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.