When a single central incisor makes the difference for human identification – a case report

The analysis of dental features and patterns figures amongst the primary means for human identification established by the International Criminal Police Organization (INTERPOL). Differently from fingerprint and genetic analyses, forensic dentistry does not necessarily require a minimum number of similarities between antemortem and postmortem data. In other words, human identification could be achieved from the analysis of a single distinctive tooth or even from a single dental identifier. This study aims to report a case of dental human identification of a charred body. Police investigations were carried out and narrowed the scenario towards a single victim. Fingerprints were destroyed by the fire, hence the relatives of the victim were requested to provide any antermotem dental data. A panoramic radiograph was provided. Developing third molars were visible as well as the endodontic treatment, post and core, and the nonmetallic crown of the maxillary right central incisor (tooth #11). Postmortem radiographs were taken from the cadaver and revealed the same therapeutic dental identifiers found in tooth #11. The observed similarities and the lack of discrepancies between antemortem and postmortem data converged to the positive identification of the victim. This study illustrated the importance of Forensic Dentistry for complex cases of human identification, such as those exposed to fire. Especial attention is driven to the possibility of safely achieving positive human identification with the contribution of a single distinctive tooth. Forenses; Radiografía panorámica; Incisivo central superior. a human rights perspective, highlighting the role of forensic dentistry in challenging human identification cases is necessary to make to society and the dentistry community aware of the importance of retrieving the identity of the missing unknown. This study aimed to report a case of positive identification of charred by means of analysis of


Introduction
Human identification is part of the main tasks of forensic dentists (Senn & Weems, 2013). In practice, this task is accomplished by comparing antemortem (AM) and postmortem (PM) data . The former is collected from dental records, while the latter is collected from the cadaver during the autopsy (Silva et al., 2015). Generally, the AM data is provided by the alleged relatives of the victim or directly by dentists that treated the victim in life (Almeida et al., 2015). The search for relatives or dentists is aided by police investigations that narrow the search from lists of missing persons (Almeida et al., 2015). The PM data, on the other hand, is obtained in the morgue from a pathway that is more straightforwardvia intraand extra-oral examination (Rosario Junior et al., 2012). Photographs, radiographs and the description of visual inspection build-up a PM dossier that aims to reproduce and to be comparable with AM photographs, radiographs and written clinical findings (Carvalho et al., 2009). In theory, the AM and PM data are compared in a reconciliation process designed to assess the similarities and discrepancies between dental features (Ata-Ali & Ata-Ali, 2014). The outcomes of this process might be positive identification, possible identification, insufficient evidences and exclusion (Queiroz et al, 2017).
Technically, the dental features analyzed during dental human identification are named identifiers and may be categorized into morphological, therapeutic and pathological (Angelakopoulos et al., 2017). The first, second and third categories are properly exemplified by peg-laterals, root canal fillings and periapical cysts, respectively. Dozens of other identifiers are known and categorized in practice (Franco et al., 2013;Franco et al., 2019). The combination of identifiers creates dental patterns that may be very distinctive, which makes forensic dentistry a reliable and scientifically acceptable method for human identification . However, challenging circumstances may occur when few identifiers are available. In this context, forensic dentistry stands out compared to other primary means for human identification, namely ridgeology and genetics (Interpol, 2018). More specifically, forensic dentistry enables human identification from a single distinctive identifierwithout necessarily requiring a higher number of minimum similarities between AM and PM evidences (Silva et al, 2009).
From a human rights perspective, highlighting the role of forensic dentistry in challenging human identification cases is necessary to make to society and the dentistry community aware of the importance of retrieving the identity of the missing and unknown. This study aimed to report a case of positive identification of a charred victim by means of radiographic analysis of dental features.

Methodology
This study had a descriptive design and was presented as a forensic case report. Any personal data were omitted in order to guarantee anonymity of the involved individuals. No image was used other than radiographs with no personal information.

Preliminary medical assessment
In 2019, two charred bodies were found in a car in Central-Western Brazil. After crime scene investigation, the bodies were sent to the local morgue for the investigation of the cause of death and identification.
The cause of death was not conclusive, but firearm projectile wounds were found in the victim's mandible. The severe carbonization did not allow additional exams such as histopathological analysis of the upper airways and carboxyhemoglobin levels. Carbonization also hampered the human identification process as it extended deeply into thoracic and abdominal organs. Hands and feet were destroyed by the fire as well, which made fingerprint analysis unfeasible.

Specific dental assessment
The dental autopsy was carried out by two forensic dentists both with more than 15 years of experience in practice.
The victim's skull was partially broken, but maxilla and mandible were preserved. Visual inspection and radiographic analyses were performed. The first revealed metallic brackets with orthodontic wire on the anterior teeth and premolars of both dental arches ( Figure 1). Radiographically, third molars were found unerupted and impacted in the maxilla and the mandible ( Figure   2). Dental age estimation was performed and suggested mean estimated age of 17.55 ± 1.22 years (Gunst et al., 2003). The dental examination progressed and revealed a maxillary right central incisor (tooth #11) with endodontic filling material, metallic post and core and aesthetic (non-metallic) crown. The other teeth did not reveal therapeutic identifiers.

Antemortem data search
Police investigations indicated that the alleged victim was a male aged 17 years reported missing for 28 days. The potential relatives of the victim were asked to provide any type of dental or medical document to support the identification process. A panoramic radiograph dating nearly one year was provided ( Figure 3). The same information found PM was found AM. The only explainable discrepancy was related to the third molarswhich presented root developed at an earlier developmental stage compared to the PM radiograph.  Research, Society andDevelopment, v. 10, n. 1, e24210111010, 2021 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v10i1.11010 6

Comparative analysis
Reconciliation was achieved by comparing and matching AM and PM identifiers (Figure 4), especially those therapeutic (i.e. root canal filling, post, core and crown) and morphological (unerupted, impacted and not completely developed third molars). Unexplainable discrepancies were not detected. Positive dental identification was established.

Discussion
Radiographs, computed tomography scans, and magnetic resonance imaging figure as supplementary exams that fundamental value to many fields of Dentistry (White & Pharoah, 2013). Specific modalities and techniques for image acquisition are chosen depending on the clinical need. In Endodontics, several periapical radiographs are taken during the treatment to guide dentist's performance (Ahmed, 2015). In orthodontics, panoramic radiographs are used to have an overview of the dentomaxillofacial structures prior treatment, while lateral cephalometric and carpal radiographs are used to predict growth and design treatment planning (Isaacson et al., 2015). Forensic Dentistry, it is not different. Every single radiograph might contribute with utmost evidence for human identification. Autopsies aided by image exams are performed with more detail and access to morphological therapeutic and pathological information (Manigandan et al., 2015). Based on the exposed, this study aimed to report a case of positive human identification of a charred victim through the radiographic analysis of dental identifiers.
At first sight, the presented case might be tricky suggesting that only a single tooth (#11) was examined and considered during the identification process. A deeper look, however, reveals that all the evidence from the available dentition was taken into account. In other words, the remaining teeth with no therapeutic identifiers were present in the mouth and their presence itself is considered an identifier (Interpol, 2018). According to Interpol, present and sound teeth are even coded (Interpol, 2018). This code is especially important in practice because it can exclude single or multiple victims with teeth missing AMas it creates unexplainable discrepancies with teeth present PM. Present teeth, clustered within morphological identifiers, were registered in the present case with other morphological identifiers namely the developing unerupted and impacted third molars . These teeth contributed each not only as identifiers but also as parameters for dental age estimation. This case became less complex when dental age estimation narrowed the search for potential victims from a missing persons list. In mass disasters, dental age estimation has even more value in open scenarios, in which forensic labor may be drastically reduced after exclusion by age.
Other identifiers considered in this case were the root canal filling, post, core and crown all found in tooth #11. These identifiers, clustered in the therapeutic group, were registered with other therapeutic identifiers, namely the orthodontic appliances (wire and brackets). In practice, they are quickly detectedespecially in radiographs, because of their radiopaque aspect and clear representation of treatment intervention in the victim. The presence of identifiers from endodontic and orthodontic treatment in the victim corroborates the idea that Dentistry is constantly supplied with image exams in daily practice. In this context, Endodontics (Berketa et al., 2019) and Orthodontics (Picoli et al., 2019) figure as powerful sources of AM data for Forensic Dentistry. It is important to note, that dental human identification should combine all the available identifiers (Pereira & Santos, 2013). The higher the number of matching identifiers AM and PM, the stronger and the identification report. Cases founded on single or very scarce match should be avoided unless the identifiers are very distinctive.
In every situation, forensic dentists must remember that uniqueness of the human dentition is accepted in Court for human identification but not scientifically proven.
The combination of several available dental identifiers is what makes the identification process reliable and ranks forensic dentistry among the primary means for human identification. Knowing the importance of examining and registering morphological, therapeutic and pathological identifiers is a must for every forensic dentist. For optimal performances in the forensic routine, morgues and autopsy rooms should be equipped with radiologic devices, so features not found via visual inspection, such as root canal fillings, can be properly searched. In order to contribute to justice, general dentists and specialists must store and update dental records and images, and provide them when requested by Law.
The case reported in this study illustrated the dental human identification process by matching morphological and therapeutic identifiers. The charred victim identified in this study had several sound teeth present and a distinctive central incisor with four identifiers (root canal filling, metallic post and core, and aesthetic crown) with utmost contribution to human identification. Despite the relevance of the distinctive tooth, the combination of all available dental identifiers is encouraged in practice for optimal performances.

Final considerations
Differently from fingerprint and DNA analyses, human identification based on dental features does not necessarily require a minimum number of matching evidences. Efforts, however, are made to combine the highest number of evidences to support the forensic report with strong data. In certain situations, forensic odontologists will face teeth with multiple identifiers (especially when it comes to therapeutic ones). These teeth deserve especial attention because they can increase the uniqueness of the victim's dental pattern. The present study illustrates a case of a very distinctive central incisor that contributed (together with other findings) for dental human identification.