Comparison of effect of SnF2 and NaF mouthrinses on caries incidence, salivary S. mutans and gingivitis in high caries prevalent adults

Abstract – The effect of SnF₂ and NaF mouthrinses were compared in subjects initially selected because of their high caries prevalence and high levels of salivary S. mutans. Subjects rinsed twice a day with either SnF₂ or NaF (200 ppm F⁻). Subjects in both groups continued to be caries active during the course of the study. However, at the first year examination subjects rinsing with SnF₂ had less S. mutans/ml saliva, a lower caries incidence and less gingivitis. After 2 yr the S. mutans levels in the SnF₂ rinsing group remained significantly less. Both caries incidence and gingivitis were lower in the SnF₂ group after 2 yr but the difference was not significant.     

Prolonged oral reduction of Streptococcus mutans in humans after chlorhexidine disinfection followed by fluoride treatment

Abstract – The effect of oral chlorhexidine gel treatment supplemented with fluoride applications was studied in subjects with high salivary levels of S. mutans. In two experiments short-term treatment with a 1% chlorhexidine gel was followed by applications of either a 1% NaF gel daily for 2 weeks or a 1% NaF gel daily for 6 weeks supplemented twice with topical application of an 8% SnF₂ solution. The salivary numbers of S. mutans were lower in the test group than in the placebo group after 6 and 12 weeks in experiments 1 and 2, respectively, and considerably lower than the pretreatment values. The findings show that fluoride applications can be a valuable adjunct to chlorhexidine treatment for combatting S. mutans.     

Streptococcus mutans in plaque and saliva after mouthrinsing with SnF2

Abstract – Mouthrinses with SnF2 in 11 subjects significantly reduced ( P <0.01) the total colony forming units (CFU) count and the numbers of Streptococcus mutans and Streptococcus sanguis in plaque. The numbers of S. mutans and S. sanguis were significantly more reduced than was the total CFU count. After rinsing with SnF2 S. sanguis was present in 97% and S. mutans in only 42% of plaque samples from tooth surfaces where they were detected after rinsing with water. SnF2 also significantly reduced ( P <0.01) the number of S. mutans in saliva. Mouthrinses with NaF did not markedly affect the number of S. mutans either in plaque or in saliva.     

Effect of penicillin on Streptococcus mutans, Streptococcus sanguis and lactobacilli in hamsters and in man

Abstract – The effect of penicillin on the numbers of oral Streptococcus mutans, Streptococcus sanguis and lactobadlii in hamsters and in man was investigated. This is of interest as S. mutans and lactobacilli are involved in the carious process while S. sanguis is not. Hamsters infected with both S. mutans and S. sanguis or only S. sanguis received penicillin in their drinking water for 14 d. The treatment reduced the proportion of S. mutants and S. sanguis in dental plaque to undetectable levels. After the penicillin treatment the population of S. mutans and S. sanguis gradually increased. In man, the effect of oral penicillin therapy was examined in 21 adults with more than 2 × 10⁵ S. mutans per ml saliva. The penicillin treatment had almost no effect on the numbers of S. sanguis and lactobacilli, but a pronounced decrease in the number of S. mutans was observed. The duration of this effect, however, was short. Consequently, such treatment alone is of limited value for the control of the oral infection of these microorganisms.     

Effect of chlorhexidine on the relative proportions of Streptococcus mutans and Streptococcus sanguis in hamster plaque

abstract — The effect of chlorhexidine on the proportions of Streptococcus mutans and Streptococcus sanguis in plaque was studied in hamsters fed a diet containing 28% sucrose. In animals given chlorhexidine in their drinking water for 10 d a decrease in the population of S. mutans and an increase of S. sanguis occurred in the plaque. Following the removal of chlorhexidine the population of S. mutans increased again in the presence of sucrose and the number of S. sanguis returned to initial values. When animals were given a sucrose-free diet the low proportion of S. mutans observed following the short-term chlorhexidine period persisted. These data indicate that there is an inverse relationship between the number of S. sanguis and S. mutans in plaque and that the sensitivity in vivo of S. mutans to chlorhexidine can be used to suppress the population of S. mutans with a concomitant rise in the proportion of S. sanguis .     

Comparative antibacterial effects of chlorhexidine and stannous fluoride-amine fluoride containing dental gels against salivary mutans streptococci

Abstract— Forty-five young adults were divided into three groups of equal size and given a professional toothcleaning (3 times during 1 wk) with dental gels containing either chlorhexidine (CHX, 1%), or a SnF₂-amine fluoride (AmF) combination (F⁻ content 1.20%). The control group received toothcleaning with a placebo gel. The study was done double blind. The number of salivary mutans streptococci was monitored for 11 wk after the gel treatment using both mitis-salivarius-bacitracin agar plates and the chairside method based on the adhesion of mutans streptococci on plastic strips (DentocuIt-SM Strip mutans). Professional toothcleaning with a CHX gel was clearly most effective ( P < 0.001) but the baseline levels of streptococci returned in 11 wk. SnF₂-AmF gel also reduced significantly ( P < 0.001) mutans streptococci but recolonization occurred already in 7 wk. Placebo gel, i.e. professional toothcleaning as such, did not show any statistically significant effect on the numbers of salivary mutans streptococci. None of the treatments affected the levels of lactobacilli or the total aerobic flora in saliva samples. Professional toothcleaning with a CHX gel, or with a SnF₂,-AmF gel, can be regarded as an alternative to the commonly used, but more patience demanding, application of gel in mouth trays at home for individuals with high caries activity.     

Effects of chlorhexidine, NaF and SnF2 on glucan formation by salivary and culture supernatant GTF adsorbed to hydroxyapatite

Abstract – Chlorhexidine, NaF and SnF₂ were tested for inhibitory activity against glucosyltrans-ferase (GTF) which had been adsorbed to hydroxyapatite. The sources of GTF were culture supernatants of S. mutans grown in BHI or stimulated whole saliva supernatants. Chlorhexidine inhibited GTF activity from culture supernatants as well as from saliva. NaF and SnF₂ had moderate effects.     

Effect of penicillin on Streptococcus mutans, Streptococcus sanguis and lactobacilli in hamsters and in man

The effect of penicillin on the number of oral Streptococcus mutans, Streptococcus sanguis and lactobacilli in hamsters and in man was investigated. This is of interest as S. mutans and lactobacilli are involved in the carious process while S. sanguis is not. Hamsters infected with both S. mutans and S. sanguis or only S. sanguis received penicillin in their drinking water for 14 d. The treatment reduced the proportion of S. mutans and S. sanguis in dental plaque to undetectable levels. After the penicillin treatment the population of S. mutans and S. sanguis gradually increased. In man, the effect of oral penicillin therapy was examined in 21 adults with more than 2 X 10(5) S. mutans per ml saliva. The penicillin treatment had almost no effect on the numbers of S. sanguis and lactobacilli, but a pronounced decrease in the number of S. mutans was observed. The duration of this effect, however, was short. Consequently, such treatment alone is of limited value for the control of the oral infection of these microorganisms.     

Antibacterial activity of dental gels containing combinations of amine fluoride, stannous fluoride, and chlorhexidine against cariogenic bacteria

Abstract – The in vitro susceptibility of Streptococcus mutans, S. sobrinus and Lactobacillus casei to dental gels containing various combinations of amine fluoride (AmF 297), stannous fluoride (SnF₂), and chlorhexidine (CHX) was studied. The combination of AmF-SnF₂ with a total fluoride content of 1.2% was the most effective against mutans streptococci but not against L. casei. At notably lower total fluoride concentration (0.4%), AmF as such or combined with SnF₂, was significantly less effective against mutans streptococci than CHX or CHX-AmF-SnF₂ combinations. CHX-AmF combination was a slightly more potent inhibitor of streptococcal growth than CHX-NaF. With L. casei the differences between various gels were small but CHX alone seemed to be the most effective. Of the studied agents, CHX seemed to be the most potent individual chemotherapeutic compound whose activity against S. mutans could be enhanced by combining it with AmF. However, clinical experiments are required to test the in vivo antibacterial efficacy of CHX-AmF and AmF-SnF₂ combinations which were most effective in our in vitro experiments.     

Effect of chlorhexidine on the relative proportions of Streptococcus mutans and Streptococcus sanguis in hamster plaque.

The effect of chlorhexidine on the proportions of Streptococcus mutans and Streptococcus sanguis in plaque was studied in hamsters fed a diet containing 28% sucrose. In animals given chlorhexidine in their drinking water for 10 d a decrease in the population of S. mutans and an increase of S. sanguis occurred in the plaque. Following the removal of chlorhexidine the population of S. mutans increased again in the presence of sucrose and the number of S. sanguis returned to initial values. When animals were given a sucrose-free diet the low proportion of S. mutans observed following the short-term chlorhexidine period persisted. These data indicate that there is an inverse relationship between the number of S. sanguis and S. mutans in plaque and that the sensitivity in vivo of S. mutans to chlorheximide can be used to suppress the population of S. mutans with a concomitant rise in the proportion of S. sanguis.     

Antineoplastic agents inhibit the growth of Streptococcus mutans and Streptococcus sanguis in vitro

The effect of methotrexate (MTX) and doxorubicin on the growth, metabolism and ultrastructure of Streptococcus mutans and Streptococcus sanguis was studied in vitro. Both anticancer drugs exerted an inhibitory effect on the oral streptococci. MTX was more inhibitory than doxorubicin. The minimum inhibitory concentrations (MICs) of MTX to S. mutans were 0.25-2.5 micrograms/ml and that of doxorubicin 0.2 mg/ml. The MICs of MTX and doxorubicin to S. sanguis were 0.025 micrograms/ml and 2.0-0.02 mg/ml, respectively. When saliva samples of patients with malignant tumors receiving various doses of MTX were analyzed, MTX was found to be secreted into the oral cavity at concentrations ranging from 0.014 to 4.486 micrograms/ml. The saliva of these patients was also found to inhibit the growth of S. mutans, and the inhibition zones were in accordance with the MIC values observed. The results suggest that anticancer therapy must be taken into account when the salivary microbiological findings of cancer patients are interpreted.     

Streptococcus mutans, not detected?

The growth of Streptococcus mutans was followed for three years in 24 healthy 12-17 year-old children, who were selected for the study on the basis of undetectable levels of salivary S. mutans. The saliva samples were cultured by a dip-slide method based on mitis-salivarius agar supplemented with sucrose and bacitracin. At the final occasion, additional examination of plaque and saliva of 10 children using TSY20B agar was performed. During the 3-year study period, S. mutans was found in saliva samples from 15 children on one or more of the 4 test occasions, suggesting that most 'S. mutans negative individuals' were those in whom S. mutans could not be temporarily detected. The additional examination of plaque did not increase the number of 'S. mutans-positive individuals'.     

Effect of a fluoride-containing varnish on Streptococcus mutans in plaque and saliva

Abstract – The effect of topical application of a fluoride-containing varnish, Duraphat®, on the level of Streptococcus mutans in saliva and in dental plaque was investigated in schoolchildren. Samples of saliva and pooled buccal plaque were taken before varnish application and 4, 10 and 21 d after treatment. Fluoride varnish treatment with or without a preceding dental prophylaxis had no significant effect on the plaque and salivary levels of S. mutans. The findings suggest that the caries-reducing effect of fluoride varnish cannot be explained by an alteration of the incidence of 5. mutans in dental plaque or in saliva.     

Suppression of Streptococcus mutans in the mouths of humans by a dental prophylaxis and topically-applied iodine.

A prophylaxis followed by three topical applications of an iodine-potassium iodide solution significantly reduced the levels of Streptococcus mutans in fissure and approximal plaques and in saliva. Reductions persisted 20--24 weeks after treatment in salivary and approximal samples. A prophylaxis alone exerted a small and temporary reduction of S. mutans in occlusal fissure plaque, but did not reduce the levels of this organism in approximal plaque or in saliva. A significant relationship existed between the levels of S. mutans in saliva and the proportions of this organism in plaque. The dorsum of the tongue does not appear to constitute a significant reservoir for S. mutans following disinfecting procedures.     

Streptococcus mutans, Iactobacilli, and caries experience in older adults

This study Investigated salivary levels of Streptococcus mutans, lactobacilli, and caries experience in a random sample of 448 black and 362 white older dentate adults living in North Carolina. Significant proportions of the participants had stimulated salivary flow rates less than 1.0 mL/min, salivary buffering capacity less than 4.0, S. mutans levels of 10⁵ cfu/mL or more in stimulated whole saliva, or lactobacilli levels of 10⁵ cfu/mL or more. Each of these factor levels could be considered, on a clinical basis, to increase caries risk. in general, people with higher levels of S. mutans or lactobacilli had more untreated coronal and root caries, but not greater total caries experience.     

Combined inhibitory effect of lactoferrin and lactoperoxidase system on the viability of Streptococcus mutans, serotype c

Abstract— We have studied the effects of iron-free lactoferrin (apo LF) and lactoperoxidase system (lactoperoxidase, LP/SCN^-/H₂O₂), separately and together, on the viability of Streptococcus mutans (serotype c) in vitro. The bacteria were incubated in buffered KCl (pH 5.5) with and without the above components which were used at concentrations normally present in human saliva. Both apo LF and LP-system had a bactericidal effect against S. mutans at low pH. Together they showed an additive, but not a synergistic, antibacterial effect against S. mutans . Apo LF enhanced the LP enzyme activity but decreased the yield of the antimicrobial component, hypothiocyanite (HOSCN/OSCN^-), when incorporated into the reaction mixtures. This decrease, which was most pronounced at low pH, was due to an LP-independent reaction between apo LF and HOSCN/OSCN^-. Our study indicates that the LP-system and apo LF can be combined to combat oral S. mutans .     

Antibacterial effect of myeloperoxidase against Streptococcus mutans

Myeloperoxidase-chloride-H₂O₂ antimicrobial system is an integral part of leukocyte defense against pathogenic microorganisms. The system is present in gingival crevicular fluid and in whole saliva and, thus, possibly contributes to the non-antibody defense in the human mouth. In fact, at physiological concentrations myeloperoxidase-Cl⁻-H₂O₂ system effectively killed Streptococcus mutans both at acid and neutral pH. However, thiocyanate (SCN⁻) ions at concentrations similar to those in human saliva abolished this bactericidal action indicating that SCN⁻ rather than Cl⁻ is the physiologic substrate of myeloperoxidase in whole saliva. The peroxidation of SCN⁻ (by myeloperoxidase or salivary peroxidase) yields oxidation products which inhibit the growth and metabolism of S. mutans without notable loss of cell viability. Our results suggest that the presence of SCN⁻ in saliva protects human oral tissues (and bacteria) from highly cytotoxic oxidation products of Cl⁻ and, instead, bacteriostatic and non-toxic oxidation products of SCN⁻ are generated. In the gingival crevices, however, the SCN⁻/ Cl⁻ ratio may be too small for effective block of Cl⁻ oxidation by myeloperoxidase, and the oxidation products of Cl⁻, such as hypochlorite or hypochlorous acid, may contribute to the breakdown of periodontal tissues during inflammation.     

Selective effects of histidine-rich polypeptides on the aggregation and viability of Streptococcus mutans and Streptococcus sanguis

Enriched preparations of histidine-rich polypeptides (HRPs) and isolated HRP pairs (1-2, 3-4 and 5-6) degrade in the presence of fresh autologous whole saliva to a series of low-molecular-weight cationic peptides (HRPs 6a-c and 7). Analysis of the HRPs during degradation indicates that: HRP 1 is not the parent molecule of the HRPs; the HRP pairs do not convert to each other in a cascade-like sequence in saliva; and the HRPs can be separated into 2 groups consisting of HRPs 1-2 and 3-7. Preparations containing HRPs 1-7, 1-2, and 3-7 were obtained by fractionation and separation on Bio-Rex 70, and tested for aggregating and antibacterial effects against Streptococcus mutans BHT, S. mutans GS-5 and Streptococcus sanguis G9B. HRPs 1-2 had significant aggregating effects on all 3 strains but the other HRPs had little to no agglutinating ability. The HRPs did not inhibit the growth of S. sanguis, and HRPs 1-2 enhanced its growth. No growth enhancement by the HRPs was observed for the 2 S. mutans strains. However, significant bacterial inhibition of the S. mutans strains was noted after incubation with HRPs 3-7. The data suggest that the dissimilar effects of HRPs 1-2 and 3-7 may be of importance in the colonization and growth of S. mutans and S. sanguis in vivo.     

Effects of acidification on growth and glycolysis of Streptococcus sanguis and Streptococcus mutans

After carbohydrate intake, pH in dental plaque decreases rapidly and reaches about 4 within a few minutes. The acidification not only promotes demineralization of tooth surface but can also cause damage to bacteria in dental plaque. We, therefore, investigated the effect of acidification on the dental plaque bacteria Streptococcus sanguis and Streptococcus mutans. At pH 4.0 and 4.2, both growth and glycolytic activities in these streptococci were repressed. Prolonged acidification (for 60 min at pH 4.0) not only repressed both growth and glycolytic activities but also impaired them in S. sanguis cells with concomitant inactivation of the glycolytic enzymes, hexokinase, phosphofructokinase, glyceraldehyde-phosphate dehydrogenase and enolase. The impaired abilities of glycolysis and growth recovered following incubation at pH 7.0 for 80–90 min, and this was accompanied by reactivation of the glycolytic enzymes. On the other hand, these impairments were not observed in S. mutans cells exposed to prolonged acidification. These results indicate that the low pH frequently occurring in dental plaque may transiently impair streptococcal glycolysis and growth and that S. mutans is more durable to the acidification than S. sanguis.     

Real-time interaction of oral streptococci with human salivary components

Oral streptococci are present in large numbers in dental plaque and several types interact with the enamel salivary pellicle to form a biofilm on tooth surfaces. The respective affinity of individual streptococci for salivary components has an influence on the etiologic properties of oral biofilm in the development of dental caries. We studied real-time biospecific interactions between oral streptococci and salivary components utilizing biosensor technology to analyze surface plasmon resonance. Streptococcus sanguis and Streptococcus mutans showed significant responses for binding to salivary components, in comparison with other bacteria. Further, the association rates (4.1 x 10-11/bacterium) and dissociation rate (5.7 +/- 0.9 x 10-3 Second(s)-1) were higher for S. sanguis than for S. mutans (2.4 x 10-11 and 2.9 +/- 0.8 x 10-3) and Streptococcus mitis (1.3 x 10-11 and 3.5 +/- 1.3 x 10-3). However, the association equilibrium constants (8.2 S/bacterium) for S. mutans was 2 times higher in than S. mitis (3.8) and slightly higher than S. sanguis (7.2). These findings may provide useful information regarding the mechanism of early biofilm formation by streptococci on the tooth surface.