The formula
20 baby teeth between 6 and 33 months
Where it comes from
The order of eruption is fairly fixed — the lower central incisors first, then the upper ones, then the laterals, the first molars, the canines and last the second molars — and the timing is not fixed at all. The first tooth can appear at four months or at twelve, and neither means anything: what matters is the sequence, not the calendar.
How to work it out by hand
- Find the baby's age in the table
- Teeth whose window has already passed should be through
- Those inside their window may be coming through now
- Count the teeth: two per row of the table, one on each side
What is worth knowing
The twenty baby teeth are complete by around three years, and start falling out at six to make room for the permanent ones. On what gets blamed on teething, it pays to be careful: studies find a link with drooling, irritability and wanting to bite, but not with high fever or diarrhoea. A real fever during teething is a fever to look into, not a symptom of the tooth. And brushing starts with the first tooth, even though it will fall out: decay in baby teeth affects the permanent tooth underneath.