Characterization of maternal mutans streptococci transmission in an African American population

Pilot GWAS of caries in African-Americans shows genetic heterogeneity

BACKGROUND

Dental caries is the most common chronic disease in the US and disproportionately affects racial/ethnic minorities. Caries is heritable, and though genetic heterogeneity exists between ancestries for a substantial portion of loci associated with complex disease, a genome-wide association study (GWAS) of caries specifically in African Americans has not been performed previously.

METHODS

We performed exploratory GWAS of dental caries in 109 African American adults (age > 18) and 96 children (age 3-12) from the Center for Oral Health Research in Appalachia (COHRA1 cohort). Caries phenotypes (DMFS, DMFT, dft, and dfs indices) assessed by dental exams were tested for association with 5 million genotyped or imputed single nucleotide polymorphisms (SNPs), separately in the two age groups. The GWAS was performed using linear regression with adjustment for age, sex, and two principal components of ancestry. A maximum of 1 million adaptive permutations were run to determine empirical significance.

RESULTS

No loci met the threshold for genome-wide significance, though some of the strongest signals were near genes previously implicated in caries such as antimicrobial peptide DEFB1 (rs2515501; p = 4.54 × 10- 6) and TUFT1 (rs11805632; p = 5.15 × 10- 6). Effect estimates of lead SNPs at suggestive loci were compared between African Americans and Caucasians (adults N = 918; children N = 983). Significant (p < 5 × 10- 8) genetic heterogeneity for caries risk was found between racial groups for 50% of the suggestive loci in children, and 12-18% of the suggestive loci in adults.

CONCLUSIONS

The genetic heterogeneity results suggest that there may be differences in the contributions of genetic variants to caries across racial groups, and highlight the critical need for the inclusion of minorities in subsequent and larger genetic studies of caries in order to meet the goals of precision medicine and to reduce oral health disparities.

Factors associated with early childhood caries among 3 to 6 year old children in India: A case control study

BACKGROUND

Early childhood caries (ECC) is a multifactorial disease as it is associated with biological, social and behavioral risk factors. However, not much research studied the influence of perinatal factors like birth weight, mode of delivery and gestational age with ECC. Aim of this study is to assess the association between ECC and risk factors, such as Socio-economic status (SES), Body mass index (BMI), Gestation age, birth weight and mode of delivery among Indian children aged 3 to 6 years.

METHODS

In this cross sectional study 690 school children aged 3-6 years were included from five government and primary schools among them 345 were suffering from ECC. Data acquisition involved an oral clinical exam, anthropometric measures and a questionnaire administered in interview form to acquire information on socio-demographic data and Gestational age; mode of delivery; birth weight and socio-economic status. Chi-squared test was used to test the association between categorical variables. Multiple logistic regression analysis used to assess strength of association between risk factors and ECC while controlling known confounders.

RESULTS

Multiple logistic regression analysis revealed that male children, increasing age, preterm birth and cesarean section are associated with increased risk of developing ECC.

CONCLUSIONS

Perinatal factors play a vital role in determination ECC burden. Early life interventions and precautions can be useful strategy to control and prevent ECC.

Survey of Oral Microbial Diversity using PCR-based Denaturing Gradient Gel Electrophoresis

Polymicrobial biofilms in the human oral cavity exhibit marked diversity. PCR-based denaturing gradient gel electrophoresis (PCR-DGGE) surveys microbial diversity by displaying PCR-generated 16S rDNA fragments that migrate at different distances, reflecting the differences in the base-pair ( i.e., % G+C) composition of the fragment. This study examined DGGE-generated diversity profiles of cultivable bacteria from individuals with different caries status. Initially, we developed a set of PCR-DGGE running conditions appropriate to oral bacteria. Next, we assessed migration standards from known oral bacterial reference strains. To test the methods, we profiled 20 bacterial saliva samples cultivated from young adults. The study produced a battery of species-specific 16S rDNA amplicons that could be used as a migration distance standard necessary for computer-assisted profile analysis. From the clinical samples, we found a significantly greater diversity of oral microbes in caries-free individuals compared with caries-active individuals ( P = 0.01). These findings suggest thtat a portion of oral microbiota of caries-active individuals may be absent, suppressed, or replaced.

Mother-to-child transmission of mutans streptococci

Mutans streptococci (MS) are the major group of pathogens implicated in dental caries. Like other infectious diseases, transmission of the causative microorganisms is the initial and essential step that should be understood relative to disease control and prevention. This review summarizes current knowledge regarding MS transmission, especially from mothers to their children. Included are methods used to study transmission, sources of MS, initial acquisition, factors concerning transmission and prevention of transmission. Information accumulated over many decades showed the involvement of MS transmission in the pathogenesis of caries, hence several preventive measurements have been proposed. Nevertheless, some essential aspects remain to be elucidated for more benefits of practical application.

Mode of delivery, mutans streptococci colonization, and early childhood caries in three- to five-year-old Thai children

OBJECTIVE

To investigate whether mode of delivery is associated with mutans streptococci (MS) colonization and early childhood caries (ECC) in preschool Thai children.

METHODS

Three hundred and fifty mothers and their 3- to 5-year-old children (184 born vaginally and 166 born by Caesarean section) participated in the study. Data included a dental examination, MS colonization assessed by the Dentocult(®) SM Strip Mutans method, and a questionnaire survey of family socio-demographic information, as well as children's birth history, dietary habits, and oral health practices.

RESULTS

Overall, ECC prevalence was 56% in 3-year-old and 78% in 5-year-old Thai children. Compared to children delivered by C-section, vaginally born children experienced increased ECC prevalence (73.8% versus 59.6%; P = 0.009) and were more likely to have higher MS scores (OR = 1.8, 95% CI = 1.1-2.9), adjusting for mother's gestational age, MS score, feeding practice habits; child's age and tooth brushing habits. Children's MS scores were highly correlated with their mothers' MS scores (P < 0.001). Additionally, children's age, MS colonization, and mothers' prechewing feeding habits were the most significant risk indicators for ECC in Thai children.

CONCLUSION

Our findings suggest that mode of delivery is significantly correlated with MS colonization and caries outcomes in young Thai children. Future studies are needed to further understand the possible biological mechanisms linking mode of child delivery to the colonization of cariogenic microbiota and development of ECC.

Mutans streptococci and caries prevalence in children after early maternal caries prevention: a follow-up at 19 years of age

AIM

The efficacy of early maternal caries prevention was evaluated. Furthermore, the difference between children colonised with mutans streptococci (MS) at an early or late stage with regard to the prevalence of carious lesions was determined.

METHODS

The children of first-time mothers selected on the basis of high salivary levels of MS for participation in a caries prevention programme were recalled at the age of 19 years. They were examined for salivary MS, lesion prevalence (decayed and filled surfaces, DFS) and MS in plaque from 12 selected proximal surfaces.

RESULTS

The recall rate was 70% for the children of both the high-control and interventional groups. All high-control children and 67% of the interventional children were colonised by MS. All the children with non-detectable MS in saliva were also negative in all plaque samples. No statistically significant difference was found between the groups in terms of DFS, although more interventional children were caries free than in the control group. Early-colonised children, irrespective of group identity, had higher salivary MS levels and DFS than later MS-colonised children.

CONCLUSION

The results indicate that it is possible to remain negative for MS into adulthood if non-colonised at an early age and this affects the development of carious lesions. Strategies for the prevention of dental caries in early childhood should, therefore, include measures to prevent or delay early colonisation by cariogenic bacteria.

Factors influencing oral colonization of mutans streptococci in young children

This paper aims to critically review current knowledge about the key factors involved in oral colonization of the cariogenic group of bacteria, mutans streptococci (MS) in young children. MS, consisting mainly of the species Streptococcus mutans and Streptococcus sobrinus, are commonly cultured from the mouths of infants, with prevalence of infection ranging from around 30 per cent in 3 month old predentate children to over 80 per cent in 24 month old children with primary teeth. MS is usually transmitted to children through their mothers, and the risk of transmission increases with high maternal salivary levels of MS and frequent inoculation. Factors that affect the colonization of MS may be divided into bacterial virulence, host-related and environmental factors. Complex interaction among these factors determine the success and timing of MS colonization in the child. As clinical studies have shown that caries risk is correlated with age at which initial MS colonization occurred, strategies for the prevention of dental caries should include timely control of colonization of the cariogenic bacteria in the mouths of young children.

The transmission of BANA-positive periodontal bacterial species from caregivers to children

BACKGROUND

The purpose of the authors' study was to use the N-benzoyl-DL-arginine-2-naphthy-lamide (BANA) test (BANAMet LLC, Ann Arbor, Mich.) to obtain information regarding the prevalence of an enzyme unique to certain periodontal pathogens in plaque samples of children, as well as the potential transmission of these pathogens from caregivers to children.

METHODS

The authors tested 218 subjects (3 to 10 years old) and 195 care-givers at four pediatric dentistry clinics in Taipei, Taiwan.

RESULTS

Forty-four percent of the children had at least one plaque sample that tested positive and/or weakly positive. Positive results were more frequent in the mixed dentition, as well as in children with gingivitis (P < .001). A logistic regression model showed that if the BANA test results for the care-giver were positive, the odds of the child's also having positive test results were 55 times greater (P < .001; confidence interval [CI] = 14 to 224) than those for a child whose caregiver had negative BANA test results. Other predictors were the presence of a mixed dentition (P < .001; odds ratio [OR] = 11; CI = 3.5 to 33.5) and the children's papillary bleeding scores (P < .001, OR = 3.1, CI = 2.0 to 4.7).

CONCLUSION

The BANA test results were positive for almost one-half of the children. A positive reaction was associated with gingivitis, a mixed dentition, a BANA-positive caregiver or a caregiver with a history of periodontal disease in the family.

CLINICAL IMPLICATIONS

The authors propose an anaerobic periodontal infection risk model in which children with a mixed dentition who have gingivitis and a caregiver with a history of periodontal disease would undergo the BANA test.

SalivaryActinomyces naeslundiiGenospecies 2 andLactobacillus caseiLevels Predict Pregnancy Outcomes

BACKGROUND

Gravida's poor periodontal health is emerging as a modifiable independent risk factor for preterm delivery and low birth weight.

METHODS

To test the hypothesis that oral bacteria other than periodontal pathogens are also associated with pregnancy outcomes, specific oral bacterial levels measured during pregnancy were evaluated in relation to gestational age and birth weight while controlling for demographic, medical, and dental variables. The study population consisted of 297 predominantly African- American women who were pregnant for the first time. The salivary bacterial levels evaluated were Streptococcus mutans, Streptococcus sobrinus, Streptococcus sanguinus, Lactobacillus acidophilus, Lactobacillus casei, Actinomyces naeslundii genospecies (gsp) 1 and 2, total streptococci, and total cultivable organisms.

RESULTS

For 1 unit increase in log(10) A. naeslundii gsp 2 levels, there was a 60 gm decrease in birth weight (beta = -59.7 g; SE = 29.1; P = 0.04), and a 0.17 week decrease in gestational age (beta = -0.17 wk; SE = 0.09; P = 0.05). In contrast, per 1 unit increase in log(10) L. casei levels, there was a 42 gm increase in birth weight (beta = 42.2 g; SE = 19.3; P = 0.03), and a 0.13 week increase in gestational age (beta = 0.13 week; SE = 0.06; P = 0.04).

CONCLUSIONS

We conclude that other oral bacterial species can also be related to pregnancy outcomes in addition to previously reported periodontal pathogens. These organism levels may not only predict poor pregnancy outcomes, but also be used as modifiable risk factors in reducing prematurity and low birth weight.