Aspartic Acid Racemization with Correlation to Age: AForensic Perspective.

OBJECTIVE

To estimate age through aspartic acid racemization of human dentin for forensic analysis, and to calculate the margin of error between chronological age and estimated age by racemization method.

STUDY DESIGN

Cross-sectional comparative study.

PLACE AND DURATION OF STUDY

Dental Outpatients' Department, Ziauddin Hospital, Karachi, from 2011 to 2014.

METHODOLOGY

Patients from dental orthodontics department were selected. Verbal expressed consent was taken from the participants. Preliminary data was entered in a specially designed performa having name, chronological age, gender, socio-economic status. Land D ratio of aspartic acid were quantified in dentin for each tooth by High-Pressure Liquid Chromatography technique. Results of 100 samples with known age were used during study to estimate co-efficient of racemization. Regression equation was derived by plotting 85 samples of known age and KR as independent and dependent variables and least square equation was derived - Age = -4.391 +347.396 (co-efficient of racemization).

RESULTS

The estimated co-efficient of determination was 0.74, meaning thereby that the regression equation was 74% correct for estimating age. The calculated correlation between chronological age and co-efficient of racemization was 0.834, which is interpreted as a very strong and positive correlation. The co-efficient of racemization increased with the age. The mean chronological age (38.44 ±13.22) years were statistically similar to the mean calibrated age (37.52 ±12.36) years. The median of actual and calibrated age was found to be 3.4 with inter-quantile value of 13. No statistically significant difference was observed among gender (p=0.837), or socioeconomic status (p=0.35).

CONCLUSION

Racemization of human dentin could be used as one of the reliable method for estimating age. HPLC is a reliable technique to estimate the co-efficient of racemization because it is highly reproducible, cost-effective and convenient. However, the procedure should be optimized and standardized within all laboratories for quality assurance.