The Identity Of Cadavers Revealed By Their Teeth

[Anonymous]

Researchers from the University of Granada have shown that a person’s dental patterns can be used as proof of their identity with the same degree of reliability as DNA testing, the method that forensic police use to reveal the identity of dead bodies. The researchers came to their conclusion after analyzing the dental patterns of more than 3,000 people.

“There is sufficient dental diversity between people to enable a scientifically-based human identification method to be developed for forensic purposes”, Stella Martín de las Heras, lead author of the study and a professor of Legal and Forensic Medicine at the University of Granada (UGR), tells SINC.

In order to reach this conclusion, the researcher and her team carried out a statistical analysis of 3,166 full and partial sets of teeth taken from the databases in the three most recent National Surveys of Oral Health (1993, 2000 and 2005).

Using these data, the team estimated “conditioned dental diversity”, eliminating cases where people had all their teeth “present and healthy” or people who were “edentulous” (without a single tooth in their mouth), as these were of no use for identification purposes.

The results of the study, published in the journal Forensic Science International, show variability values of 0.999 (on a scale of 0 to 1), “which is comparable to the rates for a scientifically-based identification method such as mitochondrial DNA”, stresses Martín de las Heras.

However, the scientist does acknowledge the limitations of using dental patterns: “Dental characteristics have low stability within the population compared with mitochondrial DNA sequences, which are only affected by mutations and heteroplasmy (different types within the same mitochondria, cell or individual)”.

The dental patterns of a population depend on oral health status and, therefore, on age (decay is a cumulative disease) and the therapeutic dental approach of the time. At present, we are in a restorative phase (where teeth are restored) as opposed to extractive (when teeth are removed), as they were previously.

“But by analysing the data bases of dental patterns in Spanish populations according to different age groups and birth cohorts, we found test results with high homogeneity for all the databases, which shows the value of this system for identifying people, and its forensic utility”, says the researcher.

Comparing teeth before and after death

In this procedure, an oral autopsy makes it possible to obtain a cadaver’s dental data. To do this, forensic scientists use a range of techniques depending upon the body’s state of preservation. In some cases they have to remove the maxillary bones in order to find details that cannot be identified in any other way.

The post mortem dental pattern is compared with the dental data of the person in life, information that is provided by dentists, although it can also come from doctors and family members. Various IT programmes are used to help in comparison and identification.

Aside from this finding, the team has developed a piece of software to identify bite marks. This tool makes it possible to superimpose, precisely and in 3D, the mark left by a bite over the tooth arrangement of a possible suspect.

References:
Stella Martin-de-las-Heras, Aurora Valenzuela, Juan de Dios Luna y Manuel Bravo. “The utility of dental patterns in forensic dentistry”. Forensic Science International 195 (1): 166.e1-166.e5, 2010. Doi: 10.1016/j.forsciint.2009.11.004.

Source:
SINC
FECYT – Spanish Foundation for Science and Technology

        

[saurabh]

I fail to understand how teeth dont undergo decay if its surrounded by millions of bacteria in cadavers..

        

[drmithila]

 Dentistry fulfills one of its most important social, moral, and professional obligations by applying its unique knowledge and expertise to the task of identifying countless persons who are tragic victims of fires, catastrophes, disasters, and homicides. Identification must proceed along the lines of gathering as much reliable evidence as possible and utilizing this evidence in an attempt to establish a positive identification. Positive body identification may be ascertained via visual means, fingerprint records, dental charts, radiographs, and study models. Visual examination includes hair and eye comparison, noting all distinguishable scars, tattoos, and birthmarks, and, most importantly, recognizing outstanding facial features overlying bony structure, which has maintained its anatomic outline.

When visual identification is impossible, fingerprints and footprints are taken from the body and sent to the appropriate local, city, and federal agencies for a positive comparison match. Many times, however, a body undergoing severe decomposition, mutilated via a sudden, high-impact explosive accident, and/ or subjected to high-intensity fire will make it impossible to finalize a visual and fingerprint identification. The forensic odontologist is then called upon to render his or her expertise in the area of oral identification. The oral remains and associated facial bones are identified, charted, x-rayed, and if necessary, anatomically repositioned to produce within reasonable certainty and facsimile the victim’s ante mortem facial and oral structure.

As with any investigation procedure, the forensic dentist must rely upon the evidence available at the time of ante mortem and post mortem dental comparison. Post mortem findings, whether a single tooth, bits of crowns and/or roots, or portions of jaw or facial bones, will be closely examined and compared to any available ante mortem evidence on hand. The ante mortem evidence will hopefully include the victim’s dental charts, radiographs, and, if possible, study models. All charts should include dates of treatment, with special attention given to dates of radiographs taken.

The approximate age of the victim is established as soon as possible. Approximate age may be determined by radiographs of deciduous, mixed, and adult dentition. The sequential, 8-step, third molar eruption cycle is used to determine approximate age from 14 to 23 years. Skeletal remains of the skull, mandible, and torso reveal distinct, age-related findings. Fontanelle, soft and hard depressions, closure of the cranial sutures, coronoid process, condylar head, attrition and abrasion of the dentition, and width of pubic and long bone epiphyseal growth pattern are all pathogonomic in determining approximate age. Age determination is critical to the investigative process.

Upon establishing a positive identification, a legal death certificate can be issued. From a legal standpoint, wills can now be probated and insurance claims granted. Many deaths are the result of mass disasters (plane crashes, eg, flight 800 and flight 587), acts of nature (earthquakes), mass suicides or sudden unexpected catastrophes (Jonestown), and attacks such as those involving the World Trade Center and Pentagon. These have the potential of inflicting hundreds and even thousands of fatalities. Immediate identification and subsequent burial are imperative, not only to bring closure but also to avoid typhoid, dysentery, and other health-related hazards brought on by rapidly decomposing bodies. The added threat of worldwide terrorism capable of causing many deaths has now become a major problem facing the forensic community. Citizens or aliens alike lacking fingerprints and dental records pose a serious problem of identification. Special attention when treating all patients should be exercised at the examination visit, whereby an accurate charting of all usual and unusual dental findings is noted and recorded. Our task now takes on a more urgent and magnified meaning.

        

[drmithila]

 

Ample time must be allowed at the first dental patient visit to judiciously and painstakingly record all the dental findings. Poignant information noted in the past and present medical history is of vital importance to the identification process. Areas of special interest would be a period of hospitalization requiring surgery, emergency room x-rays, and CT or MRI scans.

Many times the forensic dentist leans toward the unusual findings to establish a positive identification. This category will include, to mention a few, areas of dense buccal and gingival pigmentation, palatal and mandibular tori, dento-facial deformities (eg, microgenia), rotated or malposed teeth, and most importantly, any anterior diastemas. In June of 1985, a team of West German and American forensic specialists was called to Brazil to identify the remains of World War II criminal Dr. Josef Mengele, the notorious Angel of Death. Among one of many corroborating features unique to this identification was a prominent, 4-mm diastema located between the upper anterior central incisors. Hospital A/M x-rays taken in 1939 were compared to P/M x-rays of the victim. A titanium pin in the left ankle was a positive match.

Radiographic interpretation will only be as diagnostic as the clarity and contrast of the radiograph taken. Clarity, contrast, and proper angulation will help contribute to the overall identification process. Periapical, bite-wing, occlusal, lateral plates, and A/P Waters views of the skull may all be used to facilitate the identification process. Proper angulation is critical to the radiographic interpretation of root length, bone trabecular pattern, thickness of periodontal membrane and ligament, and overall pulp morphology. The Panorex, though a valuable office adjunct, does not lend itself well to the forensic process due to its lack of anterior contrast and clarity. A body in post-death rigor mortis will exhibit severe facial contraction. This chemical phenomena, together with positional instability, rules out the Panorex as the radiograph of choice.

Loss of facial contour due to decomposition, autolysis and liquefaction, and other chemical changes will rule out a visual identification. When visual, fingerprints, and dental comparison are unavailable for whatever reason, the use of mitochondrial chromatin (DNA) is done.

The role of the orthodontist and prosthodontist must not be overlooked in the forensic picture. The very young (6- to 13-year-old group) and the geriatric population (60- to 90-year-old group) comprise approximately 40% of the unknown and missing persons population. Many times, when radiographs and charts are not available, the use of study models alone will corroborate a positive identification. This was evident when several teenagers were the victims of a raging inferno that swept through Great Adventure amusement park in Jackson, NJ. The orthodontists’ corrective study models contributed to making the final positive identification for all  of the teenagers involved.

When teeth are subjected to prolonged, intense heat,  crowns and roots become brittle and disintegrate. This breakdown occurs at temperatures ranging from 400ºF to 1,796ºF (cremation temperature). Gold fillings, PFM crowns, and gold crowns will melt when subjected to temperatures of 1,832ºF to 2,228ºF. Microscopic examination of the roots at such high temperatures reveals cracking, peeling, and a powdery residue, negating root morphology in the identification process.

Due to very high tem-perature resistance of cast frameworks (eg, chrome cobalt), it would be prudent and invaluable for all removable prostheses—valplast, acrylic, or cast—to be labeled and identified. This should include the patient’s name and/or social security number.

The post mortem examination will proceed to finality using the victim’s ante mortem charts, radiographs, and study models. Very rarely does the ideal situation exist when all 3 modes of identification are available. Whatever is evident must be utilized to the fullest extent. Nothing must be overlooked nor any bits of information be considered too trivial and nonvital to the forensic examination. Every piece of ante mortem evidence is vital to the process of meticulously putting the oral puzzle together. All findings post mortem are assembled, interpreted, reviewed, and recorded. A report can now be filed with reasonable justification and certainty that the comparision finds do coincide and the identification is positive.

        

[Drsumitra]

Dentistry fulfills one of its most important social, moral, and professional obligations by applying its unique knowledge and expertise to the task of identifying countless persons who are tragic victims of fires, catastrophes, disasters, and homicides. Identification must proceed along the lines of gathering as much reliable evidence as possible and utilizing this evidence in an attempt to establish a positive identification. Positive body identification may be ascertained via visual means, fingerprint records, dental charts, radiographs, and study models. Visual examination includes hair and eye comparison, noting all distinguishable scars, tattoos, and birthmarks, and, most importantly, recognizing outstanding facial features overlying bony structure, which has maintained its anatomic outline.

When visual identification is impossible, fingerprints and footprints are taken from the body and sent to the appropriate local, city, and federal agencies for a positive comparison match. Many times, however, a body undergoing severe decomposition, mutilated via a sudden, high-impact explosive accident, and/ or subjected to high-intensity fire will make it impossible to finalize a visual and fingerprint identification. The forensic odontologist is then called upon to render his or her expertise in the area of oral identification. The oral remains and associated facial bones are identified, charted, x-rayed, and if necessary, anatomically repositioned to produce within reasonable certainty and facsimile the victim’s ante mortem facial and oral structure.

As with any investigation procedure, the forensic dentist must rely upon the evidence available at the time of ante mortem and post mortem dental comparison. Post mortem findings, whether a single tooth, bits of crowns and/or roots, or portions of jaw or facial bones, will be closely examined and compared to any available ante mortem evidence on hand. The ante mortem evidence will hopefully include the victim’s dental charts, radiographs, and, if possible, study models. All charts should include dates of treatment, with special attention given to dates of radiographs taken.

The approximate age of the victim is established as soon as possible. Approximate age may be determined by radiographs of deciduous, mixed, and adult dentition. The sequential, 8-step, third molar eruption cycle is used to determine approximate age from 14 to 23 years. Skeletal remains of the skull, mandible, and torso reveal distinct, age-related findings. Fontanelle, soft and hard depressions, closure of the cranial sutures, coronoid process, condylar head, attrition and abrasion of the dentition, and width of pubic and long bone epiphyseal growth pattern are all pathogonomic in determining approximate age. Age determination is critical to the investigative process.

Upon establishing a positive identification, a legal death certificate can be issued. From a legal standpoint, wills can now be probated and insurance claims granted. Many deaths are the result of mass disasters (plane crashes, eg, flight 800 and flight 587), acts of nature (earthquakes), mass suicides or sudden unexpected catastrophes (Jonestown), and attacks such as those involving the World Trade Center and Pentagon. These have the potential of inflicting hundreds and even thousands of fatalities. Immediate identification and subsequent burial are imperative, not only to bring closure but also to avoid typhoid, dysentery, and other health-related hazards brought on by rapidly decomposing bodies. The added threat of worldwide terrorism capable of causing many deaths has now become a major problem facing the forensic community. Citizens or aliens alike lacking fingerprints and dental records pose a serious problem of identification. Special attention when treating all patients should be exercised at the examination visit, whereby an accurate charting of all usual and unusual dental findings is noted and recorded. Our task now takes on a more urgent and magnified meaning.

 

        

[Author]

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