Comparing the accuracy of Demirjian and Nolla methods and establishing a new method for dental age estimation in northeastern Chinese children

Dental age estimation plays an important role in the field of clinic medicine and forensic medicine. The Demirjian and Nolla methods are common scoring methods for dental age estimation but there was no research about the comparison of accuracy of these two methods in northeastern Chinese children. Hence, in this study, we compared the accuracy of these two methods to explore more suitable method for our studied population. We collected 535 orthopantomograms from northern Chinese children aged from 6 to 15 years and divided them into training dataset and testing dataset according to the ratio of 7:3. The dental age of training dataset were estimated using Demirjian and Nolla methods, respectively. The results suggested that the mean differences of these two methods were 0.24 and −0.40 years, and mean absolute difference were 0.65 and 0.59 years. Then to further improve the accuracy of dental age assessment, the new improved formulas and dental age conversion tables were established after analyzing the relationship between the sum scores based on Nolla method and chronology age in training dataset. According to the new method used in testing dataset, the minimum value of mean difference (0.00) and mean absolute difference (0.49) were obtained, which are largely smaller than that of Demirjian and Nolla methods. The new developed method and dental age conversion scales may be more suitable dental age estimation method for northeastern Chinese children.     

Age Estimation from the Teeth Using a Modified Demirjian System*

Abstract: The estimation of age at time of death is often an important step in the identification of human remains. The purpose of this study was to test the applicability of the Demirjian system on a sample of the Sydney child population and to develop and test age‐prediction models using a large sample of Sydney children (1624 girls, 1637 boys). The use of the Demirjian standards resulted in consistent overestimates of chronological age in children under the age of 14 by as much as a mean of 0.99 years. Of the alternative predictive models derived from the Sydney sample, those that provided the most accurate age estimates are applicable for the age ranges 2–14 years, with R‐square = 0.94 and a 95% confidence interval of ±1.8 years. The Sydney‐based standards provided significantly different and more accurate estimates of age for that sample when compared to the published standards of Demirjian.     

Evaluation of the (hu)MANid program for sex and ancestry estimation in a diverse,contemporary CT scan-based sample

Human remains from forensic and bioarcheological contexts are often fragmentary, requiring methods for estimating a forensic profile that are based upon limited skeletal features. In 2017, Berg and Keryhercz created an online application, (hu)MANid, that provides sex and ancestry estimation from mandibular morphoscopic traits and linear measurements. In this study, we examine the utility of the (hu)MANid application in a diverse, urban US adult sample (aged 20–45; n = 143) derived from computed tomography (CT) scans. We secondarily conduct a preliminary analysis of the program's utility in a sample of adolescents (aged 15–17; n = 40). Six morphoscopic, and eleven morphometric traits were recorded as directed by the literature associated with the (hu)MANid program. Percent correct classification and posterior predictive values were calculated for the sex and ancestry estimations output by the program; chi-squared tests were employed to compare self-reported and predicted ancestry. In the adult sample, sex was accurately predicted for 75.52% of the sample. Ancestry prediction, however, was less favorable ranging from 19.3% to 50% correct. For the adolescent sample, correct sex estimation (45%) did not surpass what could occur by chance alone, though ancestry prediction fared better than in the larger adult sample (percent correct prediction overall average: 47.5%, range 35.71%–71.43%). The (hu)MANid application shows utility for use with CT scan-derived adult samples for sex estimation, but caution is warranted for ancestry estimation and use with samples that may not have reached full adult maturity.     

A simulation for exploring the effects of the "trait list" method's subjectivity on consistency and accuracy of ancestry estimations

The nonmetric "trait list" methodology is widely used for estimating ancestry of skeletal remains. However, the effects of the method's embedded subjectivity on subsequent accuracy and consistency are largely unknown. We develop a mathematical simulation to test whether variation in the application of the "trait list" method alters the ancestry estimation for a given case. Our simulation explores how variations in (i) trait selection, (ii) number of traits employed, and (iii) ancestry choice thresholds affect the ancestry estimation of an unidentified skeleton. Using two temporally and geographically diverse samples, the simulation demonstrates that trait selection, trait quantity, threshold choices, and the exclusion of high-frequency traits had minimal effect on estimation of general ancestry. For all data sets and Runs, Accuracy(AS) was maintained above 90%. The authors close with a discussion on the logistical issues present when choosing traits, and how to avoid ancestry bias.     

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.     

Testing Anatomical Methods for Stature Estimation on Individuals from the W. M. Bass Donated Skeletal Collection

Abstract:  This study compared eight versions of the anatomical method for stature estimation on a white male sample ( n  = 34) from the W. M. Bass Donated Skeletal Collection. The aim was to evaluate errors in the estimates and to discuss how useful the methods are in forensic context. The average error estimating living stature was less than 1 cm for six of the methods. The correlations between the estimates were high ( r  = 0.982–0.999). In practice, differences between the versions as well as those between long bone-based equations and anatomical methods were small. Anatomical method is nevertheless more accurate than long bone regressions when individuals with atypical body proportions are examined.     

A Comparative Assessment of the Chen et al. and Suchey‐Brooks Pubic Aging Methods on a North American Sample, ,

Accurately estimating the age‐at‐death of adult human skeletons is fundamental in forensic anthropology. This study evaluates the accuracy of two pubic bone age estimation methods—Chen et al. and Suchey‐Brooks. Specimens were obtained from a known collection of modern pubic bones curated at the Maricopa County Forensic Science Center in Phoenix, Arizona. A sample of 296 left male pubic bones of European ancestry was statistically evaluated via bias, absolute mean error, and intra‐ and inter‐observer error. Results indicate that the two methods are similar; the Suchey‐Brooks method is the most accurate for aging young adults (error c. 7 years), while the Revised Chen et al. method is most accurate for aging middle‐age adults (error c. 6 years). Thus, the Chen et al. method is an important contribution to forensic anthropology for aging older adult skeletal remains. There are, however, some limitations such as subjectivity and the intricate scoring system of Chen et al. method.     

Sex Determination from the Second Cervical Vertebra: A Test of Wescott’s Method on a Modern American Sample*

Abstract: Numerous methods for establishing a biological profile exist; however, many of these methods rely on the recovery of several specific bones or on fragile skeletal elements that are sometimes irrecoverable. It is for this reason new methods utilizing other previously under‐documented bones should be established and tested by the forensic anthropological community. This study tests the accuracy of Wescott’s (J Forensic Sci 2000;45(2)) method for determining sex from the second cervical vertebra. Specimens were drawn from the donated skeletal collection curated at the Hamilton County Forensic Center (n = 57) and the William M. Bass Donated Skeletal Collection (n = 243). Both intra‐ and inter‐observer error rates were low and accurate classifications ranged from 78% (females‐Function 1) to 90.6% (males‐Function 5). Of the five functions, Function 4 achieved the highest overall accuracy, with 260 individuals (86.7%) falling into the correct category. Overall, this method is an effective classificatory tool for sex estimation.     

Generating a Vertebrae‐based Method to Discriminate between Korean and U.S. White Male Casualties from the Korean War,

Low recovery rate of intact crania in conflict‐related contexts necessitates the use of postcranial elements for ancestry estimation. This study aimed to develop a new method to discriminate between Korean and U.S. White casualties from the Korean War using vertebrae. Maximum body heights of C2 through L5 were measured from 75 Korean and 51 U.S. males to generate discriminant functions. U.S. vertebral heights were statistically greater than Koreans in 18 out of 23 vertebrae (C2, C4‐6, T3‐6, and T8‐L5). The functions with lumbar vertebrae tended to yield higher correct classification ratios (CCR) than those with cervical or thoracic vertebrae. Inclusion of the femur and tibia lengths in the vertebrae‐involved functions enhanced the CCR's. Discriminant functions using the femur and tibia length were also presented. The results of this study are expected to complement the current practices of the Defense POW/MIA Accounting Agency and the Ministry of National Defense Agency for KIA Recovery and Identification, which are primarily based on cranial and dental morphology.     

Outline Shape Analysis on the Trochlear Constriction and Olecranon Fossa of the Humerus: Insights for Sex Estimation and a New Computational Tool,

Sex estimation through visual analysis of the distal humerus can contribute to establishing the biological profile of an unidentified skeletal individual. Using statistical shape modeling, the trochlear constriction open curves and olecranon fossa closed outlines of 151 humeri were digitized and analyzed. The shape configurations exhibited strikingly different degrees of sexual dimorphism when evaluated using linear discriminant analysis with leave‐one‐out cross‐validation. The trochlear constriction performed poorly, correctly classifying 63.6% of the individuals. However, the olecranon fossa showed high sexual dimorphism, presenting a 94.0% accuracy. A simpler model using only two principal components was also generated. While the accuracy is slightly inferior (88.1%), it has the advantage of being constrained to bidimensional components that were translated into morphoscopic variables within a simulator interface. This allowed us to implement the method through a web application that does not require users to be trained in landmark digitization or have knowledge of geometric morphometrics.     

Qualitative and Quantitative Diagnosis of Lethal Cranial Neural Tube Defects from the Fetal and Neonatal Human Skeleton,with a Case Study Involving Taphonomically Altered Remains

Abstract: Cranial neural tube defect, or anencephaly, is the absence of normal brain development because of severe developmental defect in the fetus. While the current incidence of human anencephaly ranges between 1 to 5 per 1000 births, and was higher prior to folic acid supplementation, there is no discussion of anencephaly diagnosis in the forensic literature and only one published example from the archeological record. This article presents both qualitative observations of abnormal cranial elements and an osteometric method to quantitatively determine anencephaly from forensic recovery contexts where taphonomic variables may otherwise mask diagnostic characteristics. Evidence is presented for only the second case of anencephaly diagnosed from a burial context, and the first not involving soft tissue mummification. The initial recognition and accurate prediction of anencephaly is a significant contribution to investigators recovering found human fetal remains.