Forensic Odontology

Forensic Odontology

Educational objectives:

• Determine the role of the odontologist in the forensic team.
• Define the criteria on which the dental expert bases the identification of people.
• Recognize the forensic aspects of human bites.
• Know how to diagnose child abuse.

Plan :

1. Introduction.
2. Why is the tooth an interesting tool in forensic expertise?
3. Role of the odontologist in the forensic team.
4. Areas of forensic dentistry:
5. 1- Participation in the identification of people. IV-2- The study of bites.

IV-3- Screening and diagnosis of situations of abuse and neglect of vulnerable people (children +++).

5. Conclusion.

1. Introduction :
   • Forensic odontology or forensic odontostomatology is a branch of forensic medicine concerned with the study of teeth and jaws.
   • It is a discipline of dentistry applied to the needs of justice.
   • The dentist or odontostomatologist is often called upon to resolve medico-legal issues.
2. Why is the tooth an interesting tool in forensic expertise? II-1- The tooth has qualities of extreme resistance:
   • Teeth, especially enamel and dentin, are the elements of the human body that resist

the best in time, in the physicochemical effects of the terrain and this due to their very mineral composition.

• Therefore, the resistance of teeth to fire, destructive agents such as putrefaction and dissolution (acid) is very high compared to other human tissues.

II-2- The tooth is an individual marker:

• It retains (unlike bone which undergoes remodeling) its individual characteristics throughout life (age, sex, ethnicity, etc.).
• The study of dental tissues makes it possible to determine whether isolated fragments come from the same individual or not.
• The histological study provides discriminatory indices and establishes a dental age range.

II-3- The tooth is a source of DNA:

• They can be used in genetic fingerprint identification.

3. Role of the odontologist in the forensic team:

He participates in:

• The identification of subjects found dead and whose identity is unknown, or of those for whom identification by relatives or by fingerprints is impossible.

It is irrelevant whether the subject was discovered individually or whether it is a mass catastrophe.

• Determination of dental age in living and cadaveric subjects.
• The study of bite marks left by a victim, living or deceased, in cases of assault or child abuse.
• Child abuse screening .
• Compensation for damages suffered during road accidents, assaults, accidents occurring during dental treatment. The dental expert will then have the task of providing the magistrate with the technical elements that will be necessary for him to render his judgment.

4. Areas of forensic dentistry:
5. 1- Participation in the identification of people:
   • The identification of people corresponds to one of the major aspects of the discipline of forensic dentistry.
   • This type of study should be included in a collaboration with judicial services, forensic scientists and anthropologists.
   • The data collected by the different actors will be done independently in order to avoid interdisciplinary influences. Then, the pooling of these different data will allow us to arrive at a suitable diagnosis, whether the identification is positive or not.
   • The data provided by dentistry are essential in certain situations, particularly when other forensic disciplines are no longer able to provide a diagnosis.
6. 1- 1- Why identify?
   • Identifying a stranger has psychosocial, legal, moral and ethical significance.
   • By providing proof of the death of a missing person, it allows their family to carry out the burial and begin their work of mourning.
   • It opens up civil rights in matters of insurance, inheritance law or matrimonial law.
   • In criminal matters, it is essential to the investigation and allows justice to be applied. Thus, in criminal matters, the identification of a victim is closely linked to the discovery of the identity of the perpetrator.
7. 1- 2- Why do we call on dentists?
   • Most identifications in situations where identity is not a particular problem are made on a visual basis by parents or relatives,
   • A recent, non-traumatic death usually produces a recognizable victim.
   • Post mortem putrefaction, significant head trauma or a state of carbonization exclude any visual or even dactylographic identification (fingerprint).
   • The interest in the study of dental characteristics therefore increases with the degree of tissue destruction of a body, that is to say when the recognition of the latter by classical methods is difficult, incomplete or even impossible.

IV- 1-3- How to identify?

Three types of identification are possible depending on the victim:

1. Comparative identification (comparison with a known identity):
   • It goes through three stages:
2. Research on the victim or their remains, post-mortem data called forensic evidence:
   • The search is done by:

• A postmortem oral examination that is performed during the autopsy after resection and dissection of the maxillae.
• X-ray examinations.
• Histological samples…

Forensic clues :

• They represent all the anatomical, physiological, pathological or therapeutic data that the legal dentist can collect in the oral cavity of a corpse. We distinguish:

A- Anatomical indices:

• They correspond to the different variations which characterize a tooth, an arch, a mouth or a skull and which highlight singular, curious or abnormal anatomical characteristics characterizing an individual.
• Example :

• Morphological dental anomalies: Agenesis or absence of dental germs, Supernumerary teeth, Fusions and geminations, Microdontia, Macrodontia, etc.
• Dental position anomalies: The presence of dental malpositions within the jaws constitutes a real dental imprint and can therefore differentiate one individual from another.

B- Pathological indices: correspond to all untreated oral-dental pathological manifestations:

• Dental trauma: cracks or fractures…
• Maxillofacial trauma: traumatic scars, deformations, asymmetries, occlusion disorders, etc.
• Tumor pathology of the oral cavity and jaws.
• The carious lesion: which must be described and located on the odontogram by a careful clinical and radiological examination of the necks, grooves and contact points of each tooth.
• Periodontal diseases: ranging from simple inflammation of the superficial periodontium such as gingivitis to destruction of the alveolar bone in chronic or acute periodontitis, including burns and functional trauma.

C- Therapeutic indices:

• Conservative dental care: specify their forms, their sites, the technique and the variability of the materials used to treat carious lesions.
• Pedodontics, Prosthetics, Orthodontics, Oral surgery…
• Post-mortem radiology can also highlight post-traumatic treatments, such as radiopaque osteosynthesis plates.

D- Physiological indices: group together characteristics linked to aging, hygiene, masticatory function, as well as lifestyle habits:

• The study of extrinsic (e.g. tobacco) or intrinsic (e.g. tetracyclines, fluorosis) colorations.
• The study of color change through aging and post mortem coloration.

2. Then, the search in the medical documents for ante mortem data, called forensic supports :
   • This research is only possible if an identity is presumed. This identity is established through a preliminary investigation.
   • Forensic evidence represents all the documents and ante mortem traces collected from the families, entourage and practitioners of the person supposed to be the victim. We distinguish:

• Written media :

• The patient file: this is the main source of ante-mortem information which will include the patient’s anamnesis, information on their general health (pathologies, history, treatments, etc.), the history of care and an administrative part (name, first name, address, telephone number, social security number, etc.).
• The dental record called an odontogram: it constitutes the visual representation of all the teeth and lists all the treatments carried out.
• Two-dimensional image supports:

• Radiographs of any type: bite-wing, retro-alveolar view, occlusal view, orthopantomogram, teleradiography, can be very useful provided that the incidences are identical ante and post mortem.
• Photographs: these are taken in particular in the case of dental anomalies, orthodontic treatments or during the monitoring of prosthetic and periodontal treatments.

• Three-dimensional image media : New technologies such as scanners, magnetic resonance imaging, etc.
• Classic three-dimensional supports : casts from dental impressions, prostheses and gutters, etc.
• Other media : DNA contained in the cells of the dental pulp…

3. Analysis of analogies and incompatibilities by comparison between indices and supports.

Finally, the expert will be able, thanks to his observations, to arrive at four types of conclusions:

• Perfect match: This is the case when the ante-mortem and post-mortem evidence combine sufficient details to prove, beyond any doubt, that the individual is the same.
• Partial concordance: Here the ante-mortem and post-mortem evidence agree, but a positive identification with certainty cannot be established due to the poor quality or quantity of the ante-mortem or post-mortem evidence collected.
• Possible agreement but ante-mortem or post-mortem information is insufficient to establish any conclusion.
• Exclusion: The data are clearly incompatible.

2. Estimated (or reconstructive) identification:
   • Its purpose is to assess the characteristics of an individual in the absence of ante mortem elements, when no identity is assumed or when comparative identification does not give a conclusive result.
   • It is defined as the set of techniques based on comparisons with averages (and not with ante mortem data). They allow a more or less precise estimation of sex, race, profession and habits, age.
3. Identification by facial reconstruction :
   • It is limited to the reconstruction of the face from the craniofacial skeleton.
4. The study of bites:
   1. Definition of a human bite:

• The classic human bite found in the skin appears as a round or oval shape, showing two semicircles or parabolas (U-shaped) separated at their base and positioned face to face. The diameter of the lesion generally varies from 25 to 40 mm often accompanied by a central area of ​​bruising.

2. The different types of bites:

• Sexual assaults:

• The marks will be found preferentially on the victim’s breasts, the place most sought after by the sadist, or on the neck and thighs. The marks are deep and clear.
• On the contrary, the neurotic will act hastily and without restraint, possibly going as far as tearing tissues.
• Non-sexual assaults:
• The marks are not expected in a specific region, but on any part of the body.
• Defensive wounds:
• They are the impression of the victim’s teeth on his attacker. They are generally found on the hands and wrists when the perpetrator tries to strangle his victim or wants to stop him from screaming by placing his hand over his mouth.
• Self-mutilation injuries:
• Of limited interest to the expert (but which can help investigators in the course of the homicide), this is an injury made by the victim on herself. It is found on her wrists, arms, hands.

3. Classification of bites:

• They are classified according to the lesions associated with the bites: Class 1 : Erythema: redness caused by the dilation of the capillaries, Class 2 : Contusion: rupture of the vessels without tearing of the skin,

Class 3 : Abrasion: minor injury characterized by the separation or excision of superficial fragments of the skin,

Class 4 : Laceration: forceful tearing of skin tissue,

Class 5 : Avulsion: clear amputation of tissue.

4. Methods of exploring a bite:

It includes several stages:

1. Observation of the bite mark:
   • First of all, it is essential to record the bite mark in time by creating a photographic record before any other operation.
   • Then, a delicate swab of the area must be carried out in order to detect any traces of DNA and other components contained in the salivary secretions, in the possible presence of blood or in any tissues, which will provide a lot of information on the perpetrator of the crime.
   • This must be done before any other handling that could cause contamination of the area.
   • In order to obtain the maximum quality indices, it will be necessary to act before 48 hours because the lesion evolves and changes over time.
2. Recording the bite mark:
   • If the victim is alive, the recording will be done by non-invasive methods. However, if the victim is deceased, the dentist will also start with this non-invasive method, and then proceed to invasive methods.

• Non-invasive methods:
• Photography:

• UV (ultraviolet) photography: recording surface details of the damaged area.
• IR (infrared) ray photography: recording of deep lesions of the dermis.
• Fluorescence photography: allows us to appreciate the distinctions between healthy skin and damaged skin, which absorbs more incident light.
• 3-dimensional (3D) photography.
• Imprints: making bite impressions in order to make casts.
• Invasive methods : tissue sampling and study by scanning electron microscopy.

3. Study of the suspect’s teeth:

It includes:

• Intra and extra oral examination: specify all aspects that characterize the aggressor’s oral environment. All anomalies, anatomical variations, malformations and malpositions must be noted, photographed or even X-rayed.
• Studies of maneuvers: they will be asked of him such as maximum mouth opening, lateral and protrusion movements.
• Making the prints.

4. The comparison between the two:

Four comparisons are possible:

• A positive identification : the bite mark on the victim’s skin is consistent with the suspect’s eyebrows,
• Possible identification : The bite may have been made by the suspect, but we cannot be certain,
• Probable identification : we do not have sufficient data to make a valid comparison,
• Negative identification : the suspect did not cause the bite.

3. Screening and diagnosis of situations of abuse and neglect of vulnerable people (children +++):

The roles of the dentist in the face of child abuse can be summarized in four points :

1. Participate in early detection within the practice by spotting warning signs:
   • Depending on the mechanism of abuse, we distinguish:

• Physical abuse : the dentist can identify regular, unexplained bruises, burns, superficial erosions, lacerations, repeated bone fractures, dental fractures, etc.

• In all cases, the practitioner must at all costs be alert to multiple, varied lesions of different ages or to sometimes suggestive topographies (seat burn, skull fracture, rib fracture).
• In addition, a height and weight delay, a break in the height and weight curve in a small child, delays and abnormally falling school results, a change in behavior, a very inhibited appearance, etc. are all points which should guide the practitioner towards a diagnosis of a situation of mistreatment.
• Abuse by omission : which can be just as dangerous, it refers to any type of deprivation, whether food, emotional, hygienic, medical, dental, educational or any failure in a parental duty.

• The manifestations of oral neglect are often underestimated and difficult to diagnose.
• The following signs can help identify a situation of neglect:

• Untreated rampant polycaries, untreated pain, untreated infection, bleeding or trauma;
• Anamnesis revealing a lack of follow-up despite the presence of pathologies.

2. If necessary, carry out a diagnosis in case of suspicion (oral lesions):
   • First, it is necessary to rule out any possibility of medical problems that could explain the visualized disorders (coagulation disorders, bone disease, etc.).
   • The diagnosis of abuse necessarily involves the interpretation of certain signs and attitudes of the patient and/or accompanying persons:

• Discrepancy between the story given by the child or parent and the clinical signs.
• Vague, contradictory or inconsistent story.
• The parent(s) or accompanying person speaks of “repeated accidents” and a vague “rare” illness.
• The parent or caregiver refuses to cooperate in treatment or refuses to be separated from the victim.
• Refusal to carry out diagnostic tests.
• Inappropriate behavior of the parent or caregiver (overly worried or apathetic).
• The parent or carer delays getting the child treated.
• The parent or carer continues to present symptoms unrelated to the victim’s condition.

3. Take the necessary measures to protect the child in the event of proven abuse by alerting the authorities and relevant services.
4. In some cases, help the authorities identify the perpetrator of the abuse (comparative analysis between the bite marks on the victim and the suspect’s teeth).

V- Conclusion:

• Establishing the identity of a person can sometimes be a difficult task due to post-mortem changes associated with time, temperature, humidity or other criteria depending on the circumstances of death (carbonization, fragmentation, mutilation, etc.).
• Forensic dentistry often provides great assistance in solving these problems.
• Another specialty of the expert is to assist justice in criminal cases where traces of human bites are evident, the dental surgeon will have to answer as precisely as possible the questions asked by the judge: does this trace come from such and such an individual…?
• So, when a dentist takes on the role of legal expert , he is no longer at the service of the patient but at the service of society and justice.

Forensic Odontology

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Forensic Odontology