Long-term xylitol consumption and mutans streptococci in plaque and saliva

The effect of 4 to 6 years of habitual use of xylitol gum (greater than or equal to 2 times per day) on the viable counts of mutans streptococci in both plaque and saliva was evaluated in a cross-sectional study of participants of the Ylivieska xylitol study (Finland, 1982-1984). Paraffin-stimulated saliva was collected first, whereafter the remaining plaque was collected from all available tooth surfaces and pooled. The habitual xylitol consumers (n = 15) had less plaque than the controls (n = 21). The total viable counts of mutans streptococci in the plaque collected from the habitual xylitol users were about 10% of those determined in controls (p less than 0.01). The salivary mutans streptococci levels were relatively high in both habitual xylitol consumers and controls, as determined using a plate count and with an adhesion-based assay; no significant differences were detected between these groups. Thus, habitual xylitol consumption appeared not to be associated with a reduction in the total numbers of mutans streptococci in saliva. The plaque and the mutans streptococci were, however, more loosely bound to the tooth surfaces of the habitual xylitol users. The results of the plate count and the adhesion-based assay for salivary mutans streptococci were in good agreement for both habitual xylitol consumers and the controls. This suggests that it was the accumulation of plaque rather than the adhesiveness of mutans streptococci that was affected by the habitual consumption of xylitol.     

Comparison of erythritol and xylitol saliva stimulants in the control of dental plaque and mutans streptococci

The effect of 2-month usage of saliva-stimulating pastils containing either erythritol or xylitol was studied in a cohort of 30 subjects assigned to the respective polyol groups (n = 15). The daily consumption level of both polyols was 5.2 g, used in 5 daily chewing episodes. The mean weight of total plaque mass (collectable during a standard period of 3 min from all available tooth surfaces) was reduced significantly in the xylitol-group, while no such effect was observed in the erythritol-group. This reduction in plaque mass was accompanied by a significant reduction in the turbidity readings (A(660)) of aqueous plaque suspensions; no such effect was observed in the erythritol-group. However, plaque protein levels did not differ between baseline and endpoint in either polyol group. The plaque and salivary levels of Streptococcus mutans and plaque levels of total streptococci were reduced significantly in the xylitol-group, while no such effect was detected in the erythritol-group. However, either polyol regimen had no effect on plaque levels of S. sobrinus. The results suggest that systematic use of xylitol-containing saliva stimulants may be more effective in controlling some oral-hygiene-related and caries-associated parameters than similar use of erythritol-containing products. The results also speak for a special relationship between xylitol and S. mutans. However, owing to the great potential of erythritol as a caries-reducing agent -- based on the tetritol nature of erythritol -- the present laboratory results should be considered preliminary and subject to verifying clinical studies.     

Long-term effect of xylitol gum use on mutans streptococci in adults

Many studies have shown the effects of chewing xylitol gum on mutans streptococci (MS) over short- and long-term periods in children; however, few studies have addressed long-term periods in adults. The objective of this investigation was to examine for 6 months the effects of chewing xylitol gum on MS in saliva and plaque in 127 adults (mean age 28.0 years). The participants were assigned to three groups according to gum type, in part taking preference for flavor into account and in part at random: xylitol (XYL), maltitol (MAL) and control (CR); 33, 34 and 27 subjects in each group, respectively, completed the trial. Daily gum use of the XYL and MAL groups was 7.9 and 7.1 g, respectively. MS levels, which declined significantly in saliva (p < 0.05) and plaque (p < 0.001) in the XYL group after 6 months, exhibited a significant increase in plaque in the MAL group (p < 0.001). Differences in relative changes of MS levels in plaque during the experimental period were significant between the XYL group and the CR (p < 0.05) and MAL groups (p < 0.001). Differences in relative change of amount of plaque during the experimental period were not statistically significant between the groups. The present study demonstrated that chewing xylitol gum for 6 months continued to inhibit the growth of mutans streptococci in adults.     

Influence of maternal xylitol consumption on acquisition of mutans streptococci by infants

Xylitol is effective as a non-cariogenic sugar substitute. Habitual xylitol consumption appears to select for mutans streptococci (MS) with impaired adhesion properties, i.e., they shed easily to saliva from plaque. One hundred sixty-nine mother-child pairs participated in a two-year study exploring whether the mothers' xylitol consumption could be used to prevent mother-child transmission of mutans streptococci. All mothers showed high salivary levels of mutans streptococci during pregnancy. The mothers in the xylitol group (n = 106) were requested to chew xylitol-sweetened gum (65% w/w) at least 2 or 3 times a day, starting three months after delivery. In the two control groups, the mothers received either chlorhexidine (n = 30) or fluoride (n = 33) varnish treatments at 6, 12, and 18 months after delivery. The children did not chew gum or receive varnish treatments. MS were assessed from the mothers' saliva at half-year intervals and from the children's plaque at the one- and two-year examinations. The MS were cultured on Mitis salivarius agars containing bacitracin. The salivary MS levels of the mothers remained high and not significantly different among the three study groups throughout the study. At two years of age, 9.7% of the children in the xylitol, 28.6% in the chlorhexidine, and 48.5% in the fluoride varnish group showed a detectable level of MS. In conclusion, therefore, habitual xylitol consumption by mothers was associated with a statistically significant reduction of the probability of mother-child transmission of MS assessed at two years of age. The effect was superior to that obtained with either chlorhexidine or fluoride varnish treatments performed as single applications at six-month intervals.     

Effects of Streptococcus mutans gtfC deficiency on mixed oral biofilms in vitro

The aim of this study was to examine the influence of glucosyltransferase-gene-negative (gtf-) Streptococcus mutans strains unable to synthesize water-insoluble or soluble glucan on the structure and macromolecular diffusion properties of in vitro grown mixed oral biofilms. Biofilms modeling supragingival plaque consisted of Actinomyces naeslundii OMZ 745, Candida albicans OMZ 110, Fusobacterium nucleatum KP-F2, Streptococcus oralis SK 248, Veillonella dispar ATCC 17748T and one of the S. mutans strains UA159, OMZ 966, OMZ 937 or OMZ 977. Biofilms were grown anaerobically on sintered hydroxyapatite disks for 64.5 h at 37 degrees C. To perform confocal laser scanning microscopy analyses, microorganisms were stained with Syto 13 and extracellular polysaccharides (EPS) with Calcofluor. Macromolecular diffusion properties were measured following timed biofilm exposure to Texas-Red-labeled 70-kDa dextran. Results showed that replacing wild-type S. mutans by a gtfC- mutant led to an increase in the volume fraction occupied by cells from 29 to 48% and a decrease of the EPS volume fraction from 51 to 33%. No such changes were observed when the S. mutans wild-type strain was replaced by a gtfB- or gtfD- mutant. The diffusion coefficient of 70-kDa dextran in biofilms containing the gtfC- S. mutans was 16-fold higher than in biofilms with the wild-type strain indicating a strong macromolecular sieving effect of GTF C-generated glucans. Our data demonstrate the influence of EPS on the structure and macromolecular diffusion properties of an oral biofilm model and uncover our still limited knowledge of the function of EPS in biofilms and plaque.     

Genetic diversity of plaque mutans streptococci with rep-PCR

Mutans streptococci (MS) are key organisms associated with the etiology of dental caries. Using probabilities that were tested by oversampling, we designed this study to determine the minimal number of MS isolates from an individual required to evaluate diversity of genotypes. MS isolates were genotyped by repetitive extragenic palindromic-polymerase chain-reaction (rep-PCR). Analysis of 20 isolates from individuals resulted in a mean of 1.6 and 2.4 genotypes in children (N = 12) and adults (N = 10), respectively. In a follow-up study, reducing the number of isolates to 7-10 resulted in a theoretical probability of up to 78% for detecting up to 4 genotypes. A mean of 1.5 genotypes was found in 35 children and 10 adults. These findings provide evidence for the design of studies of MS genotyping that can serve as a model for the analysis of genotypes within individuals.     

Xylitol-resistant mutans streptococci strains and the frequency of xylitol consumption in young children

Objective. Previous studies have suggested that lactobacilli-derived probiotics in dairy products may affect oral ecology, but the impact of different vehicles of ingestion has received little attention. The aim of the present study was to investigate the effect of the probiotic bacterium Lactobacillus reuteri ATCC 55730 on the levels of salivary mutans streptococci and lactobacilli in young adults when ingested by two different delivery systems. Material and Methods. The material comprised 120 healthy young adults (21–24 years) and a placebo-controlled study design with parallel arms was utilized. The subjects were randomly assigned to four equally sized groups: group A drank 200?ml of water through a prepared straw containing L. reuteri ATCC 55730 once daily for 3 weeks, while group B took 200?ml water through a placebo straw during the same period. Group C was given one tablet containing L. reuteri ATCC 55730 once daily for 3 weeks, while group D received placebo tablets without bacteria. Salivary mutans streptococci and lactobacilli were enumerated with chair-side kits at baseline and 1 day after the final ingestion. Results. A statistically significant reduction of the mutans streptococci levels was recorded after ingestion of the probiotic bacteria via the straw (p<0.05) and the tablets (p<0.01), which was in contrast to the placebo controls. A similar but non-significant trend was seen for lactobacilli. Conclusions. A short-term daily ingestion of lactobacilli-derived probiotics delivered by prepared straws or lozenges reduced the levels of salivary mutans streptococci in young adults.     

Effect of xylitol on mutans streptococci and lactic acid formation in saliva and plaque from adolescents and young adults with fixed orthodontic appliances

This study aimed to investigate two dose regimens of xylitol-containing tablets on the ecology of dental plaque and saliva during treatment with fixed orthodontic appliances. The study group comprised 56 healthy patients (mean age 15.8 yr) randomly assigned into the following groups: A, (n = 23) two xylitol tablets two times a day (1.7 g xylitol d(-1)) for 18 wk; B, (n = 23) two tablets four times per day (3.4 g xylitol d(-1)) for 18 wk; and C, (n = 10) no tablets. The levels of mutans streptococci (ms) were enumerated in plaque and saliva and the proportion of xylitol-sensitive (X(S)) strains in saliva was determined by autoradiography with [(14)C]-xylitol at baseline and at 6, 12, and 18 wk. The lactic acid formation rate was assessed enzymatically in sucrose-challenged plaque suspensions. A drop in salivary ms levels was found in Group A after 6 wk but not after 12 or 18 wk. The proportion of X(S) ms was decreased after 6 wk in groups A and B and remained so during the experimental period. The lactic acid formation rates decreased slightly ( approximately 10%) in the two xylitol groups compared with baseline. In conclusion, our results showed that although an alteration of ms strains was demonstrated following a regular daily low-dose intake of xylitol, the long-term total ms counts in plaque and saliva as well as plaque acidogenicity remained unchanged.     

Validation of an in vitro biofilm model of supragingival plaque

The study of biofilm structure and function mandates the use of model systems for which a host of environmental variables can be rigorously controlled. We describe a model of supragingival plaque containing Actinomyces naeslundii, Veillonella dispar, Fusobacterium nucleatum, Streptococcus sobrinus, and Streptococcus oralis wherein cells are cultivated anaerobically in a saliva-based medium on hydroxyapatite discs coated with a salivary pellicle, with material and pieces of apparatus common to all microbiology laboratories. After 0.5 hr, 16.5 hrs, 40.5 hrs, and 64.5 hrs, the composition of adherent biofilms was analyzed by culture techniques, live/dead fluorescence staining, and confocal laser scanning microscopy. Repeated independent trials demonstrated the repeatability of biofilm formation after 40.5 hrs and 64.5 hrs. Brief exposures of biofilms to chlorhexidine or Triclosan produced losses in viability similar to those observed in vivo. This biofilm model should prove very useful for pre-clinical testing of prospective anti-plaque agents at clinically relevant concentrations.     

Effect of xylitol consumption on the plaque-saliva distribution of mutans streptococci and the occurrence and long-term survival of xylitol-resistant strains.

Since the exposure of mutans streptococci to xylitol is known to select for xylitol-resistant (XR) natural mutants, the occurrence and long-term survival of such xylitol-resistant strains was evaluated in a cross-sectional sampling of participants of the Ylivieska xylitol study four years after the original two-year experimental period. Paraffin-stimulated whole saliva was first collected, and then plaque was collected and pooled. The salivary and dental plaque mutans streptococci were enumerated after growth on TSY20B agar. The proportion of XR strains was determined by autoradiography with 14C-xylitol. A strong and significant correlation (r = 0.645 and p = 0.005) between the number of mutans streptococci in saliva and in dental plaque was observed in non-consumers of xylitol. Such a correlation totally disappeared (r = 0.098 and p = 0.612) in xylitol-exposed consumers (habitual and former xylitol-consumers). The proportion of the salivary XR mutants (35%) in non-consumers (n = 16) was significantly lower than in the xylitol-exposed consumers (79%) (n = 27), (p = 0.0001) or in former consumers (75%) (n = 13), (p = 0.0008) or in the habitual consumers (83%) (n = 14), (p = 0.004). The proportion of XR mutants in dental plaque was, on the average, much lower than in the corresponding saliva. The proportion of XR in the plaque of xylitol non-consumers was half of that of the xylitol-exposed group, but the difference was not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of a triclosan-containing toothpaste supplemented with 10% xylitol on mutans streptococci in saliva and dental plaque. A 6-month clinical study

The aim of the present investigation was to evaluate the effect of the combination of triclosan and xylitol in toothpaste on mutans streptococci (MS) in saliva and dental plaque. 155 individuals with >10(5) MS/ml saliva were included in a 6-month double-blind clinical study. They were divided into three groups (n = 51-52) balanced according to their MS counts at baseline. Each group used one of the following types of dentifrice: (1) Colgate Total with the addition of 10% xylitol (Total-Xylitol), (2) Colgate Total and (3) Colgate Total without triclosan and without xylitol. Whole saliva and pooled plaque samples were obtained after 2, 4 and 6 months. When comparing the MS counts within the groups for saliva and plaque samples, Total-Xylitol showed significant reduction at all three sampling occasions (p < 0.001). Mean reduction at the 6-month sample for saliva was 0.81/ml and for plaque 0.89 per sample (log values). ANOVA revealed significant differences between Total-Xylitol and the two other products at 6 months for MS in saliva and dental plaque. The conclusion from this 6- month study is that the addition of 10% xylitol to a triclosan-containing dentifrice reduces the number of MS in saliva and dental plaque.     

Deletion of gtfC of Streptococcus mutans has no influence on the composition of a mixed-species in vitro biofilm model of supragingival plaque

Glucosyltransferases from Streptococcus mutans are thought to play an important role in bacterial adherence to the tooth surface. The goal of the present study was to determine the effect of the deletion of the gtfC gene, which encodes a glucosyltransferase that catalyses primarily the formation of insoluble glucan (mutan), on colonization of S. mutans in a mixed-species biofilm model of supragingival plaque. A gtfC deletion mutant of S. mutans UA159 grew poorly in biofilms on a polystyrene surface in Todd–Hewitt medium containing sucrose, but biofilm formation in the semi-defined fluid universal medium (FUM) was not affected. The S. mutans gtfC mutant colonized with the same efficiency as the wild-type strain when grown together with five other species in a mixed-species biofilm on hydroxyapatite in a mixture of FUM and saliva with pulses of sucrose and showed the same ability to demineralize enamel in vitro . Colonization of mutant and wild-type strains was also equal in an association experiment in specific-pathogen-free rats. However, the gtfC mutant gave rise to more dentinal fissure lesions and smooth surface caries than the wild-type strain; this could be caused by a change in diffusion properties as a result of to the lack of mutan.     

In vitro screening of Chinese medicinal toothpastes: their effects on growth and plaque formation of mutans streptococci

Many plant extracts or derivatives have been incorporated into commercial toothpastes to treat oral diseases related to caries or periodontal diseases in China. However, no information is available concerning their in vitro effects on oral bacteria. Thirty-one Chinese medicinal toothpastes were selected for this study. Their ability to inhibit growth, in vitro plaque formation and glucosyltransferase (GTF) activity of Streptococcus sobrinus B13 and Streptococcus mutans 3209 were examined. Eighty-seven percent of the tested toothpastes inhibited the growth of the mutans streptococci, with zones ranging from 0.8 to 2.5 cm. At 10 mg/ml, 74% of the toothpastes inhibited in vitro plaque formation by S. mutans. Among these, 60% completely suppressed water-insoluble glucan synthesis from sucrose by GTF. Based on data obtained from our study, the incorporation of natural plant products or their derivatives into dentifrices seems a feasible means of promoting oral health and controlling dental diseases.     

Influence of maternal xylitol consumption on mother-child transmission of mutans streptococci: 6-year follow-up

Xylitol is effective as a noncariogenic or even cariostatic sugar substitute. Habitual xylitol consumption appears to select for mutans streptococci (MS) which shed easily into saliva from plaque. We have earlier shown that habitual xylitol consumption of mothers was associated with a statistically significant reduction in the probability of mother-child transmission of MS assessed at 2 years of age. The aim of the present study was to assess the children's MS counts 1 and 4 years after the maternal xylitol consumption had been discontinued. At baseline, during pregnancy, all mothers (n = 195) showed high salivary levels of MS. The mothers were randomly assigned to xylitol, fluoride (F) and chlorhexidine (CHX) groups. In the xylitol group, the mothers chewed xylitol-sweetened gum, for 21 months, starting 3 months after delivery. In the two control groups, the mothers received CHX or F varnish treatments at 6, 12 and 18 months after delivery. At the 2-year examination, 169 mother-child pairs participated. At the 3-year and 6-year examinations, there were 159 and 147 children in the study, respectively. For children's MS analyses, visible plaque was collected using toothpicks at the age of 3 and paraffin-stimulated saliva at the age of 6. The persons involved in the collection and analysis of the microbiological samples were blinded as to the study design and group. Both the plaque and salivary MS were cultured on Mitis salivarius agars containing bacitracin. In all groups, the colonization percentages increased during the follow-up. At the 3-year examination, the children's risk of having MS colonization was 2.3-fold in the F group (95% CI 1.3-4.2) compared to the xylitol group. This difference was statistically significant. Even at 6 years of age, the salivary MS levels were significantly lower in the xylitol group than in the other groups (ANOVA, p<0.001). In conclusion, the earlier demonstrated, xylitol-associated reduction in the probability of mother-child transmission of MS was still found in the children's MS counts at the age of 3 and 6 years.     

Effect of dentifrices containing either xylitol and glycerol or sorbitol on mutans streptococci in saliva.

In 76 adults, randomly distributed between two groups, a comparison was made of the effect on the level of mutans streptococci in saliva between two dentifrices containing: (1) xylitol (9.9%) and glycerol (20%) or (2) sorbitol (28%) as humectants. After the use of the dentifrices twice daily for 3 months, the levels of mutans streptococci had not changed significantly in the sorbitol-treated group, whereas a significant reduction (p less than 0.0005) was found in subjects using the xylitol/glycerol dentifrice. The difference between the two dentifrice groups based on the changes observed during the 3-month period was also significant (p less than 0.02).     

Ingredients in dentifrices and their effect on plaque, gingivitis and mutans streptococci

Objective: The aim of this study was to investigate attitudes and opinions of old, independently living people about their oral health and how it has affected them through life. Material and methods: A random selection of 12 individuals was made in a group of 79 individuals who earlier participated in a study about self‐reported oral health. The average age was 78.4 years. An interview guide was used as support to focus on oral health. The respondents themselves decided what was important within the topics. The respondents were encouraged to speak freely about their childhood, family, social relations, memories from early dental care, general health situation, experience from health care, life and their future. The interviews were recorded and extended from 60 to 90 min. All of them were transcribed and analysed with phenomenological method inspired by Giogi. The analysis was made by two researchers independently. After 11 interviews, no new information was found; similar opinions, answers and stories recurred. Results: Seven of 11 respondents were born and grown up in the countryside and had moved to Stockholm in the forties. Awareness about dental care was generally low. Many of them have terrible memories from early dental visits, and the dentist was authoritarian and rough. Many had no memories of brushing their teeth as a child. Most of the respondents went to dentists as adults and when they could afford to pay by themselves. After retirement, all have continuous dental care and have visited a dental hygienist during the last 20 years. Nine of 11 have regular contact with a dental hygienist. Most of them are satisfied with their oral health and want to continue being clean and healthy in the mouth. Conclusions: Most of the respondents experienced an improved oral health, information and instructions from the dental hygienist have affected their self‐care. Many tell that they have become more aware and carry out the oral hygiene more carefully after retirement. All of them experience that oral health affects the quality of life.     

Fluoride and mutans streptococci in plaque grown on glass ionomer and composite.

The aim of this study was to compare the levels of fluoride and mutans streptococci in plaque grown on glass ionomer (Ketac-Fil) and composite (Silar) restorations in vivo. From tunnels left under the brackets bonded either with glass ionomer or composite, 14-day-old plaque samples were collected 14, 28, and 42 days after bonding. For glass ionomer the mean counts of mutans streptococci in plaque were 0.5 x 10(3), 6.7 x 10(3), and 8.8 x 10(3) CFU at the first, second, and third collection, respectively, whereas for composite restorations the corresponding values were 32.1 x 10(3), 14.6 x 10(3), and 120.6 x 10(3) CFU. For glass ionomer the mean concentrations of fluoride were 19,985, 5,788, and 5,019 ppm at first, second, and third collections of 14-day-old plaque samples, respectively, whereas for composite restorations the mean concentrations of fluoride were about 200 ppm throughout the study. The results show that the fluoride level in plaque growing on glass ionomer is much higher than that on composite restorations which seems to affect the level of mutans streptococci in dental plaque.     

Effect of chewing gums containing xylitol or probiotic bacteria on salivary mutans streptococci and lactobacilli

The aim was to evaluate the effect of xylitol and probiotic chewing gums on salivary mutans streptococci (MS) and lactobacilli (LB). The material consisted of 80 healthy young adults (21–24 years) who volunteered after informed consent. They were assigned by random into one of four parallel study groups: A, probiotic gum group; B, xylitol gum group; C, probiotic + xylitol gum group; and D, placebo gum group. The gums were taken three times daily after meals, and the intervention period was 3 weeks. The probiotic gums contained two strains of Lactobacilli reuteri (ATCC 55730 at a dose of 1 × 10⁸ CFU/gum and ATCC PTA 5289 at a dose of 1 × 10⁸ CFU/gum), and each pellet of the xylitol gum contained ≈1.0 g xylitol as single sweetener. Pretreatment and posttreatment samples of stimulated whole saliva were collected and quantified for MS and LB with chair-side kits. A statistically significant reduction (p < 0.05) of salivary MS was displayed in group A and B after the intervention when compared with baseline. A similar but nonsignificant tendency was seen in group C. No alterations of salivary LB was demonstrated in any group. In conclusion, daily chewing on gums containing probiotic bacteria or xylitol reduced the levels of salivary MS in a significant way. However, a combination of probiotic and xylitol gums did not seem to enhance this effect.