OVERVIEW OF FORENSIC ODONTOLOGY

INTRODUCTION

Forensic dentistry or forensic odontology is the application of dental knowledge to those criminal and civil laws that are enforced by police agencies in a criminal justice system. 

Forensic dentists are involved in assisting investigative agencies to identify recovered human remains in addition to the identification of whole or fragmented bodies; forensic dentists may also be asked to assist in determining age, race, occupation, previous dental history and socioeconomic status of unidentified human beings.

Photo credit: https://www.roseman.edu/2018/06/06/the-role-forensic-odontology-plays-in-identifying-human-remains/

Forensic odontologists delve into:

•  Identifying unknown human remains through comparison of postmortem dental evidence with dental records of the presumed deceased.
• Assisting at the scene of a mass disaster and in the victims’ identification.
• Eliciting the ethnicity/population affinity and assisting in building up a picture of lifestyle and diet of skeletal remains at forensic and archeological sites.
• Assessing the sex of skeletonized remains.
• Age estimation of both the living and deceased. 
• Analysis and identification of bite marks found on human tissue, animal tissue, and inanimate objects/foodstuffs.
• Presenting evidence in court as expert witnesses.

HIGH PROFILE CASES IN FORENSIC ODONTOLOGY 

• Ted bundy
• Notorious serial killer Ted Bundy confessed to 30 homicides that he committed in seven states between 1974 and 1978.
•  Forensic dentists Richard Souviron and Lowell Levine made the case that stone models and a wax bite record from Bundy’s teeth matched with a bite mark that Bundy inflicted on one of his victims

Photo credit: https://advancedentalbirmingham.com/dentists-helped-convict-ted-bundy/

Top:Dentists taking impressions of Bundy's teeth; Bottom: a record of Bundy's bite superimposed over a bite mark left on one of his victims.

• Lollia paulina
• The identification of Lollia Paulina in 49 AD was the first reported case of dental identification of an individual. Agrippina, the wife of Roman Emperor Claudius ordered her soldiers to kill Lollia who was the first wife of the Emperor. 
• After killing Lollia Paulina, the soldiers bought her head to Agrippina who identified her with her unique teeth

• John Talbot
• John Talbot, the first Earl of Shrewsbury was identified based on his missing left molar by his personal herald.

• Dr. Joseph Warren
• Dr. Joseph Warren was identified with his ivory and gold prosthesis made by Paul Revere when he was killed in the Battle of Bunker hill.

• John wilkes booth
• John Wilkes Booth who assassinated Abraham Lincoln was identified by his abnormal jaw and his gold restorations.
• About 126 people were killed in the fire in Bazar de la Charite and due to the severity of the burns, most of the bodies were identified based on their teeth.

• Adolf Hitler
• Adolf Hitler who committed suicide in 1945 was identified by his prosthesis in 1968.

Photo credit: https://www.researchgate.net/figure/Hitlers-dental-status-after-oral-information-collected-from-his-dental-technician_fig2_322248796 [accessed 27 May, 2020]

• When 158 victims aboard the Scandinavian Star ferry were burnt to death, comparative dental identification was used to identify 107 victims.

• After the 9/11 disaster, hundreds of victims were identified based on their dental remains.

• When thousands of people were killed in the tsunami in Phuket, Thailand, most of the international victims were identified based on dental comparison.

IDENTIFICATION PROCEDURE 

• PERSONAL IDENTIFICATION 

 Identification is the establishment of a person’s individuality. Proper identification of the dead is required both for legal and humanitarian reasons. It may help in the settlement of property and insurance, facilitate remarriage of a surviving spouse, and allow the cremation or burial of the body, according to appropriate religious and cultural customs. 

Methods of personal identification 

• Visual

Traditional methods of identification have included visually recognizing the body, and personal property such as clothing, jewelry and the like. These methods, however, are not very reliable in establishing the identity. 

• Fingerprints

An excellent biometric method of human identification if the soft tissue of the fingers is intact, an adequate impression or image of the friction ridges can be obtained, and antemortem fingerprint are available Obviously burned, decomposed (skin slippage or degloving), skeletonized, and fragmented remains may not readily exhibit fingerprints. 

• Anthropology or radiography

Another biometric method of identification that relies on unique characteristics of the skeleton is to compare postmortem radiographs with antemortem medical imaging and written records.radiographs such as CT/MRI are more useful

Photo credit :Dental CT Imaging as a Screening Tool for Dental Profiling: Advantages and Limitations - Scientific Figure on ResearchGate. Available from: https://www.researchgate.net/figure/Case-IRM-004-a-A-burned-victim-of-a-vehicle-accident-b-Antemortem-upper-left_fig5_227804073 [accessed May 27, 2020]

• DNA

DNA comparison relies on accessible antemortem data. Direct reference samples from the decedent during life are the best sources. 

• DENTAL IDENTIFICATION

There are essentially two forms of dental identification: 

•  COMPARATIVE IDENTIFICATION

 Identification by comparing the dead individual’s teeth with dental records of the presumed individual. 

• Oral autopsy 
• Obtaining dental records 
• Comparing post- and antemortem dental data 
• Writing a report and drawing conclusion.

Oral autopsy 

Photo credit: http://www.jfds.org/viewimage.asp?img=JForensicDentSci_2016_8_2_103_186375_f5.jpg 

• RECONSTRUCTIVE IDENTIFICATION 

Dental profiling, attempts to elicit the population affinity or race, sex, age, and occupation of the dead individual. 

FORENSIC PATHOLOGY

Forensic pathology is the scientific examination of human bodies in order to elucidate the cause, manner (e.g., natural, homicide), and circumstances involved with death. 

Duties of forensic pathology includes

• Causes of death

Deaths that result in medicolegal attention generally fall into two broad categories.

• Sudden unexpected deaths, which may or may not be under suspicious or unusual circumstances.
• Deaths involves those suspected to be due to various types of trauma, be it physical or chemical (e.g., drugs).

Causes of death includes

• Natural Deaths
• Blunt Force Trauma
• Sharp Force Trauma
• Asphyxia
• Gunshot Wounds
• Fire
• Drugs

• Changes after death 

• Early changes (immediately after death) 
• Stoppage of function of nervous system
• Stoppage of circulation
• Stoppage of respiration

• Intermediate (within few hours of death)  
• Facial pallor
• Loss of elasticity of skin
• Changes in the eye
• Post mortem staining
• Rigor mortis or post mortem rigor mortis
• Cooling of dead body
• Primary relaxation of muscle

• Late ( 24 hrs to 48 hrs after death) 
• Mummification 
• Adeporcere formation
• Putrefaction and ordinary decomposition

• Time of death

Photo credit : https://www.liberaldictionary.com/livor-mortis/

Rigor mortis

Photo credit :https://www.toppr.com/content/story/amp/rigor-mortis-summation-effect-and-all-or-none-law-77857/

VARIOUS IDENTIFICATION METHODS

• DNA

The conventional method of dental identification described thus far requires one basic element that may not always be 

readily available—dental records. 

However, Pötsh and coworkers successfully extracted DNA from the pulp of teeth recovered from decomposed and burned bodies, as well as victims of air crashes.

Photo credit :http://www.jfds.org/viewimage.asp?img=JForensicDentSci_2011_3_1_38_85295_u1.jpg

TYPES OF DNA

Pretty and Sweet have pointed out the use of two types of DNA.

•  Genomic or nuclear DNA

It located in the nucleus of cells and commonly used in forensic cases. 

•  mitochondrial DNA (mtDNA) 

It present in the mitochondria of cells

EXTRACTION OF DENTAL DNA

TEETH DNA

Teeth are known to survive most postmortem events, including natural phenomena such as decomposition and autolysis, as well as environmental insults, such as water immersion, burial, and fires to as hot as 1,100°C. 

Owing to its neurovascular nature, the tooth pulp is considered to be the best source of dental DNA. Ajayprakash and coworkers isolated DNA from dental pulp and accurately determined personal identity using HLA-DQ amplification.

SALIVARY DNA

Salivary DNA can be recovered in a variety of scenarios and from a wide range of inanimate objects, including clothing, foods, tobacco products, oral hygiene devices, drink containers, dental prostheses, stamps, and envelopes.  

Laboratory Processing 

• Extraction (Isolation of DNA) 
• Amplification (Quantitation and PCR) 
• Analysis (Electrophoresis, Detection, and Interpretation) 

Photo credit :Forensic Odontologists and Mass Disasters - Scientific Figure on ResearchGate. Available from: https://www.researchgate.net/figure/showing-possible-source-of-DNA-from-oral-cavity_fig1_304342502

[accessed 27 May, 2020]

• BITE MARKS

Bite marks have been defined by MacDonald as “a mark caused by the teeth either alone or in combination with other mouth parts"

The ABFO manual defines a bite mark as

 1. A physical alteration in a medium caused by the contact of teeth 

 2. A representative pattern left in an object or tissue by the dental structures of an animal or human. 

Photo credit :https://csidds.com/2015/01/04/junk-forensic-science-shows-up-at-the-2015-american-academy-of-forensic-sciences-meeting-again/amp/ 

Bite marks are usually associated with 

sex crimes, violent fights, and child abuse.

MacDonald’s Classification.

• Tooth pressure marks. 

Marks produced on tissue as a result of ‘direct application of pressure by teeth’. These are generally produced by the incisal or occlusal surfaces of teeth 

• Tongue pressure marks. 

When sufficient amount of tissue is taken into the mouth, the tongue presses it against rigid areas such as the lingual surface of teeth and palatal rugae. The marks thus left on the skin are referred to as ‘suckling,’ since there is a combination of sucking and tongue thrusting involved.

• Tooth scrape marks.

 These are marks caused due to scraping of teeth across the bitten material. They are usually caused by anterior teeth and present as scratches or superficial abrasions.

Histopathologic and Clinical Changes Used to Monitor the Time Elapsed (Aging) in Skin Injuries 

Associated with Bite Marks

Photo credit :Brad W. Neville,Douglas D. Damm,Carl M. Allen,Angela C(2016).Oral and Maxillofacial Pathology.Table19-4(pg-838)

• SALIVARY EVIDENCE IN BITE MARKS

Although the forensic dentist is concerned principally with the analysis of the physical evidence associated with a bite mark, biologic evidence in the form of serologic and DNA material is also of probative importance. Collection of saliva trace evidence from the surface of the bite injury of the victim is performed before other evidence-gathering manipulation of the injury. 

There is an increase in the yield of recovered DNA for analysis when this procedure is carried out according to the two-swab protocol 

 1. Thoroughly moisten the head of a cotton swab in sterile, distilled water.

2. Roll the head of this swab over the area of the saliva stain while using moderate pressure and a continuous circular motion.

3. Allow this first swab to air dry in a contamination-free environment for at least thirty minutes.

4. Within ten seconds of completing the first swab, roll the tip of the second, dry swab across the now moist area of the stain.

5. Use a circular motion and light pressure to absorb the moisture from the skin into the second swab.

6. Allow the second swab to air dry in a contamination-free environment for at least thirty minutes.

7. After drying, both swabs are packaged together, sealed, and marked with unique sample and case numbers.

8. The chain-of-custody document is completed and samples are submitted to the laboratory.

• Amylase-dependent forensic screening tests are increasingly available in the commercial sector. Some are very specific and are based on monoclonal antibody activity that focuses on human salivary α-amylase, whereas others are more general in relying on the detection of amylase activity to release a colored dye suggesting the presence of saliva.

Priyanka Kapoor, Aman Chowdhry. Salivary signature in forensic profiling: A scoping review

DOI: 10.4103/jfo.jfds_30_18

• ANIMAL BITE MARKS

Photo credit: https://csidds.com/2016/12/02/american-academy-of-forensic-sciences-asks-public-for-bitemark-validation-studies/amp/

Photo credit: Rajendran. R & Sivapatha Sundharam. B(2012). Shafer's Text Book of Oral Pathology.(pg:903)

• FINGERPRINT 

Photo credit : Fingerprint classification based on gray-level fuzzy clustering co-occurrence matrix - Scientific Figure on ResearchGate. Available from: https://www.researchgate.net/figure/Major-Fingerprint-Types-Whorl-Arc-Tent-Right-loop-Left-loop-and-Double-Loop_fig1_289246081 [accessed 27 May, 2020]

• The term fingerprint is used to describe a reproduction of the friction ridge arrangement present on the tips of the fingers when an impression is deposited on a touched surface. 
• Fingerprint identification is arguably the oldest forensic discipline known to man. 
• Fingerprints have proved over time to be the most rapid, reliable, and cost-effective means by which to identify unknown deceased individuals, especially in a mass disaster setting. 

• RUGAE IDENTIFICATION

Study of rugae pattern

Photo credit :http://www.jdas.in/article.asp?issn=2277-4696;year=2014;volume=3;issue=1;spage=13;epage=16;aulast=Balgi

•  Useful method of identifying edentate individuals is by examining the palatal rugae pattern. The rugae pattern on the deceased’s maxilla or maxillary denture may be compared to old dentures that may be recovered from the decedent’s residence, or plaster models that may be available with the treating dentist.

• Types of palatal rugae

1. Lysell  measured rugae in a straight line, from their origin on the medial side to terminus on the lateral, and divided them into three types:

1. Primary rugae (>5 mm) 

2. Secondary rugae (3–5 mm)

3. Fragmentary rugae (2<3 mm)

(Rugae < 2 mm is not taken into consideration). 

2. Thomas and Kotze have further categorized the various patterns of primary rugae as branched, unified, cross-linked, annular, and papillary. 

3. Kapali and associates, have grouped the rugae according to shape as straight, curved, wavy, and circular.

RUGAE PATTERN

Photo credit: Usefulness of palatal rugae patterns in establishing identity: Preliminary results from Bengaluru city, India - Scientific Figure on ResearchGate. Available from:https://www.researchgate.net/figure/Different-forms-of-palatal-rugae_fig1_232536047 [accessed May 27, 2020]

• Palatal rugae in race and sex identification

A recent study by Nayak and coworkers suggests that rugae patterns are also useful in identifying an individual’s population affinity or race. In particular, they examined straight, curved, wavy, and circular rugae shapes in populations originating from southern and western India and found significant differences in some of them—

• while straight rugae were more frequently found among southern Indians, 
• curved rugae had greater incidence among Western Indians. Based on rugae shape, they were able to correctly identify an individual’s population origin in 70% of cases. 
• However, this study as well as others—including the one by Kapali and associates—was unable to observe significant sex differences in rugae pattern. On the other hand, teeth are reasonably good indicators of race and sex, both of which are important for reconstructive identification.

• AGE ESTIMATION 

Photo credit: www.forensicdentistryonline.com

• Dental age is one of the few measures of physiologic development that is uniformly applicable from infancy to late adolescence. After attaining maturity, teeth continue to undergo changes, making age estimation possible in adults. 
• Dental Age Estimation Methods

Dental age estimation makes use of morphologic, radiographic, histological, and biochemical methods to examine age-dependant changes in teeth.

• Age estimation using the dentition may be grouped into three phases:
• Prenatal, neonatal and early postnatal period
• Children and adolescents
• Adults.

• Schour and Massler’s method.

 The chart of Schour and Massler 

was probably the first attempt at scientific dental age estimation. It describes 20 chronological stages of tooth development starting from five months IU until 21 years of age 

Photo credit : http://fleshandbones1.blogspot.com/2010/04/visual-aid-age-estimation-from-teeth.html?m=1

• Demirjian’s method. 

Demirjian and coworkers have developed an age estimation method that assesses the mandibular left side teeth

Photo credit: http://www.ijdr.in/article.asp?issn=0970-9290;year=2019;volume=30;issue=2;spage=291;epage=299;aulast=Shah 

• SEX DETERMINATION

Assessing the sex, or sexing, of unknown human skeletal remains is the second step in the triad of building a dental profile. Sex can be assessed based on data from morphology of skull and mandible, tooth measurements and by analyses of DNA from teeth.

Photo credit: Rajendran. R & Sivapatha Sundharam. B(2012). Shafer's Text Book of Oral Pathology.(pg:903)

• LIP PRINTS

Photo credit : www.pinterest.co.uk

• The wrinkles and grooves visible on the lips have been named by Tsuchihashi as ‘sulci labiorum rubrorum’.

• The imprint produced by these grooves is termed ‘lip print’, the examination of which is referred to as ‘cheiloscopy’. 

• These grooves are heritable and are supposed to be individualistic. 

• Lip prints, therefore, can constitute material evidence left at a crime scene, similar to fingerprints. 

• Lip prints were first classified by Santos into two categories:

• Simple wrinkles 
• Straight line
• Curved line
• Angled line
• Sine-shaped curve.

• Compound wrinkles
• Bifurcated
• Trifurcated
• Anomalous.
• Tsuchihashi later proposed a separate classification, dividing the pattern of grooves into six types
• Type I – Clear-cut vertical grooves that run across the entire lip
• Type I'– Similar to type I, but do not cover the entire lip
• Type II – Branched grooves
• Type III – Intersected grooves
• Type IV – Reticular grooves
• Type V – Grooves that cannot be morphologically differentiated.

Photo credit: Forensic dentistry in human identification: A review of the literature - Scientific Figure on ResearchGate. Available from: https://www.researchgate.net/figure/Types-of-lip-print-patterns-23_fig2_262021699 [accessed 27 May, 2020]

• Merit of Lip Print
• When the prints are not clear, i.e., only the shape of the lip is printed, individual identification of a human being  is very difficult, based on this trace.In these cases, it is allowed to examine the substance which constituted the trace, e.g., saliva as a biological tracing. 
• The huge potential for DNA typing from the lip print is evident. 
• The lines are printed unclearly in the case were the lips are covered with food or cosmetics and the trace will have the shape of the stain and can be subjected to chemical examination, to determine the substance covering the lips.
•  When a lip print is seen at the crime scene, the character of the event, the number of person involved, sexes, cosmetics used, habits, occupational traits, and the pathological changes of lips can be concluded.

• Demerits of Lip Prints
• The lip crease pattern is on the vermilion border of the lip, which is the mobile portion of the lip.
•  According to the pressure, direction, and method used in taking the print, lip prints may vary in appearance. This is the fact why the same person can produce different lip prints. 
• If lipstick is used as a recording medium, the amount applied may also affect the print. 
• Smudging of the lip prints may occur. Manual register presents with problems due to the possibility of some subjectivity. 
• Existence of some pathological conditions such as lymphangiomas, congenital lip, fistula, lip scleroderma, 

REFERENCE: 

• https://en.m.wikipedia.org/wiki/Forensic_dentistry
• Rajendran. R & Sivapatha Sundharam. B(2012). Shafer's Text Book of Oral Pathology.(pg:879-910)
• Brad W. Neville,Douglas D. Damm,Carl M. Allen,Angela C(2016).Oral and Maxillofacial Pathology (pg:819-846) 
• David R. Senn,Paul G.Stimson (2010) Second Edition. Forensic Dentistry
• David R. Senn, Richard A. Weems (2013) Fifth Edition. Manual of forensic odontology
• Kavitha B, Einstein A, Sivapathasundharam B, Saraswathi T R. Limitations in forensic odontology. J Forensic Dent Sci [serial online] 2009 [cited 2020 May 26];1:8-10. Available from: http://www.jfds.org/text.asp?2009/1/1/8/50881 
• Nalliapan G, Ulaganathan M, Andamuthu Y, Thangadurai M, Vadivel I, Periyasamy TT. Cheiloscopy: An evolving tool in forensic identification. J Indian Acad Dent Spec Res 2018;5:37-41.
• https://en.m.wikipedia.org/wiki/Comparative_Dental_Analysis