Oral health: it all comes into play before age 3?
At what age does the oral microbiota, which seems to be a sign of oral health, become established? Early—very early—says a Japanese study that followed 54 children from their first week to their fifth birthday.
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Cavities, periodontal disease and even systemic illnesses: the oral microbiota is increasingly under scrutiny. Paradoxically, its gradual development in the first years of life remains a great mystery.
Hence the importance of a Japanese study 1 that monitored the salivary microbiota of 54 children (27 girls and 27 boys) at 13 points in their early childhood: at 1 week, then at 1, 3, 6, 9, 12, 18, 24, 30, 36, 42, 48 and 60 months (5 years). Their parents' oral microbiota was also collected when the children were 18 and 36 months old, as a representative sample of adult microbiota.
3.5 billion Oral diseases (dental caries, periodontal diseases, tooth loss and oral cancers) affect nearly 3.5 billion people. ²
2 billion people suffer from caries of permanent teeth and 514 million children suffer from caries of primary teeth. ²
19% Severe periodontal diseases are estimated to affect around 19% of the global adult population, representing more than 1 billion cases worldwide. ²
Quick to set up
The microbiota of newborns is still quite poor: one week after birth, only 25% of the 110 (sidenote: Operational Taxonomic Unit groups of organisms usually not cultivated or not identified, classified on the basis of the similarity of the DNA sequencing of a given gene. Frequently used as an equivalent to the concept of species ) detected in over 85% of parents at both sampling dates are found.
The bacterial genera present at one week of age:
- generally Streptococcus
- Rothia
- and Gemella
But then the increase is very rapid, with 80% of parental OTUs present between 6 and 18 months, following the introduction of the first solid foods and the appearance of the first teeth.
The main bacterial genera that move in at this point are:
- Neisseria
- Haemophilus
- and Fusobacterium
By the time a child is 1.5 years old, their oral microbiota is already comparable to that of an adult.
At 36 months, when all baby teeth are in place and the child’s diet has become much more diverse, the rate rises to 90%; from then on, the oral microbiota undergoes no further significant changes until the age of 5.
What are the consequences for cavities?
The scientists' attention was particularly focused on Neisseria, Haemophilus and Fusobacterium. Previous studies had reported that their concentration in the mouth reflected patients' oral condition (absence or presence of cavities and/or periodontal disease).
The Japanese study shows that these three bacteria settle in early:
- starting at 6 months of age, nitrate-reducing bacteria of the genera Neisseria and Haemophilus, which prevent dental cavities and periodontal disease, increase rapidly;
- during the first 18 months, F. nucleatum, associated with periodontal disease, dental plaque and bad breath, colonizes the baby's mouth.
Thus, everything seems to come into play before the child's 3rd birthday, or even between 6 and 18 months, a window of maturation of the oral microbiota that could be essential for the future prevention of oral diseases.
Hence the importance of monitoring and advising young parents on oral care during this period: cleaning a child's teeth as soon as they break through could prove decisive for the oral microbiota of this future adult.
