Dental pattern diversity in a military population and its usefulness for assessing the degree of certainty in dental identification.

In forensic dentistry, the analysis of dental diversity forms the basis of probability calculations in dental identification. The present study aimed to contribute to the knowledge of dental diversity in a Spanish military population (considering isolated teeth, sets of different numbers of teeth, and combinations of teeth of forensic interest) and its implications for dental identification. A further aim was to compare the performance of three coding systems (detailed, generic, and binary) to assess dental pattern diversity. Dental diversity of a representative sample of the Spanish military population (3920 individuals aged between 18 and 55 years) was calculated according to a genetic (mitochondrial DNA) model in which diversity was defined as the likelihood that two randomly selected individuals in a sample would exhibit different patterns. By performing all pairwise comparisons of dental patterns in the dataset, the total number of matches was generated, and the diversity of dental patterns was then derived. First and third molars were the teeth that showed the highest levels of diversity, and a high diversity value (>0.99) was obtained with only 5 teeth (16, 36, 38, 46, and 48) when detailed coding was used. In addition, dental diversity in the full dentition and posterior teeth exceeded the threshold of 0.99 in all three coding systems. Although a very high diversity value (≥0.999) was only achieved with detailed coding, it should be noted that the generic coding system requires less time and skill to use, and can also provide high diversity values. Our findings show that further efforts should be made to establish large, periodically updated dental datasets of different populations in order to assess dental pattern diversity (without excluding third molars) based on empirical comparison, and to substantiate the certainty of dental identification.

Technical note: A mobile collaborative workspace to assist forensic experts in disaster victim identification scenarios.

Integrated approaches to disaster victim identification (DVI) management have led to a need for technologies to improve interaction among parties involved in post-mortem (PM) and ante-mortem (AM) data collection through better communication and coordination. Mobile Forensic Workspace© (MFW) is a collaborative mobile system that not only facilitates the systematic collection of high-quality data, but also allows DVI professionals to coordinate activities and exchange data through secure real-time communication at major disaster scenarios in accordance with security, privacy and legal protocols. MFW is adaptable to any communication format (text, voice calls, photographs, etc.) and is dynamically self-reconfigurable when connectivity problems arise. It also allows data integration and backup through secure communication channels between local and remote servers. The feasibility of the system has been demonstrated through implementation of MFW on the iOS platform for iPhone, iPod Touch and iPad terminals. A further strength of MFW is that it provides out-of-the-box support for INTERPOL DVI forms. The application of information and communication technologies for DVI was shown to be useful in improving DVI management by enhancing the quality of data collection and enabling non-Internet dependent real-time data sharing and communication.

DNA methylation levels and telomere length in human teeth: usefulness for age estimation.

In the last decade, increasing knowledge of epigenetics has led to the development of DNA methylation-based models to predict age, which have shown high predictive accuracy. However, despite the value of teeth as forensic samples, few studies have focused on this source of DNA. This study used bisulfite pyrosequencing to measure the methylation levels of specific CpG sites located in the ELOVL2, ASPA, and PDE4C genes, with the aim of selecting the most age-informative genes and determining their associations with age, in 65 tooth samples from individuals 15 to 85 years old. As a second aim, methylation data and measurements of relative telomere length in the same set of samples were used to develop preliminary age prediction models to evaluate the accuracy of both biomarkers together and separately in estimating age from teeth for forensic purposes. In our sample, several CpG sites from ELOVL2 and PDE4C genes, as well as telomere length, were significantly associated with chronological age. We developed age prediction quantile regression models based on DNA methylation levels, with and without telomere length as an additional variable, and adjusted for type of tooth and sex. Our results suggest that telomere length may have limited usefulness as a supplementary marker for DNA methylation-based age estimation in tooth samples, given that it contributed little improvement in the prediction errors of the models. In addition, even at older ages, DNA methylation appeared to be more informative in predicting age than telomere length when both biomarkers were evaluated separately.

mRNA expression patterns in human myocardial tissue, pericardial fluid and blood, and its contribution to the diagnosis of cause of death.

Gene expression has become an interesting research area in forensic pathology to investigate the process of death at the molecular level. The aims of this study were to analyze changes in gene expression patterns in relation to the cause of death, and to propose new molecular markers of myocardial ischemia of potential use for the postmortem diagnosis of early ischemic heart damage in cases of sudden cardiac death (SCD). We determined mRNA levels of five proteins related with ischemic myocardial damage and repair - TNNI3, MYL3, TGFB1, MMP9 and VEGFA - in specific sites of the myocardium, blood and pericardial fluid in samples from 30 cadavers with different causes of death (SCD, multiple trauma, mechanical asphyxia, and other natural deaths). TNNI3 expression in blood, and MMP9 expression in pericardial fluid, were significantly higher when the cause of death was mechanical asphyxia, probably because of the more sensitive response of these proteins to acute systemic hypoxia/ischemia. Specifically, among SCD cases, increased MYL3, VEGFA and MMP9 values in the anterior wall of the right ventricle were found when the confirmed cause of death was acute myocardial infarction (AMI). Higher TGFB1 expression was found in the interventricular septum when AMI was not the cause of death, most likely as a reflection of the short duration of ischemia. Molecular biology techniques can provide complementary tools for the forensic diagnosis of early ischemic myocardial damage and AMI, and may make it possible to determine the duration and severity of myocardial ischemia.

Estudio comparativo de la diversidad de las características clínicas dentales en poblaciones militares de Portugal y España / Diversity in dental clinical characteristics in Portuguese and Spanish military populations

Introducción: Se ha realizado una comparación de las características dentales de 2poblaciones militares de Portugal y España. El objetivo principal de esta investigación fue identificar aquellas características dentales que podrían ser de utilidad para diferenciar estas poblaciones en un análisis forense. Material y métodos: El estudio se realizó en una muestra compuesta por 5.136 militares profesionales de las fuerzas armadas, el 31,9% eran militares portugueses y el 68,1% del total de la muestra pertenecían a las fuerzas armadas españolas. Los datos dentales se registraron empleando los símbolos dentales descritos en Forensic Dental Symbols(R), gestionados con la base de datos Dental Encoder(R). Resultados: La población de estudio estaba constituida por un 86,6% de hombres (88,1% en la muestra española y 83,4% en la muestra portuguesa) y un 13,4% de mujeres (11,9% en la muestra española y 16,6% en la muestra portuguesa). La frecuencia de dientes no restaurados fue menor para los primeros molares en todos los cuadrantes, mientras que la mayor frecuencia de esta característica (>90%) se observó en los dientes anteriores, superiores e inferiores, y en los primeros premolares inferiores. Las frecuencias más altas de tratamientos restauradores fueron encontradas para los primeros y segundos molares en todos los cuadrantes, y las mayores frecuencias de ausencias dentarias se observaron en los terceros molares (superior al 28% en todos los cuadrantes). El análisis de concordancia mostró que las correlaciones entre los dientes contralaterales fueron significativamente mayores que entre los dientes antagonistas, para ambas muestras poblacionales de estudio. Conclusiones: Nuestros resultados proporcionan información potencialmente útil sobre la importancia de las bases de datos de registros dentales y el análisis de las características dentales con fines de identificación

Introduction: Dental characteristics were compared in population samples of Spanish and Portuguese military personnel. The main aim of this study was to identify those dental characteristics that could potentially serve to differentiate between these populations in a forensic analysis. Material and methods: A sample of 5136 individuals belonging to the professional military staff of the Portuguese and Spanish armed forces was studied. Dental data were recorded with the Forensic Dental Symbols(R) for the Dental Encoder(R) database. The population sample analysed in this study consisted of 68.1% Spanish and 31.9% Portuguese individuals. Results: The population was mostly male, with 86.6% men (88.1% in the Spanish sample versus 83.4% in the Portuguese sample), and 13.4% women (11.9% Spanish and 16.6% Portuguese). The frequency of unrestored teeth was lowest for first molars in all quadrants, and the highest frequency of unrestored teeth (>90%) was for the upper and lower anterior teeth and lower first premolars. The highest frequencies of restorative treatment were found for the first and second molars in all quadrants, and the highest frequencies of missing teeth were found for the third molars (always >28%). Concordance analysis showed that correlations between contralateral teeth were significantly higher than between antagonist teeth in both samples. Conclusions: Our findings provide potentially useful information on the importance of dental record databases and their value for identification purposes

Differences in non-enzymatic glycation products in human dentine and clavicle: changes with aging.

In recent decades, several methods based on biochemical and molecular changes caused by aging have been proposed to improve the accuracy of forensic age estimation. The present study aimed to measure changes in furosine and pentosidine, two markers of non-enzymatic glycation of proteins (NEGs), in human dentine and clavicle with aging, and to identify possible differences between turnover rates in different mineralized tissues. Furosine and pentosidine were quantified in 32 dentine samples from living donors between 14 and 80 years of age, and in a second group of samples consisting of a tooth and a piece of clavicle collected from the same cadaver (15 individuals aged 18 to 85 years). Furosine concentration was much higher than pentosidine concentration in the same tissue, although they were strongly correlated in both dentine and bone. A close relationship between furosine and/or pentosidine content and chronological age was found in both tissues (r > 0.93). Moreover, age estimation was more accurate when furosine or pentosidine content was determined in dentine, with specificity values for the tests higher than 82% in all age groups. In clavicle, furosine concentration and pentosidine concentration were much lower (2.6-fold and 3.1-fold, respectively) than in dentine from the same individuals. In conclusion, although the results show strong correlations between chronological age and furosine or pentosidine concentrations determined in mineralized tissues, there is still a need for further research with larger data sets, including patients with diabetes.

Usefulness of telomere length in DNA from human teeth for age estimation.

Age estimation is widely used to identify individuals in forensic medicine. However, the accuracy of the most commonly used procedures is markedly reduced in adulthood, and these methods cannot be applied in practice when morphological information is limited. Molecular methods for age estimation have been extensively developed in the last few years. The fact that telomeres shorten at each round of cell division has led to the hypothesis that telomere length can be used as a tool to predict age. The present study thus aimed to assess the correlation between telomere length measured in dental DNA and age, and the effect of sex and tooth type on telomere length; a further aim was to propose a statistical regression model to estimate the biological age based on telomere length. DNA was extracted from 91 tooth samples belonging to 77 individuals of both sexes and 15 to 85 years old and was used to determine telomere length by quantitative real-time PCR. Our results suggested that telomere length was not affected by sex and was greater in molar teeth. We found a significant correlation between age and telomere length measured in DNA from teeth. However, the equation proposed to predict age was not accurate enough for forensic age estimation on its own. Age estimation based on telomere length in DNA from tooth samples may be useful as a complementary method which provides an approximate estimate of age, especially when human skeletal remains are the only forensic sample available.

Three-dimensional analysis of third molar development to estimate age of majority.

Third molars are one of the few biological markers available for age estimation in undocumented juveniles close the legal age of majority, assuming an age of 18years as the most frequent legal demarcation between child and adult status. To obtain more accurate visualization and evaluation of third molar mineralization patterns from computed tomography images, a new software application, DentaVol©, was developed. Third molar mineralization according to qualitative (Demirjian's maturational stage) and quantitative parameters (third molar volume) of dental development was assessed in multi-slice helical computed tomography images of both maxillary arches displayed by DentaVol© from 135 individuals (62 females and 73 males) aged between 14 and 23years. Intra- and inter-observer agreement values were remarkably high for both evaluation procedures and for all third molars. A linear correlation between third molar mineralization and chronological age was found, with third molar maturity occurring earlier in males than in females. Assessment of dental development with both procedures, by using DentaVol© software, can be considered a good indicator of age of majority (18years or older) in all third molars. Our results indicated that virtual computed tomography imaging can be considered a valid alternative to orthopantomography for evaluations of third molar mineralization, and therefore a complementary tool for determining the age of majority.

Forensic Medicine and the Military Population: International Dental Records and Personal Identification Concerns.

INTRODUCTION: The first goal of this research was to perceive the global commitment towards the organization and archiving of dental records and to compare it with each country's security risk rating. The second one was to study dental records in a sample of the Portuguese military population, using the available national dental records. MATERIAL AND METHODS: An e-mail was sent to representative dentistry associations in several countries, requesting some information concerning the professionals' awareness of this issue. After obtaining permission from the Ethics Committee, the information was collected through the Forensic Dental Symbols® system into the Dental Encoder®, as an extension of a Spanish study, and a generic codification was used (unrestored, restored, missing and crowned teeth). RESULTS: The most common dental record retention period is ten years after treatment. Observing the samples' dental records (595 files), we found a total of 19 040 analyzed teeth, with the following frequencies: unrestored (89.6%), restored (7.0%), missing (2.2%) and crowned (1.1%). DISCUSSION: There is a wide range of guidelines on how long dentists should keep dental records. Especially for the military population, dental records must include detailed information concerning each tooth situation, in order to support the process of human identification. CONCLUSION: This article reinforces the need for mandatory quality dental records in all countries, which must be efficiently stored and easily accessible in case dental identification is necessary. For the military population, these requirements are especially important, due to the added risks to which this group is subject.

Introdução: Esta investigação teve o intuito de procurar conhecer o comprometimento global relativamente à organização e arquivo dos registos dentários e compará-lo com o risco de segurança de cada país. Por outro lado, procurou-se estudar os processos clínicos de uma amostra da população militar Portuguesa, utilizando-se para o efeito os registos dentários. Material e Métodos: Foi enviado um e-mail para associações dentárias e solicitada informação sobre o tempo de guarda dos registos dentários. Após autorização prévia da Comissão de Ética, a informação foi recolhida através do sistema Forensic Dental Symbols® para Dental Encoder®, como uma extensão de uma investigação realizada em Espanha e utilizada a codificação genérica (dentes sãos, com restaurações, ausentes e coroas). Resultados: Globalmente, dez anos após o último tratamento, foi o procedimento mais comum relativamente ao tempo de guarda dos documentos. Após observação dos registos dentários da amostra (595 militares) verificou-se um total de 19 040 dentes analisados, com as seguintes frequências: dentes sãos (89,6%), com restauração (7,0%), ausentes (2,2%) e coroas (1,1%). Discussão: Existe grande variedade de orientações sobre quanto tempo têm que ser guardados pelos profissionais de saúde os seus registos. Nos registos dentários da população militar deve-se incluir informação detalhada de cada dente, de maneira a suportar o processo de identificação humana. Conclusão: Este artigo reforça a necessidade de registos dentários de qualidade em todos os países, com manutenção eficiente para a identificação humana. Na população militar torna-se especialmente importante, devido ao facto de este ser um grupo sujeito a riscos acrescidos.

Cardiac troponin T determination by a highly sensitive assay in postmortem serum and pericardial fluid.

PURPOSE: The main objective of this study was to test, for the first time, a highly sensitive cardiac troponin T (cTnThs) assay in postmortem serum and pericardial fluid and to evaluate cardiac troponin T (cTnT) levels and their stability after death at different postmortem intervals, in an attempt to determine the viability of the cTnThs assay in the postmortem diagnosis of the cause of death. METHODS: cTnT levels were determined in serum and pericardial fluid samples taken from 58 cadavers at known postmortem intervals, whose causes of death were categorized into the following groups: (1) sudden cardiac deaths, (2) multiple trauma, (3) mechanical asphyxia, and (4) other natural deaths. cTnT was determined by inmunoassay, using the Troponin T highly sensitive STAT assay (Roche(®)). RESULTS: Average cTnT levels measured by a highly sensitive assay in postmortem serum were markedly higher than clinical serum levels. Moreover, similar results, higher cTnT levels in postmortem pericardial fluid, were obtained when compared to levels found in pericardial fluid taken from two living patients during coronary artery bypass surgery. cTnT levels in both postmortem fluids remained stable for up to 34 h after death. No differences in cTnT levels in either postmortem fluid by sex and age were detected. Levels of cTnT found in pericardial fluid in the other natural deaths group were significantly lower than the cTnT levels found in that postmortem fluid from any of the other causes of death groups. CONCLUSION: It is therefore reasonable to conclude that determination of cTnT by a highly sensitive assay in pericardial fluid can provide forensic pathologists with a complementary test to the diagnosis of cause of death.

Cellular extracts from post-mortem human cardiac tissue direct cardiomyogenic differentiation of human adipose tissue-derived stem cells.

BACKGROUND AIMS: Human adipose tissue-derived stem cells (hASCs) can be easily (and inexpensively) expanded in culture, and their high plasticity allows their conversion to different cell types. We study the potential capacity of postmortem cardiac tissue to direct cardiac differentiation of hASCs in vitro. METHODS: Cardiac tissue collected from autopsies was used to obtain cell extracts and conditioned medium, and both approaches were tested for cardiac induction. RESULTS: Gene expression analyses proved that post-mortem human cardiac tissue maintains genetic integrity. hASCs exposed to the cell extracts or conditioned medium for 2 weeks achieved the appearance of myotube-like structures and were positive for cardiac markers such as sarcomeric α-actinin, cardiac troponin I and T and desmin as proved by immunofluorescence. In addition, differentiated cells showed increased expression of cardiomyocyte-related genes analyzed by reverse transcriptase polymerase chain reaction (GATA-4, myocyte-enhancer factor-2c, α-cardiac actin and cardiac troponin I). CONCLUSIONS: For the first time, post-mortem human cardiac tissue was used to induce hASC differentiation into myocardial-like cells. The methodology described here would serve as a useful model to obtain cardiomyocyte-like cells in vitro.

Studies on RNA integrity and gene expression in human myocardial tissue, pericardial fluid and blood, and its postmortem stability.

Analyses of gene expression of ischemic myocardial injury and repair related proteins has been carried out for the first time in samples from five specific sites of the myocardium, pericardial fluid and blood from thirty cadavers in relation to post-mortem interval (PMI). RNA integrity was evaluated by RNA integrity number (RIN), with values ranging from 6.57 to 8.11; sufficiently high levels of integrity to permit further gene amplification. No significant correlations between RIN and PMI in any samples were detected. Prior to target gene expression analysis, a normalization strategy was carried out to assess candidate reference gene stability, involving the analysis and comparison of four common housekeeping genes (Glyceraldehide-3-phosphate dehydrogenase, beta-actin, TATA box binding protein and Cyclophilin A). Gene expression of cardiac troponin I (TNNI3), myosin light chain 3 (MYL3), matrix metalloprotease 9 (MMP9), transforming growth factor beta 1 (TGFB1), and vascular endothelial growth factor A (VEGFA) in myocardial zones and body fluids were subsequently studied by real-time quantitative PCR. Expression levels of all the proteins studied in cardiac zone samples were similar. No statistical differences for expression were detected among proteins taken from any myocardial area. No significant differences were detected for TNNI3 and TGFB1 gene expressions when compared with samples at or under 12h-PMI or over 12h-PMI. However, differences in MYL3, MMP9, and VEGFA gene expression in body fluids were found at PMI periods of over 12h. These interesting results may contribute to the refinement of current knowledge regarding cardiac metabolism and improve understanding of the underlying mechanisms involved in myocardium ischemia and its repair.

Usefulness of Forensic Dental Symbols© and Dental Encoder© database in forensic odontology.

A new universal graphic dental system, Forensic Dental Symbols(©), has been created to provide precision in the construction of dental records, improve standardization, and increase efficiency in dental identification procedures. Two hundred and thirty-four different graphic symbols representing the most frequent clinical status for each tooth were designed. Symbols can be then converted to a typographic font and then are ready to use in any computer. For the appropriate use, manipulation, and storage of dental information generated by the Forensic Dental Symbols(©), Dental Encoder(©) database has been created. The database contains all the information required by INTERPOL Disaster Victim Identification (DVI)-dental-forms. To explore the possibilities that Dental Encoder(©) offers, an antemortem dental database from a Spanish population of 3920 military personnel had been constructed. Data generated by Dental Encoder(©) were classified into sex and age groups. The program can perform an automatic search of the database for cases that match a selected clinical status presented in a single tooth or a combination of situations for several teeth. Moreover, Dental Encoder(©) allows information to be printed on INTERPOL DVI-dental-forms, or the inclusion of any completed form into any document, technical report, or identification of dental report.

Age estimation and the medial clavicular epiphysis: analysis of the age of majority in an Australian population using computed tomography.

This study was designed in order to assess the suitability of clavicular development in discriminating whether or not an individual has reached the age of 18 years. The development of the medial clavicular epiphysis was examined in an Australian population using computed tomography as the imaging modality. The sample consisted of individuals who were admitted to the Victorian Institute of Forensic Medicine, Melbourne, Australia, for the purposes of medico-legal death investigation. Comparisons were made with similar studies conducted on different populations in other countries, which revealed that the Australian population reaches maturity earlier, and the level of left/right asymmetry is higher than in other studies. The high degree of variation in fusion times is discussed, and the consequent effect upon the ability to use this epiphysis as a tool for determining if an individual has reached the age of 18 years is analysed. If an individual in this population has completely fused clavicles at stage 5, then for males they will be at least 18 years of age, with a 99% certainty of being at least 21, and for females they will be at least 20 years old. If at stage three then an individual of either sex will be at least 17 years of age.

The utility of dental patterns in forensic dentistry.

The comparison of antemortem and postmortem dental patterns, which reflect a combination of dental states, can be quantified for human identification. However, the utility derived from the uniqueness of these patterns is limited by variations in oral health status related to population, age, and birth cohort. We analyzed dental pattern diversity from reference datasets that documented differences in oral health. Our analysis was based on full dentitions and partial dentitions available in forensic situations. To analyze the diversity of dental patterns, data from 3166 adults were extracted from the last 3 contemporary Spanish National Oral Health Examination Surveys, corresponding to the years 1993, 2000, and 2005. Each survey comprised 2 adult age groups (35-44 years and 65-74 years), therefore six datasets were available for our study. Our six samples showed substantial variability in oral health status (caries history) and dental code distribution, not only between age groups within the same survey year, but also between different survey years for the same age group. To test the overall diversity of dental patterns in each datasets, pairwise comparisons were performed and the total number of pattern matches was generated. We calculated total and conditional diversity (excluding individuals in whom all teeth were classified as unrestored or missing) for each forensic situation. To test the homogeneity of diversity estimates among the six datasets we used a random effect model that requires a parameter estimate together with its standard error. Total diversity values were low and heterogeneous. However, conditional diversities were high and homogeneous, which allowed all data to be pooled into a single database. Once data were pooled, high combined diversity values (above 0.99) were obtained for each forensic situation. This indicates their usefulness for forensic purposes. We conclude that the conditional diversity value derived from dental patterns is a potentially valuable tool with broad applicability for human identification.

Third molar development according to chronological age in populations from Spanish and Magrebian origin.

Spain is frequently the entrance country into the European Union for undocumented immigrants, especially those from the Magreb (Northern Africa). Forensic age estimates for these persons are difficult because systematic studies of dental maturity are lacking. Three different populations were analyzed to determine the pattern of development of third molars as a tool for age estimation in people of different ethnic and geographic origin. Orthopantomograms from two different populations of Spanish origin (Galicia in northwestern continental Spain, and Ceuta, a Spanish province in Northern Africa) were compared to radiographs of molars from a Magrebian population (Northern Africa) resident in Ceuta. Orthopantomograms were obtained from a private dental clinic (n=344) in Galicia and from the Public Oral Health Services (n=228) in Ceuta. We looked for differences in third molar mineralization (determined with the Demirjian scale) that might serve as age indicators (older versus younger than 18 years). Differences in maturation patterns were found between sexes and populations of origin. Mineralization of tooth 38 was more advanced in males than females among subjects 18 years of age and older in all three populations. Moreover, mineralization of tooth 38 in subjects aged 18 years and older was significantly slower in the Spanish-Galicia population than in the Magrebian-Ceuta population. We found no significant differences between Magrebian and Spanish individuals from Ceuta. We conclude that differences in tooth 38 mineralization may be related more with socio-geographical than ethnic origin (ancestry), and thus constitute evidence of the relevance of socio-geographic rather than genetic factors in third molar development. We used ROC analysis to determine the accuracy of the examiner's ability to correctly estimate age as younger or older than 18 years. The results suggest that Demirjian stage for tooth 38 can be considered a good indicator of age in all three populations.

Effectiveness of comparison overlays generated with DentalPrint software in bite mark analysis.

Validation studies of the new DentalPrint software were carried out with experimental bite marks in pigskin. The bite marks were digitally photographed according to the ABFO guidelines for evidence collection. Dental casts used in the experiment were scanned in 3D and 2D, and comparison overlays were generated using DentalPrint and Adobe Photoshop software, respectively. Digitized photographs of the experimental bite marks and the biting edges obtained in the overlays were compared by two different examiners to analyze the impact of training and experience with the two methods. Receiver operating characteristic (ROC) analysis, sensitivity, specificity, and 95% confidence intervals for each cutoff point were calculated. The expert examiner using DentalPrint obtained the best results, with an area under the ROC curve of 0.76 (SE=0.057; CI at 95%=0.652-0.876). Fairly high specificity values were found for DentalPrint, and the best results were obtained for the cutoff value that discriminated between the examiner's response "biter" and the rest of the possible (specificity 97.9%, CI at 95%=93.2%-99.6%). Therefore, the results presented here indicate that DentalPrint is a useful, accurate tool for forensic purposes, although further research on the comparison process is needed to enhance the validity of bite mark analysis.

Computer-based production of comparison overlays from 3D-scanned dental casts for bite mark analysis.

Bite mark analysis assumes the uniqueness of the dentition can be accurately recorded on skin or an object. However, biting is a dynamic procedure involving three moving systems, the maxilla, the mandible, and the victim's reaction. Moreover, bite marks can be distorted by the anatomic location of the injury or the elasticity of the skin tissue. Therefore, the same dentition can produce bite marks that exhibit variations in appearance. The complexity of this source of evidence emphasizes the need for new 3D imaging technologies in bite mark analysis. This article presents a new software package, DentalPrint (2004, University of Granada, Department of Forensic Medicine and Forensic Odontology, Granada, Spain) that generates different comparison overlays from 3D dental cast images depending on the pressure of the bite or the distortion caused by victim-biter interaction. The procedure for generating comparison overlays is entirely automatic, thus avoiding observer bias. Moreover, the software presented here makes it impossible for third parties to manipulate or alter the 3D images, making DentalPrint suitable for bite mark analyses to be used in court proceedings.

Objective measurement of dental color for age estimation by spectroradiometry.

Age-related changes in tooth color have been described previously, however, the use of dental color for age estimation in forensic odontology has been limited due to the difficulty of measuring color objectively. This study presents an objective method for determining dental color to estimate the age of an individual. Dentine color in 250 teeth from patients ranging in age from 10 to 89 years was determined by spectroradiometry. Color measurements were performed as suggested in the CIE 1931 (International Commission on Illumination). Chromaticity coordinates (x, y, z), luminance (Y), whiteness index (WIC, Z%, WIC) and yellowness index (YI) were obtained. Correlations between these colorimetric variables and aging were established by linear regression analyses. All the variables fit the mathematical model with correlation coefficients ranging from 0.53 to 0.75. This method of color measurement produced an expected associated error of calibration averaging 13.7 years about the mean estimated values, at a 70% level of confidence. Two different multiple regression models for dental age estimation were tested, and variables that made the greatest contributions to age calculation were identified. To determine the effect of postmortem interval on tooth color and its influence in age estimation, 37 teeth obtained from human skeletal remains buried during an interval ranging from 21 to 37 years were also studied. In this material, the correlation between age and dental color measured by spectroradiometry was weaker than in fresh extracted teeth. It is concluded that determination of dentine color by spectroradiometry is a potentially useful objective method to estimate age in forensic studies in combination with other methods.

Multiple regression models for age estimation by assessment of morphologic dental changes according to teeth source.

The aims of this study were twofold: (1). to measure parameters that contribute significantly to estimates of dental age, using a combination of classic methods and a computer-assisted image analysis procedure to avoid the bias inherent in observer subjectivity; and (2). to develop new mathematical regression models for age prediction according to postmortem interval. Two different populations were studied. Forty-three permanent teeth (Group I), extracted for valid clinical reasons, were taken from patients 25-79 years of age. The other population group (Group II) was composed of 37 healthy erupted permanent teeth obtained from human skeletal remains (age 22-82 years) with a postmortem interval ranging from 21 to 37 years. Morphologic age-related changes were investigated by measuring variables on intact and half-sectioned teeth. Multiple regression analyses were performed with age as the dependent variable for each sample source. In fresh extracted teeth, the variables that made the greatest contributions to predictions of age were dental attrition, dentin color, and translucency width, the latter measured with a computer-assisted image analysis method. In teeth from human skeletal remains, the variables that made the greatest contributions to age calculation were cementum apposition, pulp length measured by computer-assisted image analysis, dental attrition, root translucency, and dental color. We conclude by recommending different regression models to calculate age depending on the postmortem interval.