How xylitol-containing products affect cariogenic bacteria

Rewiring of Metabolic Network in Mycobacterium tuberculosis During Adaptation to Different Stresses

Metabolic adaptation of Mycobacterium tuberculosis (M. tuberculosis) to microbicidal intracellular environment of host macrophages is fundamental to its pathogenicity. However, an in-depth understanding of metabolic adjustments through key reaction pathways and networks is limited. To understand how such changes occur, we measured the cellular metabolome of M. tuberculosis subjected to four microbicidal stresses using liquid chromatography-mass spectrometric multiple reactions monitoring (LC-MRM/MS). Overall, 87 metabolites were identified. The metabolites best describing the separation between stresses were identified through multivariate analysis. The coupling of the metabolite measurements with existing genome-scale metabolic model, and using constraint-based simulation led to several new concepts and unreported observations in M. tuberculosis; such as (i) the high levels of released ammonia as an adaptive response to acidic stress was due to increased flux through L-asparaginase rather than urease activity; (ii) nutrient starvation-induced anaplerotic pathway for generation of TCA intermediates from phosphoenolpyruvate using phosphoenolpyruvate kinase; (iii) quenching of protons through GABA shunt pathway or sugar alcohols as possible mechanisms of early adaptation to acidic and oxidative stresses; and (iv) usage of alternate cofactors by the same enzyme as a possible mechanism of rewiring metabolic pathways to overcome stresses. Besides providing new leads and important nodes that can be used for designing intervention strategies, the study advocates the strength of applying flux balance analyses coupled with metabolomics to get a global picture of complex metabolic adjustments.

Oral and Systemic Effects of Xylitol Consumption

Recent results of randomized trials testing the efficacy of xylitol in caries prevention have been conflicting. This narrative review reveals the sources of discrepancy. The following databases were searched for the terms "xylitol" or "artificial sweeteners" restricted to the English language: PubMed, Web of Science, Evidenced-Based Medicine, Scopus, and the Cochrane database. In a separate search, the terms "dental caries" or "cariogenicity" or "glucosyltransferase" or "low glycemic" or "low insulinemic" or "dysbiosis" or "gut microbiome" were used and then combined. In section I, findings regarding the role of xylitol in dental caries prevention, the appropriateness of research methods, and the causes for potential biases are summarized. In section II, the systemic effects of xylitol on gut microbiota as well as low-glycemic/insulinogenic systemic effects are evaluated and summarized. The substitution of a carbonyl group with an alcohol radical in xylitol hinders its absorption and slowly releases sugar into the bloodstream. This quality of xylitol is beneficial for diabetic patients to maintain a constant glucose level. Although this quality of xylitol has been proven in in vitro and animal studies, it has yet to be proven in humans. Paradoxically, recent animal studies reported hyperglycemia and intestinal dysbiosis with artificial sweetener consumption. Upon careful inspection of evidence, it was revealed that these reports may be due to misinterpretation of original references or flaws in study methodology. Any systemic benefits of xylitol intake must be weighed in consideration with the well-established adverse gastrointestinal consequences. The contribution of xylitol to gut dysbiosis that may affect systemic immunity warrants further research.

Genetic Diversity and Evidence for Transmission of Streptococcus mutans by DiversiLab rep-PCR

This two-part study investigated the genetic diversity and transmission of Streptococcus mutans using the DiversiLab repetitive extragenic palindromic PCR (rep-PCR) approach. For children with S. mutans and participating household members, analysis for evidence of unrelated child-to-child as well as intra-familial transmission was evaluated based on commonality of genotypes. A total of 169 index children and 425 household family members from Uniontown, Alabama were evaluated for genetic diversity using rep-PCR. Thirty-four unique rep-PCR genotypes were observed for 13,906 S. mutans isolates. For transmission, 117 child and household isolates were evaluated for shared genotype (by child and by genotype cases, multiple matches possible for each child). Overall, children had 1-9 genotypes and those with multiple genotypes were 2.3 times more likely to have caries experience (decayed, missing and filled teeth/surfaces>0). Only 28% of children shared all genotypes within the household, while 72% had at least 1 genotype not shared with anyone in the household. Children had genotype(s) not shared with any household members in 157 cases. In 158 cases children and household members shared a genotype in which 55% (87/158 cases) were shared with more than one family member. Children most frequently shared genotypes with their mothers (54%; 85/158), siblings (46%; 72/158) and cousins (23%; 37/158). A reference library for S. mutans for epidemiological surveillance using the DiversiLab rep-PCR approach is detailed. The genetic diversity of S. mutans in this population demonstrated frequent commonality of genotypes. Evidence for both child-to-child and intra-familial transmission of S. mutans was observed by rep-PCR.

Effect of Chewing Xylitol Containing and Herbal Chewing Gums on Salivary Mutans Streptococcus Count among School Children

Background:

The present study aims to assess and compare the reduction in salivary Mutans Streptococci counts after chewing Xylitol, herbal and placebo gums among high school children.

Methods:

The study was conducted among 72 school children (12–15 years) from 3 randomly selected schools (blocks). Xylitol, herbal and placebo gums were randomly allocated to 3 blocks. Subjects were instructed to chew one pellet four times a day for 21 days. The mean reduction in salivary Streptococcus mutans count was assessed.

Results:

The 100% Xylitol sweetened chewing gum “Xylitol”has shown statistically significant reduction in salivary Mutans Streptococci colony forming units at the end of 21 days (P < 0.01). The reduction was not statistically significant in herbal and placebo chewing gum.

Conclusions:

Hundred percentage Xylitol sweetened chewing gum was found to be more effective in reducing salivary Mutans Streptococci count when compared to herbal and placebo chewing gums.

The effect of xylitol on dental caries and oral flora

Dental caries, the most chronic disease affecting mankind, has been in the limelight with regard to its prevention and treatment. Professional clinical management of caries has been very successful in cases of different severities of disease manifestations. However, tertiary management of this disease has been gaining attention, with numerous methods and agents emerging on a daily basis. Higher intake of nutritive sweeteners can result in higher energy intake and lower diet quality and thereby predispose an individual to conditions like obesity, cardiovascular disorders, and type 2 diabetes mellitus. Non-nutritive sweeteners have gained popularity as they are sweeter and are required in substantially lesser quantities. Xylitol, a five-carbon sugar polyol, has been found to be promising in reducing dental caries disease and also reversing the process of early caries. This paper throws light on the role and effects of various forms of xylitol on dental caries and oral hygiene status of an individual.

Impact of an anticaries mouthrinse on in vitro remineralization and microbial control

Objective. The objective of this research was to evaluate the caries control potential of a new fluoride mouthrinse that also contained antimicrobial agents and a biofilm disrupting agent using different in vitro models. Methods. Four in vitro studies were conducted to assess the performance of this three pronged approach to caries control: (1) traditional enamel fluoride uptake, (2) surface microhardness study using pH cycling model and subsequent fluoride uptake, (3) a salivary biofilm flow-through study to determine the anti-microbial activity, and (4) a single species biofilm model measuring effect on biofilm matrix disruption. Results. The data showed that a LISTERINE rinse with fluoride, essential oils and xylitol was superior in promoting enamel fluoride uptake and in enhancing antimicrobial activity over traditional commercially available fluoridated products. An increase of the surface microhardness was observed when the LISTERINE rinse was used in combination with fluoridated toothpaste versus the fluoridated toothpaste alone. Finally, it was demonstrated that xylitol solutions disrupted and reduced the biovolume of biofilm matrix of mature Streptococcus mutans. Conclusion. These in vitro studies demonstrated that a fluoride mouthrinse with antimicrobial agent and biofilm matrix disrupting agent provided multifaceted and enhanced anti-caries efficacy by promoting remineralization, reducing acidogenic bacteria and disrupting biofilm matrix.

Clinical Efficacy and Effects of Xylitol Wipes on Bacterial Virulence

The aim of the study was to investigate whether xylitol-wipe use in young children prevented caries by affecting bacterial virulence. In a double-blinded randomized controlled clinical trial, 44 mother-child pairs were randomized to xylitol-wipe or placebo-wipe groups. Salivary mutans streptococci levels were enumerated at baseline, 6 months, and one year. Ten mutans streptococci colonies were isolated and genotyped from each saliva sample. Genotype-colonization stability, xylitol sensitivity, and biofilm formation of these isolates were studied. Despite a significant reduction in new caries at one year in the xylitol-wipe group, no significant differences were found between the two groups in levels of mutans streptococci. Children in the xylitol-wipe group had significantly fewer retained genotypes (p = 0.06) and more transient genotypes of mutans streptococci (p = 0.05) than those in the placebo-wipe group. At one year, there was no significant difference in the prevalence of xylitol-resistant genotypes or in biofilm formation ability of mutans streptococci isolates between the two groups. The mechanism of the caries-preventive effect of xylitol-wipe use may be related to the stability of mutans streptococci colonization. Further studies with genomic characterization methods are needed to determine specific gene(s) that account for the caries-preventive effect of xylitol.

Repetitive extragenic palindromic PCR for study of Streptococcus mutans diversity and transmission in human populations

Pulsed-field gel electrophoresis (PFGE) is considered the "gold standard" for molecular epidemiological study. Repetitive extragenic palindromic PCR (rep-PCR) is less time-consuming and more suitable for analyzing large numbers of bacterial strains in human populations. PFGE and rep-PCR provide comparable genotyping results for investigating Streptococcus mutans diversity and transmission.

Xylitol gummy bear snacks: a school-based randomized clinical trial

BACKGROUND

Habitual consumption of xylitol reduces mutans streptococci (MS) levels but the effect on Lactobacillus spp. is less clear. Reduction is dependent on daily dose and frequency of consumption. For xylitol to be successfully used in prevention programs to reduce MS and prevent caries, effective xylitol delivery methods must be identified. This study examines the response of MS, specifically S. mutans/sobrinus and Lactobacillus spp., levels to xylitol delivered via gummy bears at optimal exposures.

METHODS

Children, first to fifth grade (n = 154), from two elementary schools in rural Washington State, USA, were randomized to xylitol 15.6 g/day (X16, n = 53) or 11.7 g/day (X12, n = 49), or maltitol 44.7 g/day (M45, n = 52). Gummy bear snacks were pre-packaged in unit-doses, labeled with ID numbers, and distributed three times/day during school hours. No snacks were sent home. Plaque was sampled at baseline and six weeks and cultured on modified Mitis Salivarius agar for S. mutans/sobrinus and Rogosa SL agar for Lactobacillus spp. enumeration.

RESULTS

There were no differences in S. mutans/sobrinus and Lactobacillus spp. levels in plaque between the groups at baseline. At six weeks, log10 S. mutans/sobrinus levels showed significant reductions for all groups (p = 0.0001): X16 = 1.13 (SD = 1.65); X12 = 0.89 (SD = 1.11); M45 = 0.91 (SD = 1.46). Reductions were not statistically different between groups. Results for Lactobacillus spp. were mixed. Group X16 and M45 showed 0.31 (SD = 2.35), and 0.52 (SD = 2.41) log10 reductions, respectively, while X12 showed a 0.11 (SD = 2.26) log10 increase. These changes were not significant. Post-study discussions with school staff indicated that it is feasible to implement an in-classroom gummy bear snack program. Parents are accepting and children willing to consume gummy bear snacks daily.

CONCLUSION

Reductions in S. mutans/sobrinus levels were observed after six weeks of gummy bear snack consumption containing xylitol at 11.7 or 15.6 g/day or maltitol at 44.7 g/day divided in three exposures. Lactobacillus spp. levels were essentially unchanged in all groups. These results suggest that a xylitol gummy bear snack may be an alternative to xylitol chewing gum for dental caries prevention. Positive results with high dose maltitol limit the validity of xylitol findings. A larger clinical trial is needed to confirm the xylitol results.

TRIAL REGISTRATION

[ISRCTN63160504].

Dental plaque formation and salivary mutans streptococci in schoolchildren after use of xylitol-containing chewing gum

OBJECTIVE

The aim of this study was to investigate the effect of a fixed daily dose of xylitol on mutans streptococci in saliva and the amount of visible dental plaque. A second aim was to explore if the possible effects differed between children with and without caries experience.

METHODS

The study was designed as a double-blind randomized controlled trial with two parallel arms. All pupils (n=149) in grades 1-6 in a comprehensive school in northern Sweden were invited, and 128 children (mean age=12.7 years) consented to participate. The children were stratified as having caries experience (DMFS/dmfs>or=1) or not before the random allocation to a test or control group. The control group (A) was given two pellets containing sorbitol and maltitol three times daily for 4 weeks, and the test group (B) received corresponding pellets with xylitol as single sweetener (total dose=6.18 g day). Clinical scoring and saliva samples were collected at baseline and immediately after the test period. The outcome measures were visible plaque index, salivary mutans streptococci counts and salivary lactic acid production.

RESULTS

The amount of visible plaque was significantly reduced in both groups after 4 weeks (P<0.05). Likewise, the sucrose-induced lactic acid formation in saliva diminished in both groups (P<0.05). The proportion of mutans streptococci decreased significantly in the test group compared to baseline, but not in the control group (P<0.05). The alterations in the test group seemed most prominent among children without previous caries experience.

CONCLUSIONS

The results suggest that chewing gum with xylitol or sorbitol/maltitol can reduce the amount of dental plaque and acid production in saliva in schoolchildren, but only the xylitol-containing gum may also interfere with the microbial composition.

Xylitol concentration in saliva and dental plaque after use of various xylitol-containing products

The study consisted of two sets of experiments, one in saliva and one in dental plaque. The xylitol concentration in saliva was determined enzymatically in 12 children (mean age 11.5 years) after a standardised use of various xylitol products: (A) chewing gums (1.3 g xylitol), (B) sucking tablets (0.8 g xylitol), (C) candy tablets (1.1 g xylitol), (D) toothpaste (0.1 g xylitol), (E) rinse (1.0 g xylitol), and (F) a non-xylitol paraffin. Unstimulated saliva was sampled 1, 3, 8, 16 and 30 min after use. The concentration in dental plaque was determined after mouthrinses with contrasting amounts of xylitol (LX = 2.0 g, HX = 6.0 g, and control) and supragingival plaque was collected and pooled after 5, 15 and 30 min. The mean xylitol concentration in saliva at baseline was approximately 0.1 mg/ml. All xylitol-containing products resulted in significantly increased levels (p < 0.05) immediately after intake and remained elevated for 8-16 min in the different groups. The highest mean value in saliva was obtained immediately after use of chewing gums (33.7 +/- 16.4 mg/ml) and the lowest was demonstrated after using toothpaste (8.2 +/- 4.9 mg/ml). No significant differences were demonstrated between chewing gums (A), sucking tablets (B), candy (C) and rinses (E). In dental plaque, the mean values were 8.6 +/- 5.4 and 5.1 +/- 4.0 mg/ml 5 min after HX and LX rinses. Concerning the higher concentration, the values remained significantly elevated (p < 0.05) during the entire 30-min follow-up. In conclusion, commonly advocated xylitol-containing products gave elevated concentrations of xylitol in unstimulated whole saliva and dental plaque for at least 8 min after intake.

Mutans streptococci dose response to xylitol chewing gum

Xylitol is promoted in caries-preventive strategies, yet its effective dose range is unclear. This study determined the dose-response of mutans streptococci in plaque and unstimulated saliva to xylitol gum. Participants (n = 132) were randomized: controls (G1) (sorbitol/maltitol), or combinations giving xylitol 3.44 g/day (G2), 6.88 g/day (G3), or 10.32 g/day (G4). Groups chewed 3 pellets/4 times/d. Samples were taken at baseline, 5 wks, and 6 mos, and were cultured on modified Mitis Salivarius agar for mutans streptococci and on blood agar for total culturable flora. At 5 wks, mutans streptococci levels in plaque were 10x lower than baseline in G3 and G4 (P = 0.007/0.003). There were no differences in saliva. At 6 mos, mutans streptococci in plaque for G3 and G4 remained 10x lower than baseline (P = 0.007/0.04). Saliva for G3 and G4 was lower than baseline by 8 to 9x (P = 0.011/0.038). Xylitol at 6.44 g/day and 10.32 g/day reduces mutans streptococci in plaque at 5 wks, and in plaque and unstimulated saliva at 6 mos. A plateau effect is suggested between 6.44 g and 10.32 g xylitol/day.

Reducing oral health disparities: a focus on social and cultural determinants

Oral health is essential to the general health and well-being of individuals and the population. Yet significant oral health disparities persist in the U.S. population because of a web of influences that include complex cultural and social processes that affect both oral health and access to effective dental health care.

This paper introduces an organizing framework for addressing oral health disparities. We present and discuss how the multiple influences on oral health and oral health disparities operate using this framework. Interventions targeted at different causal pathways bring new directions and implications for research and policy in reducing oral health disparities.

Linear response of mutans streptococci to increasing frequency of xylitol chewing gum use: a randomized controlled trial [ISRCTN43479664]

Background

Xylitol is a naturally occurring sugar substitute that has been shown to reduce the level of mutans streptococci in plaque and saliva and to reduce tooth decay. It has been suggested that the degree of reduction is dependent on both the amount and the frequency of xylitol consumption. For xylitol to be successfully and cost-effectively used in public health prevention strategies dosing and frequency guidelines should be established. This study determined the reduction in mutans streptococci levels in plaque and unstimulated saliva to increasing frequency of xylitol gum use at a fixed total daily dose of 10.32 g over five weeks.

Methods

Participants (n = 132) were randomized to either active groups (10.32 g xylitol/day) or a placebo control (9.828 g sorbitol and 0.7 g maltitol/day). All groups chewed 12 pieces of gum per day. The control group chewed 4 times/day and active groups chewed xylitol gum at a frequency of 2 times/day, 3 times/day, or 4 times/day. The 12 gum pieces were evenly divided into the frequency assigned to each group. Plaque and unstimulated saliva samples were taken at baseline and five-weeks and were cultured on modified Mitis Salivarius agar for mutans streptococci enumeration.

Results

There were no significant differences in mutans streptococci level among the groups at baseline. At five-weeks, mutans streptococci levels in plaque and unstimulated saliva showed a linear reduction with increasing frequency of xylitol chewing gum use at the constant daily dose. Although the difference observed for the group that chewed xylitol 2 times/day was consistent with the linear model, the difference was not significant.

Conclusion

There was a linear reduction in mutans streptococci levels in plaque and saliva with increasing frequency of xylitol gum use at a constant daily dose. Reduction at a consumption frequency of 2 times per day was small and consistent with the linear-response line but was not statistically significant.

Oral health care for pregnant and postpartum women

Pregnancy may pose a number of concerns to the mother and the foetus. This can include systemic and oral issues that effect health. Transmission of caries-causing bacteria is one problem that can be minimized by utilizing simple, cost-effective measures. Chlorhexidine rinses and xylitol containing chewing gum will be discussed as possible solutions to this tremendous public health problem.

Salivary antimicrobial peptide expression and dental caries experience in children

Dental caries is a major worldwide oral disease problem in children. Although caries are known to be influenced by dietary factors, the disease results from a bacterial infection; thus, caries susceptibility may be affected by host factors such as salivary antimicrobial peptides. This study aimed to determine a possible correlation between caries prevalence in children and salivary concentrations of the antimicrobial peptides human beta-defensin-3 (hBD-3), the cathelicidin LL37, and the alpha-defensins HNP1-3 (a mixture of HNP1, 2, 3). Oral examinations were performed on 149 middle school children, and unstimulated whole saliva was collected for immunoassays of the three peptides and for assay of caries-causing bacteria in saliva. The median salivary levels of hBD-3, LL37, and HNP1-3 were in the microgram/ml range but were highly variable in the population. While levels of LL37 and hBD-3 did not correlate with caries experience, the median HNP1-3 levels were significantly higher in children with no caries than in children with caries. Children with high caries levels did not have high levels of salivary Streptococcus mutans, and the HNP1-3 level was not correlated with salivary S. mutans. By immunohistochemistry we localized HNP1-3 in submandibular salivary duct cells. HNPs are also released by neutrophils into the gingival crevicular fluid. Both sources may account for their presence in saliva. Low salivary levels of HNP1-3 may represent a biological factor that contributes to caries susceptibility. This observation could lead to new ways to screen for caries susceptibility and to new means of assessing the risk for this common oral problem.

Effect of xylitol-containing chewing gums on interdental plaque-pH in habitual xylitol consumers

OBJECTIVE

The aim was to investigate the effect of high and low amounts of xylitol on the interdental plaque-pH, directly and after sucrose challenge, in schoolchildren with habitual consumption.

MATERIAL AND METHODS

The study group consisted of 11 healthy children (10-15 years) with low caries risk and the experiment had a single-blind crossover (Latin square) design. After a 2-week run-in period with a daily 4.0 g xylitol intake, the children were subjected to single-dose exposures of chewing gums with (i) paraffin (CTR; no xylitol), (ii) low-dose xylitol (LX; 2.0 g xylitol), and (iii) high-dose xylitol (HX; 6.0 g xylitol) in a randomized order separated by a washout period of 1 week. Samples of chewing-stimulated whole saliva were collected prior to and after the experimental period for determination of bacterial counts. The outcome measures were in situ plaque-pH (micro-touch method) and area under the pH curve (AUC).

RESULTS

The AUC was significantly greater (p < 0.05) in the HX group compared to the LX and control groups during the first 5 min after chewing. After a 10% sucrose rinse, the interdental plaque-pH dropped in all groups but the HX regimen displayed significantly less reduction 0-5 min after chewing (p < 0.05). No significant alterations of the total viable counts or mutans streptococci levels in saliva were disclosed during the 4-week experimental period.

CONCLUSIONS

The present results suggested that a high single dose of xylitol had a short and limited beneficial effect on interdental plaque-pH in habitual xylitol consumers, while a low single dose, resembling normal chewing gum use, did not differ from the control.

Children's acceptance of milk with xylitol or sorbitol for dental caries prevention

Background

Xylitol, a polyol sugar, has been shown to reduce dental caries when mixed with food or chewing gum. This study examines the taste acceptability of xylitol in milk as a first step toward measuring the effectiveness of xylitol in milk for the reduction of dental caries in a public health program.

Methods

Three different types of milk (Ultra High Temperature (UHT), powder and evaporated) were tested for acceptability by 75 Peruvian children (25 per milk group, ages 4 to 7 years). Each group evaluated xylitol and sorbitol in one type of milk. In the first phase, each child was presented with a tray of four plastic cups containing 50 ml of milk with 0.021 g/ml xylitol, 0.042 g/ml xylitol, 0.042 g/ml sorbitol or no sugar. Each child was asked to taste the samples in a self-selected order. After tasting each sample, the child placed the milk cup in front of one of three cartoon faces (smile, frown or neutral) representing the child's response to the taste of each sample. In the second phase, the child was asked to rank order the milk samples within each category (smile, frown or neutral). Ranks within categories were then combined to obtain a rank ordering for all the test samples.

Results

The ranking from best to worst for the samples across categories (UHT, powder, evaporated) was xylitol (0.0.042 g/ml), sorbitol (0.042 g/ml), xylitol (0.021 g/ml) and milk alone (Friedman's ANOVA). Xylitol and sorbitol were preferred over milk alone, and xylitol (0.042 g/ml) was preferred to sorbitol (0.042 g/ml)(p < .05 sign test).

Conclusion

Milk sweetened with xylitol is well accepted by Peruvian children ages 4–7 years.