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1.0 Growth and Developmental data for Primary and Secondary Dentition

Edentulous

from birth to 6 months old. No visible teeth in mouth.

Primary dentition only

6 months to 2 years old: All primary teeth are erupting into the childs mouth over this period

2 to 6 years old: all 2- primary teeth are present, no visible permanent teeth yet

Mixed Dentition

6 years old: permanent teeth start to appear, beginning with first molars ( 6 year old molars).

These are followed by loss of mandibular central incisors

6 to 9 years old: All eight permanent incisors replace primary incisors that are exfoliated

9 to 12 years: all four permanent canines and eight premolars replace primary canines and molars

12 years old: second molars ( 12 year molars) emerge

Adult dentition only

After 12 year ( second )molars erupt, 28 permanent teeth are present, all primary teeth have been

exfoliated and replaced

17 to 21 years old: third molars emerge, if present, and full complement of 32 teeth are achieved

1.1 Order of emergence of primary teeth

The first primary teeth to erupt are the mandibular central incisors, at about 6 months of age,

followed by mandibular laterals and then the maxillary incisors( centrals before laterals). Next to

emerge are the primary first molars, then canines and finally second molars. Thus, the last

primary teeth to emerge, thereby completing the primary dentition, are the maxillary second

moalrs, at about 2 years ( 24 months of age).

Figure 1.1.1: order of primary tooth emergence

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1.2 Order of emergence of secondary teeth

The above table shows the eruption sequence for permanent teeth. After the 6 year molars

erupt , just before the childs sixth birthday, the order of eruption for the succendaneous teeth is

the same as the order of exfoliation of the primary teeth they replace. The centrals erupt before

laterals, and mandibular incisors erupt before their maxillary counterpart/ The first permanentincisors to erupt are the mandibular central incisors ( close to 6 years) and the last incisors to

erupt are the maxillary lateral incisors ( close to 9 years old). Mandibular laterals and maxillary

centrals erupt from 7to 8 years old.

Next, adult canines and premolars erupt between ages 9 and 12. First, mandibular canines

emerge (close to 9 years old), and then premolars replace primary molars( between 10 and 12

years old). Finally, maxillary canines are the last primary teeth to be replaced ( close to 12 years

old). This is often evident when the permanent maxillary canines are crowded facially as they

erupt. Note that for the adult dentition, most teeth in the mandibular arch erupt slightly earlier

than their maxillary counterparts; the only maxillary tooth to emerge before its mandibularcounterpart is the maxillary second premolar, which precedes the mandibular second premolar.

The emergence time of mandibular canines are about 9 years, while maxillary canines emerge

last, at about 12 years of age

Figure 1.2.1 the usual order of secondary dentition tooth emergence