Intraspecies interactions of Streptococcus mutans impact biofilm architecture and virulence determinants in childhood dental caries.

Early childhood dental caries (ECC) is the most common chronic disease among children with a heavy disease burden among low socioeconomic populations. Streptococcus mutans is most frequently associated with initiation of ECC. Many studies report children with multiple S. mutans strains (i.e., genotypes) having greater odds of developing ECC, studies investigating intraspecies interactions in dental caries are lacking. In this study, the impact of intraspecies interactions on cariogenic and fitness traits of clinical S. mutans isolates are investigated using in-vitro and in-vivo approaches. Initially clinical S. mutans isolates of 10 children from a longitudinal epidemiological study were evaluated. S. mutans strains (G09 and G18, most prevalent) isolated from one child were used for subsequent analysis. Association analysis was used to determine if presence of multiple S. mutans genotypes within the first-year of colonization was associated with caries. Biofilm analysis was performed for single and mixed cultures to assess cariogenic traits, including biofilm biomass, intra-polysaccharide, pH, and glucan. Confocal Laser Scanning Microscopy (CLSM) and time-lapse imaging were used to evaluate spatial and temporal biofilm dynamics, respectively. A Drosophila model was used to assess colonization in-vivo. Mean biofilm pH was significantly lower in co-cultured biofilms as compared with monoculture biofilms. Doubling of S. mutans in-vitro biofilms was observed by CLSM and in-vivo colonization in Drosophila for co-cultured S. mutans. Individual strains occupied specific domains in co-culture and G09 contributed most to increased co-culture biofilm thickness and colonization in Drosophila. Biofilm formation and acid production displayed distinct signatures in time-lapsed experiments.

Body Mass Index and Early Childhood Caries in High Caries Risk Children: A Nested Case-Control Methodological Investigation.

Purpose: To evaluate body mass index (BMI) - early childhood caries (ECC) relationships with various BMI expressions.
Methods: Healthy eight- to 18-month children with unerupted molar(s) were conveniently sampled from Uniontown, Ala., USA, a high caries risk community (i. e., rural, poor, racial minority). Staff measured height/weight, dentists conducted oral exams, and parents completed questionnaires annually (from 2008 to 2014) for BMI, ECC (decayed, missing due to caries, filled primary tooth surfaces [dmfs] score), and sociodemographic values, respectively. Nationally recognized standard (underweight-normal-overweight-obese), crude (overweight/obese-not), and continuous BMI variables were evaluated. Logistic regressions (with restricted cubic splines) assessed BMI-ECC relationships, producing odds ratios (ORs) and 95 percent confidence intervals (95% CIs).
Results: Male and female ECC ORs supported positive and negative parabolic functions, respectively, for increasing standard BMI categories; underweight males were associated with ECC (OR=4.59; 95% CI=1.06 to 19.85). Crudely expressed, overweight/obese males and females had lower and slightly increased odds of ECC, respectively. A continuous BMI produced a similar OR across sexes, while spline models suggested nonlinearity for each.
Conclusion: BMI-ECC associations might be nonlinear; being underweight could be a male ECC risk factor. Studies should include extreme BMI values without collapsing BMI categories.

Reporting stAndards for research in PedIatric Dentistry (RAPID): an expert consensus-based statement.

BACKGROUND: Reporting guidelines for different study designs are currently available to report studies with accuracy and transparency. There is a need to develop supplementary guideline items that are specific to areas within Pediatric Dentistry. This study aims to develop Reporting stAndards for research in PedIatric Dentistry (RAPID) guidelines using a pre-defined expert consensus-based Delphi process. METHODS: The development of the RAPID guidelines was based on the Guidance for Developers of Health Research Reporting Guidelines. Following a comprehensive search of the literature, the Executive Group identified ten themes in Pediatric Dentistry and compiled a draft checklist of items under each theme. The themes were categorized as: General, Oral Medicine, Pathology and Radiology, Children with Special Health Care Needs, Sedation and Hospital Dentistry, Behavior Guidance, Dental Caries, Preventive and Restorative Dentistry, Pulp Therapy, Traumatology, and Interceptive Orthodontics. A RAPID Delphi Group (RDG) was formed comprising of 69 members from 15 countries across six continents. Items were scored using a 9-point rating Likert scale. Items achieving a score of seven and above, marked by at least 70% of RDG members were accepted into the RAPID checklist items. Weighted mean scores were calculated for each item. Statistical significance was set at p < 0.05 and one-way ANOVA was used to calculate the difference in the weighted mean scores between the themes. RESULTS: The final RAPID checklist comprised of 128 items that were finalized and approved by the RDG members in the online consensus meeting. The percentage for high scores (scores 7 to 9) ranged from 69.57 to 100% for individual items. The overall weighted mean score of the final items ranged from 7.51 to 8.28 (out of 9) and the difference was statistically significant between the themes (p < 0.05). CONCLUSIONS: The RAPID statement provides guidance to researchers, authors, reviewers and editors, to ensure that all elements relevant to particular studies are adequately reported.

Children's detailed non-water beverage consumption habits and longitudinal early childhood caries experiences.

OBJECTIVES: Sugar-sweetened beverages and dental caries are prevalent among children. Measurement choices could explain their inconsistent relationships. This study evaluated associations between detailed baseline non-water beverage consumption (NWBC) behaviors and longitudinal early childhood caries (ECC) experiences in young, high-caries risk children. METHODS: Researchers followed poor, rural, African Americans, recruited at 8-18 months old from Uniontown, Alabama, through convenience sampling, annually for 5 years (N = 66). Baseline questionnaires obtained demographics, oral hygiene, and daily dietary histories, including beverage types, frequencies, and NWBC behaviors of intake speed (intermittent/rapid), container (bottles/non-bottles), and bedtime beverages (yes/no). Dentists conducted examinations annually to determine decayed, missing, filled (carious) surfaces (dmfs) scores, producing increments (dmfsfinal - dmfsinitial ). Age-adjusted logistic regressions estimated odds ratios (OR) and 95% confidence intervals (95% CI) for ECC (carious: incidence >0 versus caries-free: incidence = 0) with NWBC behavior then NWBC frequency, individually and conditional on NWBC behaviors, exposures. RESULTS: NWBC behaviors were not associated with ECC; juice was significant (OR: 2.0, 95% CI: 1.0, 4.2). Adjusting for intake speed, juice persisted as a risk factor (OR: 2.1, 95% CI: 1.0, 4.3), remaining suggestive after controlling for container or bedtime beverages (OR: 2.0, 95% CI: 0.9, 4.3; OR: 1.9, 95% CI: 0.9, 4.0, respectively). Container could be an effect modifier (ORbottle : 3.5, 95% CI: 0.8, 16.2 vs. ORnon-bottle : 1.5, 95% CI: 0.6, 3.7). Milk was not associated with ECC. CONCLUSIONS: Independently, NWBC behaviors are insufficient in evaluating NWBC/ECC relationships; beverage type, frequency, and consumption behaviors, collectively, can better evaluate associations.

Overestimation of Early Childhood Caries Using the dmfs Index.

Purpose: The preferred epidemiological caries assessment method is the decayed, missing, and filled surfaces (dmfs) score, which records all crowned/missing primary teeth's surfaces as carious. The purpose of this study was to evaluate the dmfs score's accuracy in capturing caries-affected (versus treated) surfaces of crowned/extracted teeth. Methods: A high-caries risk cohort of children, eight to 18 months old at baseline, were recruited from a nonfluoridated, rural, minority, and low-income community. Oral examinations occurred every 12 months for five years, identifying children with at least one caries-related crown/extraction (N equals 45). Observed scoring counted all crowned/extracted surfaces as carious. Private dentists' clinical records were also reviewed to determine how many surfaces were carious at crown/extraction appointments (53 actual scores for n equals 19). Differences in actual and observed scoring were evaluated (sign test; α equals 0.05 with two-tailed P-values). Results: Most children in the study group had more than one crown/extraction. Actual scoring revealed two to three fewer carious surfaces per tooth than observed scoring; cumulatively, observed scoring added two to 27 more surface counts per participant (P<0.001). Conclusions: Observed scoring exaggerated early childhood caries burdens when crowns/extractions were prevalent. Modified dmfs scoring, individualized or population-corrected crown/extraction counts, could more accurately estimate disease.

Models to Predict Future Permanent Tooth Caries Incidence in Children Using Primary Teeth Caries Experience.

Purpose: To assess permanent tooth caries incidence (ΔDMFS) among a cohort of African American children using the presence of any caries experience(decayed, missing, and filled surfaces-dmfs) in primary teeth and the presence of untreated primary tooth caries (ds) in two separate models. Methods: Data from a prospective study was used to apply two models with different clinical for predicting DMFS from ages six through 12 years. The first model used dmfs, and the second model used ds as predictors (both at age six years). Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were assessed. Results: The first model resulted in sensitivity from 81.8 percent to 100 percent, specificity from 35.6 percent to 42.6, PPV from 5.8 percent to 38.1 percent, and NPV from 90.0 percent to 100 percent. In the second model, the predictive values were from 33.3 percent to 55.6 percent, 62.7 percent to 72.7 percent, 3.4 percent to 45.5 percent, and 80 percent to 95.9 percent, respectively. Conclusions: The proposed models for permanent tooth caries incidence prediction are easy, not time consuming, and clinically applicable; if validated, they have the potential to change the current paradigm for caries risk assessment.

Average area under the curve: An alternative method for quantifying the dental caries experience in longitudinal studies.

OBJECTIVES: Field-traditional decayed, missing, filled surfaces (dmfs) increments require complete follow-up, only using initial and final visits. Repeated dmfs scores complicate sophisticated statistical models, limiting their utility. Elsewhere, area under the curve (AUC) uses all repeated measures to summarize data. This study applied AUC methodology to caries data, creating average AUCs for dmfs trajectories (dmfsaAUC ) and comparing increments and dmfsaAUC values. METHODS: Longitudinal data were obtained from high-caries risk (i.e. poor, rural, African American community in Perry County, Alabama) infants, 8 to 18 months at baseline. Baseline and five annual visual oral examinations provided dmfs scores. Differences in baseline and final dmfs scores constituted increments. The trapezoidal rule was applied to dmfs trajectories to calculate AUC values which were adjusted for varying follow-up times, producing dmfsaAUC values. Participants sharing incremental or dmfsaAUC values had their trajectories and second caries measurements compared. Within-participant increment and dmfsaAUC differences were evaluated (paired t test, α = 0.05). Comparative analyses required complete follow-up. RESULTS: The dmfsaAUC provided forty-eight additional person-years, increasing the potential sample size by 20% (N = 85). Sixty-six children, 5.7 to 6.3 year-olds at study's end, contributed 121 331 person-days to five-year increment and dmfsaAUC calculations. Trajectories and dmfsaAUC values varied for participants with equivalent increments; comparable trajectories and different increments resulted from participants with similar dmfsaAUC values. Within-participant disease amounts were similar. CONCLUSIONS: When desired, dmfsaAUC can replace increments as a more data-inclusive summary of longitudinal caries burden, incorporating intermediate visits, incomplete follow-up and time.

Streptococcus mutans serotypes and collagen-binding proteins Cnm/Cbm in children with caries analysed by PCR.

Streptococcus mutans, a primary bacterium associated with dental caries, has four known clinical serotypes (c, e, fand k). Certain serotypes, the presence of multiple serotypes and strains with collagen-binding proteins (CBP, Cnm and Cbm) have been linked with systemic disease. Evaluation of S mutans serotype distribution and caries association is needed in the United States. The purpose of this study was to evaluate the prevalence of S mutans serotypes from two cohorts of African-American children in rural Alabama using three sample types (saliva, plaque and individual S mutans isolates) by PCR detection for association with caries. Detection of CBP was also performed by PCR. In total, 129 children were evaluated and overall prevalence of serotypes were: serotype c(98%), e(26%), f(7%) and k(52%). Serotype c was statistically associated with higher caries scores in older children (P < 0.001) and serotype k was statistically more likely in females (P = 0.004). Fourteen per cent of children had CBP. Thirteen S mutans isolates from five children tested positive for both CBP. This study is the first to report on the prevalence of S mutans serotypes in a US population using the PCR-based approach. The frequency of serotype k in this study is the highest reported in any population, illustrating the need for further study to determine the prevalence of this clinically relevant serotype in the US. This is the first study to report S mutans isolates with both Cnm and Cbm in the same strain, and further analysis is needed to determine the clinical significance of these strains.

Survival analysis of caries incidence in African-American school-aged children.

OBJECTIVES: To conduct an assessment of time-dependent covariates related to dental caries of the permanent dentition among a low socioeconomic status, understudied cohort of children, incorporating time-dependent covariates through the application of extended Cox proportional hazards modeling. METHODS: This study modeled the time to first cavitated dental caries in permanent teeth among school-aged children and assessed factors associated with this event. A cohort of 98 low socioeconomic status African-American children with mean age of 5.85 years at baseline was recruited in Uniontown, Alabama and followed prospectively for 6 years. None of these children had dental caries on permanent teeth at baseline, and oral examinations were performed annually. Caries-free survival curves were generated to describe time to event (having first decayed, filled, or missing permanent surface). Bivariate and multivariable extended Cox hazards modeling was used to assess the relationships between time-dependent and time-independent covariates and time to event. RESULTS: Twenty-eight children (28.6 percent) had their first permanent tooth caries event during the 6-year follow-up. Multivariable results showed that greater consumption of water was associated with lower dental caries hazard, while previous primary tooth caries experience was associated with greater dental caries hazard after adjustment for frequency of consumptions of milk, added-sugar beverages, and 100 percent juice. CONCLUSIONS: There was a global/overall significant caries protective effect of water consumption during the school-age period of child development.

Surgical Management and Evaluation of the Craniofacial Growth and Morphology in Cleidocranial Dysplasia.

Cleidocranial dysplasia (CCD, MIM 119600) is a rare autosomal dominant disorder affecting bone, cartilage, craniofacial growth, and tooth formation leading to supernumerary teeth. Few reports delineate the genotype-phenotype correlations related to the variations in craniofacial morphology and patterning of the dentition and the complexity of treating patient's malocclusion. Successful management of the craniofacial deformities in patients with CCD requires a multidisciplinary team of healthcare specialists. Approximately 70% of patients are due to point mutations in RUNX2 and <20% due to copy number variations with the remainder unidentified. There is no literature to date, describing the orthognathic management of CCD patients with deletion in one of the RUNX2 alleles. The purpose of this study was to evaluate the craniofacial morphology and dental patterning in a 14-year-old Caucasian female with CCD resulting from a novel microdeletion of RUNX2 in 1 allele. The CCD patient with RUNX2 haploinsufficiency due to microdeletion had decreased craniofacial bone and ankyloses in the permanent dentition. An altered extraction protocol of supernumerary teeth was followed in this patient. Craniofacial growth and morphologic analysis demonstrated atypical skull shape, persistent metopic suture, and decreased mandibular size.

Transmission patterns of Streptococcus mutans demonstrated by a combined rep-PCR and MLST approach.

OBJECTIVE: Clinical typing methods of the oral pathogen Streptococcus mutans with molecular analysis can be very specific, but expensive. Repetitive extragenic palindromic PCR (rep-PCR) is a relatively inexpensive pre-screening alternative for isolate selection for additional analyses. This study evaluated the prediction accuracy of using rep-PCR to identify S. mutans multilocus sequence typing (MLST) sequence types (ST) among children and their family members. Potential S. mutans strain sources were evaluated for evidence of transmission. MATERIAL AND METHODS: Ten dendrograms (rep-PCR), with 20 isolates each of the 10 most common S. mutans genotypes, were generated from different subjects. Using a cut-off of 98% similarity, 7-11 isolates of each genotype were selected for MLST analysis to determine ST match/no-match. RESULTS: Overall, rep-PCR was 75% effective at determining MLST ST match/no-match and 90% effective when applied to related individuals. Most genotypes were further differentiated by MLST. MLST ST diversity was greatest for one genotype (genotype 12, G12) and evidence of transmission among children and their family members was identified by rep-PCR and MLST. Younger children (6 months to 4 years old) shared ST with their mothers but 50% of older children (5-9 years old) had ST not identified in their mother. Six ST were shared between different families and probable source members were identified. CONCLUSION: This study confirms that rep-PCR offers an affordable option to predict diverse isolates for downstream applications. CLINICAL RELEVANCE: Using a combined rep-PCR and MLST approach, it is possible to track probable transmission and strain sources for S. mutans genotypes.

Mutans Streptococci and Dental Caries: A New Statistical Modeling Approach.

Survival analyses have been used to overcome some of the limitations encountered with other statistical analyses. Although extended Cox hazard modeling with time-dependent variables has been utilized in several medical studies, it has never been utilized in assessing the complex relationship between mutans streptococci (MS) acquisition (time-dependent covariate) and time to having dental caries (outcome). This study involved secondary analyses of data from a prospective study conducted at the University of Alabama at Birmingham. Low socioeconomic status, African-American preschool children from Perry County, AL, USA (n = 95) had dental examinations at age 1 year and annually thereafter until age 6 years by three calibrated dentists. Salivary MS tests were done at ages 1, 1.5, 2, 2.5, 3, and 4 years. The patterns of and relationship between initial MS detection (time-dependent covariate) and dental caries experience occurrence were assessed, using extended Cox hazard modeling. The median time without MS acquisition (50% of the children not having positive MS test) was 2 years. Approximately 79% of the children had positive salivary MS tests by the age of 4 years. The median caries experience survival (50% of the children not having dental caries) was 4 years. During the follow-up period, 65 of the children (68.4%) had their initial primary caries experience. Results of the extended Cox hazard modeling showed a significant overall/global relationship between initial caries experience event at any given time during the follow-up period and having a positive salivary MS test at any time during the follow-up period (hazard ratio = 2.25, 95% CI 1.06-4.75). In conclusion, the extended Cox modeling was used for the first time and its results showed a significant global/overall relationship between MS acquisition and dental caries. Further research using causal mediation analysis with survival data is necessary, where the mediator "presence of MS" is treated as a time-dependent variable.

Potential Risk for Localized Aggressive Periodontitis in African American Preadolescent Children.

PURPOSE: This study aimed to evaluate the potential risk for localized aggressive periodontitis (LAgP) in African American children by detection of the potential periodontal pathogen Aggregatibacter actinomycetemcomitans (Aa) using polymerase chain reaction (PCR) and microbiome analysis. METHODS: Twenty-one pre-adolescents (age range equals 10.7 to 13.1 years old) were recruited, for this IRB-approved study. Oral examination included limited periodontal examination determining bleeding index (BOP) and periodontal probing (PD). An oral mucosa sample was used for analysis. RESULTS: Nine of 21 children were Aa+ by PCR. The Aa+ group had a significantly higher proportion of teeth with BOP and PD greater than four mm than the Aa- group (P=0.014 and 0.006 for percent BOP and percent PD equal to or greater than four mm, respectively; Mann Whitney Test). No significant differences in microbe abundance or composition were found from comparison of Aa+ versus Aa- samples. CONCLUSIONS: Detection of Aa from preadolescent African American children was associated with signs of periodontal inflammation. Although none of these children were diagnosed with LAgP, PCR targeting Aa could be a risk factor. Further study is indicated; however, the usefulness of PCR in dental practice setting to assess risk may be cost-effective for early diagnosis and prevention of LAgP.

Association Between Early Childhood Caries and Colonization with Streptococcus mutans Genotypes From Mothers.

PURPOSE: The purpose of this study was to evaluate Streptococcus mutans genotypes (GT) between mother and child (M-C) in a high caries risk cohort to explore the association with early childhood caries (ECC). METHODS: Sixty-nine infants (each approximately one year old) had periodic oral examinations (dmfs) and microbial samples collected from dental plaque, saliva, and other oral surfaces. Their mothers had an examination and plaque collected. S mutans isolates were genotyped using repetitive extragenic palindromic-PCR (rep-PCR). Statistical analyses were conducted for associations of S mutans in M-C dyads with caries outcomes. RESULTS: Twenty-seven S mutans genotypes (GT) from 3,414 isolates were identified. M-C were categorized as GT match (n equals 40) or no-match (n equals 29). When modeling the severity of ECC at 36 months (approximately four years old), the estimated dmfs in the match group was 2.61 times that of the no-match group (P=.014). CONCLUSIONS: Colonization of children with Streptococcus mutans genotypes that matched with mothers was shown to be highly associated with early childhood caries. Although the data suggest vertical transmission of S mutans in 40 of 69 children that shared GT with their mother, it is possible that other individuals transmitted the S mutans. Nonetheless, these findings support the importance of the mother's oral microbial status as a contributing influence to their children's oral health.

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.

Dental Caries in High-risk, School-age African American Children in Alabama: A Six-year Prospective.

PURPOSE: The purpose of this study was to assess the prevalence and incidence of dental caries in school-age African American children who received semi-annual fluoride varnish applications. METHODS: A cohort of six-year-old high caries-risk African American children (n equals 98) was recruited in Uniontown, Ala., USA, and followed for six years. Oral examinations were done annually by three trained/calibrated dentists. Tooth surfaces with cavitated caries, teeth missing due to caries, and teeth with filled surfaces were recorded using World Health Organization criteria. Also, as part of the study, children received periodic oral health instruction, fluoride varnish applications, and referrals to dentists starting at baseline. RESULTS: The person-level prevalence of decayed, missing, and filled surfaces of primary and permanent teeth (dmfs/DMFS) was: 61.2 percent at mean age of 5.9 years old (n equals 98, mean dmfs/DMFS equals 11.6); 63.8 percent at 6.7 years old (n equals 80, mean dmfs/ DMFS equals 13.2); 70.6 percent at 7.8 years old (n equals 68, mean dmfs/DMFS equals 14.2); 65.7 percent at 8.8 years old (n equals 68, mean dmfs/DMFS equals 11.8); 55.6 percent at 9.7 years old (n equals 63, mean dmfs/DMFS equals 8.8); 40.3 percent at 10.7 years old (n equals 62, mean dmfs/DMFS equals 3.4); and 37.1 percent at 11.7 years old (n equals 62, mean dmfs/DMFS equals 2.3). The six-year person-level incidence of dmfs/DMFS was 32.3 percent (mean dmfs/DMFS equals 1.6) from 5.9 to 11.7 years old (N equals 62). CONCLUSIONS: In spite of the oral health education and fluoride varnish applications, there was substantial new dental caries in this high-risk sample. Additional studies evaluating risk factors for caries development are ongoing.

Assessment of clonality and serotypes of Streptococcus mutans among children by multilocus sequence typing.

Studies using multilocus sequence typing (MLST) have demonstrated that Streptococcus mutans isolates are genetically diverse. Our laboratory previously demonstrated clonality of S. mutans using MLST but could not discount the possibility of sampling bias. In this study, the clonality of randomly selected S. mutans plaque isolates from African-American children was examined using MLST. Serotype and the presence of collagen-binding proteins (CBPs) encoded by cnm/cbm were also assessed. One-hundred S. mutans isolates were randomly selected for MLST analysis. Sequence analysis was performed and phylogenetic trees were generated using start2 and mega. Thirty-four sequence types were identified, of which 27 were unique to this population. Seventy-five per cent of the isolates clustered into 16 clonal groups. The serotypes observed were c (n = 84), e (n = 3), and k (n = 11). The prevalence of S. mutans isolates of serotype k was notably high, at 17.5%. All isolates were cnm/cbm negative. The clonality of S. mutans demonstrated in this study illustrates the importance of localized population studies and are consistent with transmission. The prevalence of serotype k, a recently proposed systemic pathogen, observed in this study, is higher than reported in most populations and is the first report of S. mutans serotype k in a United States population.