W.H. Bowen

Prevalence of Streptococcus mutans Serotypes, Actinomyces, and Other Bacteria in the Plaque of Children

Selected microbial components in dental plaque were determined for children in Biddeford, Maine and Colombia, South America. Using cultural methods, Streptococcus mutans was detected in 51.4% of the Colombian children and 63.3% of the Maine children. Serotype c was predominant in both populations. The greatest difference between the two groups occurred with serotypes d and g which were present in 25% of the Colombian children with S. mutans and were not detected in the Maine children. In the specimens examined with specific FA conjugates, Actinomyces was the predominant genus, present in all individuals and comprising an average of 52% of all cells.

The use of the o-phthalaldehyde reaction as a sensitive assay for protein and to determine protein in bacterial cells and dental plaque.

Abstract Alkaline hydrolysis of protein followed by reaction with o-phthalaldehyde has permitted the determination of less than 10 ng of protein fluorometrically. When intact proteins were analyzed with o-phthalaldehyde the reaction was less sensitive. This reaction has been applied to analysis of the protein content of dental plaque and bacterial cells.

Effects of Different Eating Patterns on Dental Caries in the Rat

Fewer smooth surface carious lesions developed in rats fed a high-sucrose diet (2000) administered by a feeding machine delivering 22 portions (‘meals’) per day when additional meals of cheese (‘snack

The influence of saliva on infection of the human mouth by mutans streptococci

The relationship between oral implantation of Streptococcus mutans IB1600 (serotype c) and Streptococcus sobrinus OMZ65 (serotype g), the aggregating activity of saliva, and its influence on the adherence of these bacterial strains in vitro was examined in seven human subjects. All the saliva samples aggregated strain IB1600 but not strain OMZ65 cells. Whole saliva from subjects with low levels of infection by Strep. mutans aggregated strain IB1600 to a greater degree than did whole saliva from those who were readily infected. Whole saliva from subjects most resistant to infection supported the adsorption of the highest number of either strain IB1600 or OMZ65 to hydroxyapatite surfaces. Thus the ability of whole saliva to aggregate Strep. mutans may influence the ability of these microorganisms to infect the mouth.

Surface adsorption of fluoride and ionic exchange reactions on hydroxyapatite

The experiments showed that a part of the fluoride which was taken up by hydroxyapatite or teeth at low concentrations of fluoride at neutral pH was soluble in alkali (IN KOH, 24 h) and was thus not fluoroapatite. Calcium fluoride could not form under the present conditions because the solubility of this compound was not exceeded. It is suggested that the alkali soluble fluoride is adsorbed to calcium ions bound as counterions in the hydration layer of the hydroxyapatite or the enamel. This is consistent with previous findings in this laboratory, showing that fluoride displaced acidic proteins adsorbed to calcium receptors on the hydroxyapatite surface in the same way as other anions displace proteins. It could also be shown that polyanions and polycations adsorbed to hydroxyapatite surfaces by ionic exchange, displacing phosphate or phosphate and calcium respectively in the process. A model is suggested which differs slightly from that proposed by Bernardi.

The Effect of Malnutrition on Caries Development and Saliva Composition in the Rat

The purpose of this study was to investigate the effect in rats of malnutrition on caries development and on some antibacterial substances in saliva. By gastric intubation, two groups of ten rats each were fed a liquid basic diet (100% diet), and two similar groups were fed the basic diet diluted with an equal volume of water to contain 50% of the nutrients of the basic diet (50% diet). One group on undiluted and one group on the diluted basic diet were offered sucrose as a supplement by mouth 17 times daily, using a programmed feeding machine, and the other two groups were offered starch in a similar manner. The extent and depth of the caries lesions were five times greater in the low-nourished (50% diet) sucrose group in comparison with the group given the undiluted diet supplemented with sucrose. The 50% diet group ate more frequently from the offered supplement. The 50% diet induced lower salivary lactoperoxidase activities, and there was an additive effect of starch as supplement. Higher concentrations of sIgA were found in the saliva of animals fed the 50% diet supplemented with sucrose than in those fed sucrose and the 100% diet. Significantly greater levels of sIgA and IgG were found in the saliva from the 50% diet-sucrose group than in the 50% diet-starch group. Plaque scores differed slightly but not significantly between the groups. The starch group receiving 100% diet showed a slightly lower level of S. mutans infection as compared with the 50% diet-starch group; the caries scores in the starch groups did not differ.

The Influence of Fluoride on the Uptake of Protein by Hydroxyapatite

A brief pretreatment of hydroxyapatite with 1 m M of fluoride caused a reduced uptake of the acidic protein albumin, whereas an increased uptake of the basic protein protamine was ob

The effect of antibacterial compounds on glucosyltransferase activity from Streptococcus mutans

Abstract The effect of several plaque-inhibiting and/or antibacterial compounds on glucan synthesis by glucosyltransferases purified from the cariogenic bacterium Streptococcus mutans strain 6715 was determined. Drugs were tested at concentrations of 0.2–2.0 mM at pH values between 6.5 and 6.8. Bis-biguanides, quaternary ammonium salts and aliphatic amines were found to be potent inhibitors of enzyme activity. The strong anionic detergent, sodium lauryl sulphate and the phenol derivative, hexylresorcinol, also caused significant inhibition. Basic nitrogen compounds lacking a functional hydrophobic group were less inhibitory or stimulated enzyme activity. Both electrostatic and hydrophobic interactions appear to be occurring between the cationic test-agents and the glucosyltransferases, with hydrophobic interaction being more important for enzyme inhibition.

Comparison of the Cariostatic Effect of Topically and Systemically Administered Controlled-Release Fluoride in the Rat

Rats treated continuously with topical fluoride from an intraoral delivery system (Intraoral Fluoride-Releasing Device) developed significantly fewer proximal, sulcal, and total carious enamel areas after 5 weeks on a caries-conducive regimen than did rats that received fluoride at a similar rate systemically from a subcutaneously implanted controlled-release delivery system. Rats treated with continual topical fluoride or with intermittent topical fluoride from drinking water had significantly fewer carious enamel areas on third-molar surfaces than rats treated with continual systemic fluoride. The findings suggest that the substantial cariostatic benefits produced by the intraoral fluoride-releasing device in rat caries trials were the result of topical effects due to the continual presence of fluoride in the oral fluids.

Simultaneous Implantation of Five Serotypes of Streptococcus mutans in Gnotobiotic Rats

Following infection by equivalent numbers of Streptococcus mutans serotypes a–e, gnotobiotic rats were monitored to determine which serotypes became implanted and