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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– No continuous care• Outdated records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