Essay: The role of forensic odontology for perpetrator identification through bite marks

The role of forensic odontology is for personal identification, perpetrator identification through bite marks, establishing legal age, analysis of facial injury and dental malpractice, and testimony in court. Odontologists identify human remains that cannot be facially identified, fingerprinted, etc., identify bodies in mass disasters, estimate the age of bones or skeletal remains, and find the source of bite mark injuries. They examine x-rays, dental impressions, photographs, etc. of a body. Bite marks are not only found on the human body, but also on edible and inedible objects like gum and cheese or bars of soap, and clay. Odontologists examine bite marks by looking at pictures; searching for any bruising on the body; determining if the bite was caused by a human or animal, self-inflicted or by perpetrator; and looking for or examining any DNA. There are different classifications to help distinguish different kinds of bite marks — a hemorrhage is a small bleeding spot, abrasions are non-damaging marks on skin, contusions are ruptured blood vessels, lacerations are a near puncture of the skin while incisions are a neat-punctured or torn skin, avulsions are a removal of skin and last but not least, artefacts are a bitten off piece of a body.
These three articles discuss bite marks in criminal cases, experiments, and its practicality in identifying a person. The process of comparing two bite marks analyzes the measurement of size, shape and position of each tooth, looking close at details similar to comparing two very similar fingerprints. They can be analyzed via dental study casts, wax impressions, radiographic comparisons, etc. physically or digitally (Verma et al., 2013). Unlike fingerprinting where parts of a fingerprint can be so similar that it’s possible for two people to have the same fingerprint, there are “over two billion possibilities in the charting of adult dentition. This would therefore rule out the possibility of two adults having exactly the identical dentition” (Verma et al., 2013). This is significant especially in cases of rape and assault on a victim.
Verma et al. (2013) discusses how bite marks are used criminology. Bite marks can be found in food, on the victim (by perpetrator), or on the criminal (by the victim as self defense). To analyze bite marks, odontologists go through a seven-step process which starts with dental history relating to the bite mark, photographing/recording evidence, observation of the bite mark, taking DNA samples from the bites, making an impression of the bite, testing the impression on different materials, and lastly studying the casts made from the impressions. After following these steps, odontologists examine images of specific areas of the bite mark close up, adding color on a grey scale to help differentiate or specify areas to look over Verma et al. (2013). I learned how the process for analyzing bite mark analysis works. It is similar to the process of analyzing x-rays on different parts of the body. I also learned that instead of analyzing bite marks in color, odontologists analyze bite marks on a grey scale since the human eye can detect forty shades of grey. The use of technology improves the accuracy of bite mark analysis, though Verma et al. (2013) still mention that more research should be done rather than only relying on bite mark evidence.
Gorea et al. (2014) furthered the idea that bite mark evidence should not be solely relied on. They compared in a study how bite mark impressions (both mandibular and maxillary) on skin and bite mark impressions on clay differentiated when hand drawn, photocopied, scanned and made into dental casts. After several trials with over 100 cases, the study showed that on skin, the hand drawn, photocopied, scanned and dental cast impressions all had an effectiveness of below 50 percent, meaning they had a low rate on leaving an impression on skin. However, all four mandibular and maxillary bite mark impressions on clay had a 90 or higher percentage of being effective on leaving an imprint. This shows that forensic scientists should not be absolutely dependent on bite mark impressions on human skin however, a bite mark on something of similar substance to clay, like cheese or gum, would be better off taking an impression from. Though this is true, Al-Amad (2016) adds that bite marks are also important to forensic odontology because “the bite mark is the only one which cannot be accidental and always indicates an act of violence” (p. 364). From this article, I learned how certain materials react under bite marks. When materials or objects are more rigid, their bite marks will last longer than an object that is more elastic or stretchy.
Al-Amad (2016) explains the general history of bite marks, describes the importance of bite marks, and the outcome of court cases because of bite mark analysis. Some interesting events on the history of bite marks not included in the article are that bite mark analysis goes all the way back to when Eve told Adam to bite into an apple, leaving (you guessed it!) a bite mark. In the United States, Paul Revere was the first known forensic dentist, identifying dead soldiers, Dr. Joseph Warren in particular by identifying his denture, from the American Revolution. Age estimation via forensic odontology was first used to see if Prince Louis XVII was actually dead, by estimating the age of the bones and teeth of the body in his coffin. It turns out that the bones and teeth they examined were not Prince Louis XVII’s. Other famous cases using forensic odontology age estimation include the identification of John Wilkes Booth, Adolf Hitler, and Ted Bundy. Returning to the article, The Bundy case shook the course of bite mark analysis because it brought a serial killer to justice. This led Al-Amad to talk about bite mark analysis in laboratories and in court.
Bite marks are useful because they usually leave DNA behind, a good source to helping find the perpetrator. On victims, females typically have more bite marks than males and in areas near their breasts, arms and legs, whereas male victims typically have bite marks on their arms and shoulders (Al-Amad, 2016, p. 364). In bite mark analysis, an image of the bite mark is overlaid with an image of where the suspect’s teeth cuts the surface of skin. Both images are altered so they have the same configuration, which causes distortion, though it can be digitally corrected, however, the ability to correct is limited. In addition, every bite mark impression on a human is swabbed for DNA with both a dry and wet cotton swab, for greater DNA analysis (Al-Amad, 2016, p. 364-365). Al Amad concluded that it is not typical for bite marks to be easily identified as unique because of the inaccuracy of examining a bite mark on skin because of its “flexibility”. This relates back to how Gorea et al. (2014) showed that impressions on skin were not the most accurate and efficient when examining bite marks.
Al-Amad (2016) also discusses the Innocence Project, which is known for exonerating people who have been wrongfully convicted because of DNA testing while also reforming the criminal justice system to help prevent other wrongly convicted cases. In these cases dealing with bite mark analysis, many of their testimonies used similar language which were broad and “inappropriate” because there was an insufficient amount of bite mark evidence to prove the people were guilty. Other convictions weren’t dutiful because several testimones were disagreed between several odontologists over the same bite mark (Al-Amad, 2016, p. 366). The Innocence Project shows the need to correct these actions in forensic odontology in the laboratory and in court. I gained from this article learning the importance of bite mark analysis and the Innocence Project. Hearing about the Innocence Project, I researched a little more on the project and learned that it is not only releasing wrongly convicted persons from bite mark analysis, but other misinterpretations of other forms of evidence. Though 336 cases in which the project has helped wrong convictions may not seem like a lot, the Innocence Project is still growing today.
Verma et al. (2013), Gorea et al. (2014), as well as Al-Amad (2016) all somehow relate to one another. While Verma et al. (2013) discusses the process of bite mark analysis, Al-Amad (2016) furthers this by describing the usefulness and importance of bite marks and its analysis as a whole. Gorea et al. (2014) actually uses the process to test efficiency of bite mark impressions on skin. However, Verma et al. (2013) is the only article who discusses the process for analyzing bite marks, while the other two articles provide commentary or evidence to support/go against bite mark analysis. All three articles are similar when stating the fact that bite mark evidence and analysis should not be the only evidence and analysis used in court testimonies. Gorea et al. (2014) describes a test using the bite mark analysis process to find out the efficiency of bite mark impressions on skin and came to the conclusion that impressions on skin are inefficient. Al-Amad (2016) confirms this saying that skin stretches, meaning it does not stay in one specific position over time.
The articles relating to each other also tie into class discussions. While bite mark analysis can be useful, there are also some technical issues with bite mark analysis. This correlates to how as discussed in class, forensic odontology is often called a junk science. This is because even when identifying bite marks with the Visual Index of Bitemark Severity and Significance Scale, they can be commonly misconstrued as a contusion (bruise). Misidentifications are much too common, provoking many wrongful convictions. There are no standards, rules, or regulations and skin does not typically record the details of each tooth, which can cause frequent distortions. In addition, the articles talking about the inaccuracy of bite mark on impressions on skin relate back to class discussion in other ways. For example, in class when watching Forensics on Trial, a scenario that came up in the film discussed bite mark analysis. In Syracuse, NY, a woman’s body was found near her home that had been burned down with bite marks all over her body. Bite mark forensics stated that everyone’s teeth make a unique mark based on their size, shape and spacing. They wrongly accused a man recently released from jail in the area for killing the woman, leading to the conclusion that bite mark analysis isn’t always the best way to identify a perpetrator since bite marks are like bruises.
The future of bite mark analysis is growing, with the help of the development of new technology. The Innocence Project can help odontologists grow their studies by learning from mistakes made by previous mistrials on bite mark analysis. Future research can possibly help improve the accuracy of examining bite mark impressions on skin, or can help forensic odontology clear its name as a junk science. From reading these articles, I learned the importance of using several pieces of evidence in court cases rather than relying solely on one piece of evidence, the intricate process of bite mark analysis, and that bite marks on skin will not last forever. I found it interesting that a forensic odontologist would have a better chance of finding a perpetrator from biting into a piece of cheese than from an actual bite mark on a victim. Both marks on the cheese and skin will leave an imprint and both marks will leave some DNA from the criminal behind, but the imprint on skin can only last so long. I personally do not think that forensic odontology is a junk science, though it may not be one of the most clear-cut disciplines in forensic science, it still is helpful and can be used in testimonies (not as the only piece of evidence).
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