Radiopacity of esthetic restorative materials compared with human tooth structure

Purpose : To compare the radiopacity of 13 restorative materials, (a conventional glass-ionomer cement, three resin-modified glass-ionomer cements, six polyacid-modified resin-based composites, and three resin-based composites) to sound tooth structure. Materials and Methods: 315 specimens were made of the restorative materials (n= 21), of 2 min height and 4.1 mm diameter. Radiographs were taken of the specimens, together with the tooth structure sample and an aluminum step wedge. The radiopacity values of each specimen were taken using a transmission densitometer. Results: ANOVA and Tukey's test (95% level of confidence) revealed that, except for a resin-based composite, a polyacid-modified resin-based composite, a resin-modified glass-ionomer cement and the conventional glass-ionomer cement, all the evaluated restorative materials were more radiopaque than the tooth structure.

Physicochemical properties and morphology of spongolite from Mato Grosso do Sul (Brazil)

The physicochemical properties and morphology of spongolite, a fibrous hollow material from Mato Grosso do Sul State (Brazil) have been studied. The results of thermal analysis, scanning electron microscopy (SEM), X-ray diffraction and NMR spectroscopy indicated that external and internal surfaces of silica spicules are covered by silica gel layers. The water evolved in the range 120-350degreesC is the result of silanol groups condensation to siloxane bonds. Total homogenization of the needles is achieved by heating spongolite over 900degreesC. This mineral may be considered as a natural composite material containing surface-immobilized reactive species. The presence of active silica gel layers opens the possibilities of attaching functional groups to spongolite surface. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Morphology of alumina: a comparison between infrared spectroscopy and X-ray diffractometry

Morphology of three samples of alumina are investigated. Infrared spectra are analysed by use of their morphology through the theory of average dielectric constant. Crystal shape is obtained from X-ray diffraction patterns by reflection intensity ratio. In the case of electron scanning microscopy, shape factor was obtained by an average axial ratio of the particles. Comparison of results show that there is agreement among these techniques and infrared spectra can be used to determine the morphology of alumina particles from 2.7 to 10 mu m, even for heterogeneous samples. (C) 1999 Elsevier B.V. B.V. All rights reserved.

Infiltrative myelopathy by paracoccidioidomycosis. A review and report of nine cases with emphasis on bone marrow morphology

Aims: To report nine additional well-defined cases with infiltrative myelopathy by paracoccidioidomycosis (PCM), to describe the specific lesions and infection-related stromal abnormalities, to review the literature on this type of involvement and to introduce a new cause of granulomatous lesions of bone marrow.Methods and results: Different bone marrow specimens were studied (aspirated smears, aspirated clots, biopsy imprints and biopsies) from nine patients with acute or subacute forms of PCM known to have PCM infiltrative myelopathy.Conclusions: the biopsy specimens were the best for demonstrating bone marrow involvement by PCM. The lesions varied from compact and focal granulomas with few fungal cells to numerous disseminated fungal cells within a loose granulomatous inflammatory reaction, with a continuum between these extremes suggesting a spectrum of immune response to the fungi. Other findings such as bone marrow fibrosis, parenchymal coagulative necrosis and bone necrosis were also observed in the affected areas.

Analysis of procedures used in tooth avulsion by 100 dental surgeons

Accurate diagnosis and adequate treatment plan may constitute very complex tasks, particularly in tooth avulsion, because several variables are involved. In addition to the technical knowledge and clinical experience directed toward the quality of treatment, patient education may favorably influence the survival of replanted teeth. The aim of this study was to analyze the procedures used in the management of tooth avulsion by 100 dental surgeons (DSs). Thus, by means of a descriptive questionnaire, information was obtained about the profile of the professionals interviewed, procedures used in cases of tooth avulsion, and patient orientation and education. One hundred properly filled questionnaires were obtained. Descriptive statistics was used for the data, and the chi-squared statistics was employed (EPI-INFO 3.2 software). According to the results, this type of trauma is part of the routine of 15 DSs, although 71 have reported some experience with avulsed,teeth. Great deficiencies were found regarding root surface treatment and occlusal adjustment. Positive findings were related to socket treatment, adjunctive therapy, and patient education and orientation (extra-alveolar period, storage medium, manipulation of the avulsed tooth, replantation by the own patient). It was possible to conclude that 47.5% of the procedures reported by, 100 professionals interviewed are adequate, and patient education is favorable in 87.7% of cases, a fact that can positively interfere with the prognosis of tooth replantation.

MORPHOLOGY AND WEIGHT OF AFRICANIZED QUEEN BEES PRODUCED IN DIFFERENT DIAMETERS OF ARTIFICIAL, CUPS

The present work showed that the newly emerged queen weight, the number of ovarioles. and the spermatheca mass are not influenced by the sizes of the wax cups. The first two characters suffered time transference influence, and the best acceptances were obtained mainly, in wax cups with diameters of 7, 8, and 9 min.

Correlation between the surface morphology and structure and the photoluminescence of amorphous PbTiO3 thin films obtained by the chemical route

A polymeric precursor method was used to synthesis PbTiO3 amorphous thin film processed at low temperature. The luminescence spectra of PbTiO3 amorphous thin films at room temperature revealed an intense single-emission band in the visible region, the visible emission band was found to be dependent on the thermal treatment history, Photoluminescence properties Versus different annealing temperatures were investigated. The experimental results (XRD, AFM, FL) indicate that the nature of photoluminescence (PL) must be related to the disordered structure of PbTiO3 amorphous thin films, Copyright (C) 2000 John Wiley & Sons, Ltd.

Apoptotic bone cells may be engulfed by osteoclasts during alveolar bone resorption in young rats

The alveolar bone is a suitable in vivo physiological model for the study of apoptosis and interactions of bone cells because it undergoes continuous, rapid and intense resorption/remodelling, during a long period of time, to accommodate the growing tooth germs. The intensity of alveolar bone resorption greatly enhances the chances of observing images of the extremely rapid events of apoptosis of bone cells and also of images of interactions between osteoclasts and osteocytes/osteoblasts/bone lining cells. To find such images, we have therefore examined the alveolar bone of young rats using light microscopy, the TUNEL method for apoptosis, and electron microscopy. Fragments of alveolar bone from young rats were fixed in Bouin and formaldehyde for morphology and for the TUNEL method. Glutaraldehyde-formaldehyde fixed specimens were processed for transmission electron microscopy. Results showed TUNEL positive round/ovoid structures on the bone surface and inside osteocytic lacunae. These structures - also stained by hematoxylin - were therefore interpreted, respectively, as osteoblasts/lining cells and osteocytes undergoing apoptosis. Osteoclasts also exhibited TUNEL positive apoptotic bodies inside large vacuoles; the nuclei of osteoclasts, however, were always TUNEL negative. Ultrathin sections revealed typical apoptotic images - round/ovoid bodies with dense crescent-like chromatin - on the bone surface, corresponding therefore to apoptotic osteoblasts/lining cells. Osteocytes also showed images compatible with apoptosis. Large osteoclast vacuoles often contained fragmented cellular material. Our results provide further support for the idea that osteoclasts internalize dying bone cells; we were however, unable to find images of osteoclasts in apoptosis. (C) 2001 Harcourt Publishers Ltd.

Surface morphology and molecular organization of lignins in Langmuir-Blodgett films

Atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR) are used to investigate molecular organization in Langmuir-Blodgett (LB) films of two kinds of lignins. The lignins were extracted from sugar cane bagasse using distinct extraction processes and are referred to here as ethanol lignin (EL) and saccharification lignin (SAC). AFM images show that LB films from EL have a flat surface in comparison with those from SAC. For the latter, ellipsoidal aggregates are seen oriented perpendicularly to the substrate. This result is confirmed by a combination of transmission and reflection FTIR measurements, which also point to lignin aggregates preferentially oriented perpendicularly to the substrate. For LB films from EL, on the other hand, aggregates are preferentially oriented parallel to the substrate, again consistent with the flat surface observed in AFM data. The vibrational spectroscopy data for cast films from both lignins show random molecular organization, as one should expect.

Light microscopy and computer three-dimensional reconstruction of the blood capillaries of the enamel organ of rat molar tooth germs

We performed a light microscope and a computer three-dimensional reconstruction study of serial sections of the molar enamel organ of 3- and 5-day-old rats perfused with Indian ink through the arterial system. The tooth germs were fixed in Bouin's solution, embedded in paraffin, sectioned and stained with haematoxylin and eosin. For the three-dimensional reconstruction, light micrographs of the serial sections were digitized, and aligned using the serial EM Align software downloaded from http://synapses.bu.edu/tools/. After alignment, the boundaries of the India-ink-filled blood vessels were manually traced with a mouse using the software IGL trace (version 1.26b), also downloaded from the above website. After tracing, a three-dimensional representation of the blood vessel contours was generated in a VRML format and visualized with the help of the software Cortona Web3D viewer (version 4.0) downloaded from http://www.parallelgraphics.com/products/cortona. Our results showed that in regions where ameloblasts are polarized the capillaries are arranged in three distinct levels: (1) penetrating and leaving capillaries in relation to the outer enamel epithelium; (2) capillaries crossing and branching inside the stellate reticulum; and (3) capillaries branching and anastomosing profusely within the stratum intermedium, thereby forming an extensive capillary plexus intimately associated with the cells of the stratum intermedium. The existence of a conspicuous capillary plexus intermingled with cells of the stratum intermedium, as shown in our results, suggests that some molecules produced by cells of the stratum intermedium could be released into the capillary plexus and thereafter carried to the dental follicle.