Accuracy of three age determination X-ray methods on the left hand-wrist: a systematic review and meta-analysis

Age estimation of living individuals often represents a forensic challenge with important legal and social implications. In an effort to better understand the accuracy of the methods of Greulich and Pyle (GP), Tanner-Whitehouse (TW) and Fels, a systematic review and a meta-analysis of articles published from 1956 to 20 December 2009 in the Medline and Trip databases were conducted. We only selected articles on healthy people. The meta-analysis showed that GP is not as accurate a method as TW2 or TW3 for both Caucasian people and Mongoloids, even if it is the one most often used. However, due to the very wide age estimation range, in line with what has already been established by several authors, our systematic review and meta-analysis confirmed that age estimation in living individuals cannot be considered accurate when only X-ray methods on the left hand-wrist are used, but exhaustive combinations of various procedures (i.e. physical examination, dental and skeletal methods) must also be used, as proposed and already applied by the International Study Group on Forensic Age Estimation.     

Age estimation of immature human skeletal remains from the diaphyseal length of the long bones in the postnatal period

Age at death in immature human skeletal remains has been estimated from the diaphyseal length of the long bones, but few studies have actually been designed specifically for the purpose of age estimation and those which have, show important caveats. This study uses regression and classical calibration to model the relationship between age and diaphyseal length of the six long bones, in a sample of 184 known sex and age individuals (72 females and 112 males), younger than 13 years of age, selected from Portuguese and English skeletal collections. Age estimation models based on classical calibration were obtained for each of the six long bones, and separately for each sex and for the sexes combined, and also for the entire sample and when it is subdivided into two subsamples at the age of 2 years. Comparisons between inverse and classical calibration show there is a systematic bias in age estimations obtained from inverse calibration. In the classical calibration models, the length of the femur provides the most accurate estimates of age. Age estimates are more accurate for the male subsample and for individuals under the age of 2 years. These results and a test of previously published methods caution against inverse calibration as a technique for developing age estimation methods even from the immature skeleton. Age estimation methods developed using cemetery collections of identified human skeletons should not be uncritically applied to present-day populations from the same region since many populations have experienced dramatic secular trends in growth and adult height over the last century.     

Deoxypyridinoline crosslinks in human dentin and estimation of age

A new biochemical method for estimation of dental age from human dentin is presented. An adaptation and modification of a dentin protein extraction protocol was developed by which deoxypyridinoline crosslinks were measured using an enzyme immunoassay technique. Deoxypyridinoline, a non-reducible collagen crosslink, was measured in human dentin samples from permanent individual molars. The measurement of this protein in dentin samples from 22 patients with ages ranging from 15 to 73 years old was carried out to obtain an estimate of age at death. By linear regression between deoxypyridinoline values and age, equations for age calculations were computed. The error between the estimated age and the known age at extraction was calculated. Our results show that this method produces an expected associated error on calibration averaging 14.9 years about the mean estimated values, at a 65% level of confidence. Values of sensitivities and specificities were calculated for deoxypyridinoline at different ages. We conclude that determination of deoxypyridinoline in human dentin extracts is a new and reliable procedure, potentially suitable for most forensic laboratories and which could be a useful tool to estimate human dental age. This method could be considered as an alternative method to calculate dental age, contributing to a more accurate estimation of chronological age when used in addition to other morphological or biochemical dental methods. Received: 15 May 1998 / Received in revised form: 16 October 1998     

Dental age estimation in Egyptian children,comparison between two methods

The need to estimate age of living individuals is becoming increasingly more important in both forensic science and clinical dentistry. The study of the morphological parameters of teeth on dental radiographs of adult humans is more reliable than most other methods for age estimation. Willems and Cameriere methods are newly presented methods. The aim of this work was to evaluate the applicability of using these methods for Egyptian children. Digitalized panoramas taken from 286 Egyptian children (134 boys, 152 girls) with age range from 5 to 16 years were analyzed. The seven left permanent mandibular teeth were evaluated using the two methods. The results of this research showed that dental age estimated by both methods was significantly correlated to real age. However, Willems method was slightly more accurate (98.62%) compared to Cameriere method (98.02%). Therefore, both methods can be recommended for practical application in clinical dentistry and forensic procedures on the Egyptian population.     

Soft tissue removal by maceration and feeding of <Emphasis Type="Italic">Dermestes</Emphasis> sp.: impact on morphological and biomolecular analyses of dental tissues in forensic medicine

Maceration techniques remove soft tissue by the destruction of biomolecules, but the applied techniques may also affect the morphology and the molecular integrity of the hard tissue itself. The impact of seven different techniques for soft tissue removal on morphological and biomolecular parameters of teeth and dental tissues was systematically examined. All methods tested showed significant changes in dental morphology and in the molecular integrity of DNA and the dental proteins, as revealed by aspartic acid racemisation (AAR). In forensic casework this may have severe impacts on the results of morphological methods (e.g. age estimation based on root translucency) and of biomolecular analyses (e.g. age estimation based on AAR and DNA analysis). Therefore, age estimation based on AAR should not be applied to tissue treated in such a manner, and it is recommended that teeth for analysis should be extracted before soft tissue removal. DNA in the hard tissue seems to be less susceptible to soft tissue removal than proteins, and several of the tested maceration techniques appear not to have a damaging effect on DNA. Generally, the indication for soft tissue removal demands a careful case management to avoid methodological collisions.     

Assessment of the accuracy of the Greulich and Pyle hand-wrist atlas for age estimation in a contemporary Australian population

Age estimation of living individuals is topical, and is particularly important globally, owing to increasing migration of undocumented individuals. Radiographic skeletal analysis of hand-wrist skeletal development is often used to infer chronological age based on direct comparison to standards such as the Greulich and Pyle atlas. However, this atlas has been criticised for being applied to foreign populations without due consideration of accuracy. The aims of the current study are to assess the precision and accuracy of the atlas in a contemporary Western Australian population and to develop population specific standards based on the latter system. The study sample comprised 360 individuals (equal sexes) and aged from birth to 25 years; a hold-out group comprising a further 50 individuals was used for model validation. Age estimation was performed through the visual comparison of the study radiographs against the atlas standards; statistical analyses were performed to assess the relationship between estimated skeletal and actual age. Prediction models were formulated; mean SEE values were ±0.005–0.90 (male) and ±0.25–0.421 years (female). Comparisons with prior research demonstrates the importance of contemporary population standards. The models presented here have forensic utility in a Western Australia jurisdiction, albeit the level of accuracy achieved is not suitable for the specific determination of legal majority.     

Effects of ethnicity on skeletal maturation: consequences for forensic age estimations

An X-ray of the hand is an important method in forensic science for estimation of the age of juvenile suspects with uncertain date of birth. Relevant X-ray standards for evaluation of skeletal maturity are available for white US Americans as well as for North and Central Europeans. The applicability of these standards to members of ethnic groups different from the reference population has been the subject of controversial discussion. More than 80 publications were analysed with the view to finding out whether skeletal maturation is affected by ethnic identity. It was concluded that skeletal maturation takes place in phases which are identically defined for all ethnic groups. Time-related differences in passing those stages of skeletal maturation within the relevant age group appear to be unaffected by ethnic identity. It is the socio-economic status of a given population which is of decisive importance to the rate of ossification. The application of X-ray standards to individuals of a socio-economic status lower than that of the reference population usually leads to underestimation of that person’s age. In terms of criminal responsibility, this is of no adverse effect on the person concerned. Received: 25 February 1999 / Received in revised form: 6 August 1999     

Dental and skeletal maturation as simultaneous and separate predictors of chronological age in post-pubertal individuals: a preliminary study in assessing the probability of having attained 16 years of age in the living

The goal of this paper is to explore whether combining dental and skeletal maturation data increases the reliability of determining whether an individual is 16 years old or older. This is tentatively done by building probabilistic models for age estimation based on dental and skeletal maturation using a longitudinal sample of eight males, with annual assessments between the ages of 13 and 19, totalling 56 observations. Skeletal maturity was assessed for the radius and ulna using the TW2 method, and dental maturity was assessed for the second and third molars using Demirjian’s scheme. Logistic regression was selected to determine the probability of an individual being 16 years of age and older, by combining dental and skeletal maturity scores and using them separately. The age estimation models combining dental and skeletal maturity scores seem to perform better than either dental or skeletal maturity in isolation. In addition, when in isolation or combination, models based on skeletal maturity scores seem to outperform models based on dental maturity scores. The findings seem to support the notion that dental development is less reliable than skeletal maturity for age estimation in adolescents, but these results have to be confirmed by further studies.     

Quality assurance in age estimation based on aspartic acid racemisation

Estimates of the age of living and dead individuals, obtained in order to answer legal or social questions, require minimum quality standards in order to guarantee data quality. We present an outline strategy (with recommendations) for the attainment of quality assurance in age estimation based on aspartic acid racemisation. The strategy is based on a definition of minimum standards for laboratories, including documentation of procedures, methodology and levels of expertise, and the formulation of guidelines for intralaboratory and interlaboratory quality control. Received: 10 January 2000 / Accepted: 15 March 2000     

Combining dental and skeletal evidence in age classification: Pilot study in a sample of Italian sub-adults

BackgroundDental and skeletal maturation have proved to be reliable evidence for estimating age of children and prior studies and internationally accredited guidelines recommend to evaluate both evidence in the same subject to reduce error in age prediction. Nevertheless the ethical and legal justification of procedures that imply a double exposition of children stands as a relevant issue. This study aims to evaluate the accuracy of age estimation provided by a combination of skeletal and dental methods applied in the same sample of children.Materials and methodsThe sample consisted of 274 orthopantomographies and left hand-wrist X-rays of Italian children, (aged between 6 and 17 years) taken on the same day. Greulich and Pyle’s (GP), Tanner-Whitehouse’s version 3 (TW3) and Willems’ (W) and the Demirjian’s (D) methods were respectively applied for estimating skeletal and dental age. A combination of skeletal and dental age estimates through Linear Discriminant Analysis (LDA) is proposed to obtain a classifier respect to an age threshold.ResultsThe combination of D and TW3 obtained an improvement of accuracy in classifying female subjects respect to the 12 years threshold respect to the original methods (from about 77% using either original methods to 83.3% combining TW3 + D) as well as a consistent reduction of false positives rate (from 17% to 21% for original methods to 5.6% with TW3 + D). For males the LDA classifier (based on TW3 and W) enable a small improvement in accuracy, whilst the decreasing of false positives was as noticeable as for females (from 17.6 to 14.1% for original methods to 6.2% combining TW3 + W).ConclusionsAlthough the study is influenced by the limited size and the uneven age distribution of the sample, the present findings support the conclusion that age assessment procedures based on both dental and skeletal age estimation can improve the accuracy and reduce the occurrence of false positives.     

Accuracy of the London Atlas,Haavikko’s Method and Cameriere’s European Formula of dental age estimation in Turkish children

Age estimation is a mandatory procedure when the chronological age is unknown or uncertain. Dental development is the preferred characteristic for estimating a child's age. There are many methods for dental age estimation, but their reliability can differ between populations. This study compared the accuracy of three of these methods—the London Atlas (LA), Haavikko's method (HM), and Cameriere's European formula (CF)—in Turkish children living in northwestern Turkey. Panoramic radiographs of 980 children from northwestern Turkey aged between 6.00 and 14.99 years were examined for the whole study group and separately for different ages and sexes by all three methods. Statistical differences between chronological age and dental age were tested using the paired sample t-test and the Wilcoxon signed-rank test. The LA, HM, and CF accuracies were determined based on the mean absolute error. Spearman's rank correlation coefficient showed that the correlation between chronological age and dental age for both sexes was linear for all methods. The LA overestimated the chronological age by 0.09 years, while HM and CF underestimated it by 0.49 and 0.11 years, respectively. The difference between dental age and chronological age was significant in all samples, for all methods, except for the LA in boys. When boys, girls, and the total sample were evaluated, values with the lowest mean absolute error were obtained by HM and were statistically significant in all three groups. Therefore, HM is more accurate than the LA and CF for dental age estimation in Turkish children living in northwestern Turkey.     

A comparison of three established age estimation methods on an adult Spanish sample

Most current methods for adult skeletal age-at-death estimation are based on American samples comprising individuals of European and African ancestry. Our limited understanding of population variability hampers our efforts to apply these techniques to various skeletal populations around the world, especially in global forensic contexts. Further, documented skeletal samples are rare, limiting our ability to test our techniques. The objective of this paper is to test three pelvic macroscopic methods [(1) Suchey-Brooks; (2) Lovejoy; and (3) Buckberry and Chamberlain] on a documented modern Spanish sample. These methods were selected because they are popular among Spanish anthropologists and because they never have been tested in a Spanish sample. The study sample consists of 80 individuals (55 males and 25 females) of known sex and age from the Valladolid collection. Results indicate that in all three methods, levels of bias and inaccuracy increase with age. The Lovejoy method performs poorly (27%) compared with Suchey-Brooks (71%) and Buckberry and Chamberlain (86%). However, the levels of correlation between phases and chronological ages are low and comparable in the three methods (<0.395). The apparent accuracy of the Suchey-Brooks and Buckberry and Chamberlain methods is largely based on the broad width of the methods’ estimated intervals. This study suggests that before systematic application of these three methodologies in Spanish populations, further statistical modeling and research into the covariance of chronological age with morphological change are necessary. Future methods should be developed specific to various world populations and should allow for both precision and flexibility in age estimation.     

Studies of the chronological course of wisdom tooth eruption in a German population

Forensic age estimation in living subjects has gained increasing significance in recent years. In dental age estimation, tooth eruption is a parameter of developmental morphology that can be analyzed by either clinical examination or by evaluation of dental X-rays. In the present study, we determined the stage of wisdom tooth eruption in 144 male and 522 female German subjects aged 12-26 years based on radiological evidence from 666 conventional orthopantomograms. The results presented here provide useful data on the age of alveolar, gingival, and complete emergence of the third molars in the occlusal plane that can be utilized for the forensic estimation of the minimum and most probable ages of individuals under investigation.     

Age determination of the molars

It has generally been acknowledged that the estimation of age may have a particular medico-legal significance, and that dental methods can be exceptionally useful (Cameron and Sims, 1973; Song and Jia, 1986a). The authors have studied the method for age estimation by using the theory of quantification (Type 1) and multiple stepwise regression analysis (Song and Jia, 1987, 1989). It is not uncommon in the practice of forensic medicine to find instances in which some teeth are missing, thereby adding to the difficulties in age estimation. Thus alternative techniques have to be used. This paper discusses a method of age estimation using only the molars in 495 females living in the Liaoning Province of the People's Republic of China.     

Age dependence of epiphyseal ossification of the distal radius in ultrasound diagnostics

By determining the ossification stage of the distal radial epiphysis, it is possible to gain important information to help clarify the question of whether various legally relevant age limits have been exceeded. Any examination of the hand by means of projection radiography such as that used in conventional skeletal age diagnostics is strictly regulated for reasons of radiation hygiene. In many areas of the law, there are no basic legal provisions authorising the performance of X-ray examinations. The present study examines the applicability of ultrasound diagnostics in assessing ossification processes in the distal radius. To this end, the ossification stages of the distal radial epiphysis were determined in 306 female and 309 male study participants aged between 10 and 25 years. In the female gender, ossification stage III was determined at an age of 13.4 years at the earliest, and ossification stage IV at 15.0 years at the earliest. In the male gender, ossification stage III was not observed until 14.3 years, and ossification stage IV not until 15.2 years. In the practice of forensic age estimation in living persons, sonographic examination of the distal radius in areas of application with no legal basis for authorising X-ray examinations makes it possible to improve the accuracy of age diagnosis by including criteria of skeletal maturation. In view of the existing legislative basis for the use of X-rays on human subjects, the exposure of individuals to radiation can be minimised.     

Applicability of the skeletal age determination method of Tanner and Whitehouse for forensic age diagnostics

The present paper analyses the applicability of the clinically prevalent skeletal age determination method of Tanner and Whitehouse for forensic age estimation in living individuals. For this purpose, the hand X-rays from 48 boys and 44 girls aged 12-16 years were evaluated retrospectively. The minima and maxima, the mean values with their standard deviations as well as the medians with upper and lower quartiles, are presented for the skeletal ages 12-16 years estimated by the TW2 and TW3 methods. In the legally relevant skeletal age group 14-16 years, the differences between the skeletal age and the mean value of the chronological age were between -0.1 and +1.4 years for the TW2 method. For the TW3 method, the differences between the skeletal age and the mean value of the chronological age were between -0.4 and +0.2 years in the relevant age group. Due to the risk of serious overestimations, the TW2 method seems to be unsuitable for forensic age diagnostics. The application of the TW3 method for forensic age estimations can be recommended.     

Validation of reference data on wisdom tooth mineralization and eruption for forensic age estimation in living persons

Estimation of dental age is an important part of forensic age estimation in living persons. As the quality of the values given in population-specific reference studies has a great impact on the estimation, the aim of this study was to validate reference data for wisdom teeth mineralization and eruption of a German population concerning the diagnosis of the age limit of 18 years in persons with known age. Mineralization and eruption was evaluated in 307 orthopantomograms of Central European subjects aged 17.5–18.5 years. Dental age was estimated using reference data and compared to chronological age. Statistical methods were used to analyze the differences and to propose adjusted reference values. Estimation of dental age relying on mineralization resulted in overestimations of 2 years on average in 76% of the males and 82% of the females. Using eruption, all men and 75% of the women were overestimated by up to 7 years. The differences between estimated and chronological age in both men and women were associated with the mineralization and eruption stage, respectively. The higher the stage, the higher was the risk of overestimation. The mineralization stages up to stage E were associated with underestimations. Using the proposed adjusted reference values resulted in more accurate estimations of dental age. Validation of reference values for dental age estimation showed great overestimations resulting in high error rates with numerous persons being younger than the estimated dental age. Adjustments are proposed which reduce differences between estimated dental age and chronological age.     

Dental age estimation from the developmental stage of the third molars in Iranian population

A sharp increase in forensic age estimation of living persons has been observed in recent years. However, ethnic populations residing in different countries have been insufficiently analyzed. The aim of this study was to achieve a referral database and regression equations for dental age estimation of unaccompanied minors of Iran nationality. A total of 1200 orthopantomograms were collected from original Iran and equally divided in age categories between 10 and 27 years. On the radiographs, the developmental stage of the third molars was scored applying a Demirjian et al. scoring technique. Inter- and intra-observer reliabilities were tested using kappa statistics. Correlation between the scores of all four wisdom maxillary and mandibular third molars teeth and left/right symmetry were evaluated with spearman correlation coefficient. Student’s t-test on asymmetry was performed and regression formulas were calculated. The present database was the first to assemble third molar developmental scores on radiographs of Iran individuals and provided more appropriate dental age estimation of unaccompanied Iran minors. To enhance the accuracy of forensic age estimates based on third molars mineralization, the use of population-specific standards is recommended.     

Molecular age estimation based on posttranslational protein modifications in bone: why the type of bone matters

Age-at-death estimation is of great relevance for the identification of unknown deceased individuals. In skeletonised corpses, teeth and bones are theoretically available for age estimation, but in many cases, only single bones or even only bone fragments are available for examination. In these cases, conventional morphological methods may not be applicable, and the application of molecular methods may be considered. Protein-based molecular methods based on the D-aspartic acid (D-Asp) or pentosidine (Pen) content have already been successfully applied to bone samples. However, the impact of the analysed type of bone has not yet been systematically investigated, and it is still unclear whether data from samples of one skeletal region (e.g. skull) can also be used for age estimation for samples of other regions (e.g. femur). To address this question, D-Asp and Pen were analysed in bone samples from three skeletal regions (skull, clavicle, and rib), each from the same individual. Differences between the bone types were tested by t-test, and correlation coefficients (ρ) were calculated according to Spearman. In all types of bone, an age-dependent accumulation of D-Asp and Pen was observed. However, both parameters (D-Asp and Pen) exhibited significant differences between bone samples from different anatomical regions. These differences can be explained by differences in structure and metabolism in the examined bone types and have to be addressed in age estimation based on D-Asp and Pen. In future studies, bone type-specific training and test data have to be collected, and bone type-specific models have to be established.

     

Age assessment by the Greulich and Pyle method compared to other skeletal X-ray and dental methods in data from Finnish child victims of the Southeast Asian Tsunami

The validity of the age assessment method based on the “Radiographic Atlas of Skeletal Development of the Hand and Wrist” by Greulich and Pyle (1st edition 1950) has been frequently questioned. The purpose of this study was to examine the reliability of this widely used method and to compare it to various dental and other skeletal age assessment methods. Forty-seven Finnish children of known ages below 16 years, who perished in Thailand in the Southeast Asian Tsunami on 26 December 2004 were examined. Every victim repatriated to Finland underwent a complete forensic autopsy including CT-scan, toxicological screening, and diatom analysis in order to establish the cause of death, as well as DNA testing and dental examination for the verification of the identification established in Thailand. Age assessment was performed by dental and skeletal methods. The average difference between the age assessment values obtained by the Greulich and Pyle method, and the chronological age was 9.7 months. In addition to the Greulich and Pyle method, an alternate skeletal method, Tanner and Whitehouse 2, resulted in an average age difference of 10.3 months. Dental age assessment methods were based either on the eruption (Nystr?m method, 8 cases, average age difference 5.6 months), or the development of the crown and roots (Demirjian method, 33 cases, average age difference 5.2 months and ABFO method, 7 cases, average differences 12.6 months). Dental methods proved to be most accurate in childhood until the teeth—with the exception of wisdom teeth—have erupted and root development is completed. In adolescence, however, the validity of skeletal methods improves considerably.