Age estimation

1. AGE ESTIMATION BY ASPARTIC ACID
RACEMIZATION IN HUMAN TEETH
GUIDED BY: S.V.SITPURIA SIR
PREPARED BY: CHIRAG D. MEHTA
MSc. FORENSIC SCIENCE
GUJARAT UNIVERSITY

2. CONTENTS
 INTRODUCTION
 SCOPE & OBJECTIVE
 METHODOLOGY
a) Sample Collection
b) Sample Preparation
c) Instrumentation
 RESULT
 FORENSIC SIGNIFICANCE

3. INTRODUCTION
 The accumulation of damage is a major component
of ageing.
 One such damage that occurs in proteins is
racemization.

4. SCOPE & OBJECTIVE
 Formation of aspartic acid in human teeth begins as
early as the development of teeth since childhood.
 In the early years of life the concentration of L-
aspartic acid remains high and with the
advancement of age the L form gets racemised into
D form.
 On the basis of proportion of racemization the
determination of age of the person can be done.

5. METHODOLOGY
 Sample Collection
 Sample Preparation
 Instrumental Analysis

6. SAMPLE COLLECTION
 Samples were collected from:
Dental college, Civil hospital , Ahmedabad.
 Type of teeth samples: Molar
 Number of samples: 20

7. DETAILS OF SAMPLES:
Age Group Number of Samples
30-35 2
36-40 3
41-45 1
46-50 2
51-55 2
56-60 1
61-65 5
66-70 4

8. SAMPLE PREPARATION
Preservation
Separation
Hydrolysis

9. INSTRUMENTAL ANALYSIS
1) Qualitative Analysis:
 FT-IR
2) Quantitative Analysis:
 HPLC
 UV-VISIBLE Spectrophotometry

10. DATA ANALYSIS
Formula Used: kinetic equation of
racemization of amino acids
Where,
t= age in years
k= constant = 0.001208
A= pre-exponential or A-factor = 0.0341
ln[(l + D/L)/(1 - D/L)] = 2kt + A

11. RESULT
No. Known
Age(years)
D/L
(%)
ln{(1+D/L)/(
1-D/L)}
Estimated
Age(years)
Error
(years)
1 30 3.33 0.0666 27 -3
2 33 3.62 0.0724 32 -1
3 36 3.75 0.0750 34 -2
4 37 3.98 0.0796 38 +1
5 38 4.04 0.0808 39 +1
6 41 4.27 0.0855 43 +2
7 46 5.05 0.0986 49 +3
8 49 4.89 0.0979 53 +4
9 51 4.92 0.0986 52 +1
10 53 4.98 0.0997 54 +1

12. No. Known
Age(years)
D/L
(%)
ln{(1+D/L)/(
1-D/L)}
Estimated
Age(years)
Error
(years)
11 57 5.18 0.1037 58 +1
12 61 5.29 0.1059 63 +2
13 62 5.32 0.1065 63 +1
14 63 5.35 0.1070 63 0
15 64 5.32 1065 63 -1
16 65 5.41 0.1083 67 +2
17 66 5.55 0.1110 68 +2
18 68 5.67 0.1132 67 -1
19 69 5.88 0.1179 69 0
20 70 5.92 0.1185 69 -1

13. CONCLUSION
 This method of using HPLC & UV-VIS
spectrophotometry to determine D/L ratio in
human teeth is easy & fast.
 In addition, the reagents used are cheaper.
 This method is more accurate in age estimation
from teeth for forensic purpose.

14. FORENSIC SIGNIFICANCE
 In mass disasters, such as air or train accident,
an entire body may not be available and
examination may have to be carried out from
the available fragmentary remains.
 Teeth being resistant to putrefaction serve as a
good source for establishing the identity of the
person.

15. THANK YOU