Endodontic images as a forensic identification: A literature review Imagens endodônticas como identificação forense: Uma revisão da literatura Imágenes endodónticas como identificación forense: Revisión de la literatura

Several radiographs are taken during endodontic treatment, thus providing a large number of images with individual characteristics that can be used for forensic identification of an individual. This study aimed to review the literature related to the use of endodontic radiographs in the identification of cadavers. A bibliographic search was carried out in the following databases: PubMed, Scielo, Periódicos Capes, and Web of Science. The keywords used were: forensic dentistry, endodontics, dental radiography, forensic identification. In total, 24 articles related to radiography in the identification of cadavers were found. Among them, 8 studies were selected for including endodontic radiographs for this purpose, comprising different types of studies: case reports of forensic identification through endodontic radiography (4); “in vitro” studies on the influence of high temperatures on endodontic materials and their radiographic images (2); a literature review on how radiographs can be used for identification (1); a comparative study between antemortem and post-mortem endodontic radiographic images (1). Overall, the present study showed that endodontic radiographs have a significant amount of information that can be used to identify a cadaver. Therefore, it is important to perform and store radiographs properly and for long periods. Literature related to the subject is still scarce and further studies are needed.


Introduction
Forensic dentistry is a specialty that provides legal information by collecting, testing, and evaluating dental evidence, which can contribute to clarify several legal aspects, and identify the remains of individuals that cannot be visually recognized, i.e. in situations where the corpse is already in an advanced stage of decomposition, skeletonized, or carbonized (Avon, 2004;Silva et al., 2006;Almeida et al., 2015). According to the Disaster Victim Identification Guide of Interpol, dental identification is considered the primary method of identifying cadavers. Its positive result is sufficient for personal identification without additional support from other methods (INTERPOL, 2018).
Endodontics is the specialty of dentistry that studies the morphology, physiology, and pathology of the dental pulp and periradicular tissues, to preserve the tooth through prevention, diagnosis, prognosis, treatment, and control of pulp and tooth changes. (Kerekes & Tronstad, 1979;Bergenholtz, 2016). Conventional two-dimensional radiography is the most used imaging method in dentistry, with periapical radiographs having a fundamental role in endodontics, requiring several radiographic shots, both at the beginning, during, and after the endodontic intervention (Ee et al., 2014;Antony et al., 2020).
Dental structures are considered the most resistant in the human body. They are usually preserved after death, even when caused by fire or water, which makes them useful in cases of identification of victims with compromised human skeletal remains (Silveira, 2013). In addition, studies show that the materials used in dental restorations and endodontic treatments are highly durable and resistant, remaining in the dental cavity even when exposed to high temperatures, being of great importance in the identification process (Weisman, 1996;Spadácio et al., 2011).
The identification of human remains through dental documentation is performed through a comparative technique, whose objective is to compare dental records and information recorded by dentists in clinical consultations performed before the death of an individual. These data include written notes, studies, radiographs, and photographs, with post-mortem (after death) dental records obtained via forensic examination. Generally, people who have undergone dental care are easier to identify than those with little or no restorative materials in the dental arcade (Pretty, 2007;Almeida et al., 2015).
Radiographs are the most reliable source of antemortem data for identifying bodies as they record morphological details; are not prone to potential errors inherent in a purely written document; and can be precisely duplicated by a different operator on the same patient, allowing comparison with post-mortem findings (Forrest & Wu, 2010).
For forensic identification, it is necessary to have the medical records of the victims in hand so that the radiographs can be compared. In some countries, it is mandatory to read and update the medical records in a legible and up-to-date manner, and it is an ethical infraction to deny the patient or a medical expert access to the medical records (Conselho Federal de Odontologia, 2012). Detailed and accurate records are a vital part of the dental practice, allowing quality care and monitoring to patients, in addition to having an important role in teaching and research, as well as in legal matters (Charangowda, 2010).
Hence, the objective of this literature review is to evaluate the importance of endodontic radiographs in the identification of cadavers.
The last access was carried out in February 2021 using combinations of the following keywords: forensic dentistry, forensic anthropology, endodontics, dental radiography. In addition, the bibliographies of all relevant articles were manually searched.
A total of 24 publications were found. The inclusion criteria were full available articles that addressed the theme of the study.
There was no restriction on language or type of study. At first, the works were selected according to their titles and then the abstracts were analyzed. Articles that did not have abstracts or did not address the proposed topic were excluded. Thus, 8 articles were selected. Table 1 provides a summary of the relevant findings from each selected study. The first clinical case report of victim identification using dental data was made by Weisman in 1996, whose radiographs of the remains found were compared to those obtained during endodontic treatment of the victim performed four years before the fire (Weisman, 1996). Other clinical cases of identification of cadavers through comparisons of antemortem and post-mortem endodontic radiographs were reported (Forrest & Wu, 2010;Silva et al., 2014;Silva et al., 2016). In vitro studies have evaluated the resistance of root canal filling materials after high-temperature incineration, to assess their use in forensic identification (Savio et al., 2006;Bonavilla et al., 2008). In addition, a clinical study was found that investigated the discriminatory potential of the radiographic morphology of filled canals in forensic identification (Khalid et al., 2016). Finally, a literature review on the relationship between endodontics and cadaver identification was found (Ahmed, 2017).

Discussion
The information obtained in this literature review shows that endodontic radiographs represent an important biometric method in the recognition of victims. Identification is usually performed by comparing antemortem and postmortem records (Charangowda, 2010). Information contained in radiographs is considered definitive evidence in legal or identification proceedings (Sholl & Moody, 2001, Kavitha et al., 2009. Forensic dentists are often called upon to identify the remains of individuals who cannot be visually identified, which covers a large number of situations such as burnt, fully decomposed, or mutilated remains (Ahmed, 2017).
Endodontics emerges as a potential source of antemortem data as radiology is widely used to record, evaluate and plan endodontic treatment, (Forrest & Wu, 2010;Silva et al., 2016). Endodontic radiographs can be accurately duplicated by any operator at different locations and times in the same patient (Khalid et al., 2016). However, the position of the radiographic images represents a challenge in identification. It may be necessary to reproduce more than one position or even technical errors present in antemortem radiography so that the post mortem radiography has similar characteristics in the comparison (Forrest & Wu, 2010).
Endodontically treated teeth contain a rich source of data that allow antemortem and postmortem comparisons due to the different possible morphologies of root canals, the strength of endodontic filling materials, and the low probability of retreatment compared to coronary restorations (Weisman, 1996;Forrest;& Wu, 2010;Silva et al., 2014;Silva et al., 2016).
Root canal filling materials remain preserved after high-temperature incineration, showing greater resistance compared to materials used in coronary restoration, such as composite resins or amalgam (Savio et al., 2006). In addition, the elementary composition of materials used in endodontic treatment (e.g. gutta-percha cones, endodontic sealers, and fractured files) remains original after being incinerated, contributing to the generation of a database to aid in forensic identification (Bonavilla et al., 2008).
The dental surgeon has an ethical and legal obligation to produce dental radiographs (conventional or digital) and store them properly, for legal purposes or forensic identification (Almeida et al., 2015;Savio et al., 2006). All information in the medical record must be clearly written, duly signed, and dated by the person responsible (Avon, 2004;Almeida et al., 2015). The time of keeping the dental record is a subject of extreme complexity. There is no defined minimum period for the mandatory maintenance of dental records. The Federal Council of Dentistry, through Opinion no. 125/92, states that the possession of the medical record belongs to the patient and its custody by the professional, and should be stored for at least ten years after the patient's last appearance (Conselho Federal de Odontologia, 2004). On the other hand, the Consumer Protection Code ensures that dental records must be considered durable, especially in cases of negligence hidden in the medical record.
For these situations, article 27 presents the limitation period in five years of the intention to repair the damage caused, starting the counting of the term from the knowledge of the damage (Saraiva, 2011).

Conclusion
Overall, this review shows that endodontic radiographs have a significant amount of information that can help to identify a cadaver, which makes Endodontics an important specialty for Forensic Dentistry. Thus, radiographs must be taken properly and stored for a long period, due to their value in identifying individuals. Literature related to the subject is still scarce and further studies are needed.