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Biomedical subjects

T Aoba

Publications and source records attributed to T Aoba.

At least 91 records · Page 5Linked to original sources
PubMed1980

A study of the mineral phase of pulp calcification.

Physico-chemical properties of pulp calcification were studied by means of X-ray microbeam diffraction, electron spin resonance (ESR), X-ray energy-dispersive analysis, and chemical analysis. The material was obtained from the second molar of the right mandible of a 25-year-old woman. X-ray diffraction and ESR analyses showed that calcium salts of the calcification are deposited in the form of apatitie, possibly carbonate-containing apatite. Furthermore, the mineral phase of the calcification was found to be similar to that of bone rather than that of dentin with regard to crystallinity and inorganic content. An unexpected finding was that high concentrations of iron were detected in some areas near the surface of the calcification. The question remains open as to what role, if any, iron may play in the formation of pulp calcification.

Adult↗
PubMed1980

Correlated microradiography, X-ray microbeam diffraction and electron probe microanalysis of calcifications in an odontoma.

Using microradiography, X-ray microbeam diffraction and electron probe microanalysis, a correlated morphologic crystallographic study was performed on dysplastic enamel in a compound odontoma. The tumor was found in the lateral incisor-canine region of the left mandible of a 36-year-old woman. A conspicuous feature was the presence of hypomineralized areas, which were situated in the proximity of enamel surface and distinctly demarcated from the adjacent enamel. X-ray microbeam diffraction and electron probe microanalysis showed that these lesions have a lower crystallinity and a higher concentration of magnesium as compared with the adjacent enamel. In addition, the present study revealed the presence of two other types of calcifications: (1) calcified structures within the fissure or on the enamel surface, which include lacunae of varying size and which resemble a form of coronal cementum, and (2) spherical calcifications which may be an epithelial product.

Adult↗
PubMed1980

Orientations of carbonate ions in human tooth enamel studied with use of the CO3-3 radical ions as probes.

With the use of CO3-3 radical ions as probes, it is concluded that the carbonate ions substitute in the apatite lattice of human tooth enamel in two different ways. Most of the carbonate ions in the apatite lattice are aligned with their symmetry axis parallel to the c axis, whereas the remaining carbonate ions are aligned with their symmetry axis perpendicular to the c axis.

Apatites↗
PubMed1979

Analysis of paramagnetic centers in X-ray-irradiated enamel, bone, and carbonate-containing hydroxyapatite by electron spin resonance spectroscopy.

Carbonate-containing hydroxyapatite, enamel, and bone were irradiated by an X-ray and investigated between 77 degrees and 350 degrees K by means of electron spin resonance (ESR) spectroscopy. The ESR spectrum of enamel irradiated at 77 degrees K in vacuum and observed at the same temperature was almost the same as that of the carbonate-containing hydroxyapatite. The temperature dependence of signal intensities confirms a spin-energy exchange between the mineral and organic constituents in bone, but in enamel no or very little spin-energy exchange between the mineral and organic constituents. Considerable similarity among the ESR spectra of enamel, bone, and carbonate-containing apatite was obtained after X-ray irradiation in air at 300 degrees K with both an X-band and a Q-band ESR spectrometer. The Q-band spectrum can be interpreted in terms of two paramagnetic species. One is identified as a CO3(3-) anion radical which has an axial symmetry with g factors of 2.0029 and 1.9972. The other species is found to be centered at g = 2.0019.

Animals↗
PubMed1979

Dystrophic calcification in calcifying epithelial odontogenic tumor: an X-ray diffraction and electron spin resonance study.

X-ray diffraction and electron spin resonance (ESR) analyses were conducted on calcifying epithelial odontogenic tumor (CEOT) associated with abundant calcification in order to compare its mineral structure with that of surrounding cortical bone. The material under investigation was removed from the canine-premolar region of the left maxilla of a 39-year-old woman. The principal findings were that the mineral phase of CEOT consists of apatite crystals and that the crystallinity of the crystals is higher than that of bone apatite. ESR spectra of CEOT are similar to those of bone sample. Quantitative ESR analysis indicates that CEOT shows a higher crystallinity coefficient -- defined by Ostrowski et al. (1972, 1974) as the ratio of spin concentration to the ash content of the sample -- than bone. Based on the data, it can be concluded that the calcification in CEOT has a higher crystalline structure than the cortical bone.

Adult↗
PubMed1978

A study of the mineral phase of cementifying fibroma.

Physico-chemical study of a case of cementifying fibroma in the mandible of 78-year-old woman was carried out by X-ray diffraction analysis and thermogravimetric and differential-thermal analyses (TGA-DTA). The center of the tumor consisted of masses of acellular cementum-like tissues; while the periphery consisted of cementicle-like tissues. X-ray powder diffraction patterns showed that the mineral phase of these tissues was apatitic in nature. X-ray line broadening analysis revealed that the crystallinity of apatite of the cementum-like tissue was higher than that of apatite of cementicle-like tissue, and lower than that of bone apatite obtained from the same patient. Furthermore, TGA-DTA studies showed that the mineral (ash) value of cementum-like tissue was slightly higher than that of bone.

Aged↗