TOOTH- A UNIQUE SOURCE OF DNA IN FORENSIC ODONTOLOGY.pptx

This presentation gives brief idea about DNA Sources,uses of forensic odontology,DNA profiling etc

1. TOOTH- A UNIQUE SOURCE OF DNA IN FORENSIC ODONTOLOGY

2. CONTENTS- INTRODUCTION ROLE OF FORENSIC ODONTOLOGY BRIEF HISTORY DNA SOURCES OF DNA FACTORS AFFECTING DNA CONTENT IN TOOTH WHY TEETH ARE UNIQUE SOURCE OF DNA DNA STERILIZATION AND SAMPLING TECHNIQUES DNA PURIFICATION DNA PROFILING/DNA FINGERPRINTING/DNA TYPING/DNA TESTING DISCUSSION CONCLUSION REFERENCES

3. Introduction- Definition: Forensic – Forum means ‘Court of Law’ Odontology – Study of teeth Branch of forensic sciences which deals with collecting, preserving, recording and interpretation of dental evidence at the interest of court of law to offer law enforcement. KEISER in 1970 defined “It as branch of Odontology which deals with the proper handling of examination of dental evidence and the proper evaluation and presentation of dental findings in the interest of justice ” This involves DNA profiling.

4. In mass disasters such as earthquakes , tsunamis, fires and explosions, severely mutilated, charred, or decomposed bodies where there are scanty remains left and morphological tests like fingerprints may not be available. Investigative or forensic genetics with DNA analysis takes up the chief role and it could be the only option for human identification in such situations. The use of DNA analysis has, in modern times, expanded the scope of forensic dentistry. Dr . Oscar Amoedo is considered as father of Forensic Dentistry)

5. The tooth has capability to survive in any extreme environment with minimum risk of contamination making it unique alternative source of DNA in any diasater .

6. Role of Forensic Odontology: The subject is divided into three major fields of activity- civil, criminal and research CIVIL: Malpractice and all aspects which may eventually lead to criminal charges in the form of fraud. The subject is divided into three major fields of activity- civil, criminal and research CRIMINAL- The identification of persons from their teeth-living or dead person. RESEARCH- Academic training and courses Post graduate tuition

7. BRIEF HISTROY H istory of forensic dentistry is 4500 years old. One of the first dental identification was logged in 2500 BC, then 2 molars were linked together by gold wire were found by Junker in a tomb located at Giza. At the time of Nero, in 66 AD, Nero’s mother Agrippina had ordered her soldiers kill Lollia Paulina, with directives to bring back her head as proof that she was dead. Agrippina, was not able to positively identify the head, examined the front teeth and on finding the discolored front tooth confirmed the victim.

8. A new era of forensic dentistry started in 17 th century when a body was recognized from its dental details of the deceased personally known to dentist. A practical application came into action in 19th century, when a criminal was convicted on the basis of dental evidence. German dictator ADOLF HITLER and Pakistani President GENERAL ZIA-UL-HAQ , AND INDIAN PRIME-MINISTER RAJIV GANDHI were identified only on the basis of dental evidences.

9. Adolf hitlar RAJIV GANDHI ZIA UL GAQ

10. DNA (deoxyribonucleic acid ) Deoxyribonucleic acid (DNA) is the genetic code of almost all the organisms including humans. DNA is a genetic material seen in each and every cell of human body. 99.9% of DNA sequences are always similar while only 0.1% of DNA is unique and distinct in every person. Due to this uniqueness in DNA SEQUENSING t he probability of two people other than identical twins showing similar DNA profiles is 1 in 594 trillion people. Only identical twins is noted to have the similar DNA profiles

11. In the year 1953 that Watson and Crick discovered the DNA structure to be a double helical in form. “DNA fingerprinting” is the result of technological advances that have led to analyzing processes at the molecular level and made available powerful ways of isolating, manipulating, and analyzing nucleic acids.So DNA fingerprinting, is the process by which distinguishing the individual’s genetic characteristics is possible.

12. 2 types of DNA are present in human. Genomic DNA – Teeth provide a good source of genomic DNA . They are within the nucleus of the cell. Mitochondrial DNA – Used when DNA sample obtained is insufficient or degraded

13. SOURCES OF DNA ARE Blood, hair, nail bone and tooth . Tooth has always been an excellent forensic tool and a good sourcof DNA. Teeth can survive decomposition and autolysis as well as environmental insults, like water immersion, burial, and Fires as hot as 1,100°C, unlike soft tissues. Teeth have have well-preserved DNA even after many years and act as alternative DNA sources. Some authors suggest that teeth are better sources of DNA than bones . In tooth DNA can be obtained from enamel ( amelogenin ), dentine, cementum, pulp and adherent periodontal ligament fibers and bone . The majority of the dental tissues are not contaminated as they are well-protected by bone and soft tissue. Dentin and pulp are good sources and provide an adequate amount of DNA.

14. The pulp with cellular structures like odontoblasts and other nucleated cells is the best source of DNA due to less chance to be contamination as it is covered by dentin and enamel. Reparative or tertiary dentin with cellular or soft tissue inclusion may serve as the DNA source . Apical and lateral canals in the root dentin and furcation area are also suggested for DNA retrieval are also source of DNA. Cementocytes within the cellular cementum can also provide DNA.

15. DNA can be isolated from the crown, root body, and root apex. The root body yields the highest quantities of DNA. Sex determination can be also done by using a tooth AMEL gene in enamel Age can be determined by estimating the telomere shortening of the chromosome from a tooth DNA

16. FACTORS AFFECTING DNA CONTENT IN TOOTH The DNA in teeth can vary among the individuals as well as within the teeth of the same individual. The factors that affect the DNA content include the following: TOOTH TYPE The best source of DNA extraction can be one with the largest pulp volume[30,31] additionally, multicoated teeth also provide a larger pulp, thus providing more cementum due to more pulp cells and hence a good source of DNA. Therefore, tooth selection for DNA extraction should be preferably started with molars are the first choice for DNAextraction. CHRONOLOGICAL AGE Advancing age leads to a decrease in DNA content,So , f actors like extent of tooth wear, attrition, and abundance of cementum should be considered while selecting the sample.

17. DENTAL DISEASE These have an ill effect on the DNA content. Diseases such as caries or microbial diseases lead to dissolution as well as the destruction of calcified structure in teeth, which facilitates the entry of bacteria into the pulp which leads not only decreases the content of DNA but also increases its potential for contamination. POST-MORTEM DEGRADATION The degradation of the DNA in dental tissues is Time-dependent. Post-mortem degradation starts with the help of intracellular endogenous enzymes like proteases, lipases and nucleases and is followed by the exogenous enzymes produced by microbial invasion . Variables affecting presence of DNA in a tooth are as follows- Type of teeth present (incisor, canine, premolar, molar) Condition of dentition before extraction or the degree of decay in teeth Condition of teeth following trauma Period from extraction to DNA isolation Age of the individual

18. WHY TEETH ARE UNIQUE SOURCE OF DNA

19. DNA STERLIZATION AND SAMPLING TECHNIQUES Before DNA extraction, the tooth is cleansed with sodium hypochlorite (0.5%) and washed with the distilled water . Now let it dry without tempering the temperature and then put-through the ultraviolet light for 1 h . in case of intact tooth recently extracted from alveolus, a regular endodontic access opening is done along with instrumentation. Pulp chamber is curetted and the pulp collected in a sterile tube . Then, tooth crushing may also be required,the pulp chamber should be irrigated with a buffer. Now tooth is ready to retrieve the DNA sample .

20. SAMPLING TECHNIQUES DNA FROM DENTAL PULP. Crushing entire tooth Vertical split of entire tooth Conventional endodontic access Cryogenic grinding Horizontal sectioning Orthograde entrance technique

21. DNA PURIFICATION

22. DNA PROFILING/DNA FINGERPRINTING/DNA TYPING/DNA TESTING DNA Profiling is the process of determining an individual’s DNA characteristics . DNA profiling is also known as DNA Fingerprinting , DNA testing, or DNA typing. The process of DNA profiling was introduced by Sir Alec Jeffrey at the University of Leicester in 1985.

23. TYPES OF DNA FINGER PRINTING TECHNIQUES - Hybridization-based technique RFLP - PCR-based assays Manual genotyping and detection with staining Fluorescent non-anchored inter simple sequence repeat STR typing Time-of-flight mass spectrometry Automated STR genotyping Random amplification of polymorphic DNA (Y-STR for sex identification) - Sequence-based technology, i.e., detection of SNPs - Reverse dot blot assay mtDNA sequence analysis Single-strand conformational polymorphism - Microchip assays Microarray-based analysis

24. Limitations of tooth DNA fingerprinting DNA lysis takes place after death due to the enzymes such as DNAases . So,it is a difficult task to obtain DNA from the remains . There are high chances of contaminations during collection, storage as well as transportation . The type of teeth available, condition of the teeth as well as the tooth structure can affect the DNA quality and hamper the DNA fingerprinting.

25. DISCUSSION The tooth can survive in extreme environment with least possible risk of contamination making it a special d ue to the unique placement of teeth in the jaw and their structure. DNA present gets extra protection compared to bones .So, it frequently becomes the only source of DNA that would be available in adverse situation for identification. DNA profiling or fingerprinting shows the genetic makeup of a person. Teeth give an excellent source of DNA . Proper DNA isolation and quantification are needed to perform a successful analysis

26. CONCLUSION Teeth are protected by bone and soft tissue for better preservation and hence become an excellent source of DNA . Various DNA profiling methods are there with their advantages and disadvantages. Obtaining a DNA sample in an adequate quantity and quality remains a challenge due to various factors as discussed . Observing all the factors it is clear that TOOTH is an excellent source of DNA. Currently , research is dedicated on developing methods that yield good DNA from degraded and compromised samples.And Teeth serve as an important DNA source in forensic odontology .

27. References- 1 . Gaensslen RE, Harris HA, Lee HC. (2007) Introduction to Forensics & Criminalistics; New York: McGraw-Hill Companies, Inc . 2.Qadri AW, Yadav S, Jain A, Shetty DC, Gulati N. Tooth as a vital source of DNA in forensic odontology: Recent perspective. J Academy Dent Educ. 2023;9:73-9. doi : 10.25259/JADE_43_2023 3. Watson JD, Crick FHC. A structure for deoxyribose nucleic acid. Nature. 1953;171:737-8. 4 . Mayall SS, Agarwal P, Vashisth P. Dental DNA finger-printing in identification of human remains. Ann Dent Spec 2013; 1:16-9 . 5 . Jeffrey AJ, Wilson V, Fein SL. Hypervariable ‘minisatellite’ regions in human DNA. Nature. 1985; 314:67-73. https://doi.org/10.1038/314067a0 PMid:385610

28. 6. Acharya AB. Role of forensic odontology in disaster victim identification in the Indian context. J Dent Specialities 2015; 3:89-91 . 7. Ababu RS, Rose D. Molecular advancements in forensic.odontology. West Indian Med J 2016; 65:369-74. https://doi.org/10.7727/wimj.2014.109 PMid:26645597 Sweet D. Forensic dental identification . Forensic Science Int. 2010; 201:3-4. https://doi.org/10.1016/j.forsciint.2010.02.030 PMid:20304570 8.Pittayapat P, Jacobs R, De Valck E, Vandermeulen D, Willems G. Forensic odontology in the disaster victim identification process. J Forensic Odontostomatol. 2012; 30:1-12. 9.Buckleton J, Triggs C, Clayton T. In John Buckleton, Christopher M. Triggs, Simon J. Walsh editors. Disaster victim identification , identification of missing persons, and immigration cases in forensic DNA evidence interpretation. CRC Press Washington, D.C; 2005. p. 406-8. https://doi.org/10.1201/9781420037920.ch1110

29. . 10. Higgins D, Austin JJ. Teeth as a source of DNA for forensic identification of human remains: A review. Sci Justice. 2013; 53:433-41. https:// doi.org/10.1016/j.scijus.2013.06.001 PMid:24188345 11 . Higgins D, Kaidonis J, Austin J, Townsend G, James H, Hughes T. Dentine and cementum as sources of nuclear DNA for use in human identification . Aust J Forensic Sci. 2011; 43:287-95 . 12 . Nunn S. Touch DNA collection versus rearm fingerprinting : Comparing evidence production and identification outcomes. J Forensic Sci. 2013; 58:601-8. https://doi.org/10.1111/1556-4029.12119 PMid:23458456 Schwartz TR, Schwartz EA, Mieszerski L, McNally L, Kobilinsky L. Characterization of DNA obtained from teeth subjected to various environmental conditions. J Forensic Sci. 1991; 36:979-90. https://doi.org/10.1520/JFS13113J PMid:1680960 Nandini D. B and Juniya Grace Joji Tooth as a Source of DNA in Forensic or Investigative Genetics: An Overview Journal of Forensic Dental Sciences, Vol 12(3), DOI: 10.18311/ jfds /12/3/2020.617, September-December 2020

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