New formulae for estimating age-at-death in the Balkans utilizing Lamendin's dental technique and Bayesian analysis.

The present study analyzed apical translucency and periodontal recession on single-rooted teeth in order to generate age-at-death estimations using two inverse calibration methods and one Bayesian method. The three age estimates were compared to highlight inherent problems with the inverse calibration methods. The results showed that the Bayesian analysis reduced severity of several problems associated with adult skeletal age-at-death estimations. The Bayesian estimates produced a lower overall mean error, a higher correlation with actual age, reduced aging bias, reduced age mimicry, and reduced the age ranges associated with the most probable age as compared to the inverse calibration methods for this sample. This research concluded that periodontal recession cannot be used as a univariate age indicator, due to its low correlation with chronological age. Apical translucency yielded a high correlation with chronological age and was concluded to be an important age indicator. The Bayesian approach offered the most appropriate statistical analysis for the estimation of age-at-death with the current sample.

A Bayesian approach to estimate skeletal age-at-death utilizing dental wear.

In the forensic context, teeth are often recovered in mass disasters, armed conflicts, and mass graves associated with human rights violations. Therefore, for victim identification, techniques utilizing the dentition to estimate the first parameters of identity (e.g., age) can be critical. This analysis was undertaken to apply a Bayesian statistical method, transition analysis, based on the Gompertz-Makeham (GM) hazard model, to estimate individual ages-at-death for Balkan populations utilizing dental wear. Dental wear phases were scored following Smith's eight-phase ordinal scoring method and chart. To estimate age, probability density functions for the posterior distributions of age for each tooth phase are calculated. Transition analysis was utilized to generate a mean age-of-transition from one dental wear phase to the next. The age estimates are based on the calculated age distribution from the GM hazard analysis and the ages-of-transition. To estimate the age-at-death for an individual, the highest posterior density region for each phase is calculated. By using a Bayesian statistical approach to estimate age, the population's age distribution is taken into account. Therefore, the age estimates are reliable for the Balkan populations, regardless of population or sex differences. The results showed that a vast amount of interpersonal variation in dental wear exists within the current sample and that this method may be most useful for classifying unknown individuals into broad age cohorts rather than small age ranges.

Inter-observer variation in methodologies involving the pubic symphysis, sternal ribs, and teeth.

For the skeletal age of a victim to be useful in victim identification, the methods on which it is based must be reliable, accurate, and the results easily duplicated. The ability of multiple investigators to duplicate results is an interesting and complex issue. The purpose of this study is to investigate how consistently multiple investigators assign skeletal traits to rib, pubic symphyseal, or tooth "phases" and measure teeth. The skeletal data from identified individuals in Kosovo are used to test inter-observer variation for a variety of skeletal and dental aging techniques. Two hundred and ninety-six (n = 296) pubic symphyses were scored in the manners of the Todd's ten-phase system and the Suchey-Brooks six-phase system. Six hundred and twenty-two (n = 622) sternal rib ends were scored in the manner of Iscan and co-author's nine-phase system. Four hundred and twelve (n = 412) single-rooted teeth were measured in the manner of Lamendin and colleagues and scored for the amount of tooth wear using Smith's nine-phase system. Repeat measures were taken by multiple observers. There appears to be a wide range of variation, even among experienced investigators in the assignment of phase or metric data. Inter-observer variation, investigated through Pearson's r correlation coefficients, the Wilcoxon signed ranks test, and paired samples t-tests demonstrate significant differences using all methods. How this variation affects the accuracy of age estimation is subject to further investigation, but what is clear is that even with collaboration among investigators to calibrate with one another, the repeatability of numerous aging methodologies is difficult to achieve. Through this investigation it appears the problem lies in the qualitative nature of broad descriptive phase categories, which contain multiple skeletal features and traits that are open to interpretation.

Application of Lamendin's adult dental aging technique to a diverse skeletal sample.

Lamendin et al. (1) proposed a technique to estimate age at death for adults by analyzing single-rooted teeth. They expressed age as a function of two factors: translucency of the tooth root and periodontosis (gingival regression). In their study, they analyzed 306 singled rooted teeth that were extracted at autopsy from 208 individuals of known age at death, all of whom were considered as having a French ancestry. Their sample consisted of 135 males, 73 females, 198 whites, and 10 blacks. The sample ranged in age from 22 to 90 years of age. By using a simple formulae (A = 0.18 x P + 0.42 x T + 25.53, where A = Age in years, P = Periodontosis height x 100/root height, and T = Transparency height x 100/root height), Lamendin et al. were able to estimate age at death with a mean error of +/- 10 years on their working sample and +/- 8.4 years on a forensic control sample. Lamendin found this technique to work well with a French population, but did not test it outside of that sample area. This study tests the accuracy of this adult aging technique on a more diverse skeletal population, the Terry Collection housed at the Smithsonian's National Museum of Natural History. Our sample consists of 400 teeth from 94 black females, 72 white females, 98 black males, and 95 white males, ranging from 25 to 99 years. Lamendin's technique was applied to this sample to test its applicability to a population not of French origin. Providing results from a diverse skeletal population will aid in establishing the validity of this method to be used in forensic cases, its ideal purpose. Our results suggest that Lamendin's method estimates age fairly accurately outside of the French sample yielding a mean error of 8.2 years, standard deviation 6.9 years, and standard error of the mean 0.34 years. In addition, when ancestry and sex are accounted for, the mean errors are reduced for each group (black females, white females, black males, and white males). Lamendin et al. reported an inter-observer error of 9+/-1.8 and 10+/-2 sears from two independent observers. Forty teeth were randomly remeasured from the Terry Collection in order to assess an intra-observer error. From this retest, an intra-observer error of 6.5 years was detected.