MEDICO-LEGAL DENTISTRY
I/ Definition:
Forensic odontology is a branch of forensic medicine concerned with the study of teeth and jaws.
The expert odontologist is an auxiliary of justice.
He participates in the identification of subjects found dead and whose identity is unknown, or those for whom identification by relatives or by fingerprints is impossible.
He can also respond to a mission concerning the study of bite marks carried by a victim, living or deceased, in cases of assault or child abuse.
II – HISTORY:
AMODEO with his “Dental Art in Legal Medicine” published in 1898 is considered the founder of legal odontostomatology.
In 1477: identification of Charles the Bold (by the absence of lower incisors lost during a fall from a horse).
In 1880, the remains of Napoleon III’s son killed in Zululand could only be identified by his dentist.
The fires at the Ringtheater in Vienna in 1878, the Opéra-Comique in 1887 and the Charity Bazaar on 4 May 1897, were to be the origin of identification techniques.
DAVENPORT, in particular, identifies the Duchess of Alençon, victim of the fire at the Charity Bazaar.
III – THE TOOTH: AN INTERESTING TOOL FOR THE FORENSIC DENTIST:
🡺The tooth has qualities of extreme resistance:
- Enamel is the hardest tissue in the body.
- The tooth resists carbonization, immersion, putrefaction, trauma by physical or chemical agents.
🡺The tooth is an individual marker:
It retains (unlike bone which undergoes remodeling) its individual characteristics throughout life.
The study of dental tissues makes it possible to determine whether isolated fragments come from the same individual.
🡺The tooth is a source of DNA:
Can be used in genetic fingerprint identification.
IV – ROLE OF THE DENTIST IN THE MEDICO-LEGAL TEAM:
1 / Participation in identifications:
– Individual;
– In mass catastrophe.
2 / Determination of dental age:
- in the living
- in the corpse
3 / Study of bites:
- human or animal.
- recording of bite marks and analysis.
- comparative study with teeth of a suspect.
V- DENTAL IDENTIFICATION METHODOLOGY:
-Observations on the corpse
-Post-mortem dental record:
– photographs.
– X-rays.
– jaw sampling.
-Reconstructive identification to guide research: search of ante-mortem dental records.
-Dental file:
– dental x-rays.
– cranial x-rays.
-Analysis of the ante-mortem file.
-Post Mortem / Ante Mortem comparative study:
- Exclusion.
- Probability.
- Positive identification.
- DENTAL IDENTIFICATION: POST-MORTEM STUDY:
1° ==> Autopsy time:
* photographs with graduated marker
* X-rays
* samples from the jaws
2° ===> Establishment of the post-mortem dental record:
For each tooth note:
* presence or absence
* anomalies of shape, position, color, degree of wear
* fractures, cracks, state of the periodontium
* ethnic or professional characteristics
* state of restoration (amalgams, composites, resins, etc.)
* prostheses.
B- DENTAL IDENTIFICATION: ANTE-MORTEM STUDY :
Analysis of ante-mortem documents collected by investigators from:
– dental records (manuscripts or computerized)
– dental x-rays
* retroalveolar
* dental panoramic
– cranial x-rays.
“Spoken portrait” indications reported by relatives of characteristics such as:
* diastema
* agenesis
* absence of an anterior tooth
* enamel dysplasia or other pathology
* prostheses.
+ Photographs
+ dental casts
🡺 Establishment of the ante-mortem dental record.
VI – DENTAL IDENTIFICATION: COMPARATIVE STUDY:
Comparison between post-mortem and ante-mortem dental elements to determine:
* points of concordance.
* points of discordance.
* points of exclusion.
1) Comparative study of post-mortem and ante-mortem records
2) Comparative study of post-mortem and ante-mortem radiographic images
Conclusion
===> 4 groups
* perfect match.
* partial match.
* possible concordance but insufficient number (or quality) of compared elements to confirm identification.
* exclusion.
VII – DETERMINATION OF DENTAL AGE IN LIVING PEOPLE:
Study of dental eruption:
– assessment by panoramic dental radiography
– comparison with reference tables (Fortier table)
Limitations:
After 12 years the last permanent tooth has erupted and it becomes difficult to assess dental age (the wisdom tooth presents a high degree of variability).
1- IN CHILDREN:
- Study of dental eruption in general:
-From 6 months to 2 ½ years: eruption of temporary teeth.
-Between 2 ½ and 6 years: period without eruption or loss.
-From 6 to 12 years: loss of temporary teeth and eruption of permanent teeth .
-At 12 years old, all the teeth are present except the wisdom tooth.
B- Study of dental calcification:
The reference tables indicate chronologically:
– the beginning of mineralization.
– the eruption.
– the complete formation of the crown.
– complete formation of the root.
C- Histological study: On thin section of tooth (150 µ): search for the neonatal Orban line and measurement of tissue thickness (pulp side).
2- IN ADULTS:
A-Histology: Study of histological criteria on thin sections of teeth.
B-Biology:
- Study of the aspartic acid rate.
- Little used in practice.
C- GUSTAFSON METHOD: established in 1947, based on the study of 6 histological criteria
* wear of the occlusal surfaces
* condition of the periodontium
* apposition of secondary dentin in the pulp cavity
* cement apposition
* root resorption
* root transparency
– each factor receives a coefficient from 0 to 3
– we realize the sum of the coefficients
AGE = 4.56 (sum of indices) + 11.43
MEDICO-LEGAL DENTISTRY
D- LAMENDIN METHOD:
Based on the study of only 2 criteria:
* height of periodontitis
* root transparency measured from the apex
AGE = (0.18 P + 0.42 T) + 25.53
P = periodontal height x 100
root height
T = translucency x 100
root height
Realization:
– direct observation of the tooth (or study of a radio negative).
– vernier caliper measurements.
Advantage:
Simple, fast, non-destructive method.
MEDICO-LEGAL DENTISTRY
Baby teeth need to be taken care of to prevent future problems.
Periodontal disease can cause teeth to loosen.
Removable dentures restore chewing function.
In-office fluoride strengthens tooth enamel.
Yellowed teeth can be treated with professional whitening.
Dental abscesses often require antibiotic treatment.
An electric toothbrush cleans more effectively than a manual toothbrush.