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Biomedical subjects

I Hoyer

Publications and source records attributed to I Hoyer.

At least 37 records · Page 2Linked to original sources
PubMed1984

In vivo remineralization of human enamel and dental calculus formation.

The aim of this investigation was to determine the inorganic composition and the surface morphology of remineralized enamel areas and of dental calculus in heavy-calculus-formers (five subjects) and to compare these results with those of non-calculus-formers (two subjects). Electron probe micro-analysis (EPMA) was carried out on sound, acid-etched, and in vivo remineralized enamel samples from heavy- and non-calculus-formers. The mean values of Ca, P, Na, Mg, Al, Si, S, Cl, and K were compared with the SEM morphology. EPMA measurements showed no significant differences in the Ca/P ratio of the surface layers of prism-oriented and/or homogeneous enamel remineralization. The variations of remineralization pattern after acid-etching are similar in teeth from heavy dental-calculus-forming patients and in teeth from non-calculus-formers. The SEM appearances of remineralized areas and of the inner surface of mature dental calculus must be considered to be totally different. The experiments carried out suggest that the remineralization of enamel is not related to the formation of calculus.

Calcium↗
PubMed1979

[The preparation trauma of the pulp and its reactive behavior (author's transl)].

The postpreparative pathophysiological reactions of the blood circulation are shown by vital microscopy examinations of the pulp of the incisors of living rats.--After twenty-four hours from the experimental preparation of cavities, functional changes are characterized by acutely inflammatory reactions. With the passage of time (seven-day check), the damage is compensated for by extensive regeneration (re-formation and new formation of vessels, functional adaptation of the circulation of blood, anastomosing), although irreversible alterations can be seen to remain in the incisors of rats.--A comparison with the results of histological reexaminations of human teeth shows that careful preparation usually avoids lesions being left behind after the fading away of localized acute inflammations.

Adaptation, Physiological↗
PubMed1978

[Superficial and marginal behavior of composite filling materials in class III and II cavities as compared with conventional filling materials (author's transl)].

The superficial and marginal behavior of composite filling materials is better than that of conventional types of front tooth filling cements as regards plaque retention, danger of marginal caries, and microleakage with potential damage to the pulp caused by bacterial toxins.--According to the results obtained in vitro, Evicrol is a positive alternative to Frontasil and Achatit-biochromatic. Plastic foils are not suitable as matrices, whereas aluminum matrices have been found to meet the requirements of surface smoothness and anatomical adaptability in cavity classes III, IV, and V. Celluloid matrices show inadequate adaptational properties, although they offer smoothest surfaces. The marginal behavior of Evicrol in class II cavities in molars is virtually the same in the case of both conventional retentive preparation and modified preparation of initial occlusal-approximal defects by the enamel etching technique. Discontinuous microretentive securing of matrix tags in the enamel etch pattern corresponds neither occlusally nor approximally to the physical definition of adhesion in different areas of the enamel. Clinical comparison in a 12-month study with the results obtained in vitro restricts safe indication to classes III and V, it being necessary to give careful consideration to the directions for use.--Long-term clinical longitudinal studies are required to determine permanent successes of treatment and possible extensions of the range of indications.

Composite Resins↗
PubMed1977

[Biological testing of pulp-preserving agents on the pulp of rat molars].

The effects of calxyl, ZOE, zinc oxide without eugenol, and zinc oxide with an antibacterial substance (glutaraldehyde) were tested on perforated molar pulps of rats. All of the substances tested were found to lead to the same initial reactions (acute inflammation and partial necrosis). Calxyl and ZOE yielded unfavorable results. There was a negligible tendency of the pulp toward hard tissue demarcation. Zinc oxide without eugenol improved the formation by the pulp of secondary tin. - The use of glutaraldehyde resulted in a less pronounced spread of inflammation as well as in the formation of new hard tissue in one half of the cases. Molars of rats are particularly suitable for biologically examining the local toxicity of pulpal protectives and the regeneration of the pulp. The results presented in this paper are discussed from the point of view of pulp-preserving therapy and of avoiding invasion by germs.

Animals↗
PubMed1977

[Pathological tooth root resorption and its clinical significance].

The author examined 316 teeth, on which total pulpotomy had been performed, for frequency and extent of resorption. Marked resorptions, always associated with chronic apical periodontitis, were radiographically disclosed in 43 teeth. It is pointed out that the clinical radiographic technique permits to visualize only resorptions of greater extent.

Dental Pulp Devitalization↗
PubMed1977

[Clinical and microstructural comparative studies on fillings made from gallium-tin-nickel alloys and from silver-tin amalgam].

The filling material "Gallodent" has been clinically controlled for a period of one year. Scanning electron microscopic examinnations revealed greater surface porosity with negligible microleakage and better marginal adaptation as compared to amalgam. Early corrosion phenomena required re-polishing every three months. This disadvantage and the brittleness of the gallium-tin-nickel alloys hinder, at present, these alloys from superseding high-silver amalgams.

Dental Amalgam↗