Introduction
Forensic dentistry, also known as odontology, is the discipline of dentistry that deals with the presentation of dental evidence for legal proceedings. This is in the interest of justice and includes the evaluation and management of dental evidence of the victim. Chronological age estimation is of important use and obtaining, or analysis of dental deoxyribonucleic acid (DNA) can also prove extremely useful for identifying the victim at a crime scene. Bite marks evaluation is another important tool of consideration that is admissible to the court if produced without distortion or with proper documentation.
What Are the Various Chronological Age Estimation Methods?
Chronological age is always useful in the field of forensic dentistry as well as for the determination of dental maturity and tooth development. This chronological age determination is possible with reasonable accuracy to an extent when used in conjunction with electronic methods that maintain a record of the dental, skeletal, and maxillofacial records of an individual by the dental surgeon.
The stages of development of skeletal tissues are used to determine the estimated age of an individual, especially in young adolescents or children. In relation to forensic dentistry, chronological age plays a crucial role in the dental age assessment of an individual, be it for the identification and investigation of human remains or to identify the perpetrators of crime, fatality, or disasters, the aging of dentition is definitively employed in forensic casework. The various methods used for chronological age determination are:
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Radiological methods.
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Biochemical methods.
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DNA analysis.
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Bite marks.
How Is Age Estimation Done Using Radiological Methods?
In cases that need forensic dentists as interdisciplinary specialists to help solve a case, the dental age estimation is pivotal for the detection and investigation of unidentified remains of an individual. By eventual comparison of both medical, dental, and, if needed, even radiographic records of an individual makes the forensic dentist possible to assess and separate the identity of individuals in events like fatality incidents and in disasters. The radiographic changes associated with dental development in children can also be of important documentation to the forensic dentist. Dental radiographs, even in the case of adults, can definitely help determine the chronological age of living and deceased individuals. Though many age estimation methods have come to the fore in the field of forensic odontology in the recent decades, radiography in the dentistry field remains an important model of evidence and documentation for age estimation and in the identification of living or deceased individuals for detecting the perpetrators of crime or in identification.
What Are Biochemical Methods for Age Estimation?
Biochemical methods are also used in estimating the chronological or dental age of the individual. These methods primarily assess the metabolically stable amino acid aspartate in living and dead subjects. This is done by the assessment of ratios of isomers, namely levorotatory and dextrorotatory isomers found in tissues of the subject or the individual. The basis of these biochemical age estimations is as the tissues of the tooth, that is, the enamel and dentin, as they undergo the aging process, the levels of D form of aspartic acid increase within these calcified structures.
The racemization process is adopted to observe the transformation of the L form of aspartic acid and whether it can be converted into the D form of aspartic acid. Hence this amino acid plays a crucial role in biochemical age estimation in forensic odontology and helps determine the chronological age of an individual.
What Is Dental DNA?
Each individual's genetic information is deemed unique as deoxyribonucleic acid, or DNA is contained within the nuclear and mitochondrial molecules of cell structure. Except for identical twins, no two individuals have the capability of sharing the same DNA. The nuclear form of DNA can be transmitted via a parent, whereas the maternal route derives only usually the mitochondrial DNA.
Hence to understand comprehensively, dental DNA is indeed a unique biologic molecule for the positive identification of an individual. On obtaining this material from tissues or be it from bodily fluids at the site of a crime or from the remains of a deceased individual, it remains a piece of important forensic evidence for law work and in delivering justice and solutions via the forensic dentist after evaluation and assessment of the crime scene or in post mortem evaluation of the dead individual.
What Are the Various DNA Analysis Techniques?
For the identification of dental DNA, the most commonly used method is the restriction fragment length polymorphism (RFLP) technique. In this technique, large amounts of DNA that are more than usually 100 pg of DNA when submitted as a sample for analysis can be forensically studied.
The alternative to this technique is the PCR or polymerase chain reaction technique. The PCR method is adopted for forensic tests when only a very small amount of DNA (less than 100 pg) is obtainable. Hence only small amounts of DNA can be evaluated using the PCR technique. The dental DNA or oral DNA can be obtained as well from saliva, blood, or any fluid samples of the individual or of the remains of the deceased individual if they are unburied. However, positive identification can still be affected as it depends on the tissue given for DNA sampling. The most protected form and uncontaminated form is always obtained from the calcified tissues of the tooth or the tooth pulp, which is most useful for analysis to the forensic team experts.
How Are Bite Marks Useful in Forensic Dentistry?
Bite marks are the characteristic size and shape geometrically derived from the tooth patterns of the individual. In the act of biting, whether a human or an animal, the imprint of the tooth surface or the dentition is upon the object or the surface. This pattern left by human teeth can be studied, evaluated, and compared by the forensic dentist or the interdisciplinary forensic expert team to the one who allegedly caused it. Even if the individual identified is a victim or a suspect, the bite marks pattern that is imprinted on the skin or object can give the team an insight into the individual characteristics of the person biting consistently with their teeth marks. In the case study of bite marks, these characteristics are routinely made by specific teeth and have a commonly associated shape:
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The maxillary central incisor bite marks resemble a large rectangle, while the maxillary lateral and mandibular incisors resemble a small rectangle.
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The cuspids or canines poise a triangular print pattern, while an eight-shaped pattern can be seen when there is a bite with the maxillary cuspid teeth.
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The mandibular molars are not clearly visualized nor routinely seen in patterns of human biters.
Hence though forensic dentistry is a continuously evolving science, the guidelines and training for forensic dentists are constantly reviewed and revised to ensure that bite marks evidence can be acceptable or admissible in the court.
Conclusion
The forensic dentist can play a crucial role in identification that is not only legally acceptable but also a piece of significant dental evidence, if documented, can prove of great value to law enforcement. In developing countries, the need to train forensic dentists is even more as it can give crucial insight into victim identification and law enforcement and is of valuable assistance to the core forensic teams. Quantitative data have not been set yet to establish the guidelines for bite marks evidence except for the above-mentioned geometric patterns associated with human dentition upon the skin surface or object (as opposed to DNA analysis or fingerprint analysis, where quantitative data play a role). Hence despite the limitation that the teeth, or rather our human dentition, is never primarily static (it is continuously subject to forces, wear and tear, alterations, treatment, periodontal disease, and aging), the inspection of the teeth and jaws is an accepted forensic method for human identification.
