Studies on age estimation using racemization of aspartic acid in cementum.

An attempt was made to estimate the age of cementum using the racemization method, which focuses on the ratio of D- and L-aspartic acids (referred to as the 'D/L ratio'). Using the whole cementum, the correlation coefficients between the D/L ratio and age were r = 0.984 to 0.997. When the use of incisors and premolars was compared, the former gave better results than the latter. We then made a comparison of cementum, enamel and dentin, using a first premolar from the same individual. For each component tissue the correlation of D/L ratio with the actual age was calculated and the highest value was shown for dentin at r = 0.992, followed by cementum at r = 0.988 and enamel at r = 0.961. These results show that the racemization reaction in cementum proceeds at a constant rate, and confirm that cementum, like dentin, is a tissue with very low metabolism. Therefore, it is clear that accurate estimation of age is practically possible using the amino acid racemization method for cementum.