Studying survivors of near-lethal suicide attempts as a proxy for completed suicide in prisons

Sex determination is a necessary step in the investigation of unidentified human remains from a forensic context. Teeth, as one of the strongest tissues in the human body, can be used for this purpose. Most studies of sexual dimorphism in teeth are based on the traditional mesiodistal and buccolingual crown measurements. The purpose of this study is to examine the degree of sexual dimorphism in permanent molars of modern Greeks using crown and cervical diagonal diameters, and to evaluate their applicability in sex determination. A total of 344 permanent molars in 107 individuals (53 male and 54 female) from the Athens Collection were examined. Crown and cervical diagonal diameters of both maxillary and mandibular molars were measured. It was found that males have larger molars than females and in 19 out of 24 dimensions measured male molars exceeded female molars significantly (P<0.05). The most dimorphic molars are the maxillary second molar, and the mandibular second and first molars. Although other molars were also sexually dimorphic they did not have a statistically significant difference in all dimensions. Cervical diagonal diameters have found to be more sexually diamorphic than crown diagonal diameters. In discriminant function analysis the variables entered more frequently were the cervical diagonal diameters mainly of mandibular molars. Classification accuracy was found to be 93% for the total sample, 77.4% for upper jaw, and 88.4% for the lower jaw. Accuracy rates were higher for cervical than crown diagonal diameters. The data generated from the present study suggest that this metric method can be useful and reliable for sex determination, especially when the traditional dental measurements are not applicable.     

Sexual variation in bucco-lingual dimensions in Turkish dentition

Sexual differences in the human skeleton have been well studied in many populations. Odontometric analysis of the human sexual variation has been less investigated and mostly derived from the dentition of extinct populations. Turkey is situated in a unique location where populations from different regions mixed with each other and created a rich gene pool. One might anticipate that modern Turkish population is composed of genes from the Balkans, Caucasus, Middle East, Iran and further as well as from ancient Romans, Byzantines, Arabs and Asiatic Turks. It is clear that contemporary Turks are a mixture of these extant and extinct people and ideal to consider it a representative study population. The purpose of this study is to analyze dental dimensions and sexual variation in living Turks and develop forensic techniques to identify human remains from the teeth when any other technique is not available or not reliable. The study is composed of Ankara University dental students (50 male and 50 female casts, average age of 21 years). Bucco-lingual breadths from 14 teeth (I1 through M2 of the maxilla and mandible) are taken from the left side and analyzed using the discriminant function statistics. An intraobserver error test did not indicate any statistically significant difference between any two measurements. Results of the study revealed that males exceeded females significantly (P<0.001) in dimensions. Coefficient of variation was most obvious in I1s and I2s of both jaws in both sexes. Stepwise discriminant function statistics suggested that upper C, and lower C and M2 are the most contributory teeth to the function. Additional formulae were calculated for situation in which only one or a fragmented jaw is available for identification. Overall accuracy of sex diagnosis ranged from 73 to 77%. In conclusion this research supports earlier studies that sexual dimorphism is population specific. While dental difference between the sexes in several human populations has been found highly dimorphic, it was not found so in Turks and accuracy of classification remained low at about 77%. The difficulty or the lack of dimorphism comes from male subjects.     

Sex determination by discriminant function analysis of lateral cranial form.

To sex the cranium, morphological features of cranial specimens were quantified with a personal computer that automatically measures distance and gradient for 39 craniometric points in the lateral contour line of the skull, which were digitized by a tablet digitizer connected to the computer. Specimens used for discriminant analysis were 50 male and 50 female adult Japanese skulls. The lateral contour showed sex differences in the nasal bone, supraorbital ridge, forehead and vertex. The nasal bone and supraorbital ridge were more developed in male contour line, and the forehead was more rounded in female contour line. But compared with the supraorbital ridge and forehead, the vertex had a wide variety of contour lines in both sexes. The vertex seemed to be less reliable as the indicator of sex. The sex differences were better reflected by gradient than distance. From variables of the gradient and distance showing significant sex differences, the discriminant function was derived and tested in 21 other specimens (13 male and 8 female skulls). The mean ratio of correct sexing of the human skull by the discriminant function was 86%.     

Measurements of ulna--a new method for determination of sex.

Identification of sex from skeleton parts is of paramount importance to medicolegal investigations. The present study makes an attempt to assess sex from the ulna by devising new measurements for fragmentary bones. Dry and adult ulnae (100 male and 60 female) of Madhya Pradesh, India were subjected to three measurements (Olecranon--coronoid angle, length, and width of inferior medial trochlear notch) that were devised specifically for this study. The data were analyzed using discriminant function analysis. Direct analysis using single or multiple variables revealed the Olecranon-Coronoid angle as the best single parameter, yielding 85% accuracy. Measurements of the inferior medial trochlear notch have an additional advantage of being used in fragmentary bone where only the upper end is available. The calibrated discriminant functions correctly classified 90.6% of all males and females in an independent test sample.     

A discriminant function analysis of deciduous teeth to determine sex

Studies of deciduous teeth have concluded that crown size differences in these teeth between males and females are not reliable sex discriminators, in contrast to such differences in permanent teeth. This study measured the mesiodistal and faciolingual crown diameters of all deciduous teeth, as well as those of the permanent first molars, of 162 children from the Burlington Orthodontic Growth Study, conducted earlier in Burlington, Ontario, Canada. All 40 deciduous tooth diameters (20 mesiolingual and 20 faciolingual) were significantly different between the sexes, as were the permanent tooth diameters. Using three to five measurements of deciduous teeth, discriminant analyses of several samplings of these children produced discriminant functions in which 76 to 90% of the holdout samples were correctly classified by sex. Combinations of deciduous and permanent measurements were used to classify 83 to 85% of the holdout samples correctly. When compared with published data on other sample populations, the Burlington group is the most dimorphic for deciduous teeth and is within the range of permanent tooth dimorphisms of other populations. The level of classification accuracy, when using discriminant analysis of the deciduous teeth, can approach the accuracy levels of analysis using the permanent teeth.     

The intergroup variability and sex dimorphism in the size of the human dental arches in personal identification]

The morphology of dental arch has been studied in representatives of 11 contrast (by anthropological characteristics) ethnic groups from regions of their compact residence. The sampling from each ethnic group consisted of 200 subjects (100 male and 100 female) aged 13-20 years. A total of 4,500 plaster models of dental arches were examined. The results were statistically processed using factor, canonical, discriminant analyses, and multidimensional scanning. The data on the variability and sex dimorphism in the size and shape of dental arches in subjects belonging to different ethnic groups may be practically significant in forensic medical personality identification.     

National survey of the incidence of missing anterior teeth: Potential use in bite mark analysis in the Brazilian context

Bite mark analysis in forensic dentistry presupposes that the human dentition is unique and that its characteristics can be transferred precisely to several materials. The aim of the present study was to register the frequency of missing anterior teeth in the Brazilian adult population, discussing its potential importance in bite mark analysis. Data from the Brazilian Oral Health Survey were used; 13,431 male and female individuals aged 35 to 44 were examined according to the criteria of the World Health Organization. The analysis of Poisson regression was performed in order to calculate the rating ratios and the respective confidence interval at 95%. A total of 13,431 adults participated in the study. Among male individuals, 2063 (47.00%) were dentate and 2036 (46.40%) had at least one missing tooth. Only 254 (5.83%) were totally edentulous. A significant number of males and females presented 6 missing teeth in the same dental arch, revealing the poor state of oral health of adult Brazilians. Missing teeth were more frequent in the upper dental arch than in the lower arch. In the upper dental arch, the incisor group (central and lateral) was missing the most. In the lower dental arch, however, a certain lack of homogeneity was observed among the different dental groups as regards missing teeth. White individuals presented a smaller proportion of missing teeth compared to the other ethnic groups. Females were 1.61 (CI 1.50–1.73) times more likely than males to present missing teeth. The absence of upper teeth and the presence of lower teeth were observed in 16.10% of the individuals. Further research should also include an analysis of different age groups. This would increase the potential of applying this kind of information to bite mark analysis.     

Prognosis of sexual dimorphism with unfused hyoid bone: Artificial intelligence informed decision making with discriminant analysis

Depending on the metric and non-metric skeletal features of various bones, forensic experts proposed diverse sex identification methods. The main focus of the present study is to calculate sexual dimorphism in human unfused or disarticulated hyoid bone and compared it with studies conducted by different researchers. For this study, 293 unfused hyoid bones were accumulated and investigated from 173 male and 120 female cadavers of the northwest Indian population from the age of 15 to 80 years. Initially, discriminant analysis was performed on the dataset to predict sex and to get an idea for the crucial variables for sexual dimorphism. Later, significant variables predicted by the discriminant analysis were used for machine learning approaches to improve accuracy for sex determination. The standard scaler method is used for pre-processing of the data before machine learning analysis and to prevent overfitting and underfitting, 70 % of the whole dataset was utilized in the training of the model and the remaining data were used for testing the model. According to the discriminant analysis, body length (BL) and body height (BH) were found to be highly significant for the sex determination and predicted sex with 75.1 % accuracy. However, implementation of machine learning approaches such as the XG Boost classifier increased the accuracy to 83 % with sensitivity, and specificity scores of 0.81 and 0.84, respectively. Moreover, the ROC-AUC score achieved by the XG Boost classifier is 0.89; indicating machine learning investigation can improve the sex determination accuracy up to the appropriate standard.     

Sexual dimorphism in teeth: discriminatory effectiveness of permanent lower canine size observed in a XVIIIth century osteological series

Recent studies have shown that the most dimorphic tooth is the mandibular canine. We have carried out a study on a random sample of 146 skeletons dating from the plague outbreak in Marseilles (1722). We studied 1284 maxillary and 1432 mandibular permanent teeth. Sexual dimorphism was tested on 89 individuals. We selected a set of four dental indices and calculated the dimorphism percentage by ratio expression male/female. Dimorphic ranking was made, by allotting the first rank to the tooth presenting the highest dimorphism and the last rank to the one presenting the lowest ratio. Comparisons of means were made on both sexes (sex determined by post-cranial data) through a Student's test (t-test). We noted that lower canines and lateral incisor are the most interesting teeth in the dimorphic dental determination. The lower index presented the highest relative risk with RR = 1.56 [1.04-2.32]. In 58% of the cases, the lower dental index enabled a correct sex determination (determined on the basis of the post-cranial skeleton). These results showed the existence of a relative dental dimorphism (male > female mesiodistal diameters) with humans. In conclusion, this method, using dental measurements, may be used as an additional technique to determine sex on fragmentary adult skeletons, immature material, missing pieces or ambiguities on post-cranial remains.     

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.     

Articular surfaces of the pectoral girdle: sex assessment of prehistoric New Zealand Polynesian skeletal remains

Prehistoric Polynesian skeletal remains are frequently being recovered in New Zealand due to the increasing pace of urbanisation. Since such material must often be reinterred quickly, it is important that the sex of individuals be determined from the remains in a relatively short time. For this purpose, discriminant function analysis was utilised for sex determination of prehistoric adult New Zealand Polynesian clavicles (31 male and 31 female) and scapulae (33 male and 38 female). Diameters of the acromial and sternal ends of the clavicle and the height and breadth of the scapular glenoid cavity were measured and subjected to Statistical Package for the Social Sciences (SPSS) direct discriminant function analysis. For the single discriminant function derived, accuracy of sex determination was 97.7% and reduction in error over random assignment by sex was 95%. This discriminant function will be a useful tool in the assessment of human remains in the forensic and archaeological context because it incorporates measurements which can be taken on incomplete bones.     

Discriminating sex in South African blacks using patella dimensions

For many years, sex determination has been carried out on skeletal remains to identify individuals in forensic cases and to assess populations in archaeological cases. Since it has been shown that not all bones are found in a forensic case, discriminant function equations should be derived for all bones of the body to assist in sex determination. Numerous studies have shown the usefulness of bones of the lower extremity (e.g. femur, tibia) in sex determination using discriminant function analysis, but the use of patella measurements has not been extensively investigated for this purpose. It is therefore the aim of this study to derive discriminant function equations for sex determination from measurements of the patella of South African blacks as represented in the Raymond A. Dart Collection of Human Skeletons. A total sample of 120 (60 male, 60 female) patellae were measured using six measurements. The Statistical Product and Service Solutions (SPSS) program was used to derive the equations. Stepwise and direct analyses were performed with the highest rate of classification of 85% thereby making the patella useful for sex determination. Thus, the proposed equations derived from this study should be used with caution and only on the South African black population group.     

Discriminant function sexing of fragmentary femur of South African blacks

When fragmentary and incomplete bones are all that are available to the forensic anthropologist for use in sex determination, non-metric and metric sex discriminating parameters that have been derived from complete bones may be of little use. In such circumstances, sex discriminating metric methods that are of specific application to fragmentary bones will be more useful. Since such studies have not been systematically carried out in bones of South African blacks, the aim of this study was to begin to provide such data. Two hundred and twenty left femurs of black South Africans were obtained from the Raymond A. Dart Collection of African Skeleton, School of Anatomical Sciences, University of the Witwatersrand, South Africa. Five variables from the upper end of the femur and three variables from the lower end of the femur were measured and subjected to univariate and multivariate discriminant function analyses. The vertical head diameter and the medial condylar length were most successful in sex identification from the upper and lower ends of the femur respectively. The combined variables were more useful than the use of variables individually. Discriminant function score equations were derived for individual and combined variables from the upper and lower ends of the femur of the South African blacks.     

Tooth eruption times of permanent teeth in male and female adolescents in Niedersachsen

The aim of this study was to determine the eruption times of permanent teeth, excluding third molars, in a defined area population of a country district in Lower Saxony. The authors investigated 2495 oral findings of 664 patients (male 315, female 349) in a longitudinal study. The minimum age was 3.00 years and the maximum age 24.00 years. The dental findings were collected over a period of about 20 years (1980-2002). The oral findings per child/adolescent were assessed between one and 16 times. The eruption times of teeth in females are earlier than those for the same teeth in males. Further, the permanent dentition in females is completed earlier than in males. The tooth eruption occurs symmetrically in both jaws. The comparison of both jaws revealed a slightly advanced eruption of the lower jaw teeth for both sexes. There is a noteworthy change in the eruption sequence of the teeth. In contrast to other reports we determined that the eruption of the canine proceeds the eruption of the second premolar. We found no acceleration of the dentition when compared to other reports and confirmed the rules of tooth eruption in man. Oral examination of teeth is a simple tool to calculate tooth eruption intervals. This first investigation on a population of Lower Saxony revealed a change in the eruption sequence of permanent teeth. The findings are relevant for dental treatment planning and should be reconfirmed at certain intervals.     

Fingerprint Ridge Density as a Potential Forensic Anthropological Tool for Sex Identification

In cases of partial or poor print recovery and lack of database/suspect print, fingerprint evidence is generally neglected. In light of such constraints, this study was designed to examine whether ridge density can aid in narrowing down the investigation for sex identification. The study was conducted on the right‐hand index digit of 245 males and 246 females belonging to the Punjabis of Delhi region. Five ridge density count areas, namely upper radial, radial, ulnar, upper ulnar, and proximal, were selected and designated. Probability of sex origin was calculated, and stepwise discriminant function analysis was performed to determine the discriminating ability of the selected areas. Females were observed with a significantly higher ridge density than males in all the five areas. Discriminant function analysis and logistic regression exhibited 96.8% and 97.4% accuracy, respectively, in sex identification. Hence, fingerprint ridge density is a potential tool for sex identification, even from partial prints.     

中国汉族6～18周岁人群下颌恒牙钙化的性别差异研究

目的通过对中国汉族男女6～18周岁人群全口曲面断层影像上所显示的下颌左侧牙齿钙化程度进行比较研究,探究牙齿生长发育的性别差异,为建立用牙齿推断中国汉族儿童及青少年年龄的线性回归模型提供理论依据。方法通过对13491张(男6568张,女6923张)中国汉族6～18周岁儿童及青少年全口曲面断层影像的牙齿钙化规律进行研究,建立牙齿钙化的分级标准,并对下颌恒牙进行分级评分;数据用SPSS 13.0软件处理。结果非参数检验结果显示大部分年龄组下颌左侧8颗恒牙钙化分级值性别间的差异有统计学意义(P0.05);在8颗恒牙发育程度同等条件下,女性年龄比男性小0.303岁。结论中国汉族6～18周岁人群牙齿发育存在着性别差异;在利用牙齿钙化程度建立推断中国汉族儿童及青少年年龄的方程模型时,应分性别建模。     

Sex discrimination potential of buccolingual and mesiodistal tooth dimensions

Abstract:  Tooth crown dimensions are reasonably accurate predictors of sex and are useful adjuncts in sex assessment. This study explores the utility of buccolingual (BL) and mesiodistal (MD) measurements in sex differentiation when used independently. BL and MD measurements of 28 teeth (third molars excluded) were obtained from a group of 53 Nepalese subjects (22 women and 31 men) aged 19–28 years. Stepwise discriminant analyses were undertaken separately for both types of tooth crown variables and their accuracy in sex classification compared with one another. MD dimensions had recognizably greater accuracy (77.4–83%) in sex identification than BL measurements (62.3–64.2%)—results that are consistent with previous reports. However, the accuracy of MD variables is not high enough to warrant their exclusive use in odontometric sex assessment—higher accuracy levels have been obtained when both types of dimensions were used concurrently, implying that BL variables contribute to sex assessment to some extent. Hence, it is inferred that optimal results in dental sex assessment are obtained when both MD and BL variables are used together.     

Sexual dimorphism in permanent teeth of modern Greeks

Sex determination is considered an important step in reconstructing the biological profile of unknown individuals from a forensic context. Forensic anthropologists have long used teeth as an additional tool for sex determination as they resist postmortem destruction. In this case the use of population-specific data is necessary since sexual dimorphism varies between different populations. Currently there are no odontometric standards for determining sex in Greek populations. The purpose of this study is to examine the degree of sexual dimorphism in permanent teeth of modern Greeks. A total of 839 permanent teeth in 133 individuals (70 males and 63 females) from the Athens Collection were examined. Mesiodistal and buccolingual crown and cervical diameters of both maxillary and mandibular teeth were measured. It was found that males have bigger teeth than females and in 65 out of 88 dimensions measured, male teeth exceeded female teeth significantly (P<0.05). Canines were the most dimorphic teeth followed by first premolars, maxillary second premolar and mandibular second molar. Although other teeth were also sexually dimorphic they did not have a statistically significant difference in all dimensions. The most dimorphic dimension was buccolingual cervical diameter followed by buccolingual crown diameter. A comparison of sexual dimorphism in teeth between different populations showed that it differs among different groups. European population groups presented the highest degree of sexual dimorphism in teeth whereas Native South Americans the lowest.     

Univariate sex dimorphism in the Nepalese dentition and the use of discriminant functions in gender assessment

Sex dimorphism in the Nepalese dentition is described using univariate and discriminant analyses. Canines showed the greatest univariate sex dimorphism, followed by the buccolingual (BL) dimension of maxillary first and second molars. Overall, the maxillary teeth and BL dimensions showed greater univariate sex differences. However, less than half of the measured variables (46.4%) showed statistically significant differences between the sexes and the magnitude of sex dimorphism was reduced when compared to other populations. Moreover, reverse dimorphism--where females showed larger teeth than males--was observed in the mesiodistal dimension of mandibular second premolars. This reflects reduction in sexual dimorphism observed through human evolution and the consequent overlap of tooth dimensions in modern males and females. A specific purpose of the study was to develop discriminant functions to facilitate sex classification. A group of functions were developed considering the possibility of missing teeth and/or jaws in forensic scenarios. The functions permitted moderate to high classification accuracy in sexing (67.9% using maxillary posterior teeth; 92.5% using teeth from both jaws). The superior expression of sex dimorphism by means of discriminant functions is in contrast to the univariate results. This is due to discriminant analysis utilising the inter-relationship between all teeth within a dentition--these tooth correlations are not utilised in univariate analysis which results in a loss of information. It is inferred that large-scale statistically significant univariate differences are not a prerequisite for sex assessment.