How many teeth would you expect an 8-year-old to have in the mouth?

Correct answer: B. 12 primary and 12 permanent

• A. This reverses the figures. At 8 years the permanent incisors and first molars are in, so permanent teeth number 12, not 9.
• B. CORRECT. By age 8 the child is in mid-mixed dentition. The permanent FIRST MOLARS (4) and the permanent INCISORS — four maxillary and four mandibular (8) — have normally erupted, giving 12 PERMANENT teeth. The eight primary incisors have exfoliated, leaving the primary canines (4) and primary first and second molars (8) — 12 PRIMARY teeth. Total 24.
• C. 20 primary teeth means no exfoliation has occurred at all, which corresponds to roughly age 5, before the first permanent molars erupt.
• D. 9 primary is not a symmetrical count and does not correspond to any standard stage of exfoliation.

Note: Useful anchors: 6 years = first permanent molars and lower central incisors erupt; 8 years = all permanent incisors plus first molars (12 permanent); 12 years = second permanent molars, dentition essentially complete apart from third molars.