Forensic Odontology: Overview
This article is submitted on November 26, 2008, published by Biology-Online.org on January 31, 2009. (Contact the submitter)
Forensic Odontology, also known as Forensic Dentistry or Bite Mark Evidence Expertise, is the application of dental knowledge to the understanding of laws. Some of the work a Forensic Odontology is involved in is: identification of bite marks on the victims of attack, comparisons of bite marks with the teeth of a suspect and presentation of this evidence in court as an expert witness, identification of bite marks in other substances such as wood, leather and foodstuffs, identification of unknown bodies through dental records, and to estimate the age of skeletal remains. All of which is uncovered at a crime scene. You may be asking yourself how this can be useful to identify someone and put them at the scene of the crime. With the ability to survive fires that destroy evidence, teeth are an excellent source of identification. As well as the fact they are hard wearing and durable.
Just like a figure print, no two set of teethes are alike. The amount of missing teeth, crowns, bridges, fillings, caps, root canals and various other treatments during a patient's routine check-up are what makes teeth unique and not like any others. While examining the DNA left at a scene, Forensic Odontologists exam the each and every routine that has been done and try to match them up with dental records. It becomes harder on the Odontologist if a good dental record is not kept on a person or parts are missing or severely damaged. When there are no dental records present the ability to make decisions about the victim's identity is very restricted, but other guidelines are useful. Some of these guidelines include the tooth roots becoming more transparent in older people and the stage of development of a child's teeth can determine their age. The teeth's pattern of wear in adult's show the person's age, diet and the materials/dentistry techniques used during dental treatment, which can point out the country in which treatment was received.
Steps in Forensic Odontology
One of the first things they'll do is obtain a saliva sample from the bite. This, of course, can be done by others, but a forensic dentist can make sure sample extraction doesn't affect quality of the bite mark. Next, the forensic dentist will take photographs. This is a technique shared by all experts, and it's fairly important to get the lighting, color, and camera angle right. A linear 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. Next, the forensic dentist makes multiple impressions, casts, or molds of the bite mark, and has access to a variety of materials in which to choose the right gum, rubber, plastic, or powder to make a cast. Some forensic dentists used the so-called 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. 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. Courts have upheld the constitutionality of involuntarily taking a dental impression from a suspect, as they have for most biological specimens from the suspect.
Bite marks are something else Forensic Odontologist look at. The specific areas of bite marks would be : the distance from cuspid to cuspid, the shape of the mouth arch, the evidence of a tooth out of alignment, teeth width and thickness, spacing between teeth, missing teeth, the curves of biting edges, unique dentistry, and wear patterns such as chips or grinding. The amount and degree of detail recorded in the bitten surface may vary from case to case. Human and animal teeth both leave conspicuous marks. In the flesh, they leave behind noticeable bruises or puncture marks and in soft foods, such as fruit, marks are also preserved. In situations where sufficient details are available, it may be possible to identify the biter to the exclusion of all others. Perhaps more significantly, it is possible to exclude suspects that did not leave the bite mark or marks. The skin is elastic, tending to slip along the upper teeth until it catches hold. Depending upon the type of victim, some bite marks last for hours and others for days, but almost all bite marks alter themselves as time elapses. Photographing bite marks at intervals over a set period of hours or days is part of the standard protocol recommended by the ABFO. Bite marks 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.
Problems and issues
It's unlikely that the qualifications of a forensic dentist will be successfully challenged on the stand since so much judicial notice has been given to this expertise. It's also doubtful that you will find a forensic dentist associated with a law enforcement agency on more than a part-time basis. Board certification requires such association, having observed autopsies, having worked 25 cases, and having accumulated 350 qualification points, which are earned by attending meetings, conferences, etc. Final certification is granted after successful passing of an examination, and is good for five years.
One issue is the problem of standard protocol. This appears to be a field in which several experts go their own way, creating their own methods. There's also a digital divide in that some dentists have access to sophisticated lab equipment and others don't. Blind reviews also tend to be either not done or reflect poorly on the profession. In a blind review, a sample of experts would be unknowingly given the same material to analyze and compare, but might come to different conclusions. Experts have not followed points of comparison approach, but instead have relied upon a probabilistic assessment of the confidence in their opinion approach. A moderate amount of literature can be found in peer-reviewed journals, but this field has a long way to go before many of its claims can be scientifically substantiated.
History behind Forensic Odontology
Identification by teeth is not new. It goes back as far back as 66 A.D. at the time of Nero. As the story goes, Nero's mother, Agrippina, had her soldiers kill Lollia Paulina, with instructions to bring back her head as proof that she was dead. Agrippina, unable to positively identify the head, examined the front teeth and on finding the discolored front tooth confirmed the identity of the victim. During the U.S. Revolutionary War, none other than Paul Revere - a young dentist - helped identify war casualties by their bridgework. Teeth are highly resistant to destruction and decomposition, so dental identification can be made under extreme circumstances. 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. The U.S. has a fairly well-developed system of dental records system (the Universal System), so it's not surprising to find it used for the identity of remains or "Jane Doe" victims. 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). With the Universal System, each tooth is assigned its own number from 1- 32 and the five surfaces of each tooth are also classified.
The first forensic odontologist in the United States was Dr. Paul Revere who identified the extremed body of Dr. Joseph Warren, a revolutionary the British in 1775 through a bridge of silver and ivory that he had constructed two years previously. Dental evidence was first accepted in the United States court in the Webster - Parkman case. Dr. J.W. Webster allegedly stabbed, dismembered on Nov., 23, 1849 in Bostan charred fragments of mineral teeth fused to gold were recognized as those of the deceased by Dr. Nathan Parkman. This evidence was enough for the jury to a verdict of guilty of premeditated murder against Dr. Webster who was subsequently hung.
The first treatise on forensic odontology was written by Dr. Oscar Amoedo in 1898 and was entitled L'Art Dentaire en Medicine Legale. Dr. Oscar is also known as father of Forensic Odontology. In 1937 in Chantilly, a murder was convicted on the evidence of the bite marks that the victim inflicted during her struggle for life. In 1946 Welty and Glasgow devised a system in which as many as 500 cards with dental data could be sorted in one minute by a computer. The following year Taltersall wrote that he advocated the Hollerith system of punch cards and thought this would be very beneficial in compiling dental data. The scope of this specialty has expanded since the end of the 1939-1945 was due to the quarter intensity of international traffic coincident are destroyed and often Internationally there is an obvious growth of interest in this field there are organizations such as the Scandinavian society of Forensic Odontology, the Federation Dentaire International. The Canadian Society of Forensic Sciences, the American society of Forensic Odontology and the American Academy of Forensic Sciences. teeth and dental restoration are the only means of identification available. The international Journal of Forensic Dentistry and the Forensic Odontology Section of INFORM are important references for members of Forensic team involved in Odontology.
The present state of education in forensic odontology is surveyed. Courses in the subject within dental schools are directed mainly towards dental students (lectures, seminars, demonstrations), but also towards chairside assistants, dental hygienists and laboratory technicians. Extra-mural postgraduate education is directed towards private practitioners, but includes community dental health officers and colleagues serving in the defence forces; the question of 'qualification' is discussed. Finally, a wide range of non-dental personnel is approached (medical and law students, community health officers, forensic medical experts, police technicians etc.). The authors concur that independent departments of forensic odontology are now needed at all major dental schools; only here can the manpower and the facilities be developed to cope with this wide spectrum of education, and only here can recognized academic positions be ensured for those who--together with other specialists--must handle an increasing extra-mural case load, from which all material for education and research is subsequently to be derived.
Forensic Odontology Vocabulary
Forensic Odontologist also uses some words that are not used in every day life. Examples of these words would be: canines, cementum, dentine, enamel, eruption, incisors, milk teeth, molars, periodontics, and premolars.