The Evolving Microbiome of Dental Caries

Dental caries is a significant oral and public health problem worldwide, especially in low-income populations. The risk of dental caries increases with frequent intake of dietary carbohydrates, including sugars, leading to increased acidity and disruption of the symbiotic diverse and complex microbial community of health. Excess acid production leads to a dysbiotic shift in the bacterial biofilm composition, demineralization of tooth structure, and cavities. Highly acidic and acid-tolerant species associated with caries include Streptococcus mutans, Lactobacillus, Actinomyces, Bifidobacterium, and Scardovia species. The differences in microbiotas depend on tooth site, extent of carious lesions, and rate of disease progression. Metagenomics and metatranscriptomics not only reveal the structure and genetic potential of the caries-associated microbiome, but, more importantly, capture the genetic makeup of the metabolically active microbiome in lesion sites. Due to its multifactorial nature, caries has been difficult to prevent. The use of topical fluoride has had a significant impact on reducing caries in clinical settings, but the approach is costly; the results are less sustainable for high-caries-risk individuals, especially children. Developing treatment regimens that specifically target S. mutans and other acidogenic bacteria, such as using nanoparticles, show promise in altering the cariogenic microbiome, thereby combatting the disease.

A preliminarily Investigation on Oral Colonization and Counts of Streptococcus mutans and Streptococcus mitis in a Group of Predentate Infants in Relation to Some Maternal and Infant Factors (A Longitudinal Observational study)

Aim

Bacterial colonization of infants' oral cavities is a key factor for future caries risk. This study sought to longitudinally assess oral bacterial colonization in a group of predentate infants in relation to some mother and infant factors.

Materials and methods

A total of 50 mother-infant pairs were enrolled. When infants were 3-month-old, data were collected about some infant and mother factors; additionally, maternal Decayed, Missing, and Filled Teeth (DMFT) scores and salivary samples of mothers and infants were obtained. At 6 months of infant's age, another infants' salivary samples were obtained. Saliva was cultured to detect and quantify Streptococcus mutans (S. mutans) and Streptococcus mitis (S. mitis).

Results

Streptococcus mitis (S. mitis) was detected in all infants at 3 months. 74 and 96% of infants acquired S. mutans at 3 and 6 months, respectively. S. mutans detection was significantly higher with higher maternal DMFT scores, salivary S. mutans counts, and lower S. mitis counts, as well as when infants were given sugar-containing complementary foods/drinks. At 3-6 months, infants' S. mutans counts were significantly positively correlated with maternal S. mutans counts and DMFT scores and negatively correlated with maternal S. mitis counts. The opposite was evident for infants' S. mitis counts. Regression analysis showed that increased maternal DMFT scores and S. mutans counts, and Cesarean delivery were strong predictors for increased infant's S. mutans counts. While increased DMFT scores and maternal S. mutans counts were strong predictors for reduced infant's S. mitis counts.

Conclusion

Poor maternal oral health, early introduction of sugars in the diet, and probably Cesarean delivery can negatively impact infants' oral bacterial colonization and possibly future caries risk.

Clinical significance

Understanding factors associated with oral colonization of both caries-producing and protective flora in infants of different populations is important for caries prevention. This, in turn, can aid tailoring oral health promotion programs for expectant mothers.

How to cite this article

Wassel MO, Salman NS, Metwalli NE. A preliminarily Investigation on Oral Colonization and Counts of Streptococcus mutans and Streptococcus mitis in a Group of Predentate Infants in Relation to some Maternal and Infant Factors (A Longitudinal Observational study). Int J Clin Pediatr Dent 2023;16(1):79-86.

Clinical characteristics of children and guardians possessing CBP-positive Streptococcus mutans strains: a cross-sectional study

Streptococcus mutans is a major etiological agent for dental caries. We previously demonstrated that S. mutans strains expressing collagen-binding proteins (CBPs) were related to the pathogenesis of systemic diseases. However, their acquisition and colonization remain unknown. Here, we investigated the detection rates of CBP-positive S. mutans strains in children and their guardians to clarify the background for the acquisition and colonization in children. Saliva samples were collected from children and their mothers, and detection of S. mutans and collagen-binding genes (cnm, cbm) was performed by PCR after DNA extraction. The oral status of each child was examined, and their mothers were asked to complete a questionnaire. The isolation rate of Cnm-positive S. mutans was significantly higher in mothers than in children. Notably, the possession rates of CBP-positive strains in children were significantly higher in children whose mothers had CBP-positive strains than in children whose mothers did not have these strains. Furthermore, children with CBP-positive strains had a significantly shorter breastfeeding period than children without these strains. The present results suggest that nutritional feeding habits in infancy are one of the factors involved in the acquisition and colonization of CBP-positive S. mutans strains.

Streptococcus Mutans Infections in Infants and Related Maternal/Child Factors

Objective

The aim of the study was to investigate the maternal-child S. mutans infection, mutual interaction and potential risk factors altering this interaction.

Material and methods

A total of 160 mothers who were paired with their children were recruited. Saliva from mothers and children was collected and S. mutans categorized levels were analyzed. A questionnaire was used to collect maternal and child conventional caries risk factors. A proportional odds regression model was used to investigate whether the level of infection of mothers would similarly affect the level of infection of their children, thus adjusting for other risk factors.

Results

The average age of mothers was 28.1 years and children had a median age of 5.1 months. Paired mother-child S. mutans cross-classification into non-infected and infected subjects showed no agreement in mutual contamination. Maternal infection of the child was highest when the mother was infected with 10^>3 S. mutans/ml of saliva. The results obtained by the regression model showed that none of the potential risk factors influenced the level of infection in the child.

Conclusion

Mothers with a high S. mutans level increase the risk of S. mutans acquisition for her five- month- old child but no evidence was found that other maternal/child factors may influence this.

Early childhood caries, primary caregiver oral health knowledge and behaviours and associated sociological factors in Australia: a systematic scoping review

BACKGROUND

Early childhood caries disproportionately affects vulnerable groups and remains a leading cause of preventable hospital admissions for Western Australian children. The Western Australia State Oral Health Plan seeks to improve child oral health through universal and targeted health promotion initiatives with primary caregivers. These initiatives require evidence of primary caregiver oral health knowledge and behaviours and baseline data on early childhood caries. The objective of this systematic scoping review was to understand current oral health knowledge and practices of primary caregivers of children aged 0-4 years, identify influential socioecological determinants, and identify data on early childhood caries in the Western Australian context.

METHODS

A systematic scoping review framework identified articles published between 2010 and 2021, using Scopus, PubMed, Medline, CINAHL, PsycINFO, selected article reference lists, and oral health websites. The lack of Western Australian specific literature prompted the inclusion of Australia-wide articles. Articles were screened via author consensus, with eight selected.

RESULTS

Western Australia and nation-wide data on early childhood caries are limited and mostly dated. WA data from children aged 2-3 years, collected in 2006, suggests the prevalence is 2.9% in this state, with national data of children from 0 to 3 years, collected from 2006 and 2008, suggesting an early childhood caries prevalence of 3.4-8% of children aged 18 months, rising sharply by 36 months of age. Nationally, fewer than half the primary caregivers reported following evidence-based oral health recommendations for their young children. Perceptions of the role of dental services for young children tends to be focussed on treatment, rather than surveillance and prevention. Knowledge of dietary and oral hygiene practices is inconsistent and awareness of the Child Dental Benefit Schedule low. Young children's oral health status is clearly associated with socioecological factors, including socioeconomic status.

CONCLUSIONS

Recent early childhood caries data and evidence of primary care-givers' oral health knowledge and behaviours are unavailable in Western Australia, a similar situation exists nationwide. To realise the Western Australian and National Oral Health Plans, research is required to address this knowledge gap.

Salivary counts of Streptococcus mutans and Lactobacillus in patients with and without cleft lip and/or palate undergoing orthodontic treatment: A meta-analysis

OBJECTIVE

To conduct a systematic review with meta-analysis to assess if cleft lip and palate (CLP) patients undergoing orthodontic treatment have a higher colonization of Streptococcus mutans and Lactobacillus than patients without this condition.

METHODS

Five electronic databases were searched systematically. The inclusion criteria were as follows: randomized clinical trials, non-randomized, or quasi-randomized controlled trials, prospective and retrospective studies published until March, 2021; articles that evaluated S. mutans and Lactobacillus profile in patients with and without cleft lip and palate undergoing orthodontic treatment. The random-effect model was used to perform the analysis of all the data collected. Statistic heterogeneity was evaluated with I² test.

RESULTS

In this systematic review, 2 cohort studies were included. The data analysis from 160 patients revealed that patients without cleft lip and palate had 4.5 times more predisposition to oral colonization with S. mutans than CLP patients. No statistical significant difference was found between these patients for colonization with Lactobacillus.

CONCLUSIONS

Despite the limitations in the included studies, this systematic review suggested that CLP patients have a lower predisposition to oral colonization with S. mutans when compared to healthy patients.

The Queensland Birth Cohort Study for Early Childhood Caries: Results at 7 Years

AIMS

This study investigated caries predictors in 378 children remaining from a birth cohort of 1,052 at 7 y and compared the efficacy of home visits (HVs) and telephone contacts (TCs) for early childhood caries (ECC) prevention.

METHODS

The HVs or TCs were made at ages 6, 12, 18, 30, and 42 mo with annual dental clinic examinations at ages 2 to 7 y. At every visit, the parents completed validated questionnaires regarding the children's family, medical, dental, and dietary histories.

RESULTS

The caries prevalence increased from 2% and 6% at ages 2 and 3 y to 15%, 33%, 42%, and 52% at ages 4 to 7 y. The mean caries experience (decayed, missing, and teeth extracted due to caries) of the total cohort increased from 0.1 ± 0.5 at age 2 y to 0.2 ± 1.1 at 3 y, 0.5 ± 1.6 at 4 y, 1.1 ± 2.4 at 5 y, 1.6 ± 2.6 at 6 y, and 2.0 ± 2.7 at 7 y. The prevalence of mutans streptococci (MS) in the total cohort at years 2 to 7 was 22%, 36%, 42%, 42%, 39%, and 44%, respectively. MS was strongly correlated with caries prevalence for all years (all P < 0.001). Statistical modeling employing the generalized estimating equations identified caries predictors as holding a Health Care Card (low socioeconomic status) (P = 0.009; odds ratio [OR] = 2.05; confidence interval [CI]: 1.20-3.52), developmental defects of enamel (DDEs) (P < 0.001; OR = 1.09; CI: 1.05-1.14), and MS counts ≤10⁵/mL (P = 0.001; OR = 1.63; CI: 1.24-2.14). By contrast, HVs were more protective than TCs for caries (P = 0.008; OR = 0.42; CI: 0.22-0.80).

CONCLUSIONS

This study provides prospective, clinical evidence that MS, DDEs, and low socioeconomic status are strongly correlated with early childhood caries and that HVs are more efficacious than TCs in ECC prevention.

KNOWLEDGE TRANSFER STATEMENT

This 7-y birth cohort study provides longitudinal clinical evidence that mutans streptococci, developmental defects of enamel, and low socioeconomic status are key risk indicators of early childhood caries.

Interspecies Interactions Between Streptococcus Mutans and Streptococcus Agalactiae in vitro

Streptococcus mutans is an oral species closely associated with dental caries. As an early oral colonizer, S. mutans utilizes interspecies coaggregation to promote the colonization of subsequent species and affect polymicrobial pathogenesis. Previous studies have confirmed several adhering partner species of S. mutans, including Candida albicans and Fusobacterium nucleatum. In this study, we discovered new intergeneric co-adherence between S. mutans and the saliva isolate Streptococcus agalactiae (GBS-SI101). Research shows that GBS typically colonizes the human gastrointestinal and vaginal tracts. It is responsible for adverse pregnancy outcomes and life-threatening infections in neonates and immunocompromised people. Our results revealed that GtfB and GtfC of S. mutans, which contributed to extracellular polysaccharide synthesis, promoted coaggregation of S. mutans with GBS-SI101. In addition, oral streptococci, including Streptococcus sanguinis, Streptococcus gordonii and S. mutans, barely inhibited the growth of GBS-SI101. This study indicated that S. mutans could help GBS integrate into the Streptococcus-associated oral polymicrobial community and become a resident species in the oral cavity, increasing the risk of oral infections.

Oral microbiome: possible harbinger for children's health

The human microbiome functions as an intricate and coordinated microbial network, residing throughout the mucosal surfaces of the skin, oral cavity, gastrointestinal tract, respiratory tract, and reproductive system. The oral microbiome encompasses a highly diverse microbiota, consisting of over 700 microorganisms, including bacteria, fungi, and viruses. As our understanding of the relationship between the oral microbiome and human health has evolved, we have identified a diverse array of oral and systemic diseases associated with this microbial community, including but not limited to caries, periodontal diseases, oral cancer, colorectal cancer, pancreatic cancer, and inflammatory bowel syndrome. The potential predictive relationship between the oral microbiota and these human diseases suggests that the oral cavity is an ideal site for disease diagnosis and development of rapid point-of-care tests. The oral cavity is easily accessible with a non-invasive collection of biological samples. We can envision a future where early life salivary diagnostic tools will be used to predict and prevent future disease via analyzing and shaping the infant’s oral microbiome. In this review, we present evidence for the establishment of the oral microbiome during early childhood, the capability of using childhood oral microbiome to predict future oral and systemic diseases, and the limitations of the current evidence.

Early Childhood Caries

Early childhood caries (ECC) is a common childhood disease with highest prevalence found in poor, socially disadvantaged, and minority groups. The main risk factors for ECC are frequent sugar consumption, lack of tooth brushing, and enamel hypoplasia. Contributory factors include environmental and psychosocial stresses that modify caregiver behaviors. Strategies for prevention include preventing mutans streptococci transmission, restricting dietary sugars, tooth brushing, topical fluoride applications, and early dental examinations. This article provides an overview of ECC based on current understanding of its cause, prevention, and management.

Infant Oral Health

It may be easy to discount oral health in infancy because most infants are not born with teeth and only a few teeth erupt during the first year of life. Infancy, however, is a critical time for formation of habits. Positive habits, such as twice-daily brushing with fluoride toothpaste starting at first teeth eruption, provides topical fluoride, which is important for remineralization of the tooth and helps establish a lifelong healthy practice. Negative habits, such as bottle propping and frequent juice consumption, reinforce behaviors that promote caries and obesity. This article reviews normal dental development and eruption. Congenital anomalies affecting the mouth as well as acquired conditions, primarily dental caries, are reviewed. Oral health preventive modalities, including professionally applied products and home-based strategies, are discussed.

Taxonomic and Functional Analyses of the Supragingival Microbiome from Caries-Affected and Caries-Free Hosts

Caries is one of the most prevalent and costly infectious diseases affecting humans of all ages. It is initiated by cariogenic supragingival dental plaques forming on saliva-coated tooth surfaces, yet the etiology remains elusive. To determine which microbial populations may predispose a patient to caries, we report here an in-depth and comprehensive view of the microbial community associated with supragingival dental plaque collected from the healthy teeth of caries patients and healthy adults. We found that microbial communities from caries patients had a higher evenness and inter-individual variations but simpler ecological networks compared to healthy controls despite the overall taxonomic structure being similar. Genera including Selenomonas, Treponema, Atopobium, and Bergeriella were distributed differently between the caries and healthy groups with disturbed co-occurrence patterns. In addition, caries and healthy subjects carried different Treponema, Atopobium, and Prevotella species. Moreover, distinct populations of 13 function genes involved in organic acid synthesis, glycan biosynthesis, complex carbohydrate degradation, amino acid synthesis and metabolism, purine and pyrimidine metabolism, isoprenoid biosynthesis, lipid metabolism, and co-factor biosynthesis were present in each of the healthy and caries groups. Our results suggested that the fundamental differences in dental plaque ecology partially explained the patients' susceptibility to caries, and could be used for caries risk prediction in the future.

Differences in carbon source usage by dental plaque in children with and without early childhood caries

Early childhood caries (ECC) is a considerable pediatric and public health problem worldwide. Preceding studies have focused primarily on bacterial diversity at the taxonomic level. Although these studies have provided significant information regarding the connection between dental caries and oral microbiomes, further comprehension of this microbial community’s ecological relevance is limited. This study identified the carbon source metabolic differences in dental plaque between children with and without ECC. We compared the microbial community functional diversity in 18 caries-free subjects with 18 severe ECC patients based on sole carbon source usage using a Biolog assay. The anaerobic microbial community in the ECC patients displayed greater metabolic activity than that of the control group. Specific carbon source metabolism differed significantly between the two groups. Subjects from the two groups were well distinguished by cluster and principal component analyses based on discriminative carbon sources. Our results implied that the microbial functional diversity between the ECC patients and healthy subjects differed significantly. In addition, the Biolog assay furthered our understanding of oral microbiomes as a composite of functional abilities, thus enabling us to identify the ecologically relevant functional differences among oral microbial communities.

Salivary Immune and Metabolic Marker Analysis (SIMMA): A Diagnostic Test to Predict Caries Risk

By using ELISA and colorimetric tests, we have measured 25 compounds in individuals with and without dental caries at different time points of dental biofilm formation and time of the day. We find that some compounds appear to be affected by circadian rhythms, others by dental plaque maturity, and others show constant values during a 24 h period. Using univariate analysis and cross-validation techniques, we have selected six components measured at specific time points that maximize the diagnostic separation of health and disease conditions. Two out of the six selected compounds are related to immune competence, another two to the adhesion capacity of micro-organisms, and another two to acid production or pH buffering. We conclude that, in order to design a robust caries risk test, the time of saliva sampling must be standardized and biomarkers from different categories must be included. The preliminary data shown in this paper provide a proof of principle of a caries risk test based on risk-associated categories. Thus, the test will provide not only a general caries risk assessment, but also the likely biological origin of that risk, namely: immune imbalance, and/or a tendency to adhesion of cariogenic organisms, and/or a lack of acid buffering. When tested longitudinally and validated in larger cohorts, this could open the possibility to develop preventive and personalized treatments.

Identification of Caries Risk Determinants in Toddlers: Results of the GUSTO Birth Cohort Study

The aim of this study was to identify risk determinants leading to early childhood caries (ECC) and visible plaque (VP) in toddlers. Data for mother-child pairs participating in the Growing Up in Singapore towards Healthy Outcomes (GUSTO) birth cohort were collected from pregnancy to toddlerhood. Oral examinations were performed in 543 children during their clinic visit at 24 months to detect ECC and VP. Following logistic regression, ECC and VP were jointly regressed as primary and secondary outcomes, respectively, using the bivariate probit model. The ECC prevalence was 17.8% at 2 years of age, with 7.3% of children having a VP score >1. ECC was associated with nighttime breastfeeding (3 weeks) and biological factors, including Indian ethnicity (lower ECC rate), higher maternal childbearing age and existing health conditions, maternal plasma folate <6 ng/mL, child BMI, and the plaque index, while VP was associated with psychobehavioral factors, including the frequency of dental visits, brushing frequency, lower parental perceived importance of baby teeth, and weaning onto solids. Interestingly, although a higher frequency of dental visits and toothbrushing were associated with lower plaque accumulation, they were associated with increased ECC risk, suggesting that these established caries-risk factors may be a consequence rather than the cause of ECC. In conclusion, Indian toddlers may be less susceptible to ECC, compared to Chinese and Malay toddlers. The study also highlights a problem-driven utilization pattern of dental services (care sought for treatment) in Singapore, in contrast to the prevention-driven approach (care sought to prevent disease) in Western countries.

Correlation of Streptococcus mutans count in Mother-child Pair of Working and Nonworking Mothers: A Cross-sectional Study

Purpose

To determine the prevalence of Streptococcus mutans (MS) in mother-child pairs and to evaluate the correlation in the levels of salivary MS of working and nonworking mothers with that of their children and their associations with other related factors.

Materials and methods

A cross-sectional study was carried out among 100 mother-child pairs residing in New Multan Nagar Colony, New Delhi, India. A total of 50 children with their mothers were included in the working group and another 50 were included in the nonworking group. A questionnaire regarding the feeding habits, oral hygiene habits, daily intake of sugars of the children along with their weaning time was carried out. All mothers and children were clinically examined for recording decayed, extracted, and filled teeth (deft)/decayed, missing, and filled teeth (DMFT), and whole unstimulated saliva was collected and cultured for MS in the laboratory. The data were collected and subjected to statistical analysis using chi-square, Spearman’s correlation, and logistic regression analysis.

Results

The prevalence of salivary MS in the children was 69%. A statistically significant correlation was found between the oral levels of MS in nonworking and working mother-child pairs. Regression analysis showed that those children who feed by bottle for more than 12 months, have daily sweet intake, have sugars in feeding bottle and have higher defts were more likely to have mutans score of 1 or 2.

Conclusion

The mother, working or nonworking, being the primary care provider is the major source of transmission of MS to their child irrespective of the amount of time spent with them.

How to cite this article

Sharma P, Goswami M, Singh D, Massod SS, Nganba K. Correlation of Streptococcus mutans count in Mother-child Pair of Working and Nonworking Mothers: A Cross-sectional Study. Int J Clin Pediatr Dent 2016;9(4):342-348.

Antimicrobial Properties of Biofunctionalized Silver Nanoparticles on Clinical Isolates of Streptococcus mutans and Its Serotypes

(1) Background: Streptococcus mutans (S. mutans) is the principal pathogen involved in the formation of dental caries. Other systemic diseases have also been associated with specific S. mutans serotypes (c, e, f, and k). Silver nanoparticles (SNP) have been demonstrated to have good antibacterial effects against S. mutans; therefore, limited studies have evaluated the antimicrobial activity of biofunctionalized SNP on S. mutans serotypes. The purpose of this work was to prepare and characterize coated SNP using two different organic components and to evaluate the antimicrobial activity of SNP in clinical isolates of S. mutans strains and serotypes; (2) Methods: SNP with bovine serum albumin (BSA) or chitosan (CS) coatings were prepared and the physical, chemical and microbiological properties of SNP were evaluated; (3) Results: Both types of coated SNP showed antimicrobial activity against S. mutans bacteria and serotypes. Better inhibition was associated with smaller particles and BSA coatings; however, no significant differences were found between the different serotypes, indicating a similar sensitivity to the coated SNP; (4) Conclusion: This study concludes that BSA and CS coated SNP had good antimicrobial activity against S. mutans strains and the four serotypes, and this study suggest the widespread use of SNP as an antimicrobial agent for the inhibition of S. mutans bacteria.

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.

Solving the etiology of dental caries

For decades, the sugar-fermenting, acidogenic species Streptococcus mutans has been considered the main causative agent of dental caries and most diagnostic and therapeutic strategies have been targeted toward this microorganism. However, recent DNA- and RNA-based studies from carious lesions have uncovered an extraordinarily diverse ecosystem where S. mutans accounts only a tiny fraction of the bacterial community. This supports the concept that consortia formed by multiple microorganisms act collectively, probably synergistically, to initiate and expand the cavity. Thus, antimicrobial therapies are not expected to be effective in the treatment of caries and other polymicrobial diseases that do not follow classical Koch's postulates.

Maternal oral mutans streptococci (MS) status, not breastfeeding, predicts predentate infant oral MS status

The purpose of this study was to investigate infant oral mutans streptococci (MS) by feeding method and by the mother's oral MS status. For this cross-sectional data collection, full-term infants at 4-6 weeks of age and their mothers were tested for oral MS using the Dentocult(®) SM chairside test (Orion Diagnostica, Espoo, Finland). For the 104 mother-infant pairs (68 breastfed, 36 formula-fed), the two groups differed by mother's race/ethnicity (p=0.006) but not by delivery mode, level of care at birth, or MS in the mothers or the infants. Thirty-one percent of mothers and 12% of infants were MS positive. Infant MS was not predicted by mother's race/ethnicity, delivery mode, feeding method, or MS status. When stratified by feeding method, the mother's MS status did significantly predict the infant's MS status in the breastfed group (odds ratio=5.97; 95% confidence interval, 1.06-33.7; p=0.043). In conclusion, oral MS at >10(4) colony-forming units/mL were detected in 12% of the 4-6-week-old infants, and the effect of the mothers' oral MS status was modified by the feeding method. Future research is needed to clarify the modifiable perinatal and maternal risks associated with the development of the infant's predentate oral microbial environment, before the introduction of the first tooth.

Bacterial colonization, enamel defects and dental caries in 4-6-year-old mono- and dizygotic twins

BACKGROUND

Knowledge of the genetic and environmental influences in caries aetiology has relevance for preventive dentistry.

AIMS

This classical twin study compared concordance of mutans streptococci (MS) and lactobacilli (LB) colonization, enamel defects, and caries in a cohort of 4-6-year-old mono- (MZ) and dizygotic (DZ) twin pairs.

DESIGN

The twins were examined for prevalence and concordance of enamel opacities and hypoplasia, oral counts of MS and LB, and dental caries. Bacterial counts were assessed using a commercial microbiological kit.

RESULTS

Thirty-four MZ and 50 DZ twins (mean gestational age 35.0 ± 2.4 weeks, and birthweight 2.4 ± 0.6 kg) were examined. There were no statistically significant differences between MZ and DZ twins in the prevalence of MS, LB, and enamel hypoplasia. Concordance rates for MS and LB presence and prevalence of enamel defects within MZ and DZ twin pairs were not significantly different. There were more children with caries in DZ compared with MZ twins (18% vs 3%, P = 0.0029), most likely due to increased daily frequency of sugar consumption and less toothbrushing.

CONCLUSIONS

Concordance data from MZ and DZ twins did not demonstrate any statistically significant difference in susceptibility for enamel defects and colonization of MS and LB.