|Year : 2021 | Volume
| Issue : 3 | Page : 105-108
Recent advances in forensic odontology: An overview
P Aishwarya Menon1, N Anoop Kumar2
1 House Surgeon, PSM College of Dental Science and Research, Thrissur, Kerala, India
2 Associate Professor, Department of Oral Pathology and Microbiology, PSM College of Dental Science and Research, Thrissur, Kerala, India
|Date of Submission||19-Jul-2020|
|Date of Decision||15-Sep-2020|
|Date of Acceptance||05-Aug-2021|
|Date of Web Publication||27-Sep-2021|
N Anoop Kumar
Department of Oral Pathology and Microbiology, PSM College of Dental Sciences and Research, Akkikavu, Thrissur, Kerala
Source of Support: None, Conflict of Interest: None
Forensic odontology is a branch of forensic sciences that uses the skill of a dentist in personal identification during mass calamities, sexual assault, and child abuse to name a few. Forensic odontology is an evolving science and has a greater scope of development. Recent advances in the field of genetics and molecular biology have contributed to the rapid growth of forensic odontology. In case of a crime scene, forensic odontologists play a major role in investigating and interpreting dental evidence. Forensic odontologists utilize the knowledge of dentistry in bite mark analysis, fixation of identity in mass disasters, and age estimation. Thus, the duty and responsibility of forensic odontologists has increased in recent years. Therefore, practicing dentists and dental students should be made aware of the available newer technologies and its use in forensic dentistry. This article gives an overview of recent advances used in identification in forensic dentistry.
Keywords: Denture, DNA, facial reconstruction, forensic odontology, microscopy, tongue prints
|How to cite this article:|
Menon P A, Kumar N A. Recent advances in forensic odontology: An overview. J Forensic Sci Med 2021;7:105-8
| Introduction|| |
According to Federation Dentaire Internationale, forensic odontology is that branch of dentistry which in the interest of justice deals with proper handling and examination of dental evidence and presentation of dental findings. Teeth are the most robust tissues of the human body, and usually most resistant to postmortem decay. The dental patterns tend to be highly individualized and are therefore very useful for identification if appropriate records are available for comparison.
Forensic odontology has three major areas of utilization: (1) diagnostic and therapeutic examination and evaluation of injuries to jaws, teeth, and oral soft tissues, (2) the identification of individuals, especially casualties in criminal investigations and/or mass disasters, (3) identification, examination, and evaluation of bite marks which occur with some frequency in sexual assaults, child abuse cases, and in personal defense situations.
Identification of the deceased is generally done visually by a relative or an acquaintance, who knew the person throughout life. This is often performed by looking at the characteristics of face, body options, or personal belongings. However, this technique becomes unreliable once the body options are lost because of postmortem changes (like decomposition, etc.). Visual identification in those cases can subject to error.
Other methods used for individual identification include personal information (such as height, build, age, presence or absence of hair), medical information (such as scars, tattoos, birth marks, implants, and amputation prosthesis), footprint records from a chiropodist/podiatrist, clothing, personal effects, fingerprints, DNA, and dental identification. Identification by dental means gains more importance because the dental tissues are often preserved even if the deceased person is skeletonized, decomposed, burnt, or dismembered. Dental tissues are often used to determine the age, sex, and ethnicity of a person.
Conventional methods used in forensic odontology include dental record maintenance, dental imaging, bite mark analysis, cheiloscopy, and rugoscopy.
In addition to this, recent concepts such as facial reconstruction, denture identification, DNA fingerprinting, and tongue prints have been introduced in the field of forensic odontology.
| Recent Advances in Forensic Odontology|| |
Techniques involving DNA in forensic dentistry offer a new tool when traditional identification methods fail due to effects of heat, traumatism, or autolytic process. There are many biological materials such as blood, semen, bones, teeth, hair, and saliva that can be used for DNA typing. Both genomic and mitochondrial DNA can be used. Teeth are an excellent source of genomic DNA. The use of techniques based on polymerase chain reaction has acquired greater importance in DNA postmortem analysis in forensic cases [Figure 1].
|Figure 1: Schematic photograph showing replication of DNA by polymerase chain reaction|
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DNA analysis/profiling or DNA fingerprinting reveals the genetic makeup of a person.
Various ways of running a DNA fingerprint are as follows:
- Restriction fragment length polymorphism method
- Polymerase chain reaction
- Short tandem repeat typing
- Analysis of mitochondrial DNA
- Analysis of Y chromosome
- Single-nucleotide polymorphism.
Teeth as a source of DNA
Teeth are normally resistant against extreme circumstances. Hence, their morphology is well- preserved and the enamel also protects the contents of the pulp chamber against external factors. The component of enamel, that is the hydroxyapatite crystals, binds to the DNA and stabilizes it. Therefore, an abundance of DNA can be obtained from the teeth.
DNA from the teeth can be obtained by crushing, but it destroys the morphology of teeth.
Other methods are:
- Conventional endodontic access
- Vertical splitting
- Horizontal section
- Cryogenic grinding.
In this technique, the tooth is frozen whole using liquid nitrogen and put in an electromagnetic chamber. The tooth is ground to a fine powder by alternating magnetic fields. This technique is easier and very effective. It also allows obtaining DNA from endodontically treated teeth because of the presence of DNA in hard tissues. Crushing gives better results than sectioning as more DNA can be obtained.
| Facial Reconstruction|| |
Facial reconstruction aims to produce a likeness that is recognizably close to that of the deceased person. A computerized facial reconstruction system was developed for three-dimensional (3D) surface data acquisition of the human face. The skull is acquired with a laser video camera. Skull data are then imaged as a fully shaded 3D surface. The face can be drawn with the help of a computer software (for e.g., Vitrea 2.3 version volumetric visualization software). 3D computed tomography (CT) imaging has been found to be more accurate than imaging performed directly on CT slices and two-dimensional (2D) CT image reconstruction [Figure 2].
|Figure 2: Steps of manual method of forensic facial reconstruction: (a) replicated skull with landmarks and already constructed eye socket and nose structure (b) advanced reconstruction of the soft facial parts, (c) crude model of the face|
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Methods of facial reconstruction
Forensic facial reconstruction can be achieved by two basic techniques. These are 2D and 3D facial reconstructions. Each of them is again divided into manual and automated/computer-aided methods.
These methods were 2D and 3D employing impressions and clay modeling techniques. In this technique, the impressions of skull were made, and casts were fabricated over which different landmarks pins were applied.
These methods were relatively simple but had a few limitations. They were time consuming, technique sensitive, and expensive.
This method is based on the application of mean tissue thickness for the given anatomical landmarks.
Advantages of computerized facial reconstruction are:
- Provides high quality and resolution along with better visualization of anatomical and pathological state
- Provides 3D images of 2D objects using soft-tissue depth markers
- Completely noninvasive procedure as it allows virtual manipulation and preservation of original object.
- Technique sensitive
- Requires highly trained specialists for the interpretation of obtained images.
| Denture Identification Methods|| |
As denture prosthesis is quite resistant to high temperatures, they can be used as aids in identification process. The denture can reveal the positive identity of a person only if it is marked. Two methods of marking have been proposed: the surface marking method and the inclusion method. The inclusion method includes metal identification bands, computer-printed denture microlabeling system, lead paper labeling, embedding the patient photograph, denture barcoding, T bar, laser etching, lenticular card system, radiographic identification tags, and electronic microchips. However, inclusion methods are more permanent and provide a more predictable result [Figure 3] and [Figure 4].
| Comparison Microscope|| |
The use of microscope plays a major role in forensic science. Microscopic examination of teeth can confirm sex by the presence or absence of Y chromatin. It is difficult with the traditional microscope to achieve different views as it is time consuming. Recently, forensic technology has developed a prototype virtual comparison microscope which helps in analyzing similar specimens. It utilizes images of deformed bullets, bullet fragments, and various types of rifling from the company's Bullet Trax-3D system [Figure 5].
|Figure 5: Virtual comparison microscope which can be used to compare two specimens simultaneously|
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| Tongue Prints|| |
The morphological aspect of the tongue dorsal surface is unique for each and every individual. For this technique to be successful, the antemortem photograph or impression of the tongue should be available. The lingual impression together with its photographic image may constitute secure methods for forensic dentistry identification, in addition to rugoscopy and cheiloscopy [Figure 6].
|Figure 6: Alginate impression of the dorsal surface of the tongue was made and a positive replica is made using Type II dental stone|
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Methods of recording tongue prints:
- Basic features of the tongue such as color, surface texture, mobility, and any other special characteristics can be inspected by simple visualization
- Alginate impression followed by cast preparation can be used
- Obtaining digital images of the tongue using digital software
- Sublingual vein analysis
- Histological examination.
Oral autopsy refers to an elaborate examination of the oral cavity as teeth are the most resistant to decomposition and can be used for identification purposes. The time elapsing between death and forensic examination is crucial as the body undergoes various stages of decomposition, thus compromising the overall examination. In the oral cavity, mouth opening is restricted due to rigor mortis as the muscles of mastication become stiff. Hence, to examine the tongue and other structures in the oral cavity, certain specific dissection techniques are used.
Extraoral incisions (facial dissection) – these are bilateral incisions from the oral commissures to the body of the ramus.
Inframandibular incision – it is the dissection of the skin inferior and medial to the mandible in a direction from the ear across the midline to the opposite ear. These approaches are followed for viewable bodies when the oral cavity is inaccessible due to rigor mortis.
| Conclusion|| |
Forensic odontology depends on the knowledge about teeth and supporting structures. The unique feature of dental tissues is that it provides accurate results. It plays a major role in identification of those individuals who cannot be identified visually or by other means. It is one of the upcoming branches in dentistry which helps in identifying victims in mass disasters and in many medicolegal investigations. Hence, forensic odontology has now become an integral part of medical and dental sciences.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]