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Biomedical subjects

A Halse

Publications and source records attributed to A Halse.

At least 55 records · Page 3Linked to original sources
PubMed1979

Dental findings in patients with Aarskog syndrome.

Dental manifestations of the Aarskog syndrome were studied in 10 individuals. There was retarded development and eruption of the permanent teeth in six boys. Dental age was less retarded than height age and bone age. The prevalence of hypodontia and the prevalence and degree of orthodontic anomalies were higher than in the general population. Caries prevalence was high.

Abnormalities, Multiple↗
PubMed1979

Radiopaque zones in the dentin beneath silicate fillings analyzed by electron microprobe.

Seven teeth which showed radiopaque zones beneath silicate fillings were sectioned and studied by microradiography and electron microprobe analysis in order to elucidate which elements were responsible for the increased absorption of X-rays and whether the presence of carious lesions could be masked by foreign elements in the tissue. The Ca concentration was frequently found to be either slightly increased or reduced compared with radiographically unaltered dentin. Increased concentrations of F and Zn occurred in the radiopaque zones. The highest F concentrations (0.4--1%) were recorded in zones with an increased Ca content. The highest Zn concentrations (5--8%) were found in the three specimens having a reduced Ca content. The possible conditions responsible for the increased Ca, F and Zn concentrations are discussed. The results indicate that both Ca and Zn may contribute to the increased absorption of X-rays. The hypothesis that carious dentin may be obscured in intraoral radiographs by the presence of foreign elements in the tissue, was not substantiated.

Calcium↗
PubMed1976

Electron probe microanalysis of secondary carious lesions adjacent to silicate fillings.

Secondary caries associated with silicate fillings is characterized by lesions at the tooth surface and lesions of the cavity wall. The mineral content of the cavity wall lesions and the penetration of elements originating from the silicate fillings were studied in experimental in vitro and in vivo lesions as well as in natural carious lesions. Dentine wall lesions, where microradiographs had shown increased radiopacity relative to intact tissue, exhibited increased Ca and P values. Elements derived from the silicate fillings were regularly found in enamel and dentine. The concentrations of fluorine (F) and of zinc (Zn) amounted to 2-3% by weight close to the cavity wall and decreased gradually to less than 0.1% at depths of 600 mum and 400 mum, respectively, from the cavity. Aluminum (Al) most often occurred in a 20-40 mum-wide zone, showing a maximum concentration of 2-3% near the cavity. Sulfur (S) was often present in the dentinal cavity walls of natural secondary caries, but not in the in vitro specimens. The findings indicate that F released from the silicate filling significantly modifies the progress of a carious lesion in the adjacent enamel and dentine. Through its tendency to form complexes with F, Al may possibly enhance the cariostatic effect of F.

Aluminum↗
PubMed1975

The ultrastructural localization of iron in rat incisor enamel.

Previous studies have shown that the pigmented surface layer of rat incisor enamel contains up to 30% iron but have left the question open as to whether iron is bound to the hydroxyapatite crystals or is present as a separate crystalline phase. Maxillary incisors from adult rats were demineralized for an extended period of time in EDTA. An insoluble membranous structure representing the remaining superficial portion of the enamel was collected and analyzed in the electron microprobe. The analyses showed that the demineralization procedure had removed calcium and phosphorus nearly completely, whereas the iron content of the surface layer had not been appreciably reduced. Electron microscopic examination of these specimens showed that the residual material contained electron-dense particles whose size, form and orientation indicated that they were remnants of the original crystal population. Several other demineralized and undemineralized specimens were also examined electron microscopically. The results indicate that iron is not present as a separate particulate phase but is, probably, bound to the surface of hydroxyapatite crystals.

Animals↗
PubMed1975

Electron probe microanalysis of secondary carious lesions associated with silver amalgam fillings.

Secondary caries associated with silver amalgam fillings is characterized by outer lesions and cavity wall lesions. In this study the content of minerals and the penetration of elements from the amalgam into such lesions were analyzed. In sections of 11 teeth including cases of natural secondary caries and experimental in vitro and in vivo lesions around silver amalgam fillings the distribution of Ca, P, Mg, Zn, Sn, Cu, Ag and Hg was studied by means of two-dimensional X-ray images, linear scans and point analyses. Dentine wall lesions where microradiographs had shown increased radiopacity relative to intact tissue, exhibited considerably reduced Ca and P values. The outer portion of the radiopaque areas contained 5--8% Zn and Sn, decreasing to less than 0.1% at a varying distance up to 130 mum from the cavity wall. Hg was not detected, nor was Ag, except in one specimen. The increased radiopacity of this zone as observed on microradiographs is, therefore, obviously caused by the presence of Zn and Sn. Zn and Sn had also penetrated into the moderately demineralized enamel lesions, but the concentrations were generally lower than those observed in the dentine.

Calcium↗
PubMed1975

Gardner's syndrome.

A 22-year-old woman had multiple osteomas of the facial skeleton that were thought to represent Gardner's syndrome. At the first examination, however, other symptoms were not present. The diagnosis was established when colonic polyposis developed four years later.

Adult↗
PubMed1975

Structure of enamel surface as demonstrated by absorbed electrons.

The current induced by absorbed electrons in electron microprobe analysis was utilized to illustrate the surface structure of dental enamel. The electron images depicted a typical arcade or key-hole pattern on the surface of human incisors, while the surface of rat incisors was characterized by polygonal structures. Differences in electron density of the two specimen materials were observed, probably due to differences in their chemical composition. Absorbed electron images appear to be a valuable supplement to light microscopy, especially in the study of curved surfaces.

Animals↗