Abstract: 97 maxillary first permanent molars of Southern Chinese were investigated in this report.
The method of study is as follows: the teeth investigated were ground into 0.5 mm thick slies through the central part of the buccolingual sides of the molar. The height and width of the pulp chamber and the dentine of the slice were measured with the micrometer through microscope. The pulp-dentine index was calculated according to the following formula:
Pulp-dentine index =(height + width of pulp chamber)/(height + width of dentine)*100. We found that there is a negative correlation between the pulp-dentine index and the age of all teeth examined. The regression formula to estmate age is： g=( —1.01) )s+ 82.82 (where： t/=pulp-dentine index, a:^estimated age).

Key words: Pulp-dentine index; Age estimation; Southern Chinese