Forensic Odontology Overview

Forensic Odontology

• Forensic odontology is a branch of forensic medicine
• It deals with the handling and examination of dental evidence
• It encompasses the evaluation and presentation of dental findings
• It's a vital area in the interest of justice
• Forensic odontology involves the management, examination, and evaluation of dental evidence in criminal or civil proceedings

Historical Evidence

• Dr. Oscar Amoedo from Paris is considered the "Father of Forensic Odontology"
• Dental evidence played a crucial role in the identification of Adolf Hitler
• Dentition was a significant factor in identifying various leaders, including Zia Ul Haq and Rajiv Gandhi

Scope and Purpose

• Management and maintenance of compliant dental records
• Identification of human remains by comparing antemortem and postmortem dental information
• Collection and analysis of patterned marks (bite marks) on inanimate or injured tissue
• Recognition of signs and symptoms of human abuse
• Assessment of the person’s age
• Determination of the person’s sex

Reasons for Identification

• Criminal: A crime investigation can't proceed until the victim is identified.
• Marriage: Many religious backgrounds require deceased partners' identities to be confirmed for remarriage.
• Monetary: Payment of pensions, life insurance, or other benefits often requires positive death confirmation.
• Burial: Some religions necessitate positive identification before burial in designated locations.
• Social: Preserving human rights and dignity demands positive identification after death.
• Closure: Identifying missing individuals brings relief to family members.

Personal Identification

• Identification means establishing a person's individuality
• Characteristics by which a person can be recognized are considered personal identification factors
• Traditional methods involve visually recognizing the body or personal items
• Identifying burned or decomposed bodies can be challenging

Analyze Physical features

• Physical features include inherited and acquired characteristics
• Inherited features include ethnicity
• Acquired features involve surgical scars, fractures and dental restorations

Basis for Dental Identification

• Human dentition is unique in each individual
• Morphology and arrangement of teeth vary between persons
• Dental identity is a combination of all characteristics of teeth and their associated structures
• Teeth are resistant to environmental factors after death

Techniques of Identification

• Comparative Dental Identification: Comparing the deceased's teeth to existing records. This involves obtaining dental records, comparing postmortem and antemortem data, and writing a report and conclusions.
• Reconstructive Groups: Using available data (age, sex, race, occupation, etc.) to make a probable identification.

DNA Profiling

• This method is utilized when dental records aren't available.
• This uses modern forensic DNA profiling for oral tissues to establish identity

Oral Autopsy

• Oral autopsy is a specialized surgical procedure
• It involves a thorough examination of a corpse
• The aim is to determine the cause and manner of death as well as evaluate any injuries or diseases present
• It is performed for legal or medical purposes

Critical Examination

• Critical examination of remains includes observations of gender, ethnicity, build, wounds, scars, and tattoos
• Photographs, radiographs, fingerprints, and fingernail scrapings, along with hair samples, are collected as required.
• Oral examination is key in post-mortem procedures.
• Jaw separation requires oral myotomy (gags) due to rigor mortis.

Dental Status of Human Remains (Form)

• A form is provided for recording specific dental characteristics for documentation

Obtaining Dental Records

• Dental records document treatments and dental status of a person during their lifetime.
• These records are important antemortem data and should be transcribed onto a standard Interpol antemortem form.

Comparing Post Mortem and Ante Mortem Records

• Comparing postmortem with antemortem records is important
• Tooth morphology and associated bony structures, as well as pathology, are among the factors to consider.
• Individuals with significant previous dental treatment and unusual features are easier to identify

Results/Conclusion

• Positive Identification: Unique, matching characteristics between the comparable items.
• Probable Identification: High concordance between data, lacking radiographic support.
• Presumptive (Possible) Identification: Missing info.
• Insufficient Identification: Lack of supportive evidence.
• Exclusion of Identification: Clearly inconsistent features.

Problems with Dental Identification

• Absence of antemortem records,
• Absence of acquired dental tracings,
• Limitations to records storage duration or poor quality of records,
• Loss of PDL (periodontal ligament) after death,
• Damage to restorations or teeth.

Identification in Mass Disaster

• Mass disasters are often chaotic events.
• Dental identification process is similar to other cases but with greater magnitude.
• Mass disasters are classified as natural, accidental, or criminal.
• Large numbers of fragmented or incinerated remains are typical scenarios

Natural Mass Disaster

• Natural mass disasters include disasters like earthquakes, tornados, volcanic eruptions, firestorms, and floods
• Environmental infrastructure is often compromised.
• Dental records containing antemortem records may be destroyed.

Accidental Mass Disaster

• Accidental mass disasters are often associated with incidents like transportation accidents, fires, and industrial accidents
• These accidents usually affect a closed population and occur over short time periods

Intentional Mass Disaster

• Intentional mass disasters typically include incidents like bombing of buildings or attacks like the World Trade Center attacks

Forensic Odontology Team

• 50% of identifications are from dental evidence
• Dental examinations are usually done after other procedures like photography, fingerprinting, and autopsy.
• The postmortem unit handles dental radiographs and arranging photos
• The antemortem unit collects as much relevant information as possible quickly.
• Software like IDENTIFY, ODONTID, CAPMI, and IDIS helps analyze and compare data

Reconstructive Post Mortem (Dental Profiling)

• Dental profiling determines race, gender, occupation, and age.
• This information aids in narrowing searches for antemortem records.

Identifying Ethnic Origin from Teeth

• Traditionally, humans are categorized into Caucasian, Mongoloid, and Negroid races.
• Traits for race estimation are found in the middle facial skeleton (nose, mouth, and cheek bones).
• Landmarks include the shape of the cranium, lateral projection of zygomatic arches, shape and contour of the orbits, and nasal aperture.

Genetic and Environmental Influences on Teeth

• Dental features have evolved over time due to genetic and environmental factors.
• There's a complex inheritance pattern, affecting populations.
• Environmental factors, along with hereditary factors, strongly influence features.
• Some features have stronger genetic influences than environmental ones.
• Dental features, like tooth size (metric), and tooth shape (non-metric), are important

Metric and non-metric features

• Metric features are based on measurements, strongly influenced by environmental factors
• Non-metric features involve the presence/absence of specific traits, further analyzed in relation to the upper/lower premolar/molars, canine, and upper central incisors

Identification from Dental DNA

• Teeth resist extreme conditions
• Teeth are a good DNA source.
• Polymerase chain reaction (PCR) allows amplification of DNA from degraded sources.
• DNA can be compared to antemortem sources like hair, epithelial (cells)
• This technique provides a useful advantage for identification of parents, siblings, etc., from biological records

Types of DNA

• Genomic or Nuclear DNA is found in cell nuclei.
• Mitochondrial DNA is present in cell mitochondria.

Extraction of Dental DNA

• Tooth pulp is considered the best source for dental DNA.
• Ajayprakash and coworkers isolated DNA from tooth pulp for accurate personal identification via HLA-DQ amplification

Cytogenic Grinding

• This method, advocated by Sweet and Hildebrand, cools the whole tooth using liquid nitrogen for grinding into powder.

According to Trivedi and coworkers, there's a less destructive method for DNA isolation

• This includes opening root canals, scraping the pulp area, and flushing out debris, retaining the tooth’s morphology and physiology

Palatal Rugae in Identification

• Palatal rugae are ridges on the palate.
• Rugae pattern is useful for identification, especially in individuals with no existing teeth.
• They're often protected from damage in incidents involving fire or high impact trauma.
• Classification of rugae includes primary (>5mm), secondary (3-5mm), and fragmentary (2<3 mm) rugae.

Analysis of Rugae Pattern

• Thomas and Van Wyk traced rugae from dentures to clear acetate, then superimposed on photographs of plaster models.
• Software methods have aided in accurately analyzing rugae.

Sex Differentiation

• Sex can be determined from skull and mandible morphology, metric features of the skull and teeth, and DNA analyses.

Sexing from Craniofacial Morphology and Dimension

• Sex determination is often not reliable until puberty.
• Multiple features for accurate sex determination.
• Williams and Rogers used 6 craniofacial traits for 94% accuracy in sex determination.

Sex Differences in Tooth Size

• Measuring mesiodistal and buccolingual dimensions help differentiate sex.
• Teeth like canines, premolars, and molars show significant sex differences.

Dental Index

• Mandibualar canines exhibit significant sexual dimorphism in teeth
• Mandibular canines are less affected by plaque, calculus, abrasion, and periodontal disease (they're often the last tooth extracted).
• They are critical for personal identification.

Cut-off points/standard MCI (mandibular canine index) value

• The cut-off point obtained for MCI value is 0.274 (by Rao et al.)
• Teeth with an MCI less than or equal to 0.274 suggest a female.
• Teeth with an MCI greater than 0.274 suggest a male.

Dental Age Estimation, Prenatal, Neonatal, Early Postnatal

• Dental age is a significant physiologic development measure.
• Dental age is applicable from infancy to late adolescence
• Estimation phases: prenatal, neonatal, early postnatal, children, adolescents, and adults.

Age Estimation in Children and Adolescents

• Tooth emergence (eruption) and calcification are key events for age estimation.
• Deciduous teeth exhibit genetic control for emergence (approximately 6–2.5 years).
• Permanent teeth are influenced by oral environment and premature tooth loss

Evaluation of Radiographs

• Radiographs are a superior tool for evaluating tooth calcification due to its ability to continuously track calcification for several years.
• They aren't affected by local factors
• Assessment is helpful in age groups where tooth emergence isn't yet visible (e.g., 2.5–6 years or over 12 years)

Demirjian's Method

• Seven mandibular teeth are used for age estimation in children and adolescents
• The teeth' developmental stages are from A (mineralized cusp tips) to H. (apices completely closed)

Third Molars in Age Estimation

• Third molars are important indicators for identifying persons aged 16-23.
• 4 completely calcified third molars suggest the individual likely is 18 years old (96.3% chance for accurate determination for both males and females).
• The presence of one or two third lower molars is highly suggestive of a 18 year old.

Age Estimation in Adults

• Age estimation in adults is challenging due to diverse lifestyle factors, like diseases, nutrition, and physical strain.
• Gustafson's method, dentin translucency, incremental cement lines, and amino acid racemization are methods to consider.
• The radiographic method by Kvaal also provides useful age estimation.

Gustafson's Method (for Age Estimation in Adults)

• Gosta Gustafson, in 1950, developed an adult age estimation method based on morphological/histological changes observed in teeth.
• Regressive changes such as occlusal attrition, secondary dentin deposition, periodontal attachment loss are evaluated.
• Data from the changes calculated using a formula such as: Age = 11.43 + 4.56X (with X being the assessed regressive change value)

Dentinal Translucency (for Age Estimation in Adults)

• Root dentin becomes translucent after the third decade
• Dentin translucency starts at the apex and progresses coronally
• Increasing diameter of dentinal tubules, and intratubular calcification, increases dentin translucency
• This method is significant for age estimation, recognized by Johnson.
• Bang and Ramm noted increased root translucency with advancing age

Age Estimation from Incremental Lines of Cementum (for Age Estimation in Adults)

• The method by Kagerer and Grupe uses acellular cementum incremental lines to reliably estimate age.
• Mandibular central incisors or third molars' mineralized, unstained cross-sections are used
• This method generally provides age accuracy to within 2-3 years

Radiographic Method of Kvaal (for Age Estimation in Adults)

• Pulp size measurements from specific teeth are utilized in Kvaal's radiographic method for establishing age.
• Teeth examined include maxillary central and lateral incisors, second premolar, mandibular lateral incisor, canine, and first premolar.
• Pulp-root length, pulp-root width, and tooth-root length measurements are necessary for the age estimation.

Amino Acid Racemisation (for Age Estimation in Adults)

• This is based on rate of racemisation of aspartic acid in teeth.
• The racemisation rate of aspartic acid is significant in root dentin.
• The change in ratio of L- and D-aspartic acid with increasing age is used for age estimation.
• This method offers estimated age accuracy to within 3 years of the actual age.

Key to Optimal Dental Estimation

• Experienced investigators, second opinions, multiple methods (not just one), multiple teeth and following established protocol are crucial for reliable dental estimations

Bite Marks

• Bite marks are marks made by teeth, either alone or with other mouth parts.
• These marks are defined as the pattern left on a surface or tissue by a person’s or animal’s dentition.
• In cases of sexual assault, including homicide, rape, and child abuse, bite marks regularly appear around areas associated with sexuality.

Classification of Bite Marks:

• Cameron and SIMS Classification: Based on the agent (human/animal) and material (skin/body tissue/food).
• Mac Donald's Classification: Identifies specific types of bite marks (pressure, scrape, tongue marks) based on the method of bite inflicted -Webster’s classification for foodstuff-theft/robbery bite marks differentiates marks based on the impact on the food item, from fractures to penetration and slide marks

Description of Some Types of Bite Marks

• Sexually-Oriented Bites: Slow, deliberate, and often characterized by suction marks.
• Child Abuse Cases: May exhibit aggressive or sexually oriented patterns.
• Self-Inflicted Bites: Often found on forearms of children (self-injuries), and mentally disturbed individuals also self inflict injury
• Lesch-Nyhan Syndrome: A rare disorder is characterized by insensitivity to pain, thus leading to frequent self-inflicted bites.

Identifying Injury as a Bite Mark

• Gross features include circular/elliptical shape, ecchymosis in center.
• Class features distinguish between teeth types (incisors, canines, premolars, molars); shapes vary with tooth type.
• Individual features in teeth include fractures, rotations, and spacing, which provide even more detailed unique characteristics

Sites of Bite Marks

• Female victims' bites typically are on breasts, abdomen, thighs, buttocks, and pubic areas.
• Male victims' bites usually include the back, arms, shoulders, and chest/pubic area.
• Cases involving self-defense, victims might have bite marks on the assailant's hands or arms

Factors Influencing Bite Marks

• Tissue Type: Loose or fatty tissues cause poor definition, and fibrous/muscle-rich tissues result in better-defined marks.
• Age: Children & older adults bruise more easily than adults, affecting bite-mark visibility.
• Sex: Females exhibit longer-lasting bite marks than males.
• Medical Status: Medical conditions (like anticoagulant therapy or skin disease) can change bruising characteristics.
• Time: Bite mark effects typically diminish (swelling, discoloration) within 10–20 minutes

Bite Mark Cases -- Step-by-Step

• Step 1: Description of bite marks (shape, size, color, etc.)
• Step 2: Evidence collection from the victim (often with photographs)
• Step 3: Evidence collection from the suspect (including dental models/photography)
• Step 4: Bite mark comparison to determine if the marks match suspect’s bite patterns.

Data Collection From The Victim

• Visual assessment of the bite mark location, contours, texture, and physical appearance.
• Photography of bite marks (orientation & close-up) is critical for documentation, especially in cases where the victim is deceased
• Saliva swabbing, when possible, can provide a DNA link

Examination of the Suspect

• Obtaining dental history (treatments, injuries).
• Photographs of their face, frontal, occlusal, lateral dental arch and teeth need to be recorded
• Examination of the TMJ (temporomandibular joint), facial, muscle tone, and maximum mouth opening/movement should be documented
• Recording the periodontal (tissues around the teeth), and tooth arrangements with saliva swabbing.
• Dental models should be prepared for possible future comparison.

Evaluation of Evidence

• Determining if bite marks are from human or nonhuman sources is essential
• Characteristics need to be analyzed critically for match confirmation

Histopathological Changes in Bite Marks

• Bite marks' histopathological changes alter over time with stages including scab formation, epithelial regeneration, subepidermal granulation, and regression.

Methods of Bite Mark Analysis

• Odontometric Triangle Method: Three points define a triangle using bite and dental model tracings, matching to areas of upper and lower canine teeth, and central incisors;
• Metric Analysis: Utilizes Vernier calipers or computer digitization methods to measure bite & suspect’s teeth' dimensions.

Pattern Association

• Direct Method: Suspect’s model is directly superimposed over the victim's bite marks photo.
• Indirect Method: Traces of suspect’s teeth are transferred to clear acetate for superimposition.

Conclusions of Bite Mark Analysis

• Positive Identification: Matches between bite mark and suspect's teeth.
• Possible Identification: Bite mark could match suspect but no conclusive characteristics.
• Exclusion of Identification: Bite mark shows that suspect’s teeth definitely do not match.

Cheiloscopy

• Lip prints’ study (cheiloscopy) aids in human identification.
• Lip prints are needed within 24 hours of death
• Accuracy depends on mouth position (open/closed) when the lip print occurred.
• Different classifications, like Santos (1967) and Suzuki and Tsuchihashi (1970) exist for lip prints.

Ameloglyphics

• The study of enamel rod end patterns is called ameloglyphics.
• Enamel rods are the basic structural units of enamel.
• Tooth prints are unique and aid forensic identification of otherwise unrecoverable bodies.

Classification of Lip Prints

• Simple Wrinkles include straight, curved, angled, and sine-shaped grooves.
• Compound Wrinkles involve bifurcated, trifurcated, or anomalous patterns.
• Suzuki and Tsuchihashi (1970): Types I, I', II, III, IV, and V for different lip print types

Radiological Methodology in Forensic Odontology

• Radiographs are crucial for accurate identification

• They aid in determining the age of victims (stages of tooth eruption) and identifying potentially concealed injuries in teeth/body

• Radiographs are useful in identifying bullets or other foreign objects that might be present in trauma or death victims

• Faulty teeth charting during postmortem data collection or recording needs to be considered

• Expert witness testimony should be clear, simple, and straightforward

Conclusion

• Forensic scientists are responsible for gathering, preserving, and interpreting evidence, relaying findings clearly to legal authorities.
• Forensic odontology deals with dental evidence for identification purposes.
• Dental records during patients’ treatment can assist in legal identification processes and should be properly documented