Priasha Dutta, Amity University Kolkata
Let’s understand what Forensic Odontology is-
Forensic odontology is a branch of forensic science that deals with the collection, intricate analysis, handling, and presentation of dental evidence related to a criminal act before a court of law. In spite of various recent advances in the field of DNA technology and next-generation sequencing, the importance of forensic odontology can be understood as dental identification still remains to be a speedy and cost-effective approach in the domain of forensic sciences. The techniques involved in forensic odontology include:
- bite mark analysis
- cheiloscopy (a forensic technique that traces humans based on their lip morphology)
- tooth prints
- radiographs
- rugoscopy (a forensic technique that identifies humans usually based on their palatal rugae morphology)
- dental DNA analysis
- dental photographs.
Who is a forensic odontologist?
Forensic odontologists are extremely skilled and trained dentists who have experience in the field of forensics. They assist the police and other crime investigation officials in detecting criminals by tracing their dental morphology and related aspects. The importance of forensic odontology is brought into reality by the intricate works of a forensic odontologist.
The work of a forensic odontologist covers the following:
• Identification of unknown human remains through dental records, producing dental evidence in the court, and assisting at the scene of a mass disaster.
• Estimation of age, sex, dentition, and oral hygiene of both living and deceased people involved in the crime.
• Analysis of orofacial trauma and bite marks found on attacked victims and in other substances found in the crime scene and related places like wood, leather, and food.
• Constructing a picture of the lifestyle and diet at an archaeological site.
Unidentified victims that have died from unnatural causes require dental evidence for identification. An accurate charting of the teeth and fillings of the victim is compared with the dental records of the missing persons. With a few teeth available, the age, eating habits, and oral hygiene may match with antemortem records. If the victim has no teeth, useful information can be obtained from studying dentures if used, and by X-ray imaging of the jaws and skull.
A real-life instance to understand the importance of forensic odontology:
Those having a penchant for knowing about thriller and true crime stories have probably heard of the infamous “Ted Bundy”. The most notorious American serial killer of the 70s was convicted of aggravated kidnapping and murder of 40 known young female victims, though the number is estimated to be over 100. Since science was not so advanced back then, the collected samples of blood, sperm, and some print smudges proved inconclusive while tracking him down. However, something distinguishable was seen on every victim’s body, a first in the history of serial killings– one or two bite marks. Here came the importance of forensic odontology.
The investigators requested Bundy who was only a suspect to provide a dental impression. They would compare it with the pictures of the suspicious bite marks that they had taken. Since he was hesitant, a surprise trip to the forensic dentist was arranged to prevent Bundy from grinding his teeth down from before to try and disguise his bite. Photographs of Bundy’s front upper and lower teeth and gums were taken. His bite prints were marked on wax and a plaster cast of his set of teeth was formed. Ted Bundy had extremely crooked teeth, leading to a uniquely uneven pattern, which would make an easier match.
When the forensic dentist testified against Ted in the trial, he highlighted the unique indentation marks and their similarities to the dental impressions of Bundy’s teeth. The structure of the unique alignment, size, and sharpness factors were outlined with the casts. When Bundy’s teeth structure and the photograph of the bite-marks were laid over each other, their overlapping showed strong resemblance. This was the first hard evidence (which Bundy later confessed about) that proved him guilty and also marked the first big win of forensic odontology.
The pieces of evidence in forensic odontology are-
• Saliva and Teeth – It is a major source of DNA because it contains sloughed epithelial cells from the oral mucosa and the inner lip surface. Teeth are preferred over bones as a major DNA source because they can withstand changes. Dental pulp, accessory canals, odontoblasts, and cellular cementum are used for DNA analysis. The vascular pulp is used for the determination of blood groups. Apart from primary identification, this DNA can also be used as a reference sample to relate to the other tissue fragments. Streptococcus salivarius and Streptococcus mutans are present in saliva and on teeth. In PCR technology, the Streptococcal DNA sequence provides helps to identify the bacterial composition from bite marks which can then be matched to the set of teeth responsible.
- Bite Marks- The bite mark is defined as the physical alteration on a substance caused by the contact of teeth. In some criminal cases, it is seen that suspect or victim has left his or her teeth marks on an inanimate object or a person. The concept of bite mark evidence is present from Roman times. As discussed above, bite marks give a lot of information. While Bundy’s case might have been a stroke of luck, relying on them solely in current cases has led to wrongful convictions because a majority of the people do not have unique dentition. Soft, malleable skin is not a clear and precise impression material that allows a lot of distortion of the marks. Additionally, teeth may make a different impression each time a bite is made, depending on many factors. Thus, bite mark evidence is nowadays accompanied by multiple DNA tests.
- Lip Print– Cheiloscopy is a forensic investigation that involves the identification of human-based lip traces on surfaces. Lip print wrinkle pattern has individual characteristics just like fingerprints. The grooves and wrinkles on the labial mucosa form a characteristic pattern and are uniform throughout life, making it a reliable form of evidence.
Age estimation is an important part of forensic odontology as human dentition follows a predictable developmental sequence. Dental aging can be due to developmental and degenerative changes. The former includes dental eruptions and hard tissue formation. Human dentition has two eruption stages and their associated ages. To assess the age of the unknown individual, the post-mortem radiographs of the individual are compared to the eruption standards. The latter implies the wearing down of teeth with age or unhealthy eating habits after an eruption. An estimation of the age can be made with the volume of the pulp cavity, as it reduces due to deposition of secondary dentine with aging.
Forensic odontology determines the sex of the individual with the following-
- Craniofacial morphology and dimensions: The morphology of the skull and mandible, a pattern formed by six traits- supraorbital ridge, nasal aperture, size and architecture of the skull, mastoid, zygomatic extensions, and frontal sinus dimension. Antemortem photographs showing prominent facial features and dental profiles help in facial reconstruction.
- Tooth dimension and morphology: Sex determination by measuring buccolingual and mesiodistal dimensions is the most reliable method. Both the dimensions are more in males compared to females. In males, the distal accessory ridge in canines is more prominent than in the female. In females, there are a lesser number of cusps in the mandibular first molar (distal or distobuccal).
- DNA analysis: The victim’s gender could be obtained from the studying of X and Y-chromosomes up to four weeks of the death.
Conclusion:
The importance of forensic odontology was not taken very seriously till recent times. If one looks up for “The awareness of Forensic Odontology among dental graduates”, the results will show numerous research articles of studies of the awareness of this branch of forensic dentistry among undergraduates and postgraduates in various places like India, Saudi Arabia, the UK, Pakistan and even among professors and legal professionals. Various forensic institutes have proposed and established independent departments in forensic dentistry.
Also read: Winemaking – Discovery or Innovation
References:
- “Ted Bundy- The final bitemark”. Link- https://sites.google.com/site/tedbundythelastbitemark/the-famous-bitemark-case
- Kaleelullah, R. A., & Hamid, P. (2020). Forensic Odontology, a Boon and a Humanitarian Tool: A Literature Review. Cureus, 12(3), e7400. https://doi.org/10.7759/cureus.7400
- Shah, P., Velani, P. R., Lakade, L., & Dukle, S. (2019). Teeth in forensics: A review. Indian journal of dental research: official publication of Indian Society for Dental Research, 30(2), 291–299. https://doi.org/10.4103/ijdr.IJDR_9_17
- Divakar K. P. (2017). Forensic Odontology: The New Dimension in Dental Analysis. International Journal of biomedical science: IJBS, 13(1), 1–5. PMCID: PMC5422639. PMID: 28533730
- Farhadian, M., Salemi, F., Shokri, A., Safi, Y., & Rahimpanah, S. (2020). Comparison of data mining algorithms for sex determination based on mastoid process measurements using cone-beam computed tomography. Imaging science in dentistry, 50(4), 323–330. https://doi.org/10.5624/isd.2020.50.4.323
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