Consequences of crown fractures with pulpal exposure: histopathological evaluation in dogs

When a crown fracture involving pulpal exposure is produced, the therapeutic treatment to be applied depends to a great extent on the general histopathological condition of the exposed pulp. Hence, the objective of this study was to evaluate histopathological and bacteriological changes occurring in dental tissue and periradicular tissue of crown-fractured teeth with pulpal exposure. Twenty-four anterior teeth (central and lateral incisors) from the maxillary teeth of four young, adult Mongrel dogs were used. At 48 and 72 h after performing the crown fractures, the animals were sacrificed and the results evaluated. Both observation periods revealed the existence of an area of superficial inflammation with the formation of hyperplastic tissue towards the external surface. Intense neutrophilic infiltrate was observed below it. Mean depth of inflammation was greater at 48 h (4633.33 mum) than at 72 h (3933.33 mum), perhaps coinciding with the bigger pulp chamber opening (x1332.14 mum at 48 h vs. x479.52 mum at 72 h). Upon approaching the cervical portion, the inflammation became less. Bacterial contamination was constant in all the cases evaluated, worsening the histopathological findings with exposure time. This study demonstrates that when a crown fracture with pulpal exposure is produced, the success in treating it depends partly on how quickly therapeutic treatment is administered.

Structure of magnetic poly(oxyethylene)-siloxane nanohybrids doped with Fe-II and Fe-III

Hybrid organic - inorganic nanocomposites doped with Fe-II and Fe-III ions and exhibiting interesting magnetic properties have been obtained by the sol - gel process. The hybrid matrix of these ormosils ( organically modified silicates), classed as di-ureasils and termed U( 2000), is composed of poly( oxyethylene) chains of variable length grafted to siloxane groups by means of urea crosslinkages. Iron perchlorate and iron nitrate were incorporated in the diureasil matrices, leading to compositions within the range 80 greater than or equal to n greater than or equal to 10, n being the molar ratio of ether-type O atoms per cation. The structure of the doped diureasils was investigated by small-angle X-ray scattering (SAXS). For Fe-II-doped samples, SAXS results suggest the existence of a two-level hierarchical structure. The primary level is composed of spatially correlated siloxane clusters embedded in the polymeric matrix and the secondary, coarser level consists of domains where the siloxane clusters are segregated. The structure of Fe-III-doped hybrids is different, revealing the existence of iron oxide based nanoclusters, identified as ferrihydrite by wide-angle X-ray diffraction, dispersed in the hybrid matrix. The magnetic susceptibility of these materials was determined by zero-field-cooling and field-cooling procedures as functions of both temperature and field. The different magnetic features between Fe-II- and Fe-III-doped samples are consistent with the structural differences revealed by SAXS. While Fe-II-doped composites exhibit a paramagnetic Curie-type behaviour, hybrids containing Fe-III ions show thermal and field irreversibilities.

Characterization of hobo element copy number and integrity in Brasilian populations of Drosophila melanogaster

We have determined the copy number and the presence of full-size hobo transposable elements in eight Brasilian strains of Drosophila melanogaster. Genomic DNA was digested with AvaII and XhoI restriction enzymes, respectively, and probed with a 963 bp sequence of the hobo element. Variable numbers of full-sized and defective elements were detected in all strains. The range of the copy number was 22.13 +/- 4.52. Blots showed the presence of a 2.6 kb fragment, corresponding to the complete element, in all strains exception of one and the 1.0 kb sequence, correponding to the Th1 and Th2 repressor elements. There was neither association among copy numbers of hobo elements and latitude nor the mean annual temperatures in the original geographical region of each strain.

Simulation of electron density maps for two-dimensional crystal structures using Mathematica

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Small-angle X-ray scattering and X-ray absorption near-edge structure study of iron-doped siloxane-polyoxyethylene nanocomposites

The local and medium-range structures of siloxane-POE hybrids doped with Fe(III) ions and prepared by the sol-gel process were investigated by X-ray absorption near-edge structure (XANES)/extended X-ray absorption fine structure (EXAFS) and small-angle X-ray scattering (SAXS), respectively. The experimental results show that the structure of these composites depends on the doping level. EXAFS data reveal that, for low doping levels ([O]/[Fe] > 40, oxygens being of the ether-type of the POE chains), Fe(III) ions are surrounded essentially by a shell of chlorine atoms, suggesting the formation of FeCl4- anions. At high doping levels ([O]/[Fe] < 20), Fe(III) ions interacts mainly with oxygen atoms and form FeOx species. The relative proportion of FeOx species increases with iron concentration, this result being consistent with the results of SAXS measurements showing that increasing iron doping induces the formation of iron-rich nanodomains embedded in the polymer matrix.

Isothermal structural evolution of SnO2 monolithic porous xerogels

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Histological evaluation of the response of apical tissues to glass ionomer and zinc oxide eugenol based sealers in dog teeth after root canal treatment

The object of the study was to compare two commercial root canal sealers: Ketac-Endo (a glass ionomer cement) and Fill Canal (a zinc oxide-eugenol cement). A total of 34 root canals from dog premolars with vital pulps were used. After instrumentation, the root canals were sealed with Ketac-Endo and Fill Canal cements using gutta-percha and a lateral condensation technique. After 270 days the animals were sacrificed with an anesthetic overdose and the maxillae and mandibles were removed and fixed in formalin for 48 h. After routine histological processing the sections were stained with hematoxylin-eosin and Mallory trichrome stains. Microscopic analysis revealed that Ketac-Endo cement presented better results than Fill Canal cement.

Nanostructure and properties of ZnO films produced by the pyrosol process

Indium doped ZnO films were deposited by the pyrosol process on glass substrates at different temperatures from solutions containing In/Zn molar ratios up to 10%. The nanostructure of the films was investigated using grazing-incidence small angle X-ray scattering (GISAXS). The mass density was determined by X-ray reflectivity and the composition by X-ray photoelectron spectroscopy. The GISAXS measurements revealed an anisotropic pattern for films deposited at 573 and 623 K and a isotropic one for those deposited at higher temperatures. The anisotropic patterns indicate the presence of elongated nanopores with their long axes perpendicular to the film surface. In contrast, the isotropic nature of GISAXS patterns of films grown at high temperatures (673 and 723 K) suggests the presence of spherical voids. The pore size distribution function determined from the isotropic patterns indicates a multimodal size distribution. on the other hand, the measured mass density of the doped films with isotropic nanotexture is higher than that of the anisotropic films while the electric resistivity is significantly lower. This is in agreement with the detected strong reduction of the void density and specific surface area at approximately constant pore size.

Thermostimulated sol-gel transition in suspensions of sulfate zirconium oxychloride

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Combined TUNEL and TRAP methods suggest that apoptotic bone cells are inside vacuoles of alveolar bone osteoclasts in young rats

Although it is generally accepted that osteoclasts breakdown and resorb bone matrix, the possibility that they may also be able to engulf apoptotic osteoblasts/ lining cells and/or osteocytes remains controversial. Apoptosis of osteoblasts/ lining cells and/or osteocytes and interactions between these cells and osteoclasts are extremely rapid events that are difficult to observe in viva. A suitable in viva model for studying these events is the alveolar bone of young rats because it is continuously. Thus, sections of aldehyde fixed alveolar undergoing intense resorption/remodeling bone of young rats were stained by the combined terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) method and the tartrate-resistant acid phosphatase (TRAP) method for the simultaneous visualization of apoptotic cells and osteoclasts in the same section. The combined TUNEL and TRAP reactions, in the same section, greatly facilitated visualization of relationship between osteoclasts and apoptotic bone cells during alveolar bone remodeling. Our results showed that several TRAP-positive osteoclasts exhibited large vacuoles containing TUNEL positive apoptotic structures, probably derived from osteoblasts/lining cells and/or osteocytes. These results support the idea that alveolar bone osteoclasts are able to internalize dying apoptotic bone cells.

Ultrastructural and histochemical examination of alveolar bone at the pressure areas of rat molars submitted to continuous orthodontic force

It is usually believed that repair in alveolar bone during orthodontic movement occurs after decreasing of force. However, we have recently observed signs of repair in previously resorbed cementum from human teeth exposed to continuous forces. In order to test the hypothesis that bone resorption and deposition occur concomitantly at the pressure areas, a continuous 15 cN force was applied in a buccal direction to upper first molars from eight 2.5-month-old male Wistar rats for 3 d (n=4) and 7 d (n=4). As a control, two additional rats did not have their molars moved. Maxillae were fixed in 2% glutaraldehyde + 2.5% formaldehyde, under microwave irradiation, decalcified in ethylenediaminetetraacetic acid, and processed for transmission electron microscopy. Specimens from one rat from each group were processed for tartrate-resistant acid phosphatase (TRAP) histochemistry. At both the times studied, the alveolar bone surface at the pressure areas showed numerous TRAP-positive osteoclasts, which were apposed to resorption lacunae. In addition, osteoblasts with numerous synthesis organelles were present in the neighboring areas overlying an organic matrix. Thus, this study provides evidence that the application of continuous forces produces concomitant bone resorption and formation at the pressure areas in rat molars.

Exfoliative cytology of the oral mucosa in type II diabetic patients: morphology and cytomorphometry

Background: In recent years, important advances have occurred in the determination of diagnostic criteria for the disease diabetes mellitus and in new strategies for its treatment. The purpose of this research was to develop a new method for diabetes diagnosis by microscopic and cytomorphometric analyses of the oral epithelium. Methods: the smears were obtained from three distinct oral sites: buccal mucosa (cheek), tongue dorsum, and floor of the mouth in 10 control individuals and 10 type II diabetic patients. The oral smears were stained with Papanicolaou EA-36 solution. The nuclear (NA) and cytoplasmic (CA) areas were evaluated from 50 integral cells predominant in each oral site by the use of the KS 300(TM) image analysis system (Carl Zeiss, Germany), by which the cytoplasmic/nuclear ratio (C/N) was calculated. Results: the results showed that: (i) the epithelial cells of the diabetic group exhibited figures of binucleation and occasional karyorrhexis in all layers; (ii) the NA was markedly higher (P<0.05) in the diabetic group; (iii) the CA did not exhibit a statistically significant difference (P>0.05) between these two groups; and (iv) the C/N mean was 37.4% lower in the type II diabetic group. Conclusions: These results associated with clinical observations suggest that diabetes mellitus can produce alterations in oral epithelial cells, detectable by microscopy and cytomorphometry, which can be used in the diagnosis of this disease.

Effect of root canal filling material and level of surgical injury on periodontal healing in dogs

Some divergencies in the literature about periodontal healing after surgical injury stimulated the development of this experiment. The root canals of dogs' teeth were negotiated and filled by the lateral condensation technique with two kinds of sealers: Sealapex and zinc oxide-eugenol cement. In the second session, the bone tissue was exposed and one cavity was made at the apical third of the root and another at the border between the coronal and middle thirds, both penetrating into the root canal. Six months later the animals were sacrificed and the specimens prepared for histopathologic analysis. The results showed that the kind of filling material and the level of the periodontal wound exposing the root canal can influence the healing process (P<0.01).

Purification, crystallization and preliminary X-ray analysis of haemoglobin I from the armoured catfish Liposarcus anisitsi

Liposarcus anisitsi is an armoured catfish that presents accessorial air oxygenation through a modified stomach, which allows this species to survive in waters with very low oxygen content. Analysis of its haemolysate has shown the presence of four haemoglobins; this work focuses on the main component, haemoglobin I. It has been crystallized in two different forms and X-ray diffraction data have been collected to 2.77 and 2.86 Angstrom resolution using synchrotron radiation. Crystals were determined to belong to the space groups C2 and P2(1) and preliminary structural analysis revealed the presence of one tetramer in the asymmetric unit in both crystal forms. The structure was determined using a standard molecular-replacement technique.