Analytical and ultrastructural studies of pellicle on primary teeth.

The pellicle on permanent enamel has been thoroughly studied. The aims of this study were to compare the chemical composition, rate of formation, and ultrastructural appearance of pellicle formed on deciduous enamel in children with those on permanent teeth. This was done by amino acid analyses, Auger analyses, and transmission electron microscopy. The amino acid composition of 2-h pellicle on deciduous and permanent enamel had an overall similar pattern, but the contents of serine, glycine, and tyrosine were statistically significantly different. An initially slower pellicle formation and a thinner 2-h pellicle without a globular structured second layer was observed on deciduous enamel. The results indicated therefore distinct differences in chemical composition, rate of formation, and ultrastructural appearance between pellicle on primary teeth and that on permanent teeth.

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.

Effects of oral rinsing with triclosan and sodium lauryl sulfate on dental plaque formation: a pilot study.

Mouthwashes containing 0.3% or 0.15% triclosan in combination with 1.5% sodium lauryl sulfate (SLS) produced a significant reduction in plaque formation in a test panel of 11 students who refrained from oral hygiene during the test periods, during which they rinsed twice daily with different mouthwashes. Pl.I. was evaluated after each test period. A mouthwash containing only 1.5% SLS inhibited plaque to almost the same degree. In both cases, the major effect was on the buccal/lingual surfaces, where score 2 was changed to score 0. Addition of triclosan appeared to reduce the untoward side-effects of mouth-washes containing SLS alone (i.e. desquamation and a burning sensation in the mouth).

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.

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.

Tooth colored dental restorative materials: porosities and surface topography in relation to bacterial adhesion.

The present investigation was carried out to determine whether differences in initial bacterial accumulation on dental restorations could be explained by differences in surface topography, particularly porosities, of the materials. A point counting method was used to determine the number and the size of the porosities in 15 materials. The results demonstrated great variation among the materials in the number of porosities. However, in vitro bacterial adhesion tests failed to show any relationship between porosities in the materials and the number of bacteria adhering to them. Nor were differences in surface topography, as measured profilometrically, associated with differences in bacterial adhesion. It is concluded that variations in surface topography including porosities do not suffice to explain differences in initial bacterial accumulation on silicate cements and composite dental restoratives.

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.

Effect of some polyvalent cations on plaque formation in vivo.

The purpose of the present study was to investigate the effect of polyvalent cations on plaque formation in a test panel of students. Heavy plaque formers were selected and plaque formation was enhanced by frequent sucrose rinses. Mouthrinses were performed twice daily with 20 mmol/l SnF2, SnCl2, AlCl3, ZnCl2 and MgCl2, and 40 mmol/l NaF and NaCl. It was found that SnF2 AND SnCl2 exhibited a marked plaque-inhibiting capacity compared with NaF or NaCl. The aluminum, zinc and magnesium salts also reduced plaque formation, although not to the same degree. Polyvalent cations may prevent plque formattion by interaction with negatively charged plaque components essential in the adsorption mechanism, or by inhibiting some enzyme activity essential in plaque formation.

[Bacterial accumulation on silicate and composite materials].

It was shown in a previous study that more plaque accumulates on composite filling materials than on silicate cement and amalgam. The purpose of the present investigation was to compare the accumulation of Streptococcus mutans on silicate cement and on composite material by scanning electron microscopy. Whether the adhesion was dependent on the presence of sucrose was also tested. Round disks, 6 mm in diameter, were made from the two materials. The disks were submerged in media with and without sucrose and inoculated with S. mutans OMZ 176. The disks were removed after 1 or 30 minutes, rinsed in saline and prepared for SEM. Along the diameter of each disk pictures were taken at similar intervals. From a total of 48 pictures from each material 18 pictures were selected at random and the number of microorganisms counted. The results indicated that bacteria initially adhered to both silicate and composite in about the same number. The presence of sucrose did not influence the initial adsorption. After 30 minutes bacteria were scarcely found on silicate, whereas large clumps of bacteria were attached to the composite. Sucrose increased bacterial accumulation on composites but did not affect the adherence to silicate cement.