Eva Söderling

Antibacterial effects of a bioactive glass paste on oral microorganisms

Bioactive glasses contain oxides of calcium, sodium, phosphorus, and silicon in a proportion that provides the material with surface activity and concomitantly with the property of forming a strong bond with bone. Bioactive glasses have been tested as bone substitutes in different clinical situations. In an aqueous environment, Ca2+, Na+, PO4(3-) , and Si4+ are released from the glass, resulting in a rise in pH and in osmotic pressure in its vicinity. Since these are factors that potentially influence the viability of oral microorganisms at the dentogingival margin, we studied the effects of bioactive glass S53P4 on the oral microorganisms Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Actinomyces naeslundii, Streptococcus mutans, and Streptococcus sanguis. This was done by incubating each microbe in a suspension, in the presence of bioactive glass S53P4 in powder form. A. naeslundii was found to lose its viability within 10 min under the experimental conditions. A. actinomycetemcomitans, P. gingivalis, and S. mutans lost their viability within 60 min. Also for S. sanguis a significant loss of viability was seen within 60 min, but it was the only microbe that had any viable cells left after 60 min. Thus, in aqueous solutions the powdered bioactive glass S53P4 appears to have a broad antimicrobial effect on microorganisms of both supra- and subgingival plaque. Consequently, it could be useful as an ingredient in tooth-care products that may have beneficial effects on oral health both from a cariologic and a periodontal point of view.

Occurrence of Dental Decay in Children after Maternal Consumption of Xylitol Chewing Gum, a Follow-up from 0 to 5 Years of Age

Studies have shown that prevention of mutans streptococci (MS) colonization in early childhood can lead to prevention of dental decay. In the microbiological part of the present study in Ylivieska, Finland, with 195 mothers with high salivary MS levels, regular maternal use of xylitol chewing gum resulted in a statistically significant reduction in MS colonization in their childrens teeth at the age of 2 years compared with teeth in children whose mothers received fluoride or chlorhexidine varnish treatment. The children did not chew gum or receive varnish treatments. For the present study, the children were examined annually for caries occurrence by experienced clinicians who did not know whether the children were colonized with MS. Regardless of the maternal prevention group, the presence of MS colonization in children at the age of 2 years was significantly related to each childs age at the first caries attack in the primary dentition. In children at the age of 5 years, the dentinal caries (dmf) in the xylitol group was reduced by about 70% as compared with that in the fluoride or chlorhexidine group. We conclude that maternal use of xylitol chewing gum can prevent dental caries in their children by prohibiting the transmission of MS from mother to child.

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.

Bifidobacterium animalis subsp. lactis BB-12 in reducing the risk of infections in infancy

The impact of controlled administration of Bifidobacterium animalis subsp. lactis BB-12 (BB-12) on the risk of acute infectious diseases was studied in healthy newborn infants. In this double-blind, placebo-controlled study, 109 newborn 1-month-old infants were assigned randomly to a probiotic group receiving a BB-12-containing tablet (n 55) or to a control group receiving a control tablet (n 54). Test tablets were administered to the infants twice a day (daily dose of BB-12 10 billion colony-forming units) from the age of 1-2 months to 8 months with a novel slow-release pacifier or a spoon. Breastfeeding habits, pacifier use, dietary habits, medications and all signs and symptoms of acute infections were registered. At the age of 8 months, faecal samples were collected for BB-12 determination (quantitative PCR method). The baseline characteristics of the two groups were similar, as was the duration of exclusive breastfeeding. BB-12 was recovered (detection limit log 5) in the faeces of 62% of the infants receiving the BB-12 tablet. The daily duration of pacifier sucking was not associated with the occurrence of acute otitis media. No significant differences between the groups were observed in reported gastrointestinal symptoms, otitis media or use of antibiotics. However, the infants receiving BB-12 were reported to have experienced fewer respiratory infections (65 v. 94%; risk ratio 0·69; 95% CI 0·53, 0·89; P = 0·014) than the control infants. Controlled administration of BB-12 in early childhood may reduce respiratory infections.

A prospective study on sucrose consumption, visible plaque and caries in children from 3 to 6 years of age

OBJECTIVES As data on the association of sugar consumption and dental caries in the industrialized countries give mixed results, we prospectively studied this association in 135 healthy Finnish children (71 boys, 64 girls). METHODS The dental health and oral hygiene of the children was first examined at the mean age (+/-SD) of 37.4 (+/-2.1) months and again at 73.7 (+/-2.6) months. On both occasions the parents were interviewed about the childs sweet intake and toothbrushing habits, and sucrose consumption was analyzed using 4-day food diaries. RESULTS The proportion of children with caries experience, enamel and dentin lesions combined, increased from 16% to 40%. Daily sucrose intake of children who developed caries by 6 years of age, whether expressed as absolute (g) or as relative (E%) amounts, was already higher at 3 years of age than that of children who stayed caries-free (P<0.05 and P<0.03, respectively). Furthermore, children who used sweets more than once a week at 3 years of age, consumed more sucrose 3 years later (P<0.01) than those who used sweets once a week or less. The proportion of children with a combination of a sweet intake more than once a week and visible plaque, increased (P<0.05) during the follow-up. The risk ratio of children with the combined risk habit at 3 years of age to develop carious lesions by 6 years of age was 1.7 compared to the rest of the children (95% confidence interval 0.9-3.0). CONCLUSIONS We conclude that the manifestation of dental caries at 6 years of age seemed to be associated with a higher daily sucrose intake that had started already at 3 years of age. Moreover, a combination of sweet intake more than once a week and visible plaque at 3 years of age may be predictive of dental health 3 years later.

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. Taken together, the results suggest that: (1) xylitol consumption modifies the mutans streptococci distribution between the dental plaque and the saliva; (2) once selected by the habitual use of xylitol and established in the mouth, the XR natural mutant population maintains itself for up to four years after the withdrawal of the selective agent or at least under minimal and irregular consumption of the agent; and (3) an unknown characteristic of the XR mutants allows them to be more easily shed into the saliva from the plaque than the xylitol-sensitive parental strains.

Xylitol, Mutans Streptococci, and Dental Plaque:

The authors declare no conflict of interest. The caries-controlling or preventing effect of xylitol is more than just excluding fermentable sugars from the diet. This review aims to discuss the specific effects of xylitol which could have contributed to the results of the caries trials. Xylitol promotes mineralization by increasing the flow of saliva, an effect it has in common with all sweeteners. What is unique for xylitol is that it is practically non-fermentable by oral bacteria. Xylitol is known to inhibit growth, metabolism, as well as polysaccharide production of mutans streptococci. During habitual xylitol consumption, the counts of mutans streptococci decrease and remain on a lower level as long as the consumption lasts. Habitual xylitol consumption also prevents mother-child transmission of mutans streptococci. In addition to growth inhibition, the reduction of insoluble extracellular polysaccharides is probably of importance for the xylitol-induced decrease in both counts and transmission of mutans streptococci.

Solubility of calcium salts, enamel, and hydroxyapatite in aqueous solutions of simple carbohydrates

SummaryThe solubility of various Ca(II) salts, hydroxyapatite, and powdered human dental enamel in the presence of simple carbohydrates was studied by determining the complex strength between Ca(II) and the carbohydrates. In 1.0m CaSO4, the following simplified sequence of complex strengths was obtained for the more common carbohydrates: Na-citrate>d-sorbitol>xylitol>d-mannitol>d-fructose>d-glucose>d-xylose. Whereas the more soluble Ca(II) compounds (like CaSO4) exerted measurable complexation with xylitol, no such complexation was found with hydroxyapatite and enamel powder. This also concerned other alditols. Calculation of the stability constants (K) showed sorbitol (K=0.81 M) and xylitol (K=0.67m) to form stronger complexes in saturated CaSO4 than other alditols. The most suitable coordination site appeared to be a vicinalcis-cis-triol. Precipitation studies showed that 0.5m xylitol and 0.5 M sorbitol significantly retarded the formation of calcium phosphate precipitates from a solution of Ca(II) and phosphate, compared with the effect caused by glucose, sorbose, or xylose. The effect caused by xylitol and sorbitol was explained in terms of partial displacement of water molecules in the primary hydration layer of Ca(II) ions, caused by competition between polyol and water molecules. In the presence of aldoses and ketoses, virtually instantaneous precipitation occurred. These results suggest that open-chain alditols may influence the chemical reactions of Ca(II) in plaque, saliva, and caries lesions. Alditols do not function as demineralizing agents of the teeth, however. Through the retarding effect on calcium phosphate precipitation, alditols may favorably govern remineralization of carious lesions.

Oral Biochemical Status and Depression of Streptococcus mutans in Children during 24- to 36-Month Use of Xylitol Chewing Gum

Plaque and whole saliva samples were collected from initially 11- to 12-year-old children randomly chosen from two groups which participated in a 2- to 3-year field trial designed to test the efficacy of xylitol chewing gums in caries prevention. No initial differences were observed between the groups with regard to the plaque levels of Streptococcus mutans, but at the end of the 2-year xylitol gum regimen, the levels were smaller (p less than 0.05) in children using xylitol gum than in control children. In a similar follow-up study on children who were considered to be at high risk with regard to dental caries and who continued the study over a 3rd year, the xylitol-consuming subjects showed at the end of the study significantly smaller (p less than 0.004) salivary S. mutans counts than the control children. These effects were achieved after using up to 3 xylitol gums/day (daily xylitol dose per child was 7-10 g). Salivary flow rate and several salivary chemical parameters did not change.

Interactions between the bioactive glass S53P4 and the atrophic rhinitis-associated microorganism klebsiella ozaenae.

In an aqueous environment, ions are released from a bioactive glass (BAG) and the pH rises in its vicinity. This may influence both growth and colonization of microorganisms. We studied the effects of the BAG S53P4 on the atrophic rhinitis-associated microorganism Klebsiella ozaenae. The glass was used in the form of granules or discs. Growth inhibition was studied using an agar plate test. Adhesion was studied by incubating bacterial suspension with the glass. The effect of the presence of the bacteria on the formation of the Si-rich layer on the bioactive glass was also analyzed. Furthermore, a follow up study of 19-74 months with ozena patients surgically treated with the BAG S53P4 was performed. The bioactive glass showed no clear growth inhibition of K. ozaenae in the agar plate test. K. ozaenae showed low adherence to the BAG S53P4. No growth of the microbe was seen on the glass during the 8 h incubations and the Si-rich layer was formed normally. The clinical follow-up study showed no infections of the implants and the symptoms of the patients were markedly reduced. Thus, the BAG S53P4 did not favor adhesion and colonization of K. ozaenae, in vitro, which is supported by the in vivo findings showing no BAG-associated infections or reinfections.