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DEPARTMENT OF ANATOMICAL SCIENCES

 

AN321 - FORENSIC DENTISTRY

 

 

W. B. Wood

Senior Lecturer

The University of Queensland

 

 

 

 

 

INTRODUCTION

 

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

                                                            periodontitis

 

            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

                                                            assailant

                                                            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

 


DENTAL TERMINOLOGY

 

            a)         Structure of Teeth

 

                        crown, neck, root, apex

                        cementum, dentin, enamel

                        cementoenamel junction

                        pulp, pulp cavity (chamber), root canal

                        cusp, ridge, groove, fissure, pit

                        cingulum

                        periodontal membrane

 

            b)         Surfaces of Teeth

 

                        labial / buccal

                        palatal / lingual

                        mesial / distal

                        occlusal

                        interproximal

 

            c)         Dental Types

 

                        incisor, canine, premolar, molar

                        deciduous (primary), permanent (secondary)

 

            d)         Dental Formulae

 

                        I2C1M2   (deciduous)

                        I2C1P2M3 (permanent)

 

            e)         Dental Coding - International Nomenclature

 

 

                                                 Permanent Dentition

                                        R                                            L

                        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

 

 

 

                                                 Deciduous Dentition

                                                   R                               L

                                        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

 

            Deciduous 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

 

 

 


SEX DIFFERENCES

 

            Differences exist in:

 

                                    rate of development

                                    eruption timing and sequence

                                    size (especially canine)

 

 

 

RACIAL DIFFERENCES

 

 

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

 

 

 

 

 

 

 

 

REFERENCES

 

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.