Estimation of missing mandible from the skull using postmortem CT images.

Skeletal remains often have missing mandibles owing to the environment in which the corpse was placed or damage caused by an animal. Loss of the mandible reduces the accuracy of skull identification. Although several studies have validated methods for estimating mandibular morphology from conventional anthropological measurements using skull specimens, there are no reports using three-dimensional computed tomography (3DCT) images. Here, we examined methods for establishing the mandibular morphology from the remaining skulls using postmortem computed tomography (PMCT) images. We used PMCT images from 200 Japanese subjects as samples. After verifying the morphological correlation between the cranium and mandible, we created and validated estimation models using multiple regression analysis (stepwise method) for seven sites that were necessary for understanding the morphology of the mandible. Among the regression models, the estimated model for bicondylar breadth had the highest coefficient of determination (adjR2 = 0.53). We verified the accuracy of the model on a sample independent from the specimen used to create the estimation model and found that the formulated model of bicondylar breadth had good estimation accuracy, with a high correlation coefficient between the measured and predicted values of 0.82 and a mean absolute error of 3.582 mm, indicating that the model had good estimation accuracy. Here, we established a novel method for estimating the missing mandibular morphology based on PMCT data from the Japanese population. Our estimation model can help determine the missing mandibular morphology in a cranium remnant.

Study on the Mechanism of the Pink Tooth Phenomenon Using Bovine Teeth: A Pilot Study.

The pink teeth phenomenon has occasionally been observed in forensic autopsies. This study aimed to establish an experimental pink tooth model and an objective color tone evaluation method in order to clarify changes in the color tone of teeth and the relationship with hemoglobin monoxide and its decomposition products and with red pigment-producing bacteria, under various external environmental factors. It was confirmed that the color tone evaluation with ΔE and the L*C*h color space was useful. The results of various examinations using this model showed that color development was suppressed under aerobic conditions, faded early under light, became bright red under a low temperature and showed a tendency to be reddish at 3 days under high humidity and in the presence of soft tissue. The biochemical analysis revealed a significant increase in carboxyhemoglobin at 7 days and a tendency toward increasing the total heme pigment and bilirubin levels over time. The bacteriological analysis revealed that red pigment-producing bacteria increased over time but that the color faded after 7 days. These results suggest that putrefaction greatly affects the pink teeth phenomenon, whereas red pigment-producing bacteria have little effect on the occurrence of pink teeth. However, further studies are needed to clarify bacteriological involvement.

Comparison of racemization rates between vital and endodontically treated teeth for age estimation.

Amino acid racemization of dentin (AAR) is among the most precise methods for age estimation in unidentified adult cadavers. Although vital teeth are generally used for this technique, cases often have endodontically treated (Endo) teeth only. Therefore, the aim of this preliminary pilot study was to determine the applicability of Endo teeth by comparing AAR rates between vital and Endo teeth. Thirty-six dentin samples from vital teeth and 18 dentin samples from Endo teeth were analyzed, including the maxillary first premolar, maxillary second molar, and mandibular second premolar. Standard calibration curves for the mandibular second premolar and maxillary second molar were compared among vital teeth, Endo teeth, and mixed vital/Endo teeth. Discrepancies between estimated and actual ages were assessed by analyzing the AAR rates for the maxillary first premolar between vital and Endo teeth. The AAR rates for Endo teeth were higher than those for vital teeth in both the mandibular second premolar and maxillary second molar, and the correlation of the standard calibration curve for vital teeth only was highest (r = 0.982836; r = 0.92011467), followed by mixed (r = 0.949579; r = 0.76158) and Endo teeth only (r = 0.896082; r = 0.744991). In the maxillary first premolar, discrepancies were more than 10 years for all 5 Endo teeth, based on the standard calibration curve of vital teeth. The present study suggests that the AAR rates for Endo teeth might be affected by variation in dentin structure between vital and Endo teeth.

Forensic Characteristics of Physical Elder Abuse and Current Status and Issues of Collaboration between Forensic Medicine Departments and Related Institutions in Japan.

This study sought to clarify the characteristics and trends of physical elder abuse and the status of collaboration between forensic medicine departments and related institutions in Japan. Questionnaires were sent to 82 forensic medicine departments and 2857 institutions randomly selected from hospitals, municipalities and public community general support centers. The survey period was February to June 2021, including an extension period for collection. Responses from 675 facilities were analyzed. The most common finding in cases of physical elder abuse at forensic medicine departments was subcutaneous hemorrhage on the head (85.7%), with mixed old and new injuries most commonly observed in the lower limbs (70%). There were few cases in which there was collaboration between forensic medicine departments and other institutions. Among the issues identified, there is a need to provide related institutions with information obtained in forensic medicine departments. A new collaboration system is needed to achieve this.

Validity of dental findings for identification by postmortem computed tomography.

Postmortem computed tomography (PMCT) images help identify individuals and extract information from corpses. PMCT may substitute for a standard examination when bodies are severely damaged or when resources are limited in a mass fatality incident. In such situations, the dental information revealed by PMCT has the potential to narrow down candidates for identification further. However, the validity of the dental findings obtained from PMCT images remains unclear. In this study, we investigated the validity of dental findings on PMCT images compared to regular dental examinations as the reference standard. We routinely collected PMCT images of 148 unidentified corpses and compared the dental findings of each tooth obtained from PMCT with those of a regular dental examination. The validity of dental findings of PMCT was measured by sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). We also evaluated the accuracy of dental findings per corpse using 32 teeth as the denominator. The dental findings with high sensitivity and high specificity were a present tooth (0.96 and 0.97), a missing tooth (0.97 and 0.97), pontic (0.92 and 1.00), a dental implant (1.00 and 1.00), and a root filling (0.94 and 0.99). The mean accuracy of the dental findings per corpse in PMCT was 95.6% (standard deviation: 6.9, minimum ≤ median ≤ maximum: 65.6 ≤ 100 ≤ 100). The number of corpses with 100% accuracy in the dental findings was 81 (54.7%). The information obtained in this study highlights the potential use of PMCT during human identification in several settings with limited resources, such as the number of specialists present and the condition of the corpses.

Sixty-eight cases of postmortem pink teeth observed in dental autopsies of unidentified cadavers.

The pink teeth phenomenon was first reported in people who died by hanging or drowning in 1829. In recent years, there have been many reports that the occurrence of postmortem pink teeth is closely related to the condition of surroundings and time after death rather than to the cause of death, as had previously been thought. We observed pink teeth in 68 of 324 unidentified cadavers autopsied during 2015-2021, and we investigated the relationship of pink teeth with age, sex, cadaveric condition, time after death, tooth type, and cause of death. The results showed no significant differences in the occurrence of pink teeth according to sex or place of discovery (indoors, outdoors, or in water). Pink teeth tended to be observed below the age of 60 years. In the 68 cases with pink teeth, 29.1% of all vital teeth were affected, with the anterior teeth being most common. No evidence was found that supported an association between pink teeth and cause of death. These results are largely consistent with recent reports on postmortem pink teeth. As it stands, the pink teeth phenomenon may be nonspecific and must not be misinterpreted in medico-legal investigations. This case series provides further evidence supporting recent reports and contributes to clarifying in greater detail the mechanisms of the coloration and fading of pink teeth.

Preparation of dentin standard samples for age estimation based on increased aspartic acid racemization rate by heating.

Age estimation in adults based on aspartic acid racemization (AAR) provides fewer errors and higher precision than that based on bone morphology for the identification of cadavers. The technique has been established in some labs as a routine method. However, as the essential requisites for the technique, a wide age range of teeth of the same type as the target tooth must be collected for calibration for each examination. We investigated whether dentin standard samples could be prepared by increasing the AAR rate via heat. Powdered dentin was prepared from a maxillary first premolar (13 years) and heated for 0-72 h at 110 °C. The extent of AAR increased significantly with heating time and the correlation was strong (r = 0.913; p < 0.01). Similar results were found for a mandibular canine (24 years, r = 0.948; p < 0.01) and a maxillary third molar (20 years, r = 0.944; p < 0.01). We attempted to estimate the age of four maxillary first premolars of persons aged 25-58 years by using the heated samples (18 years, 12 h to 7 days). The differences between the actual and estimated ages were within ±5 years. The stability of the AAR rates in the powdered dentin during storage at 22-25 °C, 4 °C, and -30 °C was examined after 1 year and no significant changes had occurred. We were able to prepare dentin standard samples and created a calibration curve. This is a pilot study that needs to be validated before it can be used in forensic practice.

Establishment of a prediction method for the mid-facial region of unknown human Mongoloid skeletal remains.

Forensic facial approximation is a technique used to estimate the antemortem facial features of unknown skeletal remains. In recent years, many researchers have reported nasal tip predictions with positive results. However, the morphological nasal features of the skull can vary widely, and it is hard to obtain accurate values using facial approximation techniques. We assumed that these variations are due to an over-dependence on the values obtained from a single distance metric factor in an anatomical area. Measurements were acquired using cephalometric radiographic images obtained from 190 Japanese individuals (90 men, aged 18-36 years and 100 women, aged 18-46 years). Soft tissue and skeletal features were traced onto acetate sheets. The orbitale (Or), porion (Po), and the Frankfurt Horizontal Plane (FHP) were plotted in addition to the rhinion (Rhi), anterior nasal spine (ANS), subnasale (Sn), prosthion, and point-A (A). From these, the following were measured: a length from rhinion to prosthion; b length from rhinion to the intersection of a line perpendicular to the anterior nasal spine; c length from the prosthion to the intersection of a line perpendicular to the anterior nasal spine; g the proportion of d/b; and f the proportion of c/b. A calculation was generated from these measurements and from proportions of a-h, and applied to the samples. An R-squared (RSQ) test and standard error (SE) were used to compare the actual and predicted values. The errors observed between the predicted and actual values were not greater than 5mm in any of the samples; 91.3% and 71.2% of predicted Sn had an error lower than 2.5 and 1.5mm respectively, from the actual. Reliable results were obtained using the method in the present study. In addition, in the process of obtaining the measurements, we found reliable proportional differences between the sexes in the piriform and axillary alveolar regions.

Pilot study to establish a nasal tip prediction method from unknown human skeletal remains for facial reconstruction and skull photo superimposition as applied to a Japanese male populations.

Skull-photo superimposition is a technique used to identify the relationship between the skull and a photograph of a target person: and facial reconstruction reproduces antemortem facial features from an unknown human skull, or identifies the facial features of unknown human skeletal remains. These techniques are based on soft tissue thickness and the relationships between soft tissue and the skull, i.e., the position of the ear and external acoustic meatus, pupil and orbit, nose and nasal aperture, and lips and teeth. However, the ear and nose region are relatively difficult to identify because of their structure, as the soft tissues of these regions are lined with cartilage. We attempted to establish a more accurate method to determine the position of the nasal tip from the skull. We measured the height of the maxilla and mid-lower facial region in 55 Japanese men and generated a regression equation from the collected data. We obtained a result that was 2.0±0.99mm (mean±SD) distant from the true nasal tip, when applied to a validation set consisting of another 12 Japanese men.

Facial soft tissue thickness differences among three skeletal classes in Japanese population.

Facial reconstruction is used in forensic anthropology to recreate the face from unknown human skeletal remains, and to elucidate the antemortem facial appearance. This requires accurate assessment of the skull (age, sex, ancestry, etc.) and thickness data. However, additional information is required to reconstruct the face as the information obtained from the skull is limited. Here, we aimed to examine the information from the skull that is required for accurate facial reconstruction. The human facial profile is classified into 3 shapes: straight, convex, and concave. These facial profiles facilitate recognition of individuals. The skeletal classes used in orthodontics are classified according to these 3 facial types. We have previously reported the differences between Japanese females. In the present study, we applied this classification for facial tissue measurement, compared the differences in tissue depth of each skeletal class for both sexes in the Japanese population, and elucidated the differences between the skeletal classes.

Root canal system of the maxillary canine.

To better assess the efficacy of mechanical preparation of root canals, transparent specimens of 250 extracted maxillary canines were investigated for canal configuration, thickness and curvature of the root canal, condition of any accessory canals, and location of the apical foramen. Fewer than 40% of the specimens showed accessory canals that were mechanically impossible to clean. The majority of the lateral branches were small, greater than a #15 file, and none of the branches were larger than a #20 file. Although apical foramina located away from the apex were observed in 30% of the maxillary teeth, 96% of all apical foramina were within 0.5 mm of the apex. Data on the thickness of the root and main canal in the apical portion and curvature of the root canal suggest that, for adequate apical preparation, a #60 file must be able to reach the apical constriction.

Facial soft tissue thickness in Japanese children.

Facial reconstruction techniques used in forensic anthropology are based on mean soft tissue thickness measurements. Numerous studies of facial tissue thickness in adults have been published on a range of subjects from different ancestral backgrounds. Data on facial thickness in children derive primarily from Caucasoid, African-American, and Hispanic subjects. There are limited data from the few studies of Japanese children (male: skeletal class I only; female: all skeletal classes). The author has previously reported facial tissue thickness data for Japanese girls and boys with skeletal class I and for all three skeletal classes in Japanese girls. The present study reports facial soft tissue thickness data in Japanese children of all skeletal classes, within age subsets. With parental informed consent, diagnostic lateral cephalometric X-ray images were obtained from 339 Japanese children aged 7-18 years (male: 162; female: 177) who attended the Matsumoto Dental University Department of Orthodontics to undergo orthodontic treatment. Soft tissue and skeletal features were traced onto acetate sheets from the X-ray images, and 10 anthropological landmarks on the midsagittal line were measured. Means, SDs, and ranges were then calculated. Differences between male and female measurements in six age groups were compared using t-tests. Significant differences were observed at some landmarks in each age group. The findings were compared with data from other juvenile populations.

Pilot study of facial soft tissue thickness differences among three skeletal classes in Japanese females.

Facial reconstruction is a technique used in forensic anthropology to estimate the appearance of the antemortem face from unknown human skeletal remains. This requires accurate skull assessment (for variables such as age, sex, and race) and soft tissue thickness data. However, the skull can provide only limited information, and further data are needed to reconstruct the face. The authors herein obtained further information from the skull in order to reconstruct the face more accurately. Skulls can be classified into three facial types on the basis of orthodontic skeletal classes (namely, straight facial profile, type I, convex facial profile, type II, and concave facial profile, type III). This concept was applied to facial tissue measurement and soft tissue depth was compared in each skeletal class in a Japanese female population. Differences of soft tissue depth between skeletal classes were observed, and this information may enable more accurate reconstruction than sex-specific depth alone.

A case of a divided maxillary artery in the infratemporal fossa.

A divided maxillary artery was found in the left infratemporal fossa of a 63-year-old male cadaver during a student dissection practice. The maxillary artery, which arose from the external carotid artery at the posterior border of the ramus of the mandible, was divided into two branches in the infratemporal fossa. The deep branch of the maxillary artery was deep to the lateral pterygoid muscle and the inferior alveolar, buccal and lingual nerves, giving off the anterior tympanic, middle meningeal, anterior deep temporal, buccal, and posterior superior alveolar arteries. The deep branch passed through the pterygomaxillary fissure. On the other hand, the superficial branch of the maxillary artery, which was superficial to the lateral pterygoid muscle, gave off the inferior alveolar artery and other branches. The maxillary artery on the right side displayed a normal branching pattern within the infratemporal fossa. These findings indicate that the deep and superficial branches of the maxillary artery remained without disappearing during the development of the maxillary artery originated from the stapedial artery.

Facial soft tissue thickness in skeletal type I Japanese children.

Facial reconstruction techniques used in forensic anthropology require knowledge of the facial soft tissue thickness of each race if facial features are to be reconstructed correctly. If this is inaccurate, so also will be the reconstructed face. Knowledge of differences by age and sex are also required. Therefore, when unknown human skeletal remains are found, the forensic anthropologist investigates for race, sex, and age, and for other variables of relevance. Cephalometric X-ray images of living persons can help to provide this information. They give an approximately 10% enlargement from true size and can demonstrate the relationship between soft and hard tissue. In the present study, facial soft tissue thickness in Japanese children was measured at 12 anthropological points using X-ray cephalometry in order to establish a database for facial soft tissue thickness. This study of both boys and girls, aged from 6 to 18 years, follows a previous study of Japanese female children only, and focuses on facial soft tissue thickness in only one skeletal type. Sex differences in thickness of tissue were found from 12 years of age upwards. The study provides more detailed and accurate measurements than past reports of facial soft tissue thickness, and reveals the uniqueness of the Japanese child's facial profile.

Facial soft tissue thickness in Japanese female children.

Facial reconstruction techniques used in forensic anthropology are based on soft tissue thickness measurements. Many studies of facial tissue thickness in adults have been published that take racial background into account. However, the only data on facial thickness in children are derived from studies of American, British, and Hispanic children. The authors therefore measured facial tissue thickness in Japanese children, with the aim of providing data for producing accurate facial likenesses and to evaluate matching of skull-photo superimposition images. Cephalometric X-ray images give an approximately 10% enlargement from true size and can demonstrate the relationship between soft and hard tissue. Facial soft tissue thickness was measured at 12 anthropological points using X-ray cephalometry.

Preliminary study of post mortem identification using lip prints.

Identification using lip prints was first performed in the 1950s and was the subject of much research in the 1960s and 70s, leading to the acceptance of this technique as evidence in the criminal justice system. Previous research has focused on identifying lip print types or on methods of obtaining hidden lip prints left at the crime scene. The present study aimed to clarify characteristics of lip prints from cadavers with various causes of death (including drowning and hanging) and to determine the effects of fixation on post mortem changes in lip impressions.

Influence of template DNA degradation on the genotyping of SNPs and STR polymorphisms from forensic materials by PCR.

Detection of single nucleotide polymorphisms (SNPs) and short tandem repeat (STR) polymorphisms by PCR is widely used to analyze degraded DNAs in forensic science. The success of DNA analysis from human remains largely depends on the quality of the template DNA. We examined two SNPs (HLA-DQA1 and ABO) and two STR polymorphisms (VWA and CD4) by SSCP gel or denaturing gel electrophoresis, using two kinds of degraded DNA samples (165 teeth and blood stains contaminated with saliva) derived from the same person and investigated the influence of template DNA degradation on genotyping. As the degradation of DNA proceeds, unbalanced amplification of alleles occurred in the analysis of both SNPs and STRs, followed by allele drop, and further by loss of amplification. Non-target allelic products of STRs were amplified from highly degraded DNA samples; however, false allelic products of SNPs were not amplified from them. Amplification efficiency increased in proportion to the decrease of PCR target size, but reduction of the PCR target sizes also increased the chances of amplifying contaminating DNA, especially in highly degraded DNA specimens. The present results will help investigators to evaluate the genotyping of highly degraded DNA samples in forensic casework.