Timings of Permanent Tooth Emergence in Children of Rural Vanuatu, Melanesia

Introduction Global patterning and timing of permanent tooth emergence is influenced by ethnicity, with no known timings reported for ethnic Melanesian children living in the tropical archipelago of Vanuatu. Aim To determine timings of permanent tooth emergence and sequencing for children who reside in rural Vanuatu. Methods Children aged 4-17 years (n=1026), part of a larger oral health cross-sectional study, were examined recording all permanent teeth present, across four spatially separated islands. Binary logistic modelling established children’s median age of emergence of each permanent tooth for each study area. Results The median emergence of first permanent molars for girls is 4.9-years and 5.3 -years for boys. In all locations, children had all permanent teeth emerge by age 11 years (excluding 3rd molars). Clinically important differences exist for permanent tooth emergence by study area. Discussion Permanent teeth emerge earlier for Ni-Vanuatu children compared to both Melanesian children of Papua New Guinea as well as other ethnicities across Oceanic countries. These results can be used as a set standard for Vanuatu. Early tooth emergence suggests oral health education programmes should target pregnant women with clinical preventive strategies commencing for their children before 5-years of age.

Growth of Neanderthal infants from Krapina (120–130 ka), Croatia

Modern humans have a slow and extended period of childhood growth, but to what extent this ontogenetic pathway was present in Neanderthals is debated. Dental development, linked to the duration of somatic growth across modern primates, is the main source for information about growth and development in a variety of fossil primates, including humans. Studies of Neanderthal permanent teeth report a pace of development either similar to recent humans or relatively accelerated. Neanderthal milk teeth, which form and emerge before permanent teeth, provide an opportunity to determine which pattern was present at birth. Here we present a comparative study of the prenatal and early postnatal growth of five milk teeth from three Neanderthals (120 000–130 000 years ago) using virtual histology. Results reveal regions of their milk teeth formed quickly before birth and over a relatively short period of time after birth. Tooth emergence commenced towards the earliest end of the eruption schedules displayed by extant human children. Advanced dental development is consistent with expectations for Neanderthal infant feeding.

Lack of association between delayed tooth emergence and single nucleotide polymorphisms in estrogen receptors

The purpose of the study was to investigate the association between single nucleotide polymorphisms (SNPs) in genes encoding estrogen receptors (ESR1 and ESR2, respectively) and delayed tooth emergence (DTE). This cross-sectional study was composed of biological unrelated children of both sexes, age ranging from 11 to 13 years old. DTE was defined when the successor primary tooth was still present in the oral cavity after its exfoliation time or the absence of the permanent tooth emergence into the oral cavity. Children were diagnosed with DTE when they had at least one delayed permanent tooth, according to age of exfoliation of each tooth proposed by The American Dental Association. Genomic DNA from saliva was used to evaluate the SNPs in ESR1 (rs9340799 and rs2234693) and ESR2 (rs1256049 and rs4986938) using Real-Time PCR. Chi-square or Fisher exact tests and Logistic Regression adjusted by age and gender were performed. SNP-SNP interaction was accessed by multifactor dimensionality reduction (MDR) analysis also adjusted by gender and age. The established alpha of this study was 5%. Among 537 included children, 296 (55%) were in the “DTE” group and the 241 (45%) were in the “Control” group. Age and gender were not statistically different among the groups (p>0.05). Genotype distribution of the SNPs rs9340799, rs2234693, rs1256049 and rs4986938 were not associated with DTE (p> 0.05). The models elected by MDR were not statistically significant either. Conclusions: The studied SNPs in ESR1 and ESR2 were not associated with permanent DTE.

Proboscidea from the Baynunah Formation

The Baynunah Formation provides the only late Miocene record of fossil proboscideans from the Arabian Peninsula, identifiable as a deinothere, tetralophodont gomphothere(s), and stegotetrabelodont elephant. Ichnofossils show the oldest evidence for modern-type elephant herd structure. The elephant sample is particularly abundant, and newly-recovered fossils yield critical evidence about their systematics and biology. Comparative results show that the Baynunah stegotetrabelodont belongs in a new species, and that in many ways it is the most primitive of all elephants —supporting a geological age of 8.0-6.0 Ma—consistent with having evolved in Afro-Arabia from Tetralophodon between 9.0-8.0 Ma. Body size analyses reveal that these elephants were exceptionally tall and heavy, possibly exceeding 10,000 kg. Tooth emergence is reconstructed as dp2-dp3-dp4-p3-m1-p4- m2-m3. The taxonomic composition and dietary preferences of the Baynunah proboscideans indicate the presence of heterogeneous local habitats in the region during the late Miocene, though the high abundance of the stegotetrabelodont, and the rarity of the deinothere and gomphothere(s) indicate a dominance of grassland habitats and a lesser representation of wooded areas.

Maternal Oral Health Influences Infant Salivary Microbiome

Oral microbiomes vary in cariogenic potential; these differences may be established early in life. A major concern is whether mothers transmit cariogenic bacteria to their children. Here we characterize early salivary microbiome development and the potential associations of that development with route of delivery, breastfeeding, and mother’s oral health, and we evaluate transmission of microbes between mother and child. We analyzed saliva and metadata from the Center for Oral Health Research in Appalachia. For this cohort study, we sequenced the V6 region of the 16S rRNA gene and used quantitative polymerase chain reaction to detect Streptococcus mitis, Streptococcus sobrinus, Streptococcus mutans, Streptococcus oralis, and Candida albicans in the saliva from mothers and their infants, collected at 2, 9, and 12 mo (Pennsylvania site) and 2, 12, and 24 mo (West Virginia site). Breastfed children had lower relative abundances of Prevotella and Veillonella. If mothers had decayed, missing, or filled teeth, children had greater abundances of Veillonella and Actinomyces. There was little evidence of maternal transmission of selected microbes. At 12 mo, children’s microbiomes were more similar to other children’s than to their mothers’. Infants’ salivary microbiomes became more adult-like with age but still differed with mothers’ microbiomes at 12 mo. There was little evidence supporting transmission of selected microbes from mothers to children, but risk of colonization was associated with tooth emergence. Children are likely to acquire cariogenic bacteria from a variety of sources, including foods and contact with other children and adults.