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Biomedical subjects

M Helft

Publications and source records attributed to M Helft.

At least 19 recordsLinked to original sources
PubMed1989

Prevalence of Candida albicans in denture wearers in an Israeli geriatric hospital.

Thirty-seven patients wearing complete dentures were investigated for Candida albicans. Twenty-five of the patients suffered from denture stomatitis and twelve had clinically normal mucosa. Candida albicans was isolated and identified from Sabouraud dextrose agar culture medium models constructed from impressions of the maxilla and from the upper dentures. The presence of Candida albicans was demonstrated in all denture wearers suffering from denture stomatitis and in 82% of denture wearers in a control group. A higher concentration of Candida was found in the denture stomatitis group. Large quantities of Candida resided in the denture base and not in the palate. Candida was also found in the denture base in areas not related to the lesion. The concentration of Candida was related to denture cleanliness.

Aged↗
PubMed1988

A gingival guard for crown preparation.

A device for subgingival margin preparation is presented. The gingival guard consists of a clamp attached to the high-speed handpiece supporting a stainless steel shank terminating in a sphere. The guard permits nontraumatic subgingival margin preparation.

Crowns↗
PubMed1988

Effect of exposure time on the depth of polymerization of a visible light-cured composite resin.

The effect of exposure time of a visible light source on the depth of polymerization and degree of hardness of a sample of Occlusin posterior composite resin was investigated. The border between cured and non-cured composite resin was identified by a change in colour and by applying pressure with a scalpel. Knoop hardness tests were performed perpendicular to the long axis of illumination. The composite resin nearer to the light source underwent more complete polymerization. Increased exposure time resulted in greater depth of cure. The rate of polymerization was greatest in the first 10 s. Maximum hardness measured up to a depth of 1 mm obtained after 80 s of exposure time. At greater depth, a decrease in Knoop hardness was observed. At exposures under 80 s, maximum hardness was not achieved even at a depth of only 1 mm.

Chemical Phenomena↗
PubMed1987

The continuous brushing acid-etch technique.

The continuous brushing of an acid-etching agent onto the enamel surface of an extracted tooth resulted in a more debris-free surface. SEM photomicrographs showed dissolution of some of the apatite crystals and a reduction in size of the remaining crystals, thus increasing the potential space between them for retention of unfilled composite.

Acid Etching, Dental↗