Presentation on theme: "Forensic Dentistry. What is Forensic Science? …the application of science to those criminal and civil laws that are enforced by police agencies in a criminal."— Presentation transcript:
What is Forensic Science? …the application of science to those criminal and civil laws that are enforced by police agencies in a criminal justice system.
Forensic Science is… Applied science Often called criminalistics
Forensic Science applies Chemistry Biology Physics Geology to civil and criminal law.
Definition of Forensic Dentistry Forensic dentistry, or forensic odontology, is the application of dental and paradental knowledge to the solution of legal issues in civil and in criminal matters.
The THEORY behind forensic dentistry is that no two mouths are alike (even identical twins are different), and that teeth, like tools, leave recognizable marks.
Identification by teeth is not new.
During the U.S. Revolutionary War, none other than Paul Revere (a young dentist) helped identify war casualties by their bridgework. Identification by teeth is not new. Teeth are highly resistant to destruction and decomposition, so dental identification can be made under extreme circumstances.(1600ºC) It was used on Adolf Hitler and Eva Braun at the end of World War II, the New York City World Trade Center bombing, the Waco Branch Davidien siege, and numerous airplane crashes and natural disasters.
Forensic Dentistry involves Identification of the living or the deceased Bitemark identification, analysis and comparison Lip print identification, analysis and comparison Rugae print identification, analysis and comparison Patterned injury identification, analysis, comparison Identification of dental specimens at crime scene or elsewhere Evaluation of oro-facial trauma Malpractice and negligence claims
Who is this??
Means of Identification TEETH : natural and synthetic (fixed and removable) BONE : trabecular pattern, toris and osseous anomalies PRESENCE OF FOREIGN BODIES : implants, unretrieved amalgam particles, surgical instruments, bullets, fragments of various origins SINUS CONFIGURATION : maxillary and frontal SKULL SUTURES SOFT TISSUE FEATURES : rugae (rugoscopy) and lip (cheiloscopy, quieloscopy) prints PHOTOGRAPHIC COMPARISON : Facial or dental superimposition or approximation DNA
There are 2 types of dental identification team organizations: Traditional: its usually community based is often lead by chief forensic dentists, & includes dentists hygienists & dental assistants. Disaster Mortuary Operational Response Team (DMORT) system…consists of: ~ Dental team ~ Forensic pathology team ~ Anthropology & laboratory support ~ Photography & communication support. ~ Logistics team ~ Mortuary science team
Possible methods for identification of bodies are: 1. Visual recognition; 2. Property identification; 3. Scientific identification: finger prints; dental comparison; Medical evidence.
Dental comparison Dental comparison affords a potentially straightforward & simple means of establishing identity. This method of identification depends upon: The relative resistance of mineralized dental tissues & dental restorations to changes resulting from decompositions or harsh environmental extremes such as conditions of temperature & forces; The unique individual characteristics of dentition the dentition & dental restorations. The availability of documentation of the ante-mortem status of the dentition in form of dental treatment records & diagnostic radiographs.
Identification is achieved by comparing dental status of deceased with the dental records of the person known or suspected to be missing in circumstances consistent with those in which the remain of the unknown, deceased person were found. Obviously, the greater the number of coincident features, more reliable will be the identification. Dental comparison
Age Estimation Age estimation is commonly the purview of the forensic anthropologist using the pubic symphysis, innominate auricular surfaces, carpal bones, sternal rib ends, cranial suture closure and long bones.
Age Estimation However human age can also be estimated in living or deceased individuals by examining teeth eruption patterns, third molar development, and translucent dentin development in intact and sectioned teeth.
In living individuals, anthropologic age determinants other than wrist radiographs are not possible, so dental age estimation can be valuable. In deceased individuals there may be no skeletal evidence other than dental structures or teeth to make an age estimation. Age Estimation
You can also tell age solely by analysis of teeth -- the Gustafson method (looking for six signs of wear) or the Lamendin method (looking at transparency of roots).
The criteria that are mostly used in forensic odontology to determine age include: Eruption of teeth Resorbtion of roots Attrition Root transparency Dental pathology such as caries Periodontal diseases
All dental records are based on a universal numbering system, and contain an amazing amount of information. For example, they note: 1. fillings 2. extractions 3. surface structure/root configuration 4. adjacent teeth 5. twisted/tilted teeth Antemortem/Postmortem match determines identity. Age Estimation
INDIVIDUAL AGE ESTIMATION BASED ON D-ASPARTIC ACID AND D-GLUTAMIC ACID CONTENT OF THE TEETH J. Csapo, Zs. Csapo-Kiss (University of Kaposvar, Faculty of Animal Sciences, Department of Biochemistry and Foodstuff Chemistry, H-7400 Kaposvar, Guba S. u. 40. Hungary)
Facial reconstruction Artists rendering may hold key to solving mystery of unidentifed man
Definitions of marks made by human teeth: Tooth mark: mark left by tooth (human or non-human) Arch mark: mark produced by four or five adjacent teeth & same arch Bite mark: :a mark made by teeth either alone or in combination with other mouthparts (Mac Donalds, 1974) : Tooth mark produced by antagonist teeth (Jacobson & Keiser-Nielsen 1981)
Bite mark comparison is fairly new, however, going back to the mid-1970s. Police investigators have always noticed that at some crime scenes, criminals seem to leave their bite impressions on food products, chewing gum, or more commonly on the skin of their victims, especially in cases of battery, rape, child abuse, and homicide.
BITE MARKS There are seven (7) types of bite marks which can be classified by four (4) degrees of impression: 1. hemorrhage -- small bleeding spot 2. abrasion -- undamaging mark on skin 3. contusion -- ruptured blood vessel, bruise 4. laceration -- punctured or torn skin 5. incision -- neat puncture of skin 6. avulsion -- removal of skin 7. artifact -- bitten-off piece of body 1. clearly defined -- significant pressure 2. obviously defined -- first-degree pressure 3. quite noticeable -- violent pressure 4. lacerated -- skin violently torn from body
Possible Bitemark: An injury showing a pattern that may or may not be caused by teeth; could e caused by other factors but biting cannot be ruled out. criteria: general shape and size are present but distinctive features such as tooth marks are missing, incomplete or distorted or a few marks resembling tooth marks are present but the arch configuration is missing.
Probable Bitemark: The pattern strongly suggests or supports origin from teeth but could conceivably be caused by something else. criteria: pattern shows (some) (basic) (general) characteristics of teeth arranged around arches.
Definite Bitemark: There is no reasonable doubt that teeth created the pattern; other possibilities were considered and excluded. criteria: pattern conclusively illustrates (classic features) (all the characteristics) (typical class characteristics) of dental arches and human teeth in proper arrangement so that it is recognizable as an impression of the human dentition.
BITE MARKS contusion
Typical presentation of bitemark injuries Females are most often bitten on the breasts and legs during sexual attacks, whereas bites on males are commonly seen on the arms and shoulders. A representative human bite is described as an elliptical or circular injury that records the specific characteristics of the teeth
Typical presentation of bitemark injuries The injury may be shaped like a doughnut with characteristics recorded around the perimeter of the mark. Alternatively, it may be composed of two U-shaped arches that are separated at their bases by an open space. The diameter of the injury typically ranges from mm. Often a central area of bruising can be seen within the marks from the teeth. This extravascular bleeding is caused by pressure from the teeth as they compress the tissue inward from the perimeter of the mark.
Typical presentation of bitemark injuries
Many times the bite marks are obvious, but at many other times bite marks are very faint or even invisible. In such cases we flash a special light on the dead body. This is called ultra violet light or UV light. Human saliva shines brightly in UV light. Wherever the attacker has bitten his victim, his saliva stains are bound to be there, although they may dry. These saliva stains start shining and we can immediately know that this is the place where bite marks are present.
Documentation of Bite mark Make a record of the injury, including descriptive, narrative notes that document the physical appearance, colour, size and orientation of the injury. What is the location on the body? What is the relative contour and elasticity of the site? Can the difference between marks from the upper and lower teeth be determined? What types of injuries are present? Cuts? Bruises? Scrapes?
Saliva swabs for diagnosis Use the double swab technique: first, a cotton swab moistened with distilled water is employed to wash the surface that was contacted by the tongue and lips using light pressure and circular motions. Then, a second swab that is dry is used to collect the remaining moisture that is left on the skin by the first swab. Both swabs are thoroughly air-dried at room temperature for at least 45 minutes before they are released to police authorities for testing.
Saliva swabs The two swabs must be kept cool and dry to reduce the degradation of salivary DNA evidence and the growth of bacteria that may contaminate the samples and reduce their forensic value. Then they should be submitted to the laboratory as soon as possible for analysis. If the time until submission is protracted, it is recommended that the swabs be stored in a paper evidence envelope or box that will allow air to continue to circulate around the swab tips. (The swabs should not be sealed in plastic bags or plastic containers.) The envelopes or boxes should be refrigerated or frozen during storage.
A DNA sample must also be collected from the victim at this time to provide the opportunity for comparison with the sample from the bitemark. This sample could consist of a buccal swab or a sample of whole blood. The victim's DNA profile will enable analysis of any mixtures that are found in the sample from the bite, which may involve contributions from the depositor and the victim. D N A
Impression Fabricate an accurate impression of the bitten surface to record any irregularities produced by the teeth, such as cuts, abrasions, etc. Use vinyl polysiloxane, polyether or other impression material available in the dental office that is recommended for fixed prosthetic applications. Dental acrylic or plaster can be used as a rigid support for the impression material. This will allow the impression to accurately record the curvature of the skin.
First aid Prompt medical attention should be provided for the living victim since human bites have a higher potential for infection than animal bites. Injuries that disrupt the integrity of the skin's surface should be treated as soon as possible.
Phases of forensic identification: Preliminary Evaluation: Nature of death Reason of dental input Phase 1 Postmortem Exam: Facial & intraoral photograph Oral structures Radiographs Dental impressions Phase 2 Data collection & ante-mortem investigation: All available dental records Original radiographs Dental models Cephalometric films Phase 3 Comparison & conclusion: All postmortem & ante-mortem information obtained & charted Results compared Conclusion reached Phase 4
Procedure in dental identification: Recovery of dental structures; Reconstruction & examination; Collection of ante-mortem records; Transcription of dental records; Comparison of odontograms; Report
HOW FORENSIC DENTISTRY WORKS medical examiners or police investigators. discovered a bite mark while conducting an autopsy or viewing the body at a crime scene. Forensic dentists called bite mark can be photographed or even excised A linear (ABFO) scale should be placed somewhere in the photograph. A camera angle of 90 degrees is best for a flat surface, while a 40 degree angle causes 25% distortion of a bite mark.
….HOW FORENSIC DENTISTRY WORKS obtain a saliva sample from the bite. Next, the forensic dentist makes multiple impressions, casts, or molds of the bitemark, and has access to a variety of materials in which to choose the right gum, rubber, plastic, or powder to make a cast.
….HOW FORENSIC DENTISTRY WORKS Some forensic dentists used the Dorion method, which advocates the removal of bitten tissue for microscopic examination. Others use advanced techniques such as scanning electron microscopy, computer-enhanced digitization, and xeroradiology. Computerized bite analysis software also exists.
HOW FORENSIC DENTISTRY WORKS Once a suspect is apprehended, the forensic dentist makes one or more impressions of the suspect's teeth, comparing them to the recorded bite marks, and if called to testify, renders an opinion of the probability of a match.
CONCLUSION Bitemark is not an accurate representation of the teeth. A lot depends on the mechanics of jaw movement and use of the tongue. Inside the mouth, the lower jaw (mandible) is movable and usually delivers the most biting force. The upper jaw (maxilla) is stationary, holding and stretching the skin, but when skin is ripped or torn, the upper teeth are involved more deeply. Most bitemarks usually show a curvature where the upper teeth, at least, made an impression.
CONCLUSION The skin is elastic, tending to slip along the upper teeth until it catches hold. Depending upon the type of victim, some bitemarks last for hours and others for days, but almost all bitemarks alter themselves as time elapses. Photographing bitemarks at intervals over a set period of hours or days is part of the standard protocol recommended by the ABFO. Bitemarks also change or become distorted when the posture of the victim changes, so the forensic dentist might be able to assist with determination of how the perpetrator moved the body.
P r o b l e m s in i d e n t i f i c a t i o n : Condition of material recovered; Errors in examination; Inadequate ante-mortem data.
Summary Conclusions from the analysis of bitemark evidence can assist the justice system to answer crucial questions about interactions between people at the scene of a crime. Willingness by dentists to recognize, collect and preserve this evidence can be invaluable in the resolution of heinous interpersonal crimes.
If you can do it, it means you have the traits of a good detective. All the best! Sounds interesting, doesn't it?
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G Gustaffson forensic odontology.staple press Nivelle Damm allen Bouquet. Oral & maxillofacial Pathology 2 nd Ed. REFERENCES
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