Torleif Sønju

Chemical composition of salivary integuments formed in vivo on solids with some established surface characteristics.

Abstract The amino acid composition of salivary integuments formed on three artificial surfaces in vivo was investigated. The test solids Mylar® and Melinex® had the same overall chemical composition but differed in their critical surface tensions. The critical surface tension of the polymers coincided approximately with that of human enamel. The third solid, glass, had a critical surface tension and a chemical composition different from both the other solids and from human enamel. The results indicated that the chemical properties of the surfaces of Mylar and Melinex were different, presumably owing to different processes of manufacturing. The results of the amino acid analyses showed that the chemical compositions of the adsorbed integuments were different and also that they differed from the previously reported amino acid composition of the pellicle formed in 2 hr on human enamel in vivo. It is concluded that the chemical composition of the surface of solids has an important influence on the type of proteins which they adsorb.

Rate of pellicle formation in vivo

The acquired enamel pellicle is thought to be the result of a selective adsorption of salivary proteins and to be involved in the protection of the enamel surfaces. The chemical composition of the 2-h acquired enamel pellicle is fairly well established. However, the rate of formation and the amino acid composition of the initially formed enamel pellicle have been little investigated. The aim of this study was therefore to examine the rate of pellicle formation and the amino acid composition of the initially formed enamel pellicle. Samples of human enamel surfaces were carried in the mouth for various periods of time (2.5 min to 10 h). Rate of pellicle formation was indicated as a function of oral exposure time and the time necessary to remove the proteinaceous film from the surfaces by argon ion sputtering. The chemical composition of the initially acquired pellicle was examined by amino acid analyses of pellicle material collected in vivo from enamel surfaces 15 min and 1 h after pumicing, respectively. The pellicle reached an initial thickness in about 2-3 min, at which level it stayed for about 30 min. The thickness of the acquired pellicle then increased to about three times the initial thickness and stayed at that level for the rest of the experimental period (10 h). Amino acid analyses of pellicle material collected after 15 min and after 1 h were different in that the amino acid profiles of the 15-min pellicle only contained traces of proline and arginine. It may be argued that the pellicle formation proceeds in two stages owing to the adsorption of protein aggregates and that the chemical compositions of the pellicles of the two stages differ.

Effect of sucrose rinses on bacterial colonization on amalgam and composite

The effect of sucrose rinses on the bacteriology of early plaque on enamel, amalgam and composite was investigated. Three test persons rinsed with a 15% sucrose solution every hour for 12 h prior to the insertion of the test materials. Round disks of amalgam and composite were carried on the buccal surfaces of the upper molars for 2 1/2 h. Sucrose rinses were found to have an effect both on plaque composition and on the amount of plaque on composite, but not no enamel or on amalgam. A small increase in the number of Streptococcus mutans as well as a general increase in the number of bacteria were found.

Fluoride release and uptake in vitro from a composite resin and two orthodontic adhesives

The aim of this study was to investigate the fluoride release and uptake characteristics of a composite resin (Tetric) and two orthodontic adhesives (VP 862 and Saga Bond), with a type-II glass ionomer cement (Ketac Fil) as a control. Test specimens in 2 ml deionized water released fluoride over a period of 33 days. Ketac Fil released 54 and 15 times more fluoride than Tetric after 24 h and 1 month, respectively, whereas the two adhesives released amounts between these values. Specimen exposure to 1000-ppm NaF solution increased the 24-h fluoride release from all materials, with near pre-exposure levels reached after 2-3 days. Ketac Fil had a tendency to recharge not seen with the other materials. The ytterbium trifluoride filler in Tetric has a very low water solubility, and it is therefore suggested that the increases in fluoride release from Tetric after exposure to fluoride were most probably due to release of surface-retained fluoride.

Survival analysis of amalgam restorations in long-term recall patients

The longevity of amalgam restorations in premolars and first and second molars in long-term recall patients has been calculated by means of survival analysis. The present retrospective longitudinal study includes information from 32 patients and their records over a time period of 17 years. The data were recorded by six dentists. The estimated time of 90% survival was 7 years. After 17 years the survival estimate decreased to 78%, indicating a favorable longevity of amalgam restorations in patients taken care of in an established recall system.

Protein adsorption to hydroxyapatite and to calcium fluoride in vitro and amino acid analyses of pellicle formed on normal enamel and on calcium-fluoride-covered enamel in vivo

Fluoride treatment of enamel has been reported to result in the formation of a layer of a CaF2-like material on the enamel surface. Protein adsorption to enamel is a specific process dependent on the nature of the surface, and little is known about protein adsorption to CaF2. Albumin and lysozyme were adsorbed to hydroxyapatite (HA) and CaF2 powder in vitro, and protein adsorption patterns constructed. In vivo pellicle was collected from three volunteers from fluoride-treated enamel and from normal enamel, and the amino acid compositions analyzed separately. The results showed that CaF2 took up small amounts of proteins as compared with HA. When the CaF2 was pretreated with a phosphate buffer, pH 6.8, the protein adsorption increased markedly. The amino acid analyses showed no major differences in the amino acid compositions between pellicle collected from CaF2-covered enamel and pellicle collected from normal enamel. This lack of difference is presumably due to the adsorption of phosphate ions to the CaF2 crystals and hence changed surface properties.

Sulphated macromolecules in dental plaque in the monkey Macaca irus.

Abstract EDTA extracts of plaque from tube-fed monkeys receiving sucrose by mouth contained radioactivity bound to macromolecules 6 hr after an intraperitoneal injection of [35S] sulphate. The isotope was presumably incorporated in sulphated glycoproteins. Gel chromatography of the extract showed two peaks of high molecular weight material, both absorbing at 215 and 280 nm and both containing radioactivity. Isoelectric focusing indicated a pI of about 3 for the radioactive macromolecules. Autoradiography of the minor salivary glands in the labial mucosa facing the dental plaque showed production of sulphated substances in these glands. It is suggested that sulphated glycoproteins may be important for the adhesion and cohesion of dental plaque because of their physico-chemical properties, and that the acidic agglutination factors described in the literature may contain such substances.

Isoelectric variants of blood-group substance A in human palatine secretion

Abstract Human palatine secretion contains blood-group substances in high concentration, but the viscous substances have been difficult to fractionate without pretreatment to render them water-soluble. We show that it is possible to fractionate human palatine secretion with retention of the viscous properties of the blood group substances. Pilocarpine-stimulated human palatine secretion from secretors of blood group A was subjected to isoelectric fractionation on a polytetrafluoroethylene-coated column. Blood-group substance activity was recovered in an acidic (pI 10) component. Virus-haemagglutination inhibition activity was found in the acidic and neutral components. The neutral component was the largest and retained the gel-like properties of the original secretion. Boiling of aliquots did not appear to affect the acidic and alkaline components. In the neutral component, an increase in the titres of blood-group substance activity and virus-haemagglutination inhibition activity was observed, concomitant with loss of viscous properties and change in electrophoretic mobility. Amino acid analysis did not reveal any significant differences between the acidic and neutral components. The alkaline one was different from the two others. It appeared possible that the water-soluble acidic and alkaline components were derived from the viscous, neutral component.

The organic film developed on metal surfaces exposed to seawater: Chemical studies

Abstract The chemical composition of the organic film formed on metal surfaces (iron, aluminum, and copper) by exposure to seawater (2 hours) was investigated. After hydrolysis the film material was shown to contain 15 different amino acids. This composition was characterized by relatively large amounts of the neutral amino acids glycine and serine and the acidic amino acids glutamic and aspartic acids, whereas the content of basic amino acids was considerably less. Glucose and ribose constituted the monosaccharides of the film material. Gas chromatographic analyses after chloroform-methanol fractionation showed myristic, palmitic, oleic, and stearic acids to be the main fatty acid constituents. The chemical composition of the surface film appeared to be similar on all the solid surfaces tested.

Chemical and morphological studies of the acquired pellicle formed subgingivally on dentin in vivo

The morphological appearance and chemical composition of the subgingival pellicle were studied, using Auger analysis and scanning and transmission electron microscopy. A pellicle was formed on pieces of dentin (2 X 2 X 1 mm), prepared from freshly extracted teeth after root planing. The dentin slabs were inserted for 2 h into healthy gingival sulci. Control slabs cemented supragingivally were used for comparison. The results confirmed the presence of an organic film on the surface of all slabs. Auger analysis of the organic film showed the presence of Ca in the supragingival integument but not in the subgingival integument. The subgingival pellicle was in all cases thicker than the supragingival pellicle. The transmission and scanning electron microscopy observations confirmed the presence of a film essentially free of bacteria on the subgingival specimens and also indicated a possible morphological difference between the supra- and sub-gingival pellicle.