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Biomedical subjects

H Lygre

Publications and source records attributed to H Lygre.

10 recordsLinked to original sources
PubMed2001

Interaction of a dental filling material eluate and membrane lipids.

The possibility that 4-N,N-dimethyl amino benzoic acid ethylester (DMABEE), a leachable lipophilic component of dental fillings, could interact with biological membranes was investigated. Interaction of DMABEE with phospholipids was studied by two methods: First, by determining the surface pressure/molecular area isotherms at 37degrees C of glycerophospholipids monolayers, using the Langmuir technique: and second, by phase transition parameters in liposomes of the same lipids, using differential scanning calorimetry (DSC). DMABEE clearly interacted, in a concentration-independent manner, with monolayers of saturated phosphatidylcholines (PC, i.e., markers of the outer membrane leaflet) and phosphatidylserines (PS, i.e., markers of the inner membrane leaflet). This interaction increased with increasing acyl length in the lipids and was greater with PC than with PS. These observations with monolayers were confirmed by the studies of liposomes of PC and PS.

4-Aminobenzoic Acid↗
PubMed1999

Organic leachables from polymer-based dental filling materials.

Results are reported from a study on the in vitro separation and identification of leachables from three different polymer-based dental filling materials by using a combined method of gas chromatography and mass spectrometry. The median number of separable organic leachables in these materials was between 14 and 22. Of these organic leachables the following were identified and quantified: DL-camphorquinone, 4-dimethylaminobenzoic acid ethyl ester (DMABEE), drometrizole, 1,7,7-trimethylbicyclo[2,2,1]heptane, 2,2-dimethoxy[1,2] diphenyletanone (DMBZ), ethyleneglycol dimethacrylate (EGDMA), and triethyleneglycol dimethacrylate (TEGDMA). Three of the leachables have previously been shown to provoke allergy. The range of log P(ow) values (representing the lipophilicity of these compounds) varied between 1.09 and 4.20. By multivariate data analysis, selected leachables from the tested materials were shown to separate into characteristic patterns. The results contribute to a characterization of potential hazardous compounds in polymer-based dental filling materials.

4-Aminobenzoic Acid↗
PubMed1995

Leaching from denture base materials in vitro.

Specimens made from denture base materials were leached in Ringer solution and in ethanol. The specimens comprised a heat-cured product processed in two different ways and two cold-cured materials. The organic compounds leaching from the specimens to the solutions were separated, identified, and quantified by a combined gas-chromatography and gas-chromatography/mass-spectrometry technique. Additives and degradation products, possibly made by free radical reactions, were released from the denture base materials. In Ringer solution only phthalates could be quantified. In ethanol solvent, biphenyl, dibutyl phthalate, dicyclohexyl phthalate, phenyl benzoate, and phenyl salicylate were quantified. In addition, copper was found in the ethanol solvent from one of the denture base materials. The amount of leachable organic compounds varies among different materials. Processing temperature influences the initial amount of leachable compounds.

Benzoates↗
PubMed1995

Fatty acid composition of palatal tissue from denture stomatitis patients.

Palatal biopsy specimens were obtained from patients with denture stomatitis. The fatty acids were extracted from the tissue, then separated, identified, and quantified by a gas-chromatographic technique. The sensitivity of this method enabled analyses of specimens with a wet weight of less than 1 mg. The concentration of the fatty acids C16:1 (n-7) and C24:1 (n-9) differed significantly between samples from hyperplastic and clinically healthy tissue in the denture stomatitis patients. By comparing specimens from denture stomatitis patients and non-denture subjects, the concentration of seven fatty acids, two saturated and five unsaturated, was found to be significantly different. A multivariate data-analytical method distinguished between the fatty acid composition in specimens from denture stomatitis patients and from non-denture subjects.

Adolescent↗
PubMed1995

Biologic testing of leachable aromatic compounds from denture base materials.

The aromatic compounds phenyl benzoate (PB), phenyl salicylate (PS), and biphenyl (BP), which have previously been found to leach from poly(methyl methacrylate) denture base materials, were tested for cytotoxicity and biologic effects by L929 cells in culture. The octanol-water partition coefficient (log P(ow), a descriptor for the lipophilicity, was determined for the compounds. Cytotoxicity was evaluated by total cell growth and the plating efficiency test, and biologic effects by the total fatty acid composition of L929 cells. The commonly used tests, total cell growth and plating efficiency, did not show any significant changes of the cells due to the compounds. On the other hand, BP and PS, in particular, induced changes in the total fatty acid composition of L929 cells. The problem of bioavailability of aromatic compounds in cell culture assays and the relation to lipophilicity was addressed.

Animals↗
PubMed1994

Leaching of additives and degradation products from cold-cured orthodontic resins.

Unstimulated saliva was collected from orthodontic patients and subjected to combined gas-chromatography and gas-chromatography/mass-spectrometry analyses. Saliva was collected before insertion of removable orthodontic appliances made of cold-cured resins. Saliva was then collected 1-2 months after insertion of the appliances and 1 week after they had been removed. Phenyl benzoate (PB) and phenyl salicylate (PS) were identified in pooled saliva samples from patients wearing the appliances. Biphenyl and 2-methoxy-4-hydroxy-benzophenone in addition to PB and PS were identified in a study with in vitro specimens made of orthodontic resin. The leaching of compounds from these test specimens processed by a powdering technique and a pre-mix technique was compared.

Biphenyl Compounds↗
PubMed1993

Leaching of organic additives from dentures in vivo.

Samples of saliva were collected from subjects with dentures. These samples were collected both before the dentures were replaced and 1 week after the subjects had received their new dentures. Dibutylphthalate and phenyl benzoate were detected in the saliva samples with a gas-chromatography and a gas-chromatography/mass-spectrometry technique. We also quantified the dibutylphthalate in the saliva. In addition, in an in vitro study, we identified biphenyl leached from heat-cured denture base polymer plates. Our study suggests that subjects with dentures have higher contents of the above organic substances in saliva than subjects without dentures and that organic additives leach from new heat-cured dentures.

Adult↗
PubMed1992

Fatty acids of healthy and periodontally diseased root substance in human teeth.

In this comparative study, samples of root substance from healthy and periodontally diseased human teeth were analyzed for fatty acids by means of a gas-chromatographic technique. The sample preparation procedure allowed specimens from individual teeth to be analyzed. The content of the fatty acids C16:0, C16:1, C18:0, and C18:1 in the superficial layer of the periodontally diseased teeth was significantly higher than that of healthy teeth. In the inner layer, there was no such difference. Four different 3-hydroxy fatty acids (3-OH C14:0, 3-OH C15:0, 3-OH C16:0, and 3-OH C17:0) were identified by combined gas-chromatography/mass-spectrometry in the tooth substance of periodontally diseased teeth. This indicates the presence of lipid A, which is the toxic component of bacterial lipopolysaccharides.

Chromatography, Gas↗