Incremental lines of dental cementum in biological age estimation.
The aim of this study is to evaluate the use of counting incremental lines of dental root cementum for biological age determination, and to compare it with alternative methods. Two samples were taken: 51 teeth from 49 individuals of known age obtained at the Stomatological Clinic, Vilnius University, as well as the canine teeth from the remains of 48 individuals from the mass graves of Tuskulenai in Vilnius (inhumed 1944-47). In the latter sample, the chronological age of 43 individuals was known through personal identification. Undecalcified teeth were sectioned with the Leica SP 1600 microtome diamond saw, and incremental line count as a blind test was made on sections of 35 to 100 microns thickness. Incremental line count was possible in 82-86 percent of cases. The results of three independent counts showed that intra-observer bias has no significant impact. Biological age was estimated by adding incremental line number to the average age of tooth eruption. It was found that mean absolute error was 6.46 years for the 1st sample, 6.27 years for the 2nd sample, and in some cases exceeded 10 years. For the 2nd sample, the results were compared to those of other methods such as endocranial suture ossification, pubic symphysis morphology and the "combined" method of Nemeskéri. All four methods yield a similar correlation in regard to an individual's chronological age. The highest correlation was found for the combined method, and the lowest one for public symphysis morphology. All correlations had a similar standard error. Thus our assessment is less enthusiastic than in some past studies; it is suggested that the incremental lines rather have a similar use as other methods.