There are several medical methods of age estimation, a few are given below:
1. General Developmental Features
e.g. appearance, height, puberty changes
2. Eruption of teeth
Eruption of teeth is completed by 25 years of age
3. Appearance of ossification centres
Ossification centers may be seen on X-rays in the living, they are valuable to estimate age up to 25 years of age.
4. Epiphyseal Union of Long Bones
Epiphyseal union begins at 12 years and concludes at 32 years of age.
5. Structural Changes in Isolated Teeth
a. Neonatal line
b. Striae of retzius
Height/weight of teeth
6. Gustafson’s Criteria
Gustafson’s method of age estimation consists of microscopic examination of the longitudinal section of the central part of the tooth, to assess the changes in teeth as a result of wear and tear with advancing age. These changes are graded into six types:
- Attrition of tooth by mastication
- Deposition of secondary dentine in pulp chamber
- Level of attached gingivae
- Deposition of cementum on the root
- Translucency of the roots
- Resorption of the roots
7. Suture closure of Skull
- Endocranial suture closure begins at 30-40 years
- Ectocranial suture closure begins 10 years later.
8. Pubic Symphysis Transformation (18-60 years)
- Component I –Dorsal half surface
- Component II –Ventral half surface
- Component III – Whole surface
Each component is divided in grades 0-5.
9. Joint Lipping –Osteophytes
After 40 years of age, lipping of lumbar vertebra occurs. These osteophytic outgrowths from the anterior and lateral margins of the intervertebral discs rarely become prominent before 40 years. The disc undergoes atrophic changes by 40-45 years.
10. Changes in Scapulae
11. Developmental Changes in Skull
a. Neonatal Skull
- Neonatal skull is large in proportion to other parts of the skeleton
- Facial part of the cranium is relatively small, forming 1/8th of the neonatal cranium, compared with ½ in adult.
- Middle and inner ears are almost of adult size
- Vault bones are smooth, unilaminar and without diploe (which begin to appear at 4 years of age)
- Glabella, superciliary arches and mastoid processes are not developed
- Ossification of skull bones is not complete
- Paranasal sinuses are rudimentary or absent
- There are six fontanellae, namely anterior fontanellae, posterior fontanellae, sphenoidal fontanellae (left and right) and mastoid fontanellae (left and right).
Post Natal Skull
- By 7 years of age, skull has almost adult dimensions
- Sphenoidal and posterior fontanellae close within 2-3 months after birth
- Mastoid fontanellae close by end of 1st year
- Anterior fontanellae close by the middle of second year (one and a half to 2 years age)
- Two tables and the intervening diploe appear about the 4th year and reach maximum differentiation by 35 years of age
- Mastoid processes appear in the 2nd year and are invaded by air cells in the sixth year.
12. Changes in Mandible
The mandible is in two separate halves, which become fused in the first year of life. Mental foramen opens below the socket of first deciduous molar and is directed forwards. In 1-2 years direction changes to upwards and backwards and then to almost horizontally backwards, as in adult.
At 70 Years
Angle of lower jaw begins to open out and becomes obtuse. The alveolar ridges become absorbed.