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Biomedical subjects

L Gettleman

Publications and source records attributed to L Gettleman.

At least 19 recordsLinked to original sources
PubMed1993

Vertical-horizontal illusion: one eye is better than two.

The vertical-horizontal illusion is the tendency for observers to overestimate the length of a vertical line relative to a horizontal line that has the same length. One explanation of this illusion is that the visual field is elongated in the horizontal direction, and that the vertical-horizontal illusion is a kind of framing effect (Künnapas, 1957a, 1957b, 1957c). Since the monocular visual field is less asymmetric than the combined visual field, this theory predicts that the illusion should be reduced with monocular presentation. This prediction was tested in five experiments, in which the vertical-horizontal illusion was examined in a variety of situations--including observers seated upright versus reclined 90 degrees, monocular presentation with the dominant versus the nondominant eye, viewing in the dark versus in the light, and viewing with asymmetrical frames of reference. The illusion was reliably reduced with monocular presentation under conditions that affected the asymmetry of the phenomenal visual field.

Adult↗
PubMed1992

Evaluation of radiopaque denture liner.

Radiopacity is needed in polymeric biomaterials to facilitate noninvasive detection. Permanent denture liner material with barium sulfate filler is nearly as radiopaque as aluminum and would be useful in radiographic identification. If 1 mm to 3 mm thicknesses are used, it should be easily observable radiographically.

Barium Sulfate↗
PubMed1991

Noble alloys in dentistry.

Noble metals used for dental castings continue to consist of alloys of gold, palladium, and silver (not a noble metal), with smaller amounts of iridium, ruthenium, and platinum. The majority are used as a backing for ceramic baking, with the rest used as inlays, onlays, and unveneered crowns. Base metal alloys, principally made of nickel, chromium, and beryllium have gained widespread usage, especially in the United States, due to their lower cost and higher mechanical properties. The current literature, for the most part, cites the use of noble alloys as controls for trials of alternative materials. Direct gold (gold foil) still retains a following and a number of new patents were founded.

Biocompatible Materials↗
PubMed1984

Denture marking.

Explore the source record for details and available documents.

Denture Identification Marking↗
PubMed1983

Acute tissue irritation of polysulfide rubber impression materials.

The acute toxic reaction to 14 polysulfide rubber impression materials certified by the ADA was measured after injection into the oral mucosa of two baboons for 48 h, and the inflammatory response was evaluated quantitatively. Two materials were significantly more toxic than the others. Although light-bodied materials were less toxic and contained less lead, toxicity was not strongly related to lead content.

Animals↗
PubMed1982

A model culture system with human gingival fibroblasts for evaluating the cytotoxicity of dental materials.

A model experimental culture system and protocol are described to screen polymerized dental materials for diffusible toxic products. The system employs cultures of human gingival fibroblasts grown in plates containing immobilized samples of polymerized resins. Comparative cytoxicity is evaluated by counting viable cells with the aid of phase optics at several time periods up to 48 h. To achieve adequate statistical sampling, multiple counts are made in four different zones at 90 degrees angles from each sample and at three distances from the centers of samples. The most significant data were generated during a 24 to 48 h test period in climate. This cytotoxicity test measured cell death as a function of time of exposure and distance from the sample (24 h, 0 to 3 mm; 48 h, 3 to 6 mm) and permitted a calculation of the relative cytoxicity for each material, which is termed the viability index (VI). This can be expressed as a percentage related to the control, which is called the time-distance cytotoxicity index (TDCI). This method is simple to carry out because it used basic laboratory equipment, is rapid, and has a sound scientific basis. It focuses on times and distances when or where, or both, the greatest cellular changes are taking place. Some data illustrated are based on the screening of eight different restorative resins. The literature of cell culture testing of dental materials is reviewed. It is concluded that biotoxicity studies ideally should employ diploid human target cells from the oral cavity because the cells retain specialized features. Secondary cultures or strains of human diploid gingival fibroblasts, which are relatively easy to obtain and maintain, are recommended as cells of choice for screening dental restorative materials in vitro.

Adult↗
PubMed1981

Effect of internal relief, vibration, and venting on the vertical seating of cemented crowns.

The presence of a vent hole in the occlusal surface, vibration during seating, and internal relief inside cast crowns were investigated individually and in all combinations for their effect on vertical seating on metal dies, using zinc phosphate cement. It was found that: 1. Vibration, applied horizontally, had no effect by itself or any interaction with venting or internal crown relief. 2. Venting and internal relief alone effectively achieved good seating. 3. Venting and internal relief together were the most effective combinations. 4. When crowns were seated well, they tended to tilt less.

Cementation↗
PubMed1981

Identification of a foreign body using energy dispersive x-ray analysis.

A foreign object, presumably swallowed during a dental appointment, was recovered by using an esophagoscope and thought to be a piece of dental impression material, probably alginate. It was identified as being of nondental origin by means of visible light and scanning electron microscopy (SEM), the latter coupled to an energy dispersive X-ray analyzer. Histologic examination revealed some amorphous crystalline material surrounded by parakeratin and exfoliated squamous cells. The material was essentially radiolucent. A known dental alginate impression material contained diatomaceous earth filler (siliceous shells of diatoms), but no microscopic symmetrical figures were seen in the foreign body. After dehydration, both materials were carbon-coated and observed in an SEM at 20 kV at magnifications up to 2000 X. The spectrum of secondary X-rays produced by the scanning electron beam revealed only magnesium in the foreign body and mostly silicon in the dental alginate. There are no known dental products that contain magnesium as the only inorganic ingredient and so the foreign body is believed to be not of dental origin. The patient may have had an antacid or laxative having magnesium as a major ingredient in the stomach, and this may have been refluxed from the stomach after stimulation of the normal gag reflex during the dental procedure.

Dental Materials↗