A mother asks when her child will have all 20 primary teeth erupted. By what age is the primary dentition usually complete?
- A 12 months
- B 18 months
- C 30 months (2.5 years) ✓
- D 4 years
Correct answer: C. 30 months (2.5 years)
Explanation
The first primary teeth, the lower central incisors, erupt at about 6 months. All 20 primary teeth are typically in place by 30 months, following the rule that the number of teeth equals the age in months minus 4 up to this point. Delayed eruption beyond 13 months for the first tooth warrants investigation, and total absence of teeth suggests ectodermal dysplasia or hypothyroidism.
Reference: Ghai Essential Pediatrics, 9th ed.
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Written and medically reviewed by the StethoPrep medical team.