Epidemiological and Microbiome Characterization of Black Tooth Stain in Preschool Children.

OBJECTIVE: To assess the epidemiologic attributes and microbial variations associated with extrinsic black tooth stain (BTS) among Chinese preschool children. METHODS: This cross-sectional study included 250 preschool children (3-4 years) from three kindergartens in Shanghai, China. Following clinical examination, and using a case-control design, saliva and dental plaque specimens were collected from caries-free participants with (n = 21, BTS group) and without (n = 48, control group) BTS. The chi-square test and logistic regression model were used to evaluate factors associated with BTS. 16S rRNA sequencing were used to characterize the associated microbial communities. RESULTS: BTS was detected in 12.4% of participants, with a mean of 13.7 black-stained teeth. Participants with BTS had a lower caries burden and better oral hygiene (P = 0.003). Children with less frequent intake of marmalade or honey (P = 0.033) and regular application of fluoride (P = 0.007) had a lower likelihood of having BTS. Microbiota analysis revealed 14 phyla, 35 classes, 63 orders, 113 families, 221 genera, 452 species, and 1,771 operational taxonomic units (OTUs). In terms of microbial diversity, no significant differences were observed in the saliva of the two groups (P > 0.05). Dental plaque from the BTS group exhibited higher OTU richness but lower evenness than that from the control group (Chao P = 0.006, Shannon P = 0.007, respectively) and showed a significant difference in ß diversity (P = 0.002). The microbiome in the two groups was characterized by various microbial biomarkers, such as Pseudomonas fluorescens, Leptotrichia sp._HMT_212, Actinomyces sp._HMT_169, and Aggregatibacter sp._HMT_898 in plaques from the BTS group. Functional analysis of the microbial species suggested the existence of a hyperactive metabolic state on teeth surfaces with BTS plaques and revealed that ferric iron, the iron complex transport system, and the iron (III) transport system were more abundant in BTS plaque samples. CONCLUSIONS: This study provides insights into the epidemiologic and microbial features of BTS in preschool children. The microbiome in BTS is characterized by various microbial biomarkers, which can serve as indicators for BTS diagnosis and prognosis.

Microbiota of preterm infant develops over time along with the first teeth eruption.

Objective: The temporal growth of the infant microbiome in the early years of life influences short- and long-term infant health. The aim of this longitudinal study was to investigate bacterial dynamics in the microbiome of preterm infants during tooth eruption. Methods: Saliva samples from normally delivered (n = 24) and preterm infants (n = 31) were collected 30 days after birth and after the eruption of two primary mandibular incisors. Based on Illumina MiSeq Sequencing of the 16S rRNA gene, the dynamic microbial changes of newborns at two-time points were investigated. Meanwhile, the Human Oral Microbiome Database was adopted for assigning taxonomy. Results: Using alpha and beta diversity analyses, different shift patterns of microbiome structures in preterm and healthy participants and bacterial diversity over time were observed. The relative abundance and shifts trend, along with the two lower primary central incisors eruption, of core oral flora varies in full-term and preterm groups, including Gemella spp., Rothia mucilaginosa, Veillonella atypica, etc. Several microorganisms colonize later in the oral microbiome development of premature babies, such as Gemella spp. In addition to teeth eruption, the growth of the saliva microbiome in preterm infants could be influenced by breastfeeding durations and birth weight. Conclusion: This study provided insights into how the oral microbiota changes during tooth eruption in preterm infants and how the colonization of the oral cavity with bacteria in preterm infants differs significantly from that in full-term infants.

[Risk factors of dental caries among young children in Pudong New District, Shanghai].

PORPOSE: To establish a prospective cohort of kindergarten children and longitudinally study the causes of early childhood caries. METHODS: Cluster random sampling was used to select a kindergarten in the urban and suburban areas of Pudong New District of Shanghai, a total of 240 small-class children joined the study. Chi-square test, analysis of variance, binomial logistic regression model and general linear regression model was used to analyze caries of the cohort children at baseline and 1 year after follow-up with SPSS 21.0 software package. RESULTS: In the first two years of this cohort study, the follow-up rate was 88.3%, the caries rate in the first year of baseline and follow-up were 58.3% and 69.8%, and the mean dmft values were 3.1±4.2 and 4.5±4.9, respectively. 56.1% of children had new caries. Logistic regression results showed that children who lived in the suburbs (P=0.010) and ate candy more frequently (P=0.036) had higher rates of new caries. The results of general linear regression equation showed that children in the suburbs (P<0.001), those who did not use fluoridated toothpaste (P=0.003) and those who ate candy more frequently (P=0.002) had higher new mean dmft values. CONCLUSIONS: Living in the suburbs, not using fluoride toothpaste and eating candy more frequently are important risk factors for new caries in preschool children in Pudong New District of Shanghai.