release systems and pressure controlled release systems. This review presents an overview of the colonic release of drugs and the strategies used to achieve such targeting.

Polissacarídeos biodegradáveis úteis para a preparação de sistemas de liberação controlada de fármacos. Parte 1: Quitosana

Due to an increasing interest, a vast number of biodegradable polymers have been obtained recently. Polymers naturally produced, such as cellulose, starch, chitosan and alginate, represent biodegradable materials, with low toxicity and low cost. Among polysaccharides, chitosan has been of great interest of the industrial and academic research, due to its special qualities of biodegradability and biocompatibility and, on the other hand, to the versatility of its use in several physical forms and products. A significant growth in the development of new dosage forms capable to deliver the drug in a controlled and targeted way has been observed in these last years. Such pharmaceutical forms search, mainly, the reduction of the dose administered and of the administration frequency, the reduction of adverse side effects and, consequently, a better patient compliance. The present paper describes the use of chitosan in pharmaceutical products, especially in drug controlled delivery systems.

Determination of calcium by atomic absorption spectrophotometry applied to the preparation of alginate:chitosan complexes

Polysaccharicles, as alginate and chitosan, have been used to obtain modified release dosage forms. Alginate, due to its property of building gels during the complex formation with calcium ions, allows the building of capsules containing a core constituted by calcium alginate. This work had for objective to determine the appropriate calcium concentration for the preparation of alginate-chitosan capsules, by means of calcium quantification using atomic absorption spectrophotometry. The methodology of calcium quantification was validated through analysis of the limit of detection, precision, accuracy and recovery of the method. The capsules, containing or not the drug, were prepared by the complex coacervation/ionotropic gelification method. Calcium was quantified after samples mineralization and dilution in lantanium solution. The results showed that the amount of calcium incorporated into the capsules depends on the amount of calcium added to the medium, and this ratio increases until the concentration of 1.5% of initial calcium chloride and above this concentration there is a decrease in the proportion of calcium bonded. It was observed that the proportion of calcium that links to the polymer is inversely proportional to the amount of calcium added. The calcium amount incorporated depends on the concentration of the polymeric dispersions used as well as on the ratio between the two polymers.

Effect of different dye solutions on the evaluation of the sealing ability of Mineral Trioxide Aggregate.

Alkaline materials have shown incompatibility with methylene blue dye in leakage experiments. The goal of the present study was to analyze the effect of different dyes on the evaluation of the apical sealing ability of Mineral Trioxide Aggregate root-end fillings. Fifty-six extracted human canines were submitted to root canal instrumentation and obturation. After apical resection, retrograde cavities were prepared and teeth were randomly divided into four experimental (n = 13) and two control groups (n = 2). The following root-end filling materials were used: groups 1 and 2--Pro Root MTA (Dentsply), groups 3 and 4--zinc oxide-eugenol cement (ZOE). Teeth in groups 1 and 3 were immersed in 2% methylene blue solution, while teeth in groups 2 and 4 were immersed in 0.2% rhodamine B in a reduced pressure environment for 48 hours. Teeth were then longitudinally sectioned and leakage was evaluated. Results were submitted to statistical analysis (ANOVA and Tukey's test). Group 1 presented the least leakage (p < 0.05). It was concluded that the evaluation of the sealing ability of MTA is influenced by the dye used, since this material presented better sealing ability when evaluated with Methylene Blue, but was similar to ZOE when evaluated with rhodamine B.

In vitro activity of zinc oxide-eugenol and glass ionomer cements on Candida albicans

The aim of this study was to evaluate in vitro the antimicrobial activity of glass ionomer (GIC) and zinc oxide-eugenol (ZOE) cements against Candida albicans. Standardized GIC and ZOE specimens were maintained in contact with C. albicans suspension (1 x 10(6) cells/ml) at 37 degrees C for 24 h, 48 h or 7 days. A control group without any testing cement was included. After the incubation period, aliquots of 0.1 ml were plated on Sabouraud's agar, and then the number of colonies was counted. The results were expressed as values of logarithms of colony-forming units per milliliter (log CFU/mL) and were analyzed statistically by Kruskal-Wallis ANOVA. After 48 h of incubation, the ZOE group presented no growth of C. albicans. GIC and control groups presented similar mean values at all tested periods. According to the results obtained, it could be concluded that, under the experimental conditions, ZOE cement was more effective in vitro against C. albicans than GIC.

Comparative study of MTA and other materials in retrofilling of pulpless dogs' teeth

This in vivo study compared the effect of mineral trioxide aggregate (MTA), IRM, Super EBA and ZOE in a puttylike consistency, used as retrofilling materials, in the healing process of periapical tissue of pulpless dogs' teeth submitted to a conventional retrofilling technique. Twenty-four premolars obtained from three dogs were used. At the first intervention, the animals were anesthetized, coronal access was obtained and pulpectomy was done. Root canals were kept open to the oral environment for 180 days to induce the formation of apical lesions. After surgical removal of the lesions with curettes, 2 mm of the apical root was cut out perpendicular to the long axis of the teeth, and root-end cavities were shaped with a low-speed round bur. The bone cavities were irrigated and dried, and the root-end cavities were filled with MTA, IRM, Super EBA and ZOE in a puttylike consistency. The bone cavities were passively filled with blood and flaps were sutured. The coronal access openings were cleaned and double-sealed with ZOE and amalgam. After 180 days, the animals were killed by anesthetic overdose, maxilla and mandible were removed and the pieces were processed for histomorphologic analysis. Data were evaluated blindly on the basis of several histopathologic events and the scores obtained were analyzed statistically using the Kruskal Wallis test. No significant differences were observed among MTA, Super EBA and IRM (p>0.05). However, ZOE had a significantly more negative influence on the apical healing (p<0.05). In conclusion, MTA, Super EBA and IRM had similar histopathologic effects among each other and better performance than ZOE used in a puttylike consistency. Furthermore, only MTA stimulated hard tissue deposition in direct contact with the retrofilling material, even when it was inserted under critical conditions.

Strong selection against hybrids at a hybrid zone in the Ensatina ring species complex and its evolutionary implications

The analysis of interactions between lineages at varying levels of genetic divergence can provide insights into the process of speciation through the accumulation of incompatible mutations. Ring species, and especially the Ensatina eschscholtzii system exemplify this approach. The plethodontid salamanders E. eschscholtzii xanthoptica and E. eschscholtzii platensis hybridize in the central Sierran foothills of California. We compared the genetic structure across two transects (southern and northern Calaveras Co.), one of which was resampled over 20 years, and examined diagnostic molecular markers (eight allozyme loci and mitochondrial DNA) and a diagnostic quantitative trait (color pattern). Key results across all studies were: (1) cline centers for all markers were coincident and the zones were narrow, with width estimates of 730 m to 2000 m; (2) cline centers at the northern Calaveras transect were coincident between 1981 and 2001, demonstrating repeatability over five generations; (3) there were very few if any putative F1s, but a relatively high number of backcrossed individuals in the central portion of transects: and (4) we found substantial linkage disequilibrium in all three studies and strong heterozygote deficit both in northern Calaveras, in 2001, and southern Calaveras. Both linkage disequilibrium and heterozygote deficit showed maximum values near the center of the zones. Using estimates of cline width and dispersal, we infer strong selection against hybrids. This is sufficient to promote accumulation of differences at loci that are neutral or under divergent selection, but would still allow for introgression of adaptive alleles. The evidence for strong but incomplete isolation across this centrally located contact is consistent with theory suggesting a gradual increase in postzygotic incompatibility between allopatric populations subject to divergent selection and reinforces the value of Ensatina as a system for the study of divergence and speciation at multiple stages. © 2005 The Society for the Study of Evolution. All rights reserved.

Studies on the formation of complex coacervates between chitosan and alginate during microparticles preparation

The formation of complex coacervates between chitosan and alginate was evaluated during microparticles formation. Mass ratio between polyelectrolytes and calcium chloride concentration were determinated by conductimetric analysis and by calcium ions quantification, respectively. Inert microparticles were prepared using a complex coacervation method in W/O emulsion and morphological analyses of microparticles were carried out. This method enabled the production of spherical particles, with slightly rough surface and narrow size distribution with maximal diameter of 10 μm.

Ethylcelullose microspheres containing sodium diclofenac: Development and characterization

The objective of the present study was the development and characterization of ethylcellulose microspheres containing diclofenac and the determination of the in vitro drug release profile. Microspheres were prepared by emulsification/solvent evaporation method using ethyl acetate as solvent for the polymer and water as non solvent. The microspheres were characterized by morphologic and granulometric analyses. The amount of encapsulated drug as well as its release profile in vitro were also determined. The product obtained was microparticles with smooth surface and narrow size distribution, about 50% of the particles being smaller than 5 μm. The methodology used allowed drug encapsulation with a good yield and the system provided a controlled release of diclofenac.

Multiparticulate systems of pectin-chitosan: Study of swelling and drug release

The aim of this study was to prepare multiparticulate systems of pectin:chitosan (PC:CS) and to evaluate their swelling ratio and the drug release in different environments. PC:CS particles containing triamcinolone were prepared by a complex coacervation/ionotropic gelation method in aqueous environment. The polymer ratio, the calcium concentration and the contact time of the capsules with chitosan dispersion for particles formation and the structures obtained were analyzed. The systems were characterized in relation to morphology, size, swelling, and drug release behavior. The methodology used allowed the production of spherical particles with narrow range of size distribution. The entrapment efficiency for triamcinolone was 84.31 ± 439. It was observed that the particles present a relatively low swelling ratio in acidic medium and a larger swelling ratio in enteric medium. The release profile was dependent on pH and can be related with the swelling ratio.

On a new species of the genus Moenkhausia Eigenmann (Ostariophysi: Characidae)

A new species of the genus Moenkhausia is described from the middle portions of the Rio Tocantins and tentatively from the Río Apure in Venezuela, Río Orinoco drainage. It is diagnosed by the presence of a dark spot in the half proximal length of the upper caudal-fin lobe, and by the presence of a large, irregularly shaped humeral spot located above the sixth to ninth perforated lateral line scale which is more posteriorly positioned along the body side in relation to other members of the genus. The distribution pattern of the new species is discussed. Copyright © 2007. Magnolia Press.

In vitro antimicrobial activity of acroseal, polifl and epiphany against Enterococcus faecalis

Using the agar diffusion method, this study evaluated the in vitro antimicrobial activity of the commercial endodontic sealers Acroseal and Epiphany, a castor-oil based experimental sealer, Polifl, and a primer agent (Epiphany self-etching primer), against Enterococcus faecalis. Zinc oxide and eugenol cement (ZOE) served as control. Five wells per dish were made at equidistant points and immediately flled with the test and control materials. After incubation of the dishes at 37°C for 24 h and 48 h, the diameter of the zones of microbial growth inhibition produced around the wells was measured (in mm) with a millimeter rule. After 48 h, the diameters of the zones of microbial growth inhibition were the same as those observed at 24 h, only the substances continued to diffuse. Epiphany and Polifl did not show antibacterial activity (no formation of zones of microbial growth inhibition). The primer produced the largest zones of inhibition (17.62 mm) followed by Acroseal (7.25 mm) and ZOE (7.12 mm). E. faecalis was resistant to Epiphany and Polifl, while the primer and Acroseal sealer were effective against this microorganism under the tested conditions.

Sealing ability of retrograde obturation materials containing calcium hydroxide or MTA

Newly available materials for retrograde obturation should have their sealing properties evaluated. The goal of this study was to evaluate the sealing ability of Endo CPM sealer, an MTA-based endodontic cement. Single-rooted extracted human teeth were endodontically treated. After apical sectioning, retrograde cavities were prepared. Teeth were divided into five experimental groups (n=12), in which the following materials were used: Sealer 26 (S26), white Mineral Trioxide Aggregate (MTA), Endo CPM Sealer (CPM1), Endo CPM Sealer in thicker consistency (CPM 2), and zinc oxide and eugenol cement (ZOE), and two control groups (n=3). After retrograde obturation, the teeth were immersed in 0.2% rhodamine B dye for 48 hours in a vacuum chamber Marginal leakage data were subjected to ANOVA and Tukey tests at 5% significance level. S26 presented greater sealing ability (p<0.05) than ZOE, MTA, CPM1, and CPM2, all of which had similar results (p>0.05). We concluded that Sealer 26 has the greatest sealing ability. Endo CPM Sealer, with sealing ability similar to MTA, could be used as a retrograde obturation material.

O romance-projeto: um estudo de Lucinde (1799), de Friedrich Schlegel

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