Dental DNA fingerprinting in identification of human remains

Comparison of gender identification using exfoliated cells obtained from toothbrush and miswak: A longitudinal study

Gender identification plays a pivotal role in forensic medicine. Among the various methods used for gender identification, deoxyribose nucleic acid (DNA) based methods are considered accurate. Exfoliated oral mucosal cells that are harvested from oral hygiene aids can be potentially used for gender identification using real-time polymerase chain rection (PCR). The aim of the present longitudinal study is to assess and compare the efficacy of toothbrush and miswak as potential tools to harvest exfoliated cells for gender identification. Forty healthy volunteers were recruited and asked to clean their teeth using new toothbrush and fresh miswak each day for 4 days. Toothbrush and miswak used by the participants were subjected to DNA analysis immediately, 1st, 2nd and 6th month. The absorbance of DNA samples were quantified and gender identification was done by amplification of sex determining gene-Sex determining region Y gene (SRY) and ALT1 genes using real-time PCR. The number of correct and positive identification for samples at various time points were tabulated and subjected to statistical analysis. Post hoc power analysis showed that the study had a power of 93%. Correct and positive gender identification was observed for the samples (100%) obtained using miswak, for tooth brush it reduced to 95%, 80%, and 35% at the end of 1st, 2nd, and 6th month. The differences seen at the end of 2nd month and 6th month were statistically significant. Miswak is a better tool to harvest exfoliated cells for gender identification when compared to a toothbrush. Hence, miswak can serve as a potential tool in forensic medicine for DNA extraction and subsequently victim identification.

D, Ramani P, Arafat A, Khairy A. SRY gene isolation from teeth for forensic gender identification-An observational study

Personal identification in forensics is possible with gender determination using DNA (deoxyribonucleic acid) analysis. DNA isolation from teeth samples subjected to extreme temperatures has been shown to predict the gender of the deceased. However, the literature lacks studies on DNA extracted from tooth samples exposed to freezing temperatures. This study aimed to isolate the SRY gene from the extirpated pulp of teeth that were subjected to varying temperatures for gender identification. Thirty teeth with vital pulps, divided into 3 groups were included in the study. Each group consisted of 5 male and 5 female tooth samples. The groups were exposed to diverse environmental factors for three weeks. Group 1: room temperature (R group); Group 2: high temperature (H group) and Group 3: freezing temperature (F group). Later, DNA was isolated from the pulp tissue, and the SRY gene was amplified using PCR (Polymerase Chain Reaction). The Sensitivity and Specificity of the results were analyzed. SRY gene detected in the study samples identified accurate gender with a 46.70% Sensitivity and 93.30% Specificity. Significant difference was found in the correlation between gene expression and gender among the three groups (p = 1.000). The study validates that dental pulp tissue can be a reliable source for DNA extraction. And SRY gene amplification from teeth exposed to diverse environmental conditions. Further investigations are required to validate its application in forensics.

Tooth as a Source of DNA in Forensic or Investigative Genetics: An Overview

Deoxyribonucleic acid (DNA) is the genetic code of most organisms including humans. In the last few years, DNA analysis methods are applied to forensic cases for human identification which is termed forensic or investigative genetics. It is often challenging to obtain and interpret DNA from routine samples like blood in severely decomposed or disfigured bodies recovered from incineration, immersion, trauma, mutilation, and decomposition as in incidents of fire, explosion, or murder. The tooth can survive any extreme environment with minimum risk of contamination making it a valuable alternative source of DNA in such cases. Tooth structures like the enamel (amelogenin protein), dentin, cementum, pulp, and adherent tissues like bone and periodontal fibers are sources from which DNA can be obtained. Various methods have been described for DNA extraction. There are numerous applications of DNA analysis like identification of the deceased or missing victim or the unknown culprit from a crime scene, solving paternity issues, determining the occurrence of any genetic disease, and determining the ancestry. This article briefly summarizes an overview of the tooth as a valuable DNA source and various methods and challenges related to DNA analysis.

Dental Radiographic/Digital Radiography Technology along with Biological Agents in Human Identification

The heavy casualties associated with mass disasters necessitate substantial resources to be managed. The unexpectedly violent nature of such occurrences usually remains a problematic amount of victims that urgently require to be identified by a reliable and economical method. Conventional identification methods are inefficient in many cases such as plane crashes and fire accidents that have damaged the macrobiometric features such as fingerprints or faces. An appropriate recognition method for such cases should use features more resistant to destruction. Forensic dentistry provides the most appropriate available method for the successful identification of victims using careful techniques and precise data interpretation. Since bones and teeth are the most persistent parts of the demolished bodies in sudden mass disasters, scanning and radiographs are unrepeatable parts of forensic dentistry. Forensic dentistry as a scientific method of human remain identification has been considerably referred to be efficient in disasters. Forensic dentistry can be used for either "sex and age estimation," "Medical biotechnology techniques," or "identification with dental records," etc. The present review is aimed at discussing the development and implementation of forensic dentistry methods for human identification. For this object, the literature from the last decade has been searched for the innovations in forensic dentistry for human identification based on the PubMed database.

Estimation of Personal Environment Via Fingertip Microbiome and Mobile Phone Surfaces

BACKGROUND

Fingerprints can serve to identify individuals, but fingerprint quality may be deteriorated, even to the point of eliminating fingerprints, due to the external environment.

OBJECTIVE

Poor fingerprint quality cannot be effectively used to identify individuals; hence, the need for other methods.

MATERIALS AND METHODS

We investigated the utility of bacterial communities and the only microorganisms present in the sample to identify internal and external factors in individuals. Samples included eight participants' fingerprints and their mobile phone surfaces. Bacterial DNA in the samples was sequenced using next-generation sequencing to target the V3-V4 region in the 16S ribosomal RNA gene. The QIIME program was used to perform a taxonomic assignment and alpha diversity and beta diversity analyses based on the sequence data.

RESULTS

Until now, personal identification has only relied on microbial communities. However, this study identified microbial differences according to Korean mobile phones, fingertips, or gender, and confirmed the possibility of characterization of samples when it was difficult to identify individuals by the microbial community. The biodiversity and composition of individual bacterial communities were affected by internal and external environments. Bacteria from individuals and mobile phones were shared due to contact between mobile phone surfaces and fingertips. Of the eight Koreans, six of the fingertips and mobile phone samples matched each other for personal identification.

CONCLUSIONS

This study confirmed that the bacteria from an individual could be matched with the contact object and could be used as forensic evidence. Such bacterial profiling of individuals may confer forensic evidence and serve as a basis for improving the accuracy of forensic verification.

A novel identification method using perceptual degree of concordance of occlusal surfaces calculated by a Python program

One of the important issues during the response to a mass disaster is the identification of victims. In this study, we verified the use of the occlusal morphology of molars for individual identification. The aim of this study was to establish a simple new method for identifying individuals from molar data. Using Python, we developed programming that included the perceptual Hash (pHash) function and the Hamming distance (HD) between antemortem data (AMD) and postmortem data (PMD). The AMD comprised 2,215 dental models. The PMD were selected from the AMD set and comprised 17 models from the same individual with changes over time. As a result, 16 PMD models (over 90%) were ranked in the top 5%. Although identification using only a single molar is difficult, there is the possibility of narrowing down victims' identity with high accuracy through verification using multiple teeth. This system is expected to be useful as a very simple method of identification.

Forensic Odontology, a Boon and a Humanitarian Tool: A Literature Review

Our society faces fresh challenges in every conceivable way, from an increase in the crime rate to a rise in natural disasters. In spite of the leaps in modern technology, medical breakthroughs in the identification of criminals remain a cumbersome task.  The modern-day criminal investigation typically involves many different disciplines to solve a crime. The identification of a person's body is required when it is completely mutilated, disfigured, or beyond recognition -- which might be due to any barbaric crime, accident, war, fire, or any natural disaster. Dental identification is one of the most reliable methods, as teeth and dental structures may survive adverse conditions. The techniques involved in forensic odontology include: bite mark analysis, tooth prints, rugroscopy, cheiloscopy, dental DNA analysis, radiographs, and photographs.

A Review of Bomb Pulse Dating and its Use in the Investigation of Unidentified Human Remains

In cases where there is limited antemortem information, the examination of unidentified human remains as part of the investigation of long-term missing person's cases is a complex endeavor and consequently requires a multidisciplinary approach. Bomb pulse dating, which involves the analysis and interpretation of 14C concentration, is one technique that may assist in these investigations by providing an estimate of year of birth and year of death. This review examines the technique of bomb pulse dating and its use in the identification of differentially preserved unknown human remains. Research and case studies implementing bomb pulse dating have predominantly been undertaken in the Northern Hemisphere and have demonstrated reliable and accurate results. Limitations were, however, identified throughout the literature. These included the small sample sizes used in previous research/case studies which impacted on the statistical significance of the findings, as well as technique-specific issues. Such limitations highlight the need for future research.

Forensic Genetics and Genotyping

Forensic genetics represents a combination of molecular and population genetics. Personal identification and kinship analysis (e.g. paternity testing) are the two main subjects of forensic DNA analysis. Biological specimens from which DNA is isolated are blood, semen, saliva, tissues, bones, teeth, hairs. Genotyping has become a basis in the characterization of forensic biological evidence. It is performed using a variety of genetic markers, which are divided into two large groups: bi-allelic (single-nucleotide polymorphisms, SNP) and multi-allelic polymorphisms (variable number of tandem repeats, VNTR and short tandem repeats, STR). This review describes the purpose of genetic markers in forensic investigation and their limitations. The STR loci are currently the most informative genetic markers for identity testing, but in cases without a suspect SNP can predict offender’s ancestry and phenotype traits such as skin, eyes and hair color. Nowadays, many countries worldwide have established forensic DNA databases based on autosomal short tandem repeats and other markers. In order for DNA profile database to be useful at a national or international level, it is essential to standardize genetic markers used in laboratories.

Sex determination from tooth pulp deoxyribonucleic acid using polymerase chain reaction

Introduction

In this fast era of numerous unwanted disasters and because of the severely devastated and degenerated body remains, personal identification of unknown remains has become the most difficult and challenging task. In such instances, dental pulp plays a vital role in identification through deoxyribonucleic acid (DNA).

Aim

The aim of the study is to determine sex from tooth pulp tissues by DNA analysis using polymerase chain reaction amplification method under different environmental conditions.

Materials and Methods

The human extracted teeth were exposed to different conditions such as heat, soil, and open environment. The DNA was extracted from all these teeth including freshly extracted teeth, then quantified, and further amplified with male and female primers.

Results

Quantity of DNA content achieved ranged from 5.21 to 62.87 ng/μl. The accuracy in determining sex from pulp DNA ranged from 92% to 100% in the study groups, except from the teeth exposed to uncontrolled heat, as the pulp tissue was burnt completely. The intergroup analysis was statistically highly significant (P < 0.001). Gender determination using the quantity of DNA was found to be nonsignificant (P > 0.05).

Conclusion

The dental pulp is the reliable source for sex determination in the humid or dry environment compared to uncontrolled heat.

Microbial Degradation of Forensic Samples of Biological Origin: Potential Threat to Human DNA Typing

Forensic biology is a sub-discipline of biological science with an amalgam of other branches of science used in the criminal justice system. Any nucleated cell/tissue harbouring DNA, either live or dead, can be used as forensic exhibits, a source of investigation through DNA typing. These biological materials of human origin are rich source of proteins, carbohydrates, lipids, trace elements as well as water and, thus, provide a virtuous milieu for the growth of microbes. The obstinate microbial growth augments the degradation process and is amplified with the passage of time and improper storage of the biological materials. Degradation of these biological materials carriages a huge challenge in the downstream processes of forensic DNA typing technique, such as short tandem repeats (STR) DNA typing. Microbial degradation yields improper or no PCR amplification, heterozygous peak imbalance, DNA contamination from non-human sources, degradation of DNA by microbial by-products, etc. Consequently, the most precise STR DNA typing technique is nullified and definite opinion can be hardly given with degraded forensic exhibits. Thus, suitable precautionary measures should be taken for proper storage and processing of the biological exhibits to minimize their decaying process by micro-organisms.

Enamel hypoplasia and its role in identification of individuals: A review of literature

Identification of individuals is the mainstay of any forensic investigation especially in cases of mass disasters when mutilated remains are brought for examination. Dental examination helps in establishing the identity of an individual and thus, has played a vital role in forensic investigation process since long. In this regard, description on the role of enamel hypoplasia is limited in the literature. The present article reviews the literature on the enamel hypoplasia and discusses its utility in forensic identification. Enamel hypoplasia is a surface defect of the tooth crown caused by disturbance of enamel matrix secretion. Enamel defects can be congenital or acquired. In cases of mass disasters, or when the body is completely charred, putrefied and mutilated beyond recognition, the unique dental features can help in identification of the victims.

Role of DNA profiling in forensic odontology

The recent advances in DNA profiling have made DNA evidence to be more widely accepted in courts. This has revolutionized the aspect of forensic odontology. DNA profiling/DNA fingerprinting has come a long way from the conventional fingerprints. DNA that is responsible for all the cell's activities, yields valuable information both in the healthy and diseased individuals. When other means of traditional identification become impossible following mass calamities or fire explosions, teeth provide a rich source of DNA as they have a high chemical as well as physical resistance. The recent evolution in the isolation of DNA and the ways of running a DNA fingerprint are highlighted in this literature review.

A study of the palatal rugae pattern among male female and transgender population of Bhopal city

Context:

Transgenders are highly disadvantaged people, deprived of adequate opportunities of earning a respectable living. The forensic literature has emphasized on two genders, male and female, the existence of a third gender (Transgenders) is almost negligible in the literature, and this makes it compulsive to determine their identity through forensic approaches at the time of disasters. Previous studies have demonstrated that no two palatal rugae pattern are alike in their configuration and this unique feature has led us to undertake a study to establish individual identities using palatal rugae pattern.

Aims:

The purpose of this study was to compare the palatal rugae pattern among male, female, and transgender population of the Bhopal city.

Settings and Design:

This study was cross sectional in nature and conducted on a convenience sample of 148 subjects selected from Bhopal city, Madhya Pradesh. The study involved 49 males, 51 females, and 48 eunuchs in the age range of 17 to 35 years.

Materials and Methods:

Maxillary impression using alginate impression material was made and the cast was prepared using die stone on palatal area and dental stone as a base. The palatal rugae pattern was assessed on the basis of number, length, shape, direction, and unification.

Statistical Analysis Used:

One way ANOVA was used for comparing the mean values between different genders. The multiple pairwise comparisons were done with the Bonferroni post hoc correction. The statistical significance was fixed at 0.05.

Results:

The statistically significant difference with regard to some parameters like number of rugae, fragmentary rugae, wavy rugae, curve rugae, forwardly directed, and backwardly directed rugae between transgender and other gender groups were present.

Conclusion:

The difference in the parameters of the palatal rugae pattern among the transgender population and the other gender group is attributed to be the genetic makeup and sexual dimorphism.

The use of a DNA stabilizer in human dental tissues stored under different temperature conditions and time intervals

Objective

The present study evaluated the use of a reagent to stabilize the DNA extracted from human dental tissues stored under different temperature conditions and time intervals.

Material and Methods

A total of 161 teeth were divided into two distinct groups: intact teeth and isolated dental pulp tissue. The samples were stored with or without the product at different time intervals and temperature. After storage, DNA extraction and genomic DNA quantification were performed using real-time PCR; the fragments of the 32 samples that represented each possible condition were analyzed to find the four pre-selected markers in STR analysis.

Results

The results of the quantification showed values ranging from 0.01 to 10,246.88 ng/μL of DNA. The statistical difference in the quantity of DNA was observed when the factors related to the time and temperature of storage were analyzed. In relation to the use of the specific reagent, its use was relevant in the group of intact teeth when they were at room temperature for 30 and 180 days. The analysis of the fragments in the 32 selected samples was possible irrespective of the amount of DNA, confirming that the STR analysis using an automated method yields good results.

Conclusions

The use of a specific reagent showed a significant difference in stabilizing DNA in samples of intact human teeth stored at room temperature for 30 and 180 days, while the results showed no justification for using the product under the other conditions tested.

Forensic dentistry in human identification: A review of the literature

An update is provided of the literature on the role of odontology in human identification, based on a PubMed-Medline search of the last 5 years and using the terms: “forensic dentistry” (n = 464 articles), “forensic odontology” (n = 141 articles) and “forensic dentistry identification” (n = 169 articles). Apart from these initial 774 articles, others considered to be important and which were generated by a manual search and cited as references in review articles were also included. Forensic dentistry requires interdisciplinary knowledge, since the data obtained from the oral cavity can contribute to identify an individual or provide information needed in a legal process. Furthermore, the data obtained from the oral cavity can narrow the search range of an individual and play a key role in the victim identification process following mass disasters or catastrophes. This literature search covering the last 5 years describes the novelties referred to buccodental studies in comparative identification, buccodental evaluation in reconstructive identification, human bites as a method for identifying the aggressor, and the role of DNA in dental identification. The oral cavity is a rich and noninvasive source of DNA, and can be used to solve problems of a social, economic or legal nature.

Key words:Forensic identification, DNA, forensic dentistry, rugoscopy, cheiloscopy, saliva.

Teeth as a source of DNA for forensic identification of human remains: a review

Teeth and bones are frequently the only sources of DNA available for identification of degraded or fragmented human remains. The unique composition of teeth and their location in the jawbone provide additional protection to DNA compared to bones making them a preferred source of DNA in many cases. Despite this, post-mortem changes in the structure and composition of teeth, and the location and diagenesis of DNA within them are poorly understood. This review summarises current knowledge of tooth morphology with respect to DNA content and preservation, and discusses the way in which post-mortem changes will affect the recovery of DNA from teeth under a range of commonly used extraction protocols. We highlight the benefits and pitfalls of using specific tooth tissues for DNA extraction and make recommendations for tooth selection and sampling that will maximise DNA typing success. A comprehensive understanding of tooth structure and an appreciation of the relationship between DNA and mineralized tissues in post-mortem teeth are critical for optimal sample selection. More informed sampling methods that target specific tooth tissues will increase the likelihood of successful genetic analysis and allow for efficient and timely missing persons case work and disaster victim identification response.