DEPARTMENT OF ANATOMICAL SCIENCES
AN321 - FORENSIC DENTISTRY
W. B. Wood
The University of Queensland
Forensic dentistry is the application of dental knowledge or expertise to the science of human identification for coronial or legal purposes.
Usually the establishment of the identity of an unknown deceased person rests upon recognition of the remains (usually the face) by relatives, friends, or other acquaintances of the deceased person.
In the case of severe charring, mutilation, decomposition or skeletonisation of the remains, other methods of identification must be used. This usually relies upon the expertise of the forensic dentist and the availability of dental records from missing persons.
Dental identification depends upon the availability, comparison and eventual matching of the dental records of a missing individual with the dental findings of the remains.
Where dental records are unavailable, the existance of a photographic portrait of a missing person, especially if they are smiling, may reveal sufficient dental detail to achieve identification by exact matching using videosuperimposition of the photograph with the skeletonised cranium.
In other situations, the impressions or marks left by the teeth on a victim or an assailant, or on disposed food or other material may be used to establish an identity.
REQUIREMENTS AND SCOPE
Forensic dentistry requires a knowledge of:
the development and eruption of teeth
the structure and function of the normal teeth and jaws
dental types: heterodont - differing tooth types
homodont - similar tooth types
monophyodont - one set of teeth
diphyodont - two sets of teeth
polyphyodont - many sets of teeth
dental pathology: plaque, calculus
caries, apical abscesses
dental anomalies: size, gaps (diastemas), crowding, fusion, supernumerary
extra cusps, enamel pearls
dental wear (attrition): generalised, localised
dental colour changes: pigmentation, staining, painting
dental repair work: fillings, restorations, crowns, bridges
dentures: plates and prostheses
bite marks: victim
discarded food etc
lip patterns: cheiloscopy
palate patterns: rugoscopy
saliva residues: on cups, stamps, envelopes etc
may allow sex to be determined for up to six months
a) Structure of Teeth
crown, neck, root, apex
cementum, dentin, enamel
pulp, pulp cavity (chamber), root canal
cusp, ridge, groove, fissure, pit
b) Surfaces of Teeth
labial / buccal
palatal / lingual
mesial / distal
c) Dental Types
incisor, canine, premolar, molar
deciduous (primary), permanent (secondary)
d) Dental Formulae
e) Dental Coding - International Nomenclature
18 17 16 15 14 13 12 11 : 21 22 23 24 25 26 27 28
49 47 46 45 44 43 42 41 : 31 32 33 34 35 36 37 38
55 54 53 52 51 : 61 62 63 64 65
85 84 83 82 81 : 71 72 73 74 75
f) Jaw Relationship (patterns of occlusion)
edge to edge bite class 1 occlusion
overbite class 2 occlusion
underbite class 3 occlusion
IDENTIFICATION OF LOOSE TEETH
Problems arise in the identification of individual teeth when they are displaced from the alveolus. The less complex the root structure the more easily a tooth is displaced from its socket. The common order of postmortem loss of teeth is; incisors, canines, lower premolars, lower third molars, upper premolars/lower molars, third upper molars, first/second upper molars.
Always use comparative sets of known dental types and beware definitive identification when the teeth are well worn.
STEPS IN THE IDENTIFICATION OF UNKNOWN TEETH
a) Human or not?
b) Deciduous or permanent?
c) Type of tooth? incisor, canine, premolar, molar
d) Upper or Lower?
e) Right or left side?
DIFFERENCES BETWEEN DECIDUOUS TEETH AND PERMANENT TEETH
a) are smaller in size
b) are more yellow in colour (thin enamel)
c) lack premolars
d) have crowns that are more bulbous
e) have roots that are thinner, shorter, and often partly resorbed
f) have molars with thin widely divergent roots
Differences exist in:
rate of development
eruption timing and sequence
size (especially canine)
Differences in shape, form, attrition, pathological processes, staining etc may occasionally be used as racial indicators eg
shovel shaped incisors Asiatics
very large dental size Australian Aborigines
excessive wear patterns Australian Aborigines
anterior dental avulsion Australian Aborigines
betelnut staining Melanesians
dental caries +/- post/precontact Aborigine
Bass WM 1987 "Human Dentition" in Human Osteology - A Laboratory and Field Guide. Missouri Archaeological Society Publishers pp259-290.
Steele DG & CA Bramblett 1988 "The Dentition" in The Anatomy and Biology of the Human Skeleton. Texas A&M University Press pp70-110
White TD & PA Folkens 1991 "Dentition" in Human Osteology Academic Press pp101-128.