1. Suture and fontanelle closure
The skull sutures estimates are unreliable due to too much variation. Suture closure begins on the inner surface and proceeds outwards to completion ten years later. Sutures are usually obliterated between 25 and 30 years of age. Partial obliteration for the sagittal suture is during the early 30’s, for the coronal suture it is during the 40’s, and the lamboidal during the 50’s.
Obliteration proceeds towards the bregma towards the medio-frontal and is complete by the 2nd year. Frontal suture is called metopism. A small supra-nasal portion is retained until the 6th year.
With regard to the fontanelle obliteration the sagittal or obelion is gone after the first two months of birth. The posterior or occipital apex fontanelle also seals two months after birth. For the antero-lateral or pterion the time scale is three months. The postero-lateral or parietal fontanelle disappears by the end of the first year followed by the bregmatic in the second year.
Fusion of the mandible two halves and symphysis is by the end of the second year.
2. Dental eruption
With regard to the milk dentition sex differences in dental maturation are slight. The approximate age of tooth eruption for deciduous or ‘milk teeth’ is as follows: lower central incisors is between 5 to 12 months; lower lateral incisors between 6 and 14 months; first molars between 13 to 20 months; the canines between 13 to 30 months; and the second molars between 18 to 38 months.
For the permanent dentition the first molars appear during the 6th year, the central incisors during the 7th, the lateral incisors during the 8th year, followed by the first premolars in the 9th. The second premolars appear in the 10th year followed by the canines from the 11th to 12th year. The second molars erupt during the 12th to 13th years with the third molars, or ‘wisdom teeth during the period 17th to 25th year.
The deciduous dental eruption of 20 teeth provides incisors 2/2; canines 1/1, and molars 2/2/. The permanent dentition of 32 teeth provides incisors 2/2, canines 1/1, premolars 2/2, and molars 3/3. Dental attrition relates to the eruption process in terms of years.