Search PubMed⌕ Search

Biomedical subjects

G Shklar

Publications and source records attributed to G Shklar.

At least 109 records · Page 6Linked to original sources
PubMed1979

Jawbone cavities and trigeminal and atypical facial neuralgias.

The possible role of dental and oral disease in the etiology of idiopathic trigeminal and atypical facial neuralgias has been examined. Among thirty-eight patients with idiopathic trigeminal neuralgia and twenty-three patients with atypical facial neuralgia, there was in nearly all instances a close relationship between pain experienced and the existence of cavities in alveolar bone and jawbone of the patients. The cavities were at the sites of previous tooth extractions and, although at times more than 1 cm. in a given diameter, were usually not detectable by x-rays. A new method for their detection and localization was developed empirically, based on the observation that peripheral infiltration of local anesthetic into or very close to the bone cavity rapidly abolished trigger and pain perception by patients during persistence of the anesthetic action. Histopathologic examination of bone removed from cavities by curettage revealed, in both idiopathic trigeminal and atypical facial neuralgias, a similar pattern characterized by a highly vascular abnormal healing response of bone. Some lesions presented a mild chronic inflammatory (lymphocytic) infiltration. Preliminary microbiologic studies of material from the walls of the cavities showed the existence within them of a complex, mixed polymicrobial aerobic and anaerobic flora. Treatment consisted of vigorous curettage of the bone cavities, repeated if necessary, plus administration of antibiotics to induce healing and filling-in of the cavities by new bone. Responses of patients to the above treatment consisted of marked to complete pain remissions, the longest of which has been for 9 years. Complete healing leads to complete and persistent pain remissions. It was concluded that in both idiopathic trigeminal and atypical facial neuralgias, dental and oral pathoses may be major etiologic factors.

Adult↗
PubMed1979

Ultrastructural alterations in experimental lingual leukoplakia and carcinoma.

Epidermoid carcinomas, preceded by dysplastic leukoplakic lesions, were produced on the right lateral borders of the tongues of Syrian hamsters by the application, three times per week, of DMBA in acetone after the area had been scratched with a root canal broach. Animals were killed at 12 to 13 weeks and 15 to 16 weeks. Electron microscopic studies of both the dysplastic leukoplakic lesions and the well-differentiated epidermoid carcinomas revealed clumping of tonofilaments and widening of intercellular spaces, in addition to the cellular pleomorphism, altered nuclear-cytoplasmic ratio, and prominent nucleoli observed with the light microscope. In the carcinomas, there were variations in the morphology of mitochondria, with tubular forms in evidence. The basal lamina in the carcinomas was discontinuous. Pseudopodia arising from basal cells were seen in areas of basal lamina discontinuity.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1979

Transplantation of hamster buccal pouch carcinoma to neonatal hamsters.

Epidermoid carcinomas of oral mucosa were induced with DMBA in the buccal pouches of hamsters. The well-differentiated primary tumors were allografted into the peritoneal cavities of neonatal hamsters that had been treated with antilymphocyte serum. Solid tumors grew rapidly in the peritoneum and were harvested 6 to 31 days postimplantation. Gross and histopathologic specimens revealed infiltrative masses of tumor that had become more anaplastic than the original tumor. This in vivo model has considerable potential as a means of studying the immunology of oral cancers during tumor progression.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1978

Histologic response to porous PMMA implant materials.

Poly(methyl methacrylate) as used in polymer replica tooth implants was fabricated into 6 X 6 mm cylindrical specimens and cured in either an air oven, pressure pot, autoclave, or microwave oven. Polymer porosity was achieved by means of either 1) intrinsic foaming agents, or 2) compacting different sizes of large beads with a minimum of monomer, with dense PMMA used as a control. Specimens were then implanted in the long bones of baboons. Histology of thin-sectioned and ground specimens from the sacrificed animals revealed complete tissue ingrowth into implanted material made of medium and large PMMA beads, very superficial ingrowth into material containing foaming agents and anorganic bone chips, and no ingrowth into dense PMMA implants. None of the implants were rejected or caused chronic inflammation. The effect on histologic response of the different curing methods could not be distinguished.

Animals↗
PubMed1978

Surface texture and strength of vitreous carbon-poly(methyl methacrylate) dental implant materials.

A study has been carried out on the surface texture and the strength of several dental implant materials composed of vitreous carbon microballoons (6, 24, and 48 wt %)and poly(methyl methacrylate). Two sizes of microballoons were used--particle size less than 100 micrometer and particle size greater than 100 micrometer. Square wafers of the materials (10 X 10 X 1 mm) were studied with the surface sandblasted in half of the specimens. SEM studies revealed a rough porous surface with scattered moderately sized deep cavities in the 6% and 24% specimens with an increase in the number of cavities in the 24% specimens. The 48% specimens revealed a rough, porous surface composed of large shallow craters. Prepared specimens of the materials, processed by a gas-fired air oven and by a microwave oven, were tested for compressive strength and tensile strength using an Instron Universal Testing Machine. Compressive strengths of the various mixtures were similar, but mixtures using VC particle size over 100 micrometer demonstrated somewhat reduced compressive strength. Tensile strengths of the mixutres decreased significantly as the amount of VC increased, with a 20% reduction at 24 wt % and a 45% reduction at 48 wt %.

Carbon↗
PubMed1978

Alcohol and hamster buccal pouch carcinogenesis.

Alcohol was shown to enhance the carcinogenic effect of DMBA applied to hamster buccal pouch. DMBA animals given alcohol developed dysplastic leukoplakic lesions and epidermoid carcinomas 2 weeks ahead of water-drinking control animals. The tumors also grew to larger size, were more invasive, and were more anaplastic histologically. Forty young adult Syrian hamsters were divided into four groups (alcohol-DMBA, DMBA control, untreated control, and alcohol control) and were killed after 10, 12, and 14 weeks of DMBA applications three times weekly. Alcohol was given as a 10 percent solution instead of drinking water.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1978

Effects of tobacco smoking and age on the keratinization of palatal mucosa: a cytologic study.

Cytologic smears of palatal mucosa were evaluated for degree of keratinization in 217 healthy men ranging in age from 30 to 74 years. Two slides were prepared for each participant, and each slide was read by two different pathologists. Three separate high-power fields were examined on each slide, and the percentage of orange-brown cells, either without nuclei or with pyknotic or fragmented nuclei, was recorded. A mean value was obtained for each participant. Each participant had an extensive medical and dental work-up as part of the Veterans Administration Longitudinal Study of Oral Health in Healthy Veterans. Nonsmokers and smokers were divided into five age groups. Smokers at all ages presented a greater degree of palatal keratinization than nonsmokers, but age differences in keratinization were not statistically significant.

Adult↗
PubMed1978

Lingual carcinogenesis in an inbred strain of hamsters.

Epidermoid carcinoma of the lateral border of the tongue can be induced in a standard strain of hamsters, applying DMBA in acetone after traumatizing the area with a root canal broach. Employing the same technique in an inbred strain of hamsters resulted in the more rapid development of carcinomas. The inbred strain should be a useful model for experimental carcinogenesis of tongue.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1978

Preliminary evaluation of the histotoxicity and radiopacity of lead-containing elastic impression materials.

Severe reactions can be caused when elastic impression materials are trapped beneath soft tissues. To develop a rank order of severity of responses, a series of these materials was injected beneath the oral mucosa of a baboon. Alginate and polysulfide rubbers containing lead peroxide produced severe reactions; hydrocolloid, polysulfide without lead, silicone, and polyether produced more mild reactions. The more toxic materials proved to be more radiopaque than the others. Tests for foreign body toxicity should be made a part of future specifications for these materials, and the use of toxic ingredients should be reduced as much as possible. These materials should be made opaque to X rays and of a different color than those of soft or hard tissues.

Abscess↗