TEETH IN

FORENSICS

Desiré BritsSchool of Anatomical Sciences

Room 2B07

Overview

FORENSIC DENTISTRY

Human identificationHuman identification Bite mark analysisBite mark analysis

Comparative identificationComparative identification

Postmortem dental profiling

Postmortem dental profiling

Dental recordsDental records Forensic anthropologyForensic anthropology

AgeRace SexFOI

Forensic dentistry

• Major role of teeth in forensic dentistry– Human identification– Bite mark analysis

• Why study teeth– Most durable structure in the human body– Enamel is one of the hardest biological substances– Easily recognized, thus routinely recovered

Human identificationCOMPARATIVE

IDENTIFICATION

• Establish if deceased remains and antemortem records represent same individual

• Compare postmortem dental remains with antemortem dental records (written notes, casts, radiographs)

POSTMORTEM DENTAL PROFILING

• Antemortem dental records are unavailable

• No clues as to the identification of the deceased

• Compile a postmortem dental profile

Comparative identification

• Compare– Similarities – Discrepancies

• Explainable • Unexplainable

• Numerous and complex dental treatments = easier identified

Comparative identification

• Conclusions that can be made include:– Positive identification

• Antemortem and postmortem = sufficient data match

– Possible identification • Antemortem and postmortem data = consisted features

– Insufficient evidence• Insufficient information

– Exclusion• Antemortem and postmortem = inconsistent

Dental records• Developing countries

– Unemployed individuals• No dental care

– Dental care = expensive– No access to facilities

• No dental records– Migrating workers

• International (local)– No dental records

– Illegal immigrants• No dental records

– No continuous care• Outdated records

– Visit various dental facilities

Postmortem dental profiling• Provide information:

– Age– Ancestry – Sex – Factors of individualization

• Trauma– Tooth loss

• Dental pathology– Dietary habits

» Socio-economic status • Dental variation• Dental treatment• Dental modification / mutilation• Habitual behaviours and/ occupation

Age estimation• Mammals

– Two sets of teeth• Deciduous (or milk teeth)

– Deciduous dental formula 2:1:0:2 = 20• Permanent teeth

– Adult dental formula 2:1:2:3 = 32

• The development and eruption is fairly consistent • Particularly in immature individuals

• Tooth formation begins in utero for:– Deciduous teeth– First permanent molar teeth

• Rest of the dentition – Develops after birth

Population affinity

• Race assessment from teeth are not easy!• Not race related:

– Root numbers– Congenital absence of third molars

• Asian dental complex– Shovel shaped incisors– Shorter roots– More occlusal enamel pearl in premolars– Frequently fused molar roots– Extra distolingual root on 1st and 3rd molars

Population affinity

• European dental complex– High frequencies of Carabelli’s cusp

• An extra cuspid on the mesiolingual surface of upper molars

• African dental complex– First mandibular molar

• 5-cusped with a Y-shaped groove

– 4th molars!

Sex determination

• Sexual dimorphism in dentition is variable– Sexing teeth alone = risky

• Discriminant function analysis– Accuracies between 88 - 95 %

• ♀ teeth = smaller– Mesio-distal diameter

• Misclassification more common in males

FACTORS OF INDIVIDUALIZATION

• Features unique to an individual – Reduces population pool – Positive identification

• TRAUMA– Motor vehicle accidents– Pedestrian accidents– Fights– Antemortem tooth loss

FACTORS OF INDIVIDUALIZATION

• DENTAL PATHOLOGY– Dental caries– Abscess– Periodontal disease– Enamel hypoplasia

Socioeconomic statureDietary habits

FACTORS OF INDIVIDUALIZATION

• DENTAL VARIATION– Abnormal tooth number

• Hyperdontia • Hypodontia

– Abnormal tooth size• Macrodontic• Microdontic

– Dental crowding– Impacted teeth

FACTORS OF INDIVIDUALIZATION

• DENTAL TREATMENTS– Dental crown– Dental bridge– Braces

FACTORS OF INDIVIDUALISATION

DENTAL MODIFICATION• Old practice

– Rare• Very noticeable

– Groups/tribes association

– Categories:• Filing• Chipping• Extraction• Decoration with inlays

• Practice of dental decoration arose in the Preclassic– Persons 15 yrs and older

• Filling – Mainly in females

• Incrustation – Mainly in men

tooth extraction

• South African modification:– Tooth extraction

• Some or all incisors– 2nd decade of life– Male and female

– “Passion gap”• “CAPE FLATS SMILE”

– Gang sign– Early 1980’s

Dental modification• Modern South African modification

– Dental inlays– Upper central incisors

• Middle class individuals

• HABIT OR OCCUPATION– Pipe-smoker’s wear

M Steyn, EN L’Abbé, M Loots; 2004

Bite mark analysis

www.greggoldendds.com/bites1.htm

Summary

• Human identification– Comparative identification

• Dental records– Postmortem profiling

• Sex determination• Race determination• Age estimation• Factors of individualization

• Suspect “identification”– Bite mark analysis