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PubMed1993

Molecular characterization of a negative regulator of Streptococcus sobrinus surface protein antigen gene.

Mutans streptococci have been shown to give rise to variants in terms of expression of surface protein antigens by repeated subculturing of the organisms, which in turn induces changes in colonial morphologies. A 2,850-bp upstream region of the gene (pag) for a surface protein antigen, PAg, of Streptococcus sobrinus MT3791 was determined. Analysis of the nucleotide sequence revealed the existence of three open reading frames (ORFs) located upstream of the pag gene. ORF1 extended from an undetermined further upstream sequence to the termination codon TAG lying 1,943 bp upstream of the pag gene. ORF2, consisting of 609 bp lying 1,689 bp upstream of the pag gene, encoded a protein of 23,347 Da and a protein of 22,792 Da. The synthesis of these proteins (protein antigen regulators) was demonstrated by using the in vitro T7 RNA polymerase/promoter system. ORF3, extending from 314 bp upstream of the pag gene to 712 bp upstream of the pag gene, encoded a protein of 14,802 Da. Disruption of chromosomal ORF2 of parent strain MT3791 by allelic exchange resulted in isogenic mutants, termed PAREm-1 and PAREm-2, that synthesized larger amounts of cell-free and cell-associated PAg than did the parent strain. RNA dot blot analysis demonstrated that expression of PAg-specific mRNA transcripts by mutants PAREm-1 and PAREm-2 was about 32-fold higher than that by strain 3791. Mutants PAREm-1 and PAREm-2 were found to be more hydrophobic than strain MT3791. Resting cells of these mutants attached in larger numbers to saliva-coated hydroxyapatite than did those of the parent strain. These results suggest that protein antigen regulator regulates the expression of PAg gene in a negative fashion, affecting the colonization of tooth surfaces by the organism. Thus, ORF2 is concluded to be a negative regulator gene of PAg synthesis and was designated par.

Amino Acid Sequence↗

PubMed1997

Effect of antibodies on the chain length and growth of Streptococcus sobrinus.

Passive immunization has been suggested as a method to prevent colonization of teeth by mutans streptococci. However, the mechanism of action of antibodies, both polyclonal and monoclonal, is not clear. In this study we investigated the effect of polyclonal antibodies (pAbs) and a monoclonal antibody (OMVU10) on the chain length and growth of Streptococcus sobrinus. During growth in broth S. sobrinus formed significantly longer chains in the presence of pAbs in comparison to pre-immune serum (p < 0.01), but pAbs did not influence the growth rate of S. sobrinus in broth. OMVU10 did not influence the growth rate nor the chain length. In order to study the effect of the antibodies on adhesion and growth on a surface, S. sobrinus was grown on hydroxyapatite discs in the presence of two other bacteria, Streptococcus oralis and Actinomyces viscosus. No effect of the antibodies was found on the total cultivable count of the three bacteria after growth on hydroxyapatite discs. However, the morphology of the S. sobrinus microcolonies was different after growth in the presence of both pAbs and OMVU10. The colonies were less dense and chains of S. sobrinus could be seen using a confocal laser microscope. After growth in the presence of the control antibodies, the colonies were dense and no long chains could be observed. It was concluded that pAbs influenced the chain length, in broth and on hydroxyapatite discs, and the colony morphology of S. sobrinus on hydroxyapatite discs, whereas OMVU10 influenced the colony morphology of S. sobrinus on hydroxyapatite discs.

Aggregatibacter actinomycetemcomitans↗

PubMed1996

Oral immunization with recombinant Salmonella typhimurium expressing surface protein antigen A (SpaA) of Streptococcus sobrinus: effects of the Salmonella virulence plasmid on the induction of protective and sustained humoral responses in rats.

Recombinant strains of Salmonella typhimurium have been studied as antigen delivery systems to determine their effectiveness as multivalent vaccines. Here we compare the efficacy of two strains of S. typhimurium. chi 4072 (pYA2905) and chi 3987 (pYA2905), expressing SpaA of Streptococcus sobrinus 6715 as oral vaccines for dental caries. Both strains are attenuated delta cya delta crp delta asd mutants with their Asd phenotypes complemented by the Asd+ plasmid pYA2905, which also encodes a peptide fragment of SpaA. S. typhimurium chi 3987 (pYA2905), unlike S. typhimurium chi 4072 (pYA2905), contains the 100 kb S. typhimurium virulence plasmid. Fischer rats were orally immunized with approximately 10(9) S. typhimurium chi 3987 (pYA2905) or chi 4072 (pYA2905) and then challenged with cariogenic S. sobrinus 6715. Rats orally immunized with either strain of recombinant Salmonella developed salivary IgA anti-SpaA responses and had lower levels of S. sobrinus-induced dental caries than nonimmunized, infected animals. In a second series of experiments, the kinetics and isotype of the serum and salivary antibody responses were determined in rats orally immunized with S. typhimurium chi 3987 (pYA2905) or chi 4072 (pYA2905) on weeks 0 and 8. IgG and IgM serum antibody responses to SpaA and S. typhimurium were detected after the primary and secondary immunizations, and the secondary immunization boosted serum IgG anti-Salmonella activity. In general, animals immunized with chi 3987 (pYA2905) had higher serum anti-SpaA, as well as serum and salivary anti-Salmonella, responses than animals immunized with chi 4072 (pYA2905). This study demonstrates the effective use of two recombinant S. typhimurium strains as oral vaccines for inducing protective and sustained immune responses against a mucosal pathogen and suggests that the recombinant Salmonella vaccine strain carrying the virulence plasmid induced similar or higher protective immune responses than the strain lacking the virulence plasmid.

Administration, Oral↗

PubMed1991

Substrate specificity of hydrolase activity of the primer-dependent glucosyltransferases from Streptococcus sobrinus.

Four kinds of glucosyltransferases, P1, P2, P3 and P4, were separately purified from the culture supernatant of Streptococcus sobrinus. Their dependencies on primer were analysed. There were two primer-dependent glucosyltransferases (P3 and P4). In the absence of primer 1,6-alpha-D-glucan, P3 was not able to produce glucan from sucrose. However, P3 showed sucrose hydrolase activity, whereas P4 was still able to produce glucan without primer 1,6-alpha-D-glucan. Consequently, glucosyltransferase activity of P4 was incompletely primer-dependent. Both P3 and P4 showed high substrate specificity for sucrose, failing to use melezitose, raffinose, or stachyose as the substrates.

Chromatography, High Pressure Liquid↗

PubMed1995

Effect of Lactobacillus rhamnosus strain GG (ATCC 53103) on the growth of Streptococcus sobrinus in vitro.

Lactobacillus GG, a recently characterized L. rhamnosus GG strain (ATCC 53103), has been shown to exert inhibitory activity against a variety of bacterial species, including streptococci. We isolated and studied the effect of the inhibitory substance of Lactobacillus GG on some oral streptococci. The inhibitory activity of the isolated substance was weak, but some growth inhibition was observed in Streptococcus sobrinus pretreated with the substance in comparison with untreated controls. Zones of growth inhibition on agar plates were apparent only at pH values below 5, indicating that the inhibitory activity was restricted to a low pH range. Growth curve experiments showed a statistically significant inhibition between series with and without the isolated substance (P < 0.05). The ultrastructure of S. sobrinus was not affected when treated with the inhibitory substance. The Lactobacillus GG itself did not ferment sucrose. The results offer interesting perspectives for future research focusing on the protective function of normal flora and in the attempt to replace harmful bacterial species in oral microflora with less harmful ones.

Antibiosis↗

PubMed1989

Ultrastructural changes in Streptococcus sobrinus induced by xylitol, NaF and ZnCl2.

The effect of xylitol, NaF, or ZnCl2 on the ultrastructure of Streptococcus sobrinus OMZ 176 was studied. The bacteria were grown statically in air for 8 h in brain-heart infusion broth supplemented with 33 mM Xylitol, 2.5 mM NaF, 0.5 mM ZnCl2, separately or in combination. The bacteria were washed briefly and prepared for scanning and transmission electron microscopy. All three agents and their combinations induced distinct ultrastructural alterations. The alterations were related to various aspects of cell morphology and varied in nature and extent among the agents. The most pronounced ultrastructural alterations were seen in bacteria grown in the presence of zinc ions. At the concentrations used, fluoride appeared to induce the least effect.

Chlorides↗

PubMedDate not supplied

Powdered milk micellar casein prevents oral colonization by Streptococcus sobrinus and dental caries in rats: a basis for the caries-protective effect of dairy products.

Three animal studies were performed to investigate the influence of the macromolecular structure of milk casein on caries incidence and the possible ecological changes of the oral microbiota by such casein fractions. Towards this end, rats were infected with mixed bacterial suspensions of Streptococcus sobrinus OMZ 176 and Actinomyces viscosus Ny1. Various milk protein fractions were incorporated into carefully balanced powdered cariogenic diets to constitute the sole major protein component. Diets containing micellar casein had a pronounced and highly significant effect on almost all clinical and microbiological parameters examined. Both the formation of advanced dentinal fissure (B) and smooth surface (E) caries lesions was inhibited by diets containing micellar casein; this caries-inhibiting effect appeared to be due mainly to modifications within the plaque microbiota. The proportion of S. sobrinus in the oral cavity of rats was reduced (73-80%) by micellar casein-containing preparations, whereas the A. viscosus population was increased. Both these microbiological parameters were always negatively correlated. This appears to be the first example of a food component other than dietary sugars, selectively modifying the composition of the dental plaque microbiota of rats in such a way as to reduce its pathogenic potential. It also demonstrates the importance of establishing a molecular basis for the role of food components, which prove to be beneficial to oral health.

Actinomyces viscosus↗

PubMed2000

Nigerooligosaccharide acceptor reaction of Streptococcus sobrinus glucosyltransferase GTF-I.

Nigerose and nigerooligosaccharides served as acceptors for a glucosyltransferase GTF-I from cariogenic Streptococcus sobrinus to give a series of homologous acceptor products. The soluble oligosaccharides (dp 5-9) strongly activated the acceptor reaction, resulting in the accumulation of water-insoluble (1-->3)-alpha-D-glucan. The enzyme transferred the labeled glucosyl residue from D-[U-13C]sucrose to the 3-hydroxyl group at the non-reducing end of the (1-->3)-alpha-D-oligosaccharides, as unequivocally shown by NMR 13C-13C coupling patterns. The values of the 13C-13C one-bond coupling constant (1J) are also presented for the C-1-C-6 of the 13C-labeled alpha-(1-->3)-linked glucosyl residue and of the non-reducing-end residue.

Bacterial Proteins↗

PubMed1987

Characterization by affinity electrophoresis of an alpha-1,6-glucan-binding protein from Streptococcus sobrinus.

Glucan-binding protein 1 (GBP1), the most abundant glucan-binding protein isolated from culture supernatants of Streptococcus sobrinus 6715-49, has been purified by affinity chromatography on Sephadex G-50 followed by gel permeation chromatography with Bio-Gel P-10. The specificity and affinity of GBP1 for glucans were assessed by affinity electrophoresis. GBP1 did not detectably bind to glucans lacking linear arrays of alpha-1,6 linkages. The association constant for the linear alpha-1,6-glucan Dextran T2000 was 3 x 10(7) M-1. Providing small isomaltosaccharide ligands to compete with this dextran indicated that the binding site maximally accommodated isomaltosaccharides with a degree of polymerization of 8. When glucans produced by purified S. sobrinus glucosyltransferases were tested, GBP1 displayed the highest affinity for the glucan from the soluble-product, primer-independent glucosyltransferase.

Bacterial Proteins↗

PubMed1997

Generation of bovine immune colostrum against Streptococcus mutans and Streptococcus sobrinus and its effect on glucose uptake and extracellular polysaccharide formation by mutans streptococci.

Due to potential side-effects of active immunization by cariogenic mutans streptococci, oral administration of passively-derived antibodies could be a more acceptable way to reduce colonization and virulence of these microorganisms in human dentition. The aim of this study was to produce antistreptococcal immunoglobulins into bovine colostrum and explore the possible antibacterial mechanisms of these immunoglobulins against mutans streptococci. Specific serum IgG antibodies to whole cell antigens of both Streptococcus mutans and Streptococcus sobrinus increased rapidly in cows during immunization and were high also in the final whey-product. Low concentration (0.5% w/v) of bovine immune preparation inhibited significantly the incorporation of [14C]glucose by both S. mutans and S. sobrinus. Higher concentration (> 1%) was needed to inhibit the glucosyltransferase or fructosyltransferase activities of these bacteria. No such inhibitory effects were observed with the control preparation from the non-immunized cows. Our results indicate that bovine immune colostrum has a significant inhibitory potential against mutans streptococci, apparently dependent on the presence of specific IgG antibodies against S. mutans and S. sobrinus.

Animals↗

PubMed2002

Stability and activity of specific antibodies against Streptococcus mutans and Streptococcus sobrinus in bovine milk fermented with Lactobacillus rhamnosus strain GG or treated at ultra-high temperature.

Passive local immunization against dental caries is a promising approach to its prevention, as clinical evidence of active oral or nasal immunization is still limited and controversial. By means of systemic immunization of pregnant cows with a multivalent vaccine, high titres of IgG antibodies against human cariogenic bacteria, Streptococcus mutans and Streptococcus sobrinus, were produced in bovine colostrum. The purified immune product (IP) of this preparation has a number of anticariogenic properties, such as inhibition of streptococcal adherence to saliva-coated hydroxyapatite and inhibition of glucosyltransferase enzymes. This study investigated whether IP antibodies remained active and functional when added to ultra-high temperature (UHT)-treated milk or to Lactobacillus rhamnosus GG (LGG)-fermented milk stored for an extended time. LGG was chosen because of its widely known health benefits in humans and animals. A commercial UHT toddler's milk was supplemented with IP and stored for 2 months at 5, 21 and 30 degrees C. The antistreptococcal titres in UHT milk did not decline at any temperature during storage, and UHT-IP inhibited the adherence of S. mutans for up to 2 months. This was not the case with UHT toddler's milk without IgG antibodies. Milk was fermented with live LGG cells in the presence or absence of 5% IP. The antistreptococcal titres declined to about 30% of the original titres after storage. Fresh milk alone slightly enhanced streptococcal adhesion but fresh milk with IP inhibited the adherence of S. mutans by over 50%. LGG-positive fermented milk without antibodies also inhibited (P < 0.05) the adhesion by about 40%. In both LGG-fermented and UHT immune milk, the activity of antibodies against cariogenic streptococci was maintained during the expected shelf-life of these products. From the anticariogenic point of view it may be beneficial to add bovine-specific antibodies against mutans streptococci to probiotic LGG-containing milk products.

Animals↗

PubMedDate not supplied

The anticariogenic effect of amine fluorides on Streptococcus sobrinus and glucosyltransferase in biofilms.

Dental caries is a chronic infectious disease caused by the accumulation of bacterial plaque (biofilm) on tooth surfaces. Antibacterial agents, in addition to other preventive measures, can control dental plaque accumulation. Amine fluorides (AmF) are known anticaries agents for over 30 years. The purpose of our study was to assess the adsorption and desorption of AmF to experimental dental biofilm and to evaluate the effect of AmF on Streptococcus sobrinus 6715 and glucosyltransferase (GTF) activity in experimental dental biofilms. The experimental plaque model used in this study consists of hydroxyapatite beads coated with human saliva (sHA), followed by adsorption of S. sobrinus and synthesis of in situ polysaccharides. Our results show that the viability of S. sobrinus in biofilm decreased as the concentration of AmF and chlorhexidine (CHX) increased. The concentration of AmF and CHX required to kill S. sobrinus adherent to sHA is about 100 times greater than the concentration required to kill the same amount of planktonic bacteria. Adsorption of AmF to surfaces was more than 90% and the desorption of AmF from our experimental model was limited. Pre-adsorption of AmF on the surface increased adhesion of S. sobrinus but also resulted in surface killing of the adsorbed bacteria. At low concentrations AmF increased GTF activity in solution by about 10%, but at concentrations above 0.1 mM it inhibited GTF activity. Inhibition of GTF on the surface required about 100 times more AmF than in solution. Our results show that AmF retains its anticariogenic effects in solution and in biofilm systems.

Adult↗

PubMed2005

Effects of disinfectants on resilient denture-lining materials contaminated with Staphylococcus aureus, Streptococcus sobrinus, and Candida albicans.

OBJECTIVES: Resilient denture-lining materials are more susceptible to microbial adhesion than are denture base acrylic resin. As denture hygiene is essential to maintain the serviceability of the denture, disinfectant solutions have been suggested as a method for effectively cleaning resilient liners. The aim of this study was to determine the effectiveness of four different disinfectant solutions on four different resilient lining materials contaminated with Staphylococcus aureus, Streptococcus sobrinus, and Candida albicans. METHOD AND MATERIALS: Three microorganisms (Sta aureus, Str sobrinus, and C albicans), four resilient lining materials (Tempo, Immediate, Flexacryl soft, Ufi Gel P), and four disinfectant solutions (5.25% sodium hypochlorite, 2% sodium hypochlorite, 5% Deconex, and 3.5% Savlex solutions) were investigated. The four resilient lining materials were contaminated with each of the microorganisms, then the disinfection tests were applied to detect the efficacy of disinfectant solutions on resilient denture base materials in an in vitro test. The specimens (n = 5, total = 240) were soaked for 5 minutes in each solution to disinfect the microorganisms. The control specimens (one of each material; n = 5, total = 60) were soaked in distilled water for 5 minutes. As a result, a reduction in microorganism counts was determined. The Kruskal-Wallis and one-way analysis of variance tests were used to analyze for significant differences among test groups at the level of significance. RESULTS: For all microorganisms, soaking in 5.25% sodium hypochlorite reduced the number of viable adherent microorganisms significantly compared to soaking in 2% sodium hypochlorite, which led to greater reduction than soaking either 5% Deconex or 3.5% Savlex. The use of 5.25% sodium hypochlorite in all groups is statistically significant. CONCLUSION: Disinfection of four different resilient denture-lining materials with 5.25% sodium hypochlorite solution was the most effective immersion technique. To achieve an efficient disinfection, the immersion time of the other disinfectant solutions could be increased.

Analysis of Variance↗

PubMed1987

Purification and partial characterization of the multicomponent dextranase complex of Streptococcus sobrinus and cloning of the dextranase gene.

The presence of proteases in culture supernatant fluids and on the cell surface of Streptococcus sobrinus and the aggregation of multicomponent enzyme complexes make the isolation and characterization of cell surface proteins difficult. We report a simple purification procedure for dextranase and the cloning of the dextranase structural gene. S. sobrinus culture supernatant fluids were precipitated with 70% ammonium sulfate, and the precipitate was dialyzed against sodium acetate buffer and loaded onto a hemoglobin-Sepharose 4B column connected to a blue dextran-agarose column at 4 degrees C. After being washed with low concentrations of salt, the dextranase and the dextran-binding proteins were eluted with 5 M KI and further purified by gel filtration. Two dextranases (molecular weights, 175,000 and 160,000) were purified and partially characterized. The structural gene for the dextranase of S. sobrinus 6715 strain UAB66, serotype g, was cloned into the cosmid vector, pHC79. Clones were selected for expression of dextranase activity by detection of zones of enzyme-mediated hydrolysis of a blue dextran substrate incorporated into minimal medium agar plates. Release of dextranase was achieved by induction of thermoinducible, excision-defective Escherichia coli K-12 lysogens containing recombinant cosmid molecules of S. sobrinus DNA. Recombinant cosmid molecules were repackaged simultaneously into infectious lambdoid particles. Recombinant clones expressing dextranase activity which varied in size from the high-molecular-weight protein produced by S. sobrinus (i.e., 175,000) to lower-molecular-weight forms expressed by S. sobrinus have been identified and partially characterized.

Bacterial Proteins↗

PubMed1996

Peroxidase-catalyzed generation of catechin oligomers that inhibit glucosyltransferase from Streptococcus sobrinus.

Oolong tea extract (OTE) and the purified polymeric polyphenols from OTE have been found to inhibit glucosyltransferase (GTase) of mutans streptococci. In view of the partial fermentation characteristic of oolong tea, we describe here an in vitro model reaction system to produce partially fermented products of D-(+)-catechin or green tea extract (GTE) using horseradish peroxidase. A dimeric catechin molecule was identified as dehydro-dicatechin A by instrumental analyses. The molecular size of some oligomeric catechins was estimated by the elution profile with HPLC. These catechin oligomers markedly inhibited GTase from Streptococcus sobrinus 6715. As the degree of polymerization of catechin or GTE increased, GTase was inhibited more effectively. These results suggest that polymeric polyphenols found in OTE are synthesized by partial fermentation due to oxidases/peroxidases present in tea leaves.

Bacterial Adhesion↗

PubMed2004

Effect of carbohydrate fatty acid esters on Streptococcus sobrinus and glucosyltransferase activity.

Mutans streptococci are oral bacteria with a key role in the initiation of dental caries, because their glucosyltransferases synthesize polysaccharides from sucrose that allow them to colonize the tooth surface. Among the strategies to prevent dental caries that are being investigated are (1) the inhibition of bacterial growth of mutans streptococci or (2) the inhibition of glucosyltransferases involved in polysaccharide formation. Pure fatty acid esters of sucrose, maltose and maltotriose were synthesized by an enzyme-catalyzed process and tested as inhibitors of two glucosyltransferases of great homology, those from Streptococcus sobrinus and Leuconostoc mesenteroides NRRL B-512F. In spite of having their nonreducing end glucose blocked at 6-OH, they did not inhibit dextran synthesis. However, their effect on the growth of S. sobrinus in the solid and liquid phase was notable. 6-O-Lauroylsucrose, 6'-O-lauroylmaltose and 6"-O-lauroylmaltotriose at 100 microg/mL showed complete inhibition of S. sobrinus in agar plates. Consequently, these nontoxic derivatives are very promising for inclusion in oral-hygiene products aimed at disrupting plaque formation and preventing caries.

Agar↗

PubMed1989

Sucrose 6-alpha-D-glucosyltransferase from Streptococcus sobrinus: characterization of a glucosyl-enzyme complex.

A covalent glucosyl-enzyme was isolated from a quenched reaction of Streptococcus sobrinus sucrose 6-alpha-D-glucosyltransferase and radiolabeled sucrose. No complex was observed with heat-inactivated enzyme or when sucrose was replaced with radiolabeled maltose or glucose. The complex was stable at pH 2 in 1% sodium dodecyl sulfate, 6.0 M urea, and 4.0 M guanidine hydrochloride, but became increasingly labile with increased pH (32-min half-life at pH 7.0). D-Glucose was the exclusive radiolabeled compound identified when all radioactivity was released under mild alkaline conditions. Glucosyl-enzyme hydrolysis rates were linearly dependent on hydroxide ion concentration, giving a second-order rate constant of 2.15 x 10(5) M-1 min-1. When compared to the base lability of known glycosyl amino acid derivatives, the pH dependency of the glucosyl-enzyme most closely paralleled a glucosyl linkage to a carboxyl group. A novel application of a carbohydrate high-performance liquid chromatography column in aqueous solution was used to identify the anomeric form of D-glucose released on (i) alkaline hydrolysis of denatured glucosyl-enzyme and (ii) native enzyme hydrolysis of sucrose. The beta-anomer was identified in the former case and the alpha-anomer in the latter. The results with the denatured glucosyl-enzyme are consistent with a beta-glucosyl ester linkage to an aspartic or glutamic acid that hydrolyzes at the ester carbon with retention of anomeric configuration; for native glucosyltransferase catalysis, the data are consistent with a beta-glucosyl covalent intermediate as well, where deglucosylation occurs by attack at the acetal carbon with anomeric inversion.(ABSTRACT TRUNCATED AT 250 WORDS)

Carbon Radioisotopes↗

PubMed1987

Effects of bicarbonate-based dental powder, fluoride, and saccharin on dental caries and on Streptococcus sobrinus recoveries in rats.

The effects of NaHCO3-based dental powder containing NaF and sodium saccharin on dental caries and Streptococcus sobrinus recoveries in rats were studied. Weanling specific-pathogen-free Osborne-Mendel (SPFOM) rats were inoculated with S. sobrinus 6715-13WT. One of six infected groups was topically treated with either demineralized water (DW), a dental powder suspended such that there was 1 part solid per 2 parts DW, 0.073% NaF, 0.5% Na-saccharin (Nas), or a combination of NaF and Nas at the same concentrations. NaF-supplemented DW (at 10 ppm F-) was provided to the 6th group of infected rats as a positive treatment control, but this group was otherwise untreated. A seventh but uninfected group was topically treated with DW. All topical treatments were given once for one min daily per rat, for five days per week. Animals' teeth were swabbed for recovery of 6715-13WT and total recoverable flora. At 37 days after start of treatment, S. sobrinus recoveries were lower only for those rats topically treated with the dental powder (p less than 0.05) by comparison with recoveries from the infected, topical DW-treated group. Caries scores, however, were 42% lower for the groups receiving the dental powder (p less than 0.005), 30% lower for those treated with the combined NaF-Nas (p less than 0.005), and 47% lower for the NaF-supplemented drinking water group (p less than 0.005). The dental powder effects, like those for the combined NaF-Nas and NaF drinking water, were evident on both smooth and fissure tooth surfaces. Both the 10 ppm F- drinking water and the dental powder significantly (p less than 0.005) reduced fissure caries scores below the level elicited by the indigenous mutans-free flora in the DW-treated uninfected rats; however, these reduction were not significantly different from one another. Thus, the 10 ppm F- drinking water and the dental powder equally inhibited not only the S. sobrinus-attributable component of caries but probably also the component of caries attributable to the indigenous oral flora.

Administration, Topical↗