Dental caries: prospects for prevention

Oral health and caries/gingivitis-associated factors of adolescents aged 12-15 in Shandong province, China: a cross-sectional Oral Health Survey

Background

We aimed to analyse the oral health status of adolescents in Shandong province, including dental caries and gingivitis, and their associated factors.

Methods

Adolescents aged 12–15-years in Shandong province were recruited. Caries and gingival status were assessed following the World Health Organisation diagnostic criteria. Information including the sociodemographic, oral hygiene knowledge, attitudes and practices were collected through the questionnaire. Chi-square test and multivariate logistic regression analysis were used to investigate the oral diseases associated factors.

Results

In total, 3868 students (50.2% males) were enrolled. Of these, 39.9% of the participants experienced caries, and 81.7% and 31.3% had calculus and bleeding gingival, respectively. Multivariate logistic regression analysis revealed that there was an association between dental caries and toothaches, dental visits and sleeping troubles caused by oral problems (P < 0.024). A low-frequency of brushing, high sugar consumption and no flossing were more associated with calculus formation and gingival bleeding (P < 0.008).

Conclusion

Compared to caries, worse gingival condition was more prevalent among adolescents in Shandong province. Brushing behaviour is associated with gingivitis, while dental visits and toothaches are associated with caries. Hence, prevention-oriented dental visits and oral hygiene training are strongly recommended to improve oral health status.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-021-01640-x.

Breastfeeding and Oral Health: Evidence and Methodological Challenges

Breastfeeding is a powerful health-promoting behavior. A 2016 Lancet global collaboration to review the health implications of breastfeeding was among the first to consider oral health outcomes. While a role was suggested for breastfeeding in preventing malocclusion, caries was the only included disease condition unfavorably associated with breastfeeding. The present critical review examines the evidence connecting breastfeeding practices to these outcomes and discusses the methodological challenges inherent in reaching causal conclusions. Published systematic reviews show some evidence of a protective effect of breastfeeding against primary dentition malocclusion but no supportive evidence for mixed dentition and permanent dentition malocclusions. Regarding caries, well-conducted studies report a benefit with breastfeeding up to 12 mo but a positive association between caries and breastfeeding of longer duration, at times that vary between 12 and 24 mo, as well as nocturnal feeding. Future studies would be methodologically stronger if focused on specific malocclusion traits that are plausibly associated with sucking movements rather than using general malocclusion indices. Studies should use detailed and consistent terminology for breastfeeding definition, including frequency, intensity, and timing. Analytical studies should be carried out to distinguish between confounders (e.g., prematurity) and mediators (e.g., use of pacifier). Regarding a link to caries, standard terminology for exposures (e.g., nocturnal feeding) is recommended. Statistical analyses must account for known confounding factors (e.g., socioeconomic conditions) but avoid inappropriate adjustment for variables on a causal path between exposure and outcome or for variables not associated with breastfeeding (e.g., tooth brushing), as can be guided using tools such as direct acyclic graphs. For dental practice, the potential caries risk of long-duration breastfeeding should be part of individual patient counseling that incorporates patient values and circumstances. Given the unquestioned overall health benefits of breastfeeding, the dental community should support World Health Organization guidelines that encourage and promote breastfeeding.

Buffering or non-buffering; an action of pit-and-fissure sealants

OBJECTIVES

The aim of this study was to evaluate the buffering capacity of glass-ionomer material in vitro. The null hypothesis tested was that there is no effect of cured glass-ionomer pit-and-fissure sealant (PFS) pastes on the environmental acidity as well as the tooth substrate.

METHOD

For each material, a cured PFS disk and a section of human enamel were simultaneously soaked in lactic acid solution in a conical tube, and the pH of the solution was measured daily for one week. Subsequently, the total amount of calcium leached out in solution was also measured with ICP-AES.

RESULTS

The results showed that the acidity of the solutions changed over time. Significant differences of calcium ion concentration in solution were observed as a result of decalcification. As the PFS products tested did not include calcium, the concentration of calcium ion released indicated acidic erosion of the tooth enamel.

CONCLUSIONS

The glass-ionomer countered the acid of the solution rapidly and preserved the structure of human tooth enamel.

Comparing the effect of different mouthrinses on de novo plaque formation

PURPOSE

Several antiplaque agents are being available in the market in spite of vast development of modern medical science, satisfactory treatment of 'oral diseases' by newer drugs is not fully achieved, rather the chemical compounds has exposed the patients to it is different ill effects, therefore, there is interest to find out effective remedy of any disease by harmless herbal drugs thus the aim of this study was to compare plaque formation at 24 hours after the use of Triphala, Hi ora, Chlorhexidine and Colgate Plax mouth washes.

METHODS

A controlled, randomized, double-blind, crossover clinical trial was designed. Thirty subjects underwent four consecutive experimental phases with four treatments: Triphala, Hi Ora, Chlorhexidine and Colgate Plax. On the day of study, the subjects discontinued all other oral hygiene habits and were randomly assigned for treatment with the experimental mouthwash. Each experimental phase was preceded by a 28-day washout period. Plaque formation was recorded after one undisturbed day.

RESULTS

Triphala, Hi Ora and Chlorhexidine reduced de novo plaque formation to a greater extent than the colgate plax mouthwash (p < 0.05).

CONCLUSION

Triphala and Hi Ora presents an anti-plaque efficacy similar to that of chlorhexdine, and was more effective at inhibiting plaque formation than the Colgate Plax mouth wash.

Some Immunochemical Properties of Dextransucrase and Invertase from Streptococcus mutans

Dextransucrase and invertase of some strains of Streptococcus mutans were examined by immunodiffusion with antisera against enzymes purified from strain HS-6 (Bratthall's serotype a). Both antisera cross-reacted with crude enzyme preparations from the other serotype a (strains HS-1 and AHT) and d organisms (strains KIR, OMZ176, and OMZ65) but not with those from serotype b (strains FA-1 and BHT) or c organisms (strains GS-5, Ingbritt, and NCTC 10449). Based upon the antiserum used, the orders of antigenic similarity of the cross-reacting enzymes to the HS-6 enzymes were HS-6 > HS-1 > AHT = KIR = OMZ176 = OMZ65 for dextransucrase and HS-6 = HS-1 > AHT = KIR = OMZ176 = OMZ65 for invertase. It was found that the enzymes from serotype a organisms were not always antigenically homogeneous, as seen between strains HS-6, HS-1, or AHT for dextransucrase, and between the HS group and strain AHT for invertase. Antiserum against the HS-6 dextransucrase markedly inhibited the heterologous dextransucrases of serotype a organisms with the exception of strain HS-1 and d organisms, with or without the addition of dextran.

Microbiological Evaluation of 0.2% Chlorhexidine Gluconate Mouth Rinse in Orthodontic Patients

Objective: To assess the effectiveness of 0.2% chlorhexidine gluconate mouth rinse on Streptococcus mutans and lactobacilli in orthodontic patients with fixed appliances.

Materials and Methods: Twenty patients, aged 13–18, with fixed orthodontic appliances participated in the study. The levels of S mutans and lactobacilli in saliva samples were evaluated at four stages: at the beginning of the orthodontic treatment, at least 2 weeks after the bonding of brackets, 1 week after the introduction of 0.2% chlorhexidine gluconate mouth rinse, and at the fourth week. The changes in S mutans and lactobacilli levels were analyzed via Wilcoxon test.

Results: Increases in bacterial levels of S mutans and lactobacilli were detected after the orthodontic appliances were bonded. A significant decrease in S mutans levels was observed 1 week after the introduction of chlorhexidine mouth rinse.

Conclusions: An 0.2% chlorhexidine gluconate mouth rinse decreased S mutans levels, but had no effect on lactobacilli levels.

Glucan-binding proteins of the oral streptococci

The synthesis of extracellular glucan is an integral component of the sucrose-dependent colonization of tooth surfaces by species of the mutans streptococci. In investigators' attempts to understand the mechanisms of plaque biofilm development, several glucan-binding proteins (GBPs) have been discovered. Some of these, the glucosyltransferases, catalyze the synthesis of glucan, whereas others, designated only as glucan-binding proteins, have affinities for different forms of glucan and contribute to aspects of the biology of their host organisms. The functions of these latter glucan-binding proteins include dextran-dependent aggregation, dextranase inhibition, plaque cohesion, and perhaps cell wall synthesis. In some instances, their glucan-binding domains share common features, whereas in others the mechanism for glucan binding remains unknown. Recent studies indicate that at least some of the glucan-binding proteins modulate virulence and some can act as protective immunogens within animal models. Overall, the multiplicity of GBPs and their aforementioned properties are testimonies to their importance. Future studies will greatly advance the understanding of the distribution, function, and regulation of the GBPs and place into perspective the facets of their contributions to the biology of the oral streptococci.

The buccale puzzle: The symbiotic nature of endogenous infections of the oral cavity

The indigenous, 'normal', microflora causes the majority of localized infectious diseases of the oral cavity (eg, dental caries, alveolar abscesses, periodontal diseases and candidiasis). The same microflora also protects the host from exogenous pathogens by stimulating a vigorous immune response and provides colonization resistance. How can a microflora that supports health also cause endogenous oral disease? This paradoxical host-symbiont relationship will be discussed within the dynamic of symbiosis.Symbiosis means 'life together' - it is capable of continuous change as determined by selective pressures of the oral milieu. Mutualistic symbiosis, where both the host and the indigenous microflora benefit from the association, may shift to a parasitic symbiosis, where the host is damaged and the indigenous microflora benefit. Importantly, these are reversible relationships. This microbial dynamism, called amphibiosis, is the essential adaptive process that determines the causation of endogenous oral disease by a parasitic microflora or the maintenance of oral health by a mutualistic microflora.Complex microbial consortiums, existing as a biofilm, usually provide the interfaces that initiate and perpetuate the infectious assault on host tissue. The ecology of the various oral microhabitats is critical for the development of the appropriate selecting milieux for pathogens. The microbiota associated with dental caries progression is primarily influenced by the prevailing pH, whereas periodontal diseases and pulpal infection appear to be more dependent on redox potential. Candidiasis results from host factors that favour yeast overgrowth or bacterial suppression caused by antibiotics. Oral health or disease is an adventitious event that results from microbial adaptation to prevailing conditions; prevention of endogenous oral disease can occur only when we realize that ecology is the heart of these host-symbiont relationships.

Potential of the aqueous extract of Terminalia chebula as an anticaries agent

The aqueous extract from Terminalia chebula was tested for its ability to inhibit the growth and some physiological functions of Streptococcus mutans. The extract strongly inhibited the growth, sucrose induced adherence and glucan induced aggregation of S. mutans. Mouthrinsing with a 10% solution of the extract inhibited the salivary bacterial count and salivary glycolysis. Mouthrinsing with the extract significantly reduced total bacterial counts and the total streptococcal counts in the saliva samples obtained up to and including 3 h after rinsing, compared with the counts obtained prerinsing or after placebo rinsing. The extract successfully inhibited glycolysis of salivary bacteria for up to 90 min postrinsing.

Productivity and some properties of immunoglobulin specific against Streptococcus mutans serotype c in chicken egg yolk (IgY)

Hens were immunized on thighs by using whole cells of Streptococcus mutans MT8148 serotype c strain as antigen through intramuscular (im) and subcutaneous (sc) routes to investigate the difference of immunization reactions and the changes in yolk antibody activities against antigen after initial immunization. Several properties of crude IgY were examined to evaluate the stability during food processing. Results showed that the specificity of IgY of im treated hens was nearly 10 times as high as those of sc treated antibody. IgY from the hens immunized with the serotype c strain showed significant cross-reactions against serotypes e and f, while minor reactions against serotypes a, b, d, and g were observed. In thermal stability tests, IgY activity in both yolk and crude IgY decreased with the increasing temperature, from 70 to 80 degrees C, but the thermal denaturation rates between those two samples were not significantly different. The addition of high levels sucrose, maltose, glycerol, or 2% glycine displayed effective protection against thermal denaturation of IgY. Lyophilized yolk-5% gum arabic powder showed better stability against proteases.

Ontogeny of immunity to oral microbiota in humans

This article reviews the ontogeny of immune systems in the human oral cavity that may influence the colonization, accumulation, or pathogenesis of oral microbiota. The prenatal development of cellular components associated with the secretory immune system reveals that the initial organization of tissue into Peyer's patches can first be detected immunohistologically at 11 weeks gestation. Epithelial cells positive for secretory component and immunocytes positive for IgM can be detected in salivary gland tissue by 19 to 20 weeks and continue to predominate during gestation. After birth, immunocytes containing IgA begin to dominate. Essentially, no IgA can be detected in saliva at birth. However, salivary IgA and IgM often appear soon thereafter, presumably in response to environmental antigenic and mitogenic challenges. Salivary IgA in young infants has molecular characteristics of secretory IgA and becomes the quantitatively predominate Ig in saliva. Both IgA subclasses are present in proportions characteristic of adult pure glandular salivas in many 1- to 2-month-old infants, although the appearance of IgA2 is delayed in some subjects. Many innate, antibody, and cellular immune components are found in maternal colostrum and breast milk. The antibacterial properties of these maternal factors are diverse and can exert multifaceted protective effects on the infant's alimentary tract. The infant apparently can mount mucosal immune responses quite early in life. For example, salivary antibody activity to organisms that originally colonize the gut (e.g., E. coli) or the oral cavity (e.g., S. mitis, S. salivarius) can be detected by 1 to 2 months of age. Most of this antibody activity has characteristics of secretory IgA, although some IgM antibody can also be initially detected. Salivary IgA1 and IgA2 antibody specificities to S. mitis and S. salivarius components increase qualitatively and quantitatively during the first few years of life. Salivary IgA antibody to components of streptococci that require hard surfaces for colonization (e.g., S. sanguis and mutans streptococci) generally appear after tooth eruption. The loss of placentally derived maternal IgG antibody specificities to these microbiota in the circulation is replaced by de novo synthesis, presumably as a result of the teething process. These IgG antibodies can enter the oral cavity in the gingival crevicular fluid and by the process of teething.(ABSTRACT TRUNCATED AT 400 WORDS)

Cross-reactive polysaccharide antigens (types a, d, and h) of the mutans group of streptococci: different molecular forms of the type as distinguishable by monoclonal antibodies

As compared to the previous precipitin inhibition tests differences were found in the reactivities of monoclonal antibodies (MAbs), a-4 and a-84 with Streptococcus cricetus (serotype a) in an enzyme immunoassay using whole cells, purified cell wall antigen and haptenic sugars coated onto microtitre wells. Investigation into the differences led to the finding that the purified antigen from S. cricetus cells consisted mainly of three forms with different molecular weights and sugar contents. MAb a-4 reacted with a high molecular weight form (AgI, molecular weight of 46,000) and low molecular weight forms (AgII and AgIII, molecular weights of 9,800 and 20,000, respectively) whereas MAb a-84 reacted only with the high-molecular form. Gas chromatographic analysis revealed that all antigens contained rhamnose, galactose and glucose but in different ratios of the sugars. Although the binding site of AgII/AgIII with MAb a-4 seemed to be slightly different from that of AgI with MAb a-84, the predominant immunodeterminant of the antigens was considered to be the same. On the basis of these results, the chemical structures of the antigenic determinants are suggested. The nature of the antigen-antibody reactions is discussed.

Salivary Streptococcus mutans and caries prevalence in Brazilian schoolchildren

The aim of the present study was to determine the levels of salivary Streptococcus mutans in Brazilian schoolchildren, and its possible correlation with caries prevalence. A positive correlation between different levels of S. mutans and caries prevalence was observed, individuals with high levels of S. mutans (greater than 100 colonies) had a DMFS significantly higher than those with low or no detectable S. mutans (0, 1-20, 21-40 colonies).

Immunological study of cross-reactive polysaccharide antigens (types a, d, and h) of oral Streptococcus spp. with monoclonal antibodies

Two monoclonal antibodies against the cross-reactive antigens of S. cricetus (type a) and S. sobrinus (type d) were isolated. Galactose and especially melibiose inhibited the precipitin reaction markedly. Inhibition by melibiose was over 200-fold stronger than that by galactose. This may indicate that galactose-alpha 1, 6-glucose is the predominant antigenic determinant of this cross-reactive antigen. This antigen was also found in S. sobrinus type h strains, but no antigen was found in one type d strain (OMZ176).

Monoclonal antibody to Streptococcus mutans type e cell wall polysaccharide antigen

A monoclonal antibody against the polysaccharide antigen of Streptococcus mutans serotype e was prepared. It was found that beta-methyl-D-glucopyranoside and cellobiose markedly inhibited the precipitin reaction, whereas maltose showed no inhibition. The beta-glucosyl moiety of the type e polysaccharide seems to be the predominant antigenic determinant of the antigen.

Difference in mode of inhibition between alpha-D-xylosyl beta-D-fructoside and alpha-isomaltosyl beta-D-fructoside in synthesis of glucan by Streptococcus mutans D-glucosyltransferase

Both alpha-isomaltosyl beta-D-fructoside and alpha-D-xylosyl beta-D-fructoside show strong inhibition of the synthesis of water-insoluble and water-soluble D-glucans from sucrose by a partially purified preparation of a D-glucosyltransferase (GTase) from Streptococcus mutans 6715; however, the inhibitory modes differ substantially. In the presence of alpha-isomaltosyl beta-D-fructoside, the production of reducing sugars and the consumption of sucrose are remarkably enhanced, compared with a control of sucrose alone. Under these conditions, a large proportion of low-molecular-weight glycan (lmwg) and a series of nonreducing oligosaccharides (both containing D-fructosyl groups or residues) are produced. In contrast, in the presence of alpha-D-xylosyl beta-D-fructoside, the production of reducing sugars and the sucrose consumption are strikingly suppressed, and no lmwg or oligosaccharides are produced. Thus, it may be concluded that alpha-isomaltosyl beta-D-fructoside acts as an alternative acceptor for the D-glucosyl and/or D-glucanosyl transfer reactions of the enzyme, and serves to lessen the formation of insoluble and soluble D-glucan, although it stimulates the transferring activity of the enzyme. On the other hand, alpha-D-xylosyl beta-D-fructoside competitively inhibits the sucrose-splitting activity of the enzyme as an analog to sucrose, and thereby diminishes the synthesis of D-glucan.

Isolation and characterization of a 60-kilodalton salivary glycoprotein with agglutinating activity against strains of Streptococcus mutans

A bacterial agglutinin specific for strains of Streptococcus mutans was isolated from human saliva. Physiochemical analyses showed the agglutinin to be a glycoprotein with a molecular weight of 60,000. The agglutinin aggregated four of the eight strains of Streptococcus mutans tested but did not aggregate the strains of Streptococcus salivarius, Streptococcus sanguis, and Streptococcus mitis tested. Chemical modification of carbohydrate moieties of the agglutinin with sodium metaperiodate had no effect on aggregation, whereas modification of the polypeptide portion with trypsin abolished aggregating activity. A set of five murine hybridoma antibodies was employed to further analyze the agglutinin. Two carbohydrate-specific antibodies, directed against D-mannose and N-acetylgalactosamine moieties, respectively, failed to block agglutinin- or whole saliva-mediated aggregation of S. mutans cells. In contrast, two antibodies directed against pronase-sensitive antigenic sites blocked both agglutinin- and saliva-mediated aggregation of S. mutans cells. Western blot analysis with the agglutinin-specific hybridoma antibodies demonstrated the agglutinin in whole saliva and in artificial tooth pellicles formed on hydroxyapatite beads incubated with saliva. These results suggest that a 60-kilodalton glycoprotein of human saliva is a bacterial agglutinin with specificity for certain strains of S. mutans. They further suggest that aggregation is mediated by polypeptide rather than carbohydrate determinants of the glycoprotein.

Purification, and comparison, of two forms of dextransucrase from Streptococcus sanguis

A procedure has been developed whereby native and proteolyzed forms of dextransucrase have been purified; it involves gel filtration, and hydroxylapatite chromatography in the presence of 0.10% sodium dodecyl sulfate. This procedure is highly reproducible, and permits approximately 30% recovery of high purity (94% homogeneous) enzyme as an inactive, SDS complex that can be reactivated by the addition of Triton X-100. The purified enzymes have been compared with regard to amino acid compositions, and isoelectric and catalytic properties. An analysis of the structure of their product D-glucans was also made. Although the structural characteristics of the enzyme forms differ, proteolysis does not cause alterations in their catalytic properties.

Interaction of deoxyhalosucrose derivatives with dextransucrase

Members of a series of deoxyhalosucrose analogs substituted at one, two, or three primary carbon atoms with bromine or chlorine were prepared. Dextransucrase isolated from Streptococcus sanguis was separately treated with 6-bromo-6-deoxysucrose, 6,6'-dibromo-6,6'-dideoxysucrose, 6,1',6'-tribromotrideoxysucrose, and 6,6'-dichlorodideoxysucrose, in order to determine if they were inactivators. Variation in time of exposure, and in the concentration of the sucrose analogs, did not yield significant irreversible inactivation. In supplementary studies, it was found that the compounds serve as weak, reversible inhibitors.

Screening of sugars inhibitory against sucrose-dependent synthesis and adherence of insoluble glucan and acid production by Streptococcus mutans

Various sucrose derivatives and a sucrose analogue were enzymatically synthesized on the assumption that structural similarities of the sugars to sucrose would endow them with an ability to inhibit the cariogenicity of sucrose. The effect of these sugars on sucrose-dependent synthesis and adherence of insoluble glucan and on acid fermentation of sucrose by Streptococcus mutans was examined in vitro. Although none of them inhibited the acid fermentation, several sugars not only inhibited the synthesis and adherence of insoluble glucan, but were themselves only slightly fermented as well.

Lack of cross-reactivity of antibodies to ribosomal preparations from Streptococcus mutans with human heart and kidney antigens

Previous studies have suggested that sera from animals immunized with whole Streptococcus mutans cells may cross-react with human and monkey heart sarcolemmal tissues. In the present study, sera and saliva from rats and rabbits immunized peripherally with ribosomal preparations from S. mutans 6715 (serotype g) or GS-5 (serotype c) were examined for their ability to react with normal human heart sarcolemmal and kidney glomerular tissues by using enzyme-linked immunosorbent and immunofluorescence assays. The results showed that antibodies to serotype g and c ribosomal preparations do not react with either the human heart or renal antigens. Sera from mice immunized with human heart tissue and from a patient with a high anti-streptolysin O titer reacted strongly with human heart sarcolemmal and kidney glomerular tissues. These data indicated that ribosomal preparations from S. mutans lack the putative human heart cross-reactive determinant and suggest that the use of an S. mutans ribosomal vaccine against dental caries may not be pathogenic to human heart or renal tissues.

The synthesis of some fluoro derivatives of sucrose

2,3,1',3'4',6'-Hexa-O-benzylsucrose was obtained by mild acid-catalysed hydrolysis of the 4,6-O-isopropylidene derivative and then converted into its 4,6-di-O-mesyl derivative. Selective displacement of this disulphonate with fluoride anion (from tetrabutylammonium fluoride) then afforded the 6-fluoro-4-mesylate. Removal of the protecting groups yielded 6-deoxy-6-fluorosucrose, which was characterised as its crystalline hepta-acetate. A derivative of 6-deoxy-6-fluoro-galacto-sucrose was formed when the above 6-fluoro-4-mesylate was subjected to nucleophilic displacement with benzoate anion.

Immunologic cross-reactivity between Streptococcus mutans and mammalian tissues

The presence of cross-reacting antigens shared by oral streptococci and human and monkey tissue was investigated by indirect immunofluorescence. Rabbit antisera prepared against two strains of each of the seven serotypes of Streptococcus mutans were incubated on sections of cardiac muscle, skeletal muscle, kidney, brain, liver, and skin. Antisera to S. mutans, serotype g, strain OMZ-65 reacted with cardiac muscle components. This reactivity could be reduced by absorption with bacterial cell membranes. Antisera to S. mutans serotype g, strain K-1 reacted with both cardiac and skeletal muscle but could not be reduced by absorption with bacterial cells, cell walls, or cell membranes. Antisera to S. mutans serotype g, strain OMZ-65 reacted with kidney glomeruli and could be completely absorbed by a cell wall preparation. S. mutans, serotype e, strain MT703 also reacted with kidney glomeruli but could not be reduced by absorption with bacterial antigens.

Expression of a Streptococcus mutans glucosyltransferase gene in Escherichia coli

Chromosomal DNA from Streptococcus mutans strain UAB90 (serotype c) was cloned into Escherichia coli K-12. The clone bank was screened for any sucrose-hydrolyzing activity by selection for growth on raffinose in the presence of isopropyl-beta-D-thiogalactoside. A clone expressing an S. mutans glucosyltransferase was identified. The S. mutans DNA encoding this enzyme is a 1.73-kilobase fragment cloned into the HindIII site of plasmid pBR322. We designated the gene gtfA. The plasmid-encoded gtfA enzyme, a 55,000-molecular-weight protein, is synthesized at 40% the level of pBR322-encoded beta-lactamase in E. coli minicells. Using sucrose as substrate, the gtfA enzyme catalyzes the formation of fructose and a glucan with an apparent molecular weight of 1,500. We detected the gtfA protein in S. mutans cells with antibody raised against the cloned gtfA enzyme. Immunologically identical gtfA protein appears to be present in S. mutans cells of serotypes c, e, and f, and a cross-reacting protein was made by serotype b cells. Proteins from serotype a, g, and d S. mutans cells did not react with antibody to gtfA enzyme. The gtfA activity was present in the periplasmic space of E. coli clones, since 15% of the total gtfA activity was released by cold osmotic shock and the clones were able to grow on sucrose as sole carbon source.

Effect of a glucosyltransferase inhibitor on glucan synthesis and cellular adherence of Streptococcus mutans

The effects of mutastein, a glucosyltransferase inhibitor derived from an Aspergillus terreus strain, on the glucan synthesis by glucosyltransferases of Streptococcus mutans and sucrose-dependent adherence of S. mutans cells were examined in vitro. The synthesis of insoluble glucan by crude glucosyltransferase of S. mutans strain B13 was markedly inhibited by mutastein at a final concentration of 10 micrograms of protein/ml. The synthesis of insoluble glucan adherent to glass surfaces was almost completely inhibited by mutastein at this concentration. In addition, mutastein inhibited the sucrose-dependent adherence to glass surfaces of resting and growing cells of various S. mutans strains. These results suggest that mutastein could be useful for controlling dental plaque and dental caries in vivo.

Comparison of methods for monitoring changes in the pH of human dental plaque

Changes in human dental plaque pH can be used to obtain estimates of the acidogenic potential of ingested foods. The presence of acid in plaque is influenced by a large number of host, microbial, and substrate factors. Several useful methods have been developed for monitoring changes in plaque pH. Plaque sampling involves repeated removal of small samples of plaque from a number of teeth at intervals after food ingestion, dispersion of the sample, and in vitro measurement of pH. Touch electrode methods utilize glass or antimony microelectrodes, which are placed onto plaque in situ where direct readings can be obtained. Telemetry methods involve placement of glass microelectrodes or ion-sensitive field effect transistors within the dentition. Plaque is allowed to accumulate, and pH changes can subsequently be transmitted with radio or wire. Each of the methods has clear advantages and limitations. The methods have been simultaneously compared in human volunteers using solutions of fermentable carbohydrate. Inter-method differences in response were observed depending upon the site of measurement. Data obtained from caries-prone surfaces via telemetry showed lower pH minima and retarded returns to resting pH levels. The technology is available for controlled comparative plaque pH studies, with the method of choice depending upon the goals of the investigation. It is essential that the results be compared to data obtained with other models designed to evaluate the cariogenic potential of foods.

Extracellular iodophilic polysaccharide synthesized by Neisseria in human dental plaque

Dental plaque collected from the label aspect of the anterior dentition of children harbored Neisseria that synthesized an extracellular iodophilic polysaccharide (EIP) from sucrose. Gas chromatograms of fully-acetylated EIP derivatives indicated that glucose (97%) and galactose (3%) were the only monosaccharide constituents present. The characterization of the partially-methylated alditol acetate (PMAA) derivatives of EIP indicated that it was primarily a linear 1,4 glucan (75.5%), with some 1,6 glucan (8.4%). The relative linearity of EIP (96.6%) as compared to that of amylose and glycogen was confirmed by spectrophotometric absorption studies.

The prevention of dental caries: ten years later

By any standards, progress toward caries prevention has been impressive during the past decade. It is arguable that more information on the precise etiology of caries and on potential new preventive methods has been acquired during the 1970s than in any comparable period previously. Substantial advances have been made toward the understanding of the complex interaction among oral microorganisms, host resistance, and dietary substrate in the initiation and progression of a caries lesion. The various mechanisms of action of the fluoride ion have been further elucidated; vaccination against caries and a reduction in the cariogenic potential of sweet foods have both become realistic possibilities. Conspicuous successes have also been achieved in the application of existing knowledge. At least 12 million more children than in 1971 are receiving partial protection against caries through self-applied fluoride programs. Other effective preventive methods, including adhesive sealants and, possibly, antimicrobial agents, could be widely and advantageously utilized if manpower and regulatory constraints were overcome, as their scientific feasibility has, for the most part, already been demonstrated. Of course, it would be naive to predict the early disappearance of dental caries as a major health problem. This will occur only gradually, and will require a much more extensive use of preventive methods--those already available as well as those still being developed by research. Nevertheless, a major step toward the goal of caries prevention has already been taken, and there is good reason to expect even more rapid progress during the 1980s.

Effects of exogenous insoluble glucan primer on insoluble glucan synthesis by Streptococcus mutans

The effects of exogenous glucans on WIG synthesis by S. mutans were investigated by turbidimetric measurement. The rapid synthesis of WIG by an enzyme preparation from PS-14 culture fluid proceeded after a lag period of several min. The addition of exogenous WIG, which was previously prepared using the PS-14 enzyme, caused a marked reduction of the lag period with little change in the reaction rate. The length of lag period was affected by the concentrations of WIG primer, enzyme and salts, and the reaction pH. The WIGs from other strains and the periodate-treated WIGs also exhibited effects similar to the PS-14 glucan. In contrast, dextran, starch, dextrin, laminarin, cellulose, chitin, and inulin were without any effect. These results suggest that such lag-reducing effect is specific to glucans containing a significant amount of alpha-(1 leads to 3) linkages.

Immunoglobulin class of agglutinins to oral microorganisms in post-irradiation cancer patients

Fractionation of serum samples from head and neck cancer patients and their assay for agglutination activity toward oral microorganisms showed that the activity was derived from IgG, 7S IgA, 10S (dimeric) IgA, and IgM, with considerable activity in the 10S IgA region. These findings probably account for the lack of a significant relationship among levels of individual serum immunoglobulins, agglutination titers, and caries activity presented in an earlier study. Conversely, most of the agglutinating activity in fractionated saliva was attributed to 11S IgA, presumably secretory IgA, with some activity from a 19S substance and, in the caries-active patients, from a higher molecular weight factor. These data correspond to positive correlations between saliva IgA levels, agglutination titers, and absence of caries in these patients.

Genetic transformation of Streptococcus mutans

Three strains of Streptococcus mutans belonging to serotypes a, c, and f were transformed to streptomycin resistance by deoxyribonucleic acids derived from homologous and heterologous streptomycin-resistant strains of S. mutans and Streptococcus sanguis strain Challis. Homologous transformation of S. mutans was less efficient than heterologous transformation by deoxyribonucleic acids from other strains of S. mutans.

Rapid quantitative determination of the effect of antiplaque agents and antisera on the growth, acid production, and adherence of Streptococcus mutans

A rapid quantitative in vitro assay measured the effects of antiplaque agents and antiserum on growth and sucrose-mediated adherence of radio-labeled S. mutans 6715. Acid production was measured by change in pH. In this assay the primary effect of chlorhexidine and fluoride was bacteriostasis and inhibition of acid production, respectively; the primary effect of dextran, dextranase, and specific antiserum was inhibition of sucrose-mediated adherence.

Biology, immunology, and cariogenicity of Streptococcus mutans

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Virulence of Streptococcus mutans: restoration of pathogenesis of a glucosyltransferase-defective mutant (C4)

Previous studies have shown that a mutant (designated C4) of Streptococcus mutans 6715 wild type (WT) is defective in glucosyltransferase (GTF)-synthesized insoluble glucan and is avirulent in gnotobiotic rats. This study investigated the factors which would render this mutant virulent in gnotobiotic rats. Microbial analysis of plaque from gnotobiotic rats (45 days old) infected with a mixture of C4 and virulent S. mutans PS-14 (approximately 15,000 C4 organisms to each S. mutans PS-14) yielded higher numbers of C4 organisms than S. mutans PS-14. These animals exhibited significantly lower caries scores than did gnotobiotic rats (age, 45 days) monoassociated with S. mutans PS-14. Similar mixed infection studies using C4 and an avirulent, aggregation-defective mutant of S. mutans 6715 WT (designated UAB 165) which exhibits GTF activity similar to that of the parent strain resulted in plaque consisting almost exclusively of UAB 165 and low caries activity. However, high levels of both C4 and UAB 165 in plaque and high caries activity were observed in gnotobiotic rats infected at weaning with C4 followed by UAB 165 3 days later. When dried S. mutans 6715 WT culture supernatant containing GTF activity was mixed with diet provided rats monoassociated with C4, significant caries activity was observed. Insoluble glucan supplemented in diet did not restore C4 to virulence; however, admixture of suboptimal GTF-rich supernatant with insoluble glucan and C4 resulted in high caries activity in gnotobiotic rats. These results suggest that in vivo restoration of pathogenesis of a GTF-defective mutant of S. mutans can be achieved either by complementation with a mutant defective in aggregation properties or by providing exogenous GTF and glucan from the parent S. mutans 6715 WT.

Binding of streptococcal antigens to muscle tissue in vitro

Antigens extracted from cells of Streptococcus pyogenes T6 and Streptococcus mutans strains AHT, BHT, 10449, OMZ175, and K1R adsorbed to the sarcolemmal sheath of cardiac muscle cells in vitro. Similar preparations from S. salivarius, S. sanguis, Staphylococcus aureus, and Lactobacillus casei had weak or negligible tissue-binding activity. Tissue-bound bacterial antigens were detected with homologous rabbit antisera with both indirect immunofluorescence tests and an indirect radioimmunoassay. Serological cross-reactivity was observed between the tissue-binding factors of S. pyogenes and S. mutans cells but not between the bacteria and muscle tissue. In a comparative study of extraction procedures, the greatest yield of tissue-binding factors was obtained from group A streptococci by cell disruption in buffer at 4 degrees C. Hot aqueous phenol and hot water extracts were inactive. Antibodies specific for the tissue-binding factor(s) were readily adsorbed from rabbit anti-S. pyogenes serum by a preparation of isolated cytoplasmic membranes but not by a suspension of cell wall fragments. The heart-binding component of S. pyogenes cell extracts was inactivated by protease digestion and heat treatment and to a lesser extent by periodic acid oxidation. The capacity of heart cell components to adsorb streptococcal antigens was reduced by protease treatment but not by the action of neuraminidase, hyaluronidase, organic solvents, or detergents.

Effects of chlorhexidine and iodine on in vitro plaques of Streptococcus mutans and Streptococcus sanguis

Both chlorhexidine and iodine showed greater antimicrobial effect on in vitro grown S. mutans plaque than on plaque composed of S. sanguis. One treatment with iodine for 8 min inhibited the acid production of S. Mutans plaque whereas S. sanguis plaque required 20 min to be similarly affected. In contrast one treatment with chlorhexidine for up to 20 min did not completely inhibit the acid production of plaque of either microorganism. Repeated short term exposures increased the bactericidal effect of chlorhexidine but not that of iodine. The difference in antimicrobial effect between chlorhexidine and that of iodine on S. mutans and S. sanguis should be investigated in persons heavily infected by S. mutans.

The purification and properties of dextransucrase from Streptococcus sanguis ATCC 10558

Dextransucrase has been purified from the culture fluids of S. sanguis 10558 by a combination of hydroxylapatite, ion-exchange, and gel-filtration steps. Two active proteins were isolated with specific activities approaching one order of magnitude higher than other preparations reported. The enzymes have mol. wt. on the order of 100 000 and exhibit pH optima between 5,8 and 6.2. In addition, detailed analysis of one of the enzymes indicates that the enzyme undergoes two ionizations that are important for activity. One pK is at 4.4 and the second at 7.4. The structures of dextrans produced by the two enzymes have been examined by p.m.r. spectroscopy, and a substantial degree of similarity was observed, with only minor differences in the proportion of alpha-(1 leads to 3) and alpha-(1 leads to 6) bonds. No evidence could be obtained that either of the enzymes was capable of catalyzing a rearrangement of alpha-(1 leads to 6) to alpha-(1 leads to 3) bonds.