Writers: Vian Lai, Austin Li, Manying Zita Tam
What is Forensic Odontology?
Firstly, what is forensic odontology? Forensic dentistry, otherwise known as forensic odontology, involves the handling, examination, and evaluation of dental evidence in a criminal justice context. It helps identify unknown remains and trace bite marks relating to a criminal. It makes use of odontological science within the legal field to solve crimes. Forensic dentistry or odontology applies anthropological techniques to human remain identification using dentition and related orofacial structures.
Forensic odontologists participate in the autopsy and collection of images, x-rays, cranial measurements, and dental impressions from the remains. These samples are then compared to those of known missing individuals. If a match can be made, the remains can be identified. The forensic odontologist works hand in hand with a practicing dentist to help provide accurate and comprehensive dental records as evidence for presumptive identification or rule out tentative matches. In contrast, the forensic odontologist analyzes and describes the unidentified remains. Teeth are the most durable part of the human skeleton, they are highly genetically influenced, and the specific developmental characteristics (such as spacing, winging) and dental treatment add to their importance in the identification of an individual’s remains. Although teeth have individualized features that enable identification, the methodology is based on comparison, so suitable and exact records are needed from the lifetime of the individual in question (antemortem (AM) data) so that they can be compared with the information obtained from the cadaver (postmortem (PM) data). Certain parts of the teeth, namely the pulp and dentin, provide a source of DNA, which is individualized and hence can be trusted in identifying criminals.
These methods of practice can be used to determine the age, sex, the race of a person at hand with general descriptions of as-yet-unidentified remains from the dentition hence ascertaining the identity or the time of death of the individual.
Firstly, the age of an individual can be estimated from the dentition. Subadult dentitions help with the estimation based on the regular development and eruption sequence of primary and secondary teeth, to the time of the eruption of the third molars. Eruption sequence charts such as the “London Atlas of Tooth Development and Eruption” are commonly used by both academic and forensic anthropologists. Adult dentitions cause the age estimation to become less reliable. Hence, forensic odontologists tend to classify age into broad intervals (e.g. greater than 50). Methods of dental age assessment include radiographic, microscopic, and gross visual examination of tooth structures following the development of the adult dentition. Some parts of the teeth are used to determine the age group of an individual including root translucency, secondary dentin deposition, periodontal attachment, cementum apposition, attrition, and root resorption. This is because there are various position changes in different parts of the teeth as we age. Gustafon’s Method is used to carry out investigations on the cementum apposition. Countable cemental annulations (chemical reaction) are present in human teeth and Quantification of cementum annuli is a moderately reliable means that is used for age estimation in humans. The incremental lines of the cementum were found to gradually increase with the advance in age and hence can be used as one of the adjuvant tools in dental age estimation.
Moreover, the gender of an individual can be determined from the adult dentition. Research from medical journals, and source quotes at the end of the slide, have shown that humans’ milk teeth and permanent teeth exhibit sexual dimorphism of approximately 7%, affected by ancestry. The difference in size between male and female teeth leads to a 75-80% accuracy in determining sex based on dentition. Men typically have canines and incisors with larger diameters in contrast to women. The pulp and dentin of teeth also provide a reservoir of DNA which enables sex to be determined from even fragmentary remains.
Furthermore, ancestry or race can be assessed from the dentition. Several metric and non-metric features can help assess geographic ancestry, although analysis of combinations of features and statistical probabilities is necessary for accurate results. No single dental feature can determine the population or “race” of an individual, but rather “complexes” of features help distinguish certain populations from others. Shovel-shaped incisors are more common in Asian, especially Native American, populations, and the expression of accessory cusps, particularly Carabelli’s cusp, varies among populations; European-Americans tend to exhibit such nonmetric dimorphism in the anterior dentition, African-Americans exhibit nonmetric variation more frequently in the posterior dentition. African populations typically display larger molars, European-American dentitions are smaller and more crowded. In addition, DNA retrieved from dental material can be analyzed for general indicators of ancestry or physical features including eye, hair, and skin color.
Lastly, bitemark analysis. Bitemark analysis does not directly identify a potential victim but provides identifiable information about a perpetrator who might have left an imprint of the anterior dentition (bite mark) which might be matched to dental records. It is worth noting that a number of studies have corroborated the accuracy of a bite mark analysis, and its legal and scientific value has been brought under public scrutiny in recent decades.
History
The cases of Agrippina and Lollia Pauline in 66 AD marked the beginning of well-documented evidence supporting the use of teeth for identification. Agrippina after her marriage with Claudius, emperor of Rome, tries to secure her position. She was worried that wealthy divorcee Lollia Paulina would continue to pose a threat to her spouse. She concluded that Lollia Paulina's death would be a safer option. As a result, he gave her soldier orders to kill Lollia Paulina and then to return the head. She was satisfied by Lollia Paulina's death by the identification of dental alignments and certain distinctive characteristics. It was the first use of dental identification where there is a record.
In 1775, American patriot Paul Revere used his skills as a dentist to identify the body of his friend Dr. Joseph Warren, who was killed during the Revolutionary War. Revere recognized the custom denture he had made for Warren. This was an early example of dental evidence being used for identification. In 1849, dental evidence was used to convict murderer John Webster in Boston. Fragments of a victim's jawbone and teeth were matched to dental work done by the victim's dentist. This was the first time dental evidence was used to secure a murder conviction.
Case Studies
To provide more real-life examples of forensic odontology, one of these case studies is Ted Bundy. Ted Bundy was an American serial killer and rapist who was born in Burlington, Vermont, on November 24, 1946. He was one of the most well-known criminals of the late 20th century. Bundy had confessed to 30 murders, though the actual number of his victims remains unknown. Due to the bite mark evidence (forensics odontology) which was also used to convict Bundy, he was found guilty of murder despite his numerous attempts at defense. Dr. Richard Souviron, a forensic odontologist, testified that an impression of Bundy's teeth was exactly matched to a bite mark discovered on one of his victims.
Another relevant real-life case study is Josef Mengele. Josef Mengele was a German anthropologist and physician affiliated with the SS (Nazi Party) from 1937. He would often do experiments in the extermination camps in Germany on the orders of Adolf Hitler. At the end of WWII, he escaped to Latin America, living as a fugitive from justice and constantly changing residences. His location became a mystery, and his death did too (with an assumption that he had died in Brazil). His body had started to decompose significantly due to the soil environment, and this advanced state of decay made it challenging to recognize or identify the individual as Mengele. But with forensic odontology and American dental scientist Lowell J. Levine, these discovered dental X-rays prove with “absolute certainty” that a skeleton unearthed near Sao Paulo last year was that of Nazi war criminal Josef Mengele, experts said Thursday.
Pros/Cons
Although forensic odontology is an extremely advanced method, there are still many drawbacks we have yet to find a solution. For instance, there are limitations in the accuracy and reliability of some forensic odontology techniques, such as bite mark analysis, which can be subjective and controversial. Proper collection and preservation of dental evidence is crucial but can be challenging in some cases. Forensic odontology requires specialized training and expertise, which can limit the availability of qualified practitioners in some areas. The legal admissibility of certain forensic odontology methods is still debated, and they may not always be accepted as conclusive evidence in court. Ethical concerns have been raised about the use of dental records for identification without consent from the individual or their family.
However there are some advantages: teeth are the hardest and most durable part of the human body, making them a valuable source of evidence even in cases of severe decomposition or trauma. Forensic odontologists can use dental records, bite marks, and other unique dental features to positively identify unknown remains. Forensic odontology can provide important information about the age, sex, and ancestry of an individual based on their dental characteristics. Forensic odontologists can assist in disaster victim identification by analyzing dental remains. Bite mark analysis can help link a suspect to a crime scene or victim.
Sources & Works Cited
National Library of Medicine: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4411915/#:~:text=Dr%20Ascor%20Amoedo%2C%20who%20is,their%20lives%20in%20a%20disaster.
ScienceDirect: https://www.sciencedirect.com/topics/medicine-and-dentistry/forensic-odontology
Journal of Forensic Science and Medicine: https://journals.lww.com/jfsm/fulltext/2021/07030/recent_advances_in_forensic_odontology__an.5.aspx
Aboney Orthodontics: https://abdoneyortho.com/masculine-vs-feminine-smiles#:~:text=Men%2C%20typically%20have%20canines%20and,teeth%20look%20squarer%20and%20bulkier.’
Semantic Scholar: https://www.semanticscholar.org/paper/Modified-Gustafson%E2%80%99s-Method-for-Age-Estimation-from-Sonjaya-Nambiar/1b05923f6eb14eb5ef56f78b46f75fe34604de42
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