Pernilla Lif Holgerson

Oral microbial profile discriminates breast-fed from formula-fed infants

Objectives: Little is known about the effect of diet on the oral microbiota of infants, although diet is known to affect the gut microbiota. The aims of the present study were to compare the oral microbiota in breast-fed and formula-fed infants, and investigate growth inhibition of streptococci by infant-isolated lactobacilli. Methods: A total of 207 mothers consented to participation of their 3-month-old infants. A total of 146 (70.5%) infants were exclusively and 38 (18.4%) partially breast-fed, and 23 (11.1%) were exclusively formula-fed. Saliva from all of their infants was cultured for Lactobacillus species, with isolate identifications from 21 infants. Lactobacillus isolates were tested for their ability to suppress Streptococcus mutans and S sanguinis. Oral swabs from 73 infants were analysed by the Human Oral Microbe Identification Microarray (HOMIM) and by quantitative polymerase chain reaction for Lactobacillus gasseri. Results: Lactobacilli were cultured from 27.8% of exclusively and partially breast-fed infants, but not from formula-fed infants. The prevalence of 14 HOMIM-detected taxa, and total salivary lactobacilli counts differed by feeding method. Multivariate modelling of HOMIM-detected bacteria and possible confounders clustered samples from breast-fed infants separately from formula-fed infants. The microbiota of breast-fed infants differed based on vaginal or C-section delivery. Isolates of L plantarum, L gasseri, and L vaginalis inhibited growth of the cariogenic S mutans and the commensal S sanguinis: L plantarum >L gasseri >L vaginalis. Conclusions: The microbiota of the mouth differs between 3-month-old breast-fed and formula-fed infants. Possible mechanisms for microbial differences observed include species suppression by lactobacilli indigenous to breast milk.

Snacking Habits and Caries in Young Children

Dental caries is caused by a combination of infection and diet. This disease, if left untreated, may lead to pain, and impair the quality of life, nutritional status and development of young children. The objective was to investigate the association between snacking and caries in a population at high risk of dental caries. American preschool children (n = 1,206) were recruited in the offices of paediatricians. Data on sociodemographic characteristics, oral hygiene, breast-feeding, use of bottle and snacking were collected by questionnaire. Plaque presence, the number of teeth and their caries status (deft) were scored. The children sampled were 61% Black, 27% White and 10% Asian. Of the 1- to 2-, 2- to 3- and 3- to 4-year-old children, 93.8, 82.4 and 77.3% were caries free, and their mean caries scores were 0.16, 0.58 and 0.93, respectively. Multivariate partial least squares (PLS) modelling revealed plaque presence, lowest income, descriptors for tooth exposure time (number of teeth and age) and cariogenic challenge (total intake of sugar-containing snacks and chips/crisps, and chips intake with a sugar-containing drink) to be associated with more caries. These differences were also found in univariate analyses; in addition, children who continued breast-feeding after falling asleep had significantly higher deft values than those who did not. PLS modelling revealed that eating chips clustered with eating many sweet snacks, candies, popcorn and ice cream. We conclude that, in addition to the traditional risk indicators for caries – presence of plaque, sugar intake and socioeconomic status –, consumption of chips was associated with caries in young children.

Validation of an age-modified caries risk assessment program (Cariogram) in preschool children

Objectives. (i) To validate caries risk profiles assessed with a computer program against actual caries development in preschool children, (ii) to study the possible impact of a preventive program on the risk profiles, and (iii) to compare the individual risk profiles longitudinally. Material and methods. Caries risk was assessed in 125 two-year-old children invited to participate in a 2-year caries-preventive trial with xylitol tablets. At 7 years of age, 103 were available for follow-up, 48 from the former intervention group and 55 from the control group. At baseline and after 5 years, 7 variables associated with caries were collected through clinical examinations and questionnaires, and scored and computed with a risk assessment program (Cariogram). Results. Children assessed as having a “low chance (0–20%) of avoiding caries” had significantly higher caries at 7 years of age compared to children with a lower risk in the control group (p<0.05) but not in the intervention group. Overall predictive accuracy and precision, however, were moderate in both groups. Less than half of the children remained in the same risk category at both ages, despite a largely unchanged consumption pattern of sugar. The majority of the children who changed category displayed a lowered risk at 7 years. The intervention program seemed to impair the predictive abilities of Cariogram. Conclusion. A modified Cariogram applied on preschool children was not particularly useful in identifying high caries risk patients in a low-caries community.

Diet Intake and Caries Prevalence in Four-Year-Old Children Living in a Low-Prevalence Country

Preventive measures have dramatically decreased the prevalence of dental caries in children. However, risk factors for the disease in children living in low-prevalence areas remain elusive. In the present study we evaluated associations between dental caries, saliva levels of mutans streptococci and lactobacilli, and diet with special emphasis on the intake of fermentable carbohydrates and dairy products in 4-year-old children living in an area where the overall caries prevalence was low. Dietary intake was recorded in 234 infants as part of the Study of Infant Nutrition in Umeå, Sweden (SINUS). Of these the parents of 124 children gave consent to participate in a follow-up at 4 years of age. Dietary intake, height and weight, dental caries, oral hygiene, including tooth brushing habits, presence of plaque and gingival inflammation, fluoride habits and numbers of mutans streptococci and lactobacilli in saliva were recorded. Using multivariate stepwise logistic regression, caries experience was negatively associated with intake frequency of cheese (OR = 0.67; 95% CI = 0.44–0.98) and positively associated with the salivary level of mutans streptococci (OR = 1.57; 95% CI = 1.21–2.03). Caries experience was not correlated with intake frequency or amounts of carbohydrate-containing foods, with any other particular food, or with daily intake of energy, carbohydrate or any other macro- or micronutrient. We conclude that cheese intake may have a caries-protective effect in childhood populations where the overall caries prevalence and caries experience are low and the children are regularly exposed to fluoride from toothpaste.

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.

Effect of xylitol and xylitol-fluoride lozenges on approximal caries development in high-caries-risk children

AIM To evaluate the effect of xylitol- and xylitol/fluoride-containing lozenges on approximal caries development in young adolescents with high caries risk. STUDY DESIGN A 2-year double-blind trial with two parallel arms and a nonrandomized reference group. MATERIAL AND METHODS One hundred and sixty healthy 10- to 12-year-old children with high caries risk were selected. After informed consent, they were randomly assigned into a xylitol and a xylitol/fluoride group. They were instructed to take two tablets three times a day (total xylitol and fluoride dose 2.5 g and 1.5 mg, respectively). The compliance was checked continuously and scored as good, fair, or poor. A reference no-tablet group was also selected (n = 70) for group comparison. The outcome measure was approximal caries incidence. RESULTS The dropout rate was 28%, and 41% exhibited a good compliance with the study protocol. No statistically significant differences in caries incidence could be found between the study groups (P > 0.05). Among a subgroup of children who demonstrated good compliance, the mean DeltaDMFSa value was significantly lower in the xylitol/fluoride group compared to the xylitol group, 1.0 +/- 2.3 vs. 3.3 +/- 4.6 (P < 0.05), while no difference could be displayed between any of the study groups and the reference group (P > 0.05). CONCLUSION The results from this 2-year trial did not support a self-administered regimen of xylitol- or xylitol/fluoride-containing lozenges for the prevention of approximal caries in young adolescents with high caries risk.

Characterization and in vitro properties of oral lactobacilli in breastfed infants

BackgroundLactobacillus species can contribute positively to general and oral health and are frequently acquired by breastfeeding in infancy. The present study aimed to identify oral lactobacilli in breast and formula-fed 4 month-old infants and to evaluate potential probiotic properties of the dominant Lactobacillus species detected. Saliva and oral swab samples were collected from 133 infants who were enrolled in a longitudinal study (n=240) examining the effect of a new infant formula on child growth and development. Saliva was cultured and Lactobacillus isolates were identified from 16S rRNA gene sequences. Five L. gasseri isolates that differed in 16S rRNA sequence were tested for their ability to inhibit growth of selected oral bacteria and for adhesion to oral tissues. Oral swab samples were analyzed by qPCR for Lactobacillus gasseri.Results43 (32.3%) infants were breastfed and 90 (67.7%) were formula-fed with either a standard formula (43 out of 90) or formula supplemented with a milk fat globule membrane (MFGM) fraction (47 out of 90). Lactobacilli were cultured from saliva of 34.1% breastfed infants, but only in 4.7% of the standard and 9.3% of the MFGM supplemented formula-fed infants. L. gasseri was the most prevalent (88% of Lactobacillus positive infants) of six Lactobacillus species detected. L. gasseri isolates inhibited Streptococcus mutans binding to saliva-coated hydroxyapatite, and inhibited growth of S. mutans, Streptococcus sobrinus, Actinomyces naeslundii, Actinomyces oris, Candida albicans and Fusobacterium nucleatum in a concentration dependent fashion. L. gasseri isolates bound to parotid and submandibular saliva, salivary gp340 and MUC7, and purified MFGM, and adhered to epithelial cells. L. gasseri was detected by qPCR in 29.7% of the oral swabs. Breastfed infants had significantly higher mean DNA levels of L. gasseri (2.14 pg/uL) than infants fed the standard (0.363 pg/uL) or MFGM (0.697 pg/uL) formula.ConclusionsLactobacilli colonized the oral cavity of breastfed infants significantly more frequently than formula-fed infants. The dominant Lactobacillus was L. gasseri, which was detected at higher levels in breastfed than formula-fed infants and displayed probiotic traits in vitro.

Maturation of Oral Microbiota in Children with or without Dental Caries

Background The aim of this longitudinal study was to evaluate the oral microbiota in children from age 3 months to 3 years, and to determine the association of the presence of caries at 3 years of age. Methods and findings Oral biofilms and saliva were sampled from children at 3 months (n = 207) and 3 years (n = 155) of age, and dental caries was scored at 3 years of age. Oral microbiota was assessed by culturing of total lactobacilli and mutans streptococci, PCR detection of Streptococcus mutans and Streptococcus sobrinus, 454 pyrosequencing and HOMIM (Human Oral Microbe Identification Microarray) microarray detection of more then 300 species/ phylotypes. Species richness and taxa diversity significantly increased from 3 months to 3 years. Three bacterial genera, present in all the 3-month-old infants, persisted at 3 years of age, whereas three other genera had disappeared by this age. A large number of new taxa were also observed in the 3-year-olds. The microbiota at 3 months of age, except for lactobacilli, was unrelated to caries development at a later age. In contrast, several taxa in the oral biofilms of the 3-year-olds were linked with the presence or absence of caries. The main species/phylotypes associated with caries in 3-year-olds belonged to the Actinobaculum, Atopobium, Aggregatibacter, and Streptococcus genera, whereas those influencing the absence of caries belonged to the Actinomyces, Bergeyella, Campylobacter, Granulicatella, Kingella, Leptotrichia, and Streptococcus genera. Conclusions Thus, during the first years of life, species richness and taxa diversity in the mouth increase significantly. Besides the more prevalent colonization of lactobacilli, the composition of the overall microbiota at 3 months of age was unrelated to caries development at a later age. Several taxa within the oral biofilms of the 3-year-olds could be linked to the presence or absence of caries.

Oral Microbiota Shift after 12-Week Supplementation with Lactobacillus reuteri DSM 17938 and PTA 5289; A Randomized Control Trial

Background Lactobacillus spp. potentially contribute to health by modulating bacterial biofilm formation, but their effects on the overall oral microbiota remain unclear. Methods and Findings Oral microbiota was characterized via 454-pyrosequencing of the 16S rDNA hypervariable region V3-V4 after 12 weeks of daily Lactobacillus reuteri DSM 17938 and PTA 5289 consumption. Forty-four adults were assigned to a test group (n = 22) that received lactobacilli lozenges (108 CFU of each strain/lozenge) or a control group that received placebo (n = 22). Presence of L. reuteri was confirmed by cultivation and species specific PCR. Tooth biofilm samples from 16 adults before, during, and after exposure were analyzed by pyrosequencing. A total of 1,310,292 sequences were quality filtered. After removing single reads, 257 species or phylotypes were identified at 98.5% identity in the Human Oral Microbiome Database. Firmicutes, Bacteroidetes, Fusobacteria, Proteobacteria, and Actinobacteria were the most abundant phyla. Streptococcus was the most common genus and the S. oralis/S. mitis/S. mitis bv2/S. infantis group comprised the dominant species. The number of observed species was unaffected by L. reuteri exposure. However, subjects who had consumed L. reuteri were clustered in a principal coordinates analysis relative to scattering at baseline, and multivariate modeling of pyrosequencing microbiota, and culture and PCR detected L. reuteri separated baseline from 12-week samples in test subjects. L. reuteri intake correlated with increased S. oralis/S. mitis/S. mitis bv2/S. infantis group and Campylobacter concisus, Granulicatella adiacens, Bergeyella sp. HOT322, Neisseria subflava, and SR1 [G-1] sp. HOT874 detection and reduced S. mutans, S. anginosus, N. mucosa, Fusobacterium periodicum, F. nucleatum ss vincentii, and Prevotella maculosa detection. This effect had disappeared 1 month after exposure was terminated. Conclusions L. reuteri consumption did not affect species richness but induced a shift in the oral microbiota composition. The biological relevance of this remains to be elucidated. Trial Registration ClinicalTrials.gov NCT02311218

Milk and oral health.

Oral health includes freedom from disease in the gums, the mucosa and the teeth. There has been a striking reduction in dental caries and periodontitis in industrialized countries, although the proportion with severe disease has remained at 10-15%, and the prevalence increases in less developed countries. If left untreated, these diseases may lead to pain, and impaired quality of life and nutritional status. Prevention and treatment need, besides traditional implementation of proper oral hygiene, sugar restriction and use of fluoride, newer cost-effective strategies. Non-sweetened dairy products, which are proven non-cariogenic, or specific bioactive components from alike sources might prove to be part of such strategies. Thus, milk proteins, such as bovine and human caseins and lactoferrin, inhibit initial attachment of cariogenic mutans streptococci to hydroxyapatite coated with saliva or purified saliva host ligands. In contrast, both bovine and human milk coated on hydroxyapatite promotes attachment of commensal Actinomyces naeslundii and other streptococci in vitro, and phosphorylated milk-derived peptides promote maintenance of tooth minerals, as shown for the β-casein-derived caseino-phosphate peptide. Observational studies are promising, but randomized clinical trials are needed to reveal if dairy products could be a complementary treatment for oral health.