23 Dental Anthropology 2020 │ Volume 33 │ Issue 01 A Systematic Literature Review and Case Report of Bilateral Two- Rooted Mandibular Deciduous Canines and Their Usefulness in Forensic Identification Liliana Marín 1 , Sandra Moreno 2 , and Freddy Moreno 2* 1 Technical Criminal Investigative Body at Office of the Attorney General, Bogotá, Co- lombia 2 Faculty of Health Sciences of Pontificia Universidad Javeriana Cali, Colombia There are two maxillary and two mandibular ca- nine teeth located on each hemi-arcade among the incisors and premolars (Kraus et al., 1969). The root of the maxillary canine is convex on its vestib- ular and lingual surface; its mesial and distal sur- faces are broad and somewhat flattened; while the root of the mandibular canine is shorter and flatter with marked longitudinal grooves. The apical por- tions of the root could exhibit mesial drift, which may still have a bifurcation, making a double root (Hillson, 1996). Anatomically, the canines have a bulkier (in the vestibular-palatal or lingual) and longer root than the other teeth. This anatomy al- lows a strong anchor in the alveolar bone and gives a high resilience to forces generated in the mastica- tory cycle, depending on its high nociceptive ca- pacity during the action of the muscles of mastica- tion to sensory stimuli. This protection is achieved through the occlusal relationship between the max- illary and mandibular canines, in which, when the lateral movement of the mandible occurs the lower canines slide on the upper. This function is de- scribed in the literature as “canine function” or “canine key” to produce posterior teeth disclusion; hence, canines are seen as fundamental teeth of dental occlusion (Scott & Turner, 1998). These mor- pho-physiological traits and strategic position in the maxillaries give the canine teeth high re- sistance; for this reason, they are the teeth with the lowest prevalence of loss. Therefore, canines have value in forensic odontological identification pro- cesses. In this context, dental anthropology through the characterization of individuals by analysis of expression and variation of root and coronal dental morphological traits is fundamental (Rodríguez & Delgado, 2000). In single-rooted teeth, as canines, the root sheath grows as a tube shape as radicular odonto- blasts are differentiated. These odontoblasts regu- late the process of dentinogenesis around the den- tal pulp, and are fragmented to allow the passage of cells that differentiate into cementoblasts from the dental follicle, which lead the process of ce- mentogenesis. In multiradicular teeth, two or three primary apical foramen constitute the radicular trunk (according to the number of roots and their ABSTRACT A systematic review of the literature in PubMed was made by combining the terms “cuspid” and “tooth root” as MeSH health descriptors, combined with the Boolean operators “+” and “&” to obtain describing publications about two roots canines in order to sustain, on scientific evidence, the application of dental anthropology (dental morphological variations) in forensic science (forensic processes of dental identification). This literature review identified reports that describe the presence of two-rooted canines and the number and distribution of root canals for diagnostic and therapeutic pur- poses; and one report in which description was performed for forensic identification purposes. The de- scriptions corresponded to different cases of permanent maxillary canines with left unilateral expres- sion, permanent mandibular canines with right unilateral expression, left unilateral expression with bi- lateral expression. There were no reports of deciduous dentition. Likewise, a case report in which skele- tonized human remains were identified by the presence of bilateral two-root mandibular deciduous ca- nines is described. *Correspondence to: Freddy Moreno Faculty of Health Sciences Pontificia Universidad Javeriana Cali Colombia fmorenog@javerianacali.edu.co Keywords: forensic dentistry, dental identification, dental anthropology, deciduous tooth, canine teeth, two-roots 24 Dental Anthropology 2020 │ Volume 33 │ Issue 01 position). Each root grows longitudinally as if it were a single-rooted tooth. Therefore, the existence of a number of roots higher than normal is associ- ated with hyperactivity of Hertwig’s epithelial root sheath (HERS) (Holtzman, 1997) or its partial pathological degeneration, which causes an invagi- nation by the dental papilla inducing an accessory root (Sohn et al., 2014). This paper reports the case of skeletonized hu- man remains that were identified using ante- mortem-postmortem dental comparison, due to the presence of a bilateral mandibular two-rooted de- ciduous canine. Also presented is a review of the clinical literature on two-rooted canines. The goal of this paper is to demonstrate the application of dental anthropology (i.e., dental morphological variations) in the forensic dental identification pro- cesses. Forensic Odontology The process of identifying humans has particular relevance in human societies, because every single individual has an identity that must be conclusive- ly proven at the time of death for social, cultural, religious, legal, and economic purposes. Usually, the legal life begins with a birth certificate and ends with the death certificate (Mertz, 1977). In the forensic sciences and during criminal investiga- tions, investigators, prosecutors, and forensic ex- perts (including the dentist) must interpret and classify the information collected. A careful exami- nation of the soft and hard tissues of the stomatog- nathic system provides physical evidence that helps to establish the identity of a person (Krishan et al., 1997). Dental analyses and scrutiny of the soft and hard tissues that make up the stomatog- nathic system document physical evidence and/or injuries. If these are documented, it may help to establish the identity of an individual, to refute or confirm a testimony, or objectively link a victimiz- er with the victim and the crime scene; such as part of the comprehensive forensic analysis of a corpse and related elements within the context of each particular case (Whittaker, 1995). Teeth are used as an identification tool in foren- sic odontology investigations. Their high identifi- cation value relies on the number of teeth, patho- logical conditions, restorations, dental materials used, prostheses, and implants. Therefore, if a set of remains is missing teeth, it can be difficult to identify the individual (Krishan et al, 1997; Whit- taker, 1995; Rothwell, 2001; Pretty & Sweet, 2001a, 2001b). Overall, dental identification is based on a comparison between the antemortem and postmor- tem record, which provides the forensic odontolo- gist with enough distinctive features to make a positive identification (Pretty & Sweet, 2001a, 2001b). Such characteristics are scientifically sup- ported by the morphological individuality of the skeleton and teeth. This identification process can be comparative through analyses of antemortem dental records (medical history, dental chart, perio- dontal chart, radiographs, study models, cephalo- metric analysis, treatment plan, etc.) with postmor- tem and anthropological data. After performing the postmortem dental record of an unidentified individual or unknown set of human remains and having circumstantial evidence to suggest the pos- sible identity of these, the next step is to obtain a dental medical history to collate postmortem- antemortem dental records. Which, according to the American Board of Forensic Odontology (1994) and supported by national and international law, allows the establishment of a positive (total coinci- dence), possible (compatibility), insufficient (inadequate information available), or exclusive (incoherence and incompatibility) identification in a particular case. Case History A male minor with a chronological age of 5 years was reported missing. The initial search to find this minor was unsuccessful. Despite this, enquires in rural forensic units about cases of unidentified per- sons were made, finding out that in one of them, a set of unknown human skeletal remains was re- ported. The remains were found in a sugarcane plantation on the same date. The clothing worn by the individual on the day of his disappearance was found to be compatible with those on the skeletal remains. With this circumstantial evidence, the odontological medical history was obtained. This antemortem dental history did not contain radio- graphic images of the individual; however, the dentist noted in the chart the presence of decidu- ous lower two-rooted canines. A dental compari- son was performed for the process of forensic iden- tification. During which two reliable characteristics were discovered: The presence of deciduous lower two-rooted canines (Figures 1 and 2), whose inter- radicular septum was evident in the alveolar pro- cess of the mandible (Figure 3). In the postmortem radiographs of the deciduous canines it was possi- ble to observe the presence of a root canal in every root and one pulp chamber in the crown of the tooth (Figure 4). In the dental clinical setting, Ver- tucci (2005) classified the number of roots and the number, shape, and configuration of the root ca- 25 Dental Anthropology 2020 │ Volume 33 │ Issue 01 nals for diagnostic and endodontic therapeutic purposes. In such a way, according to the configu- ration of the pulp chamber of the tooth and root canals, the case reported is classified as a type I, where each root has a single canal that ends in its own apical foramen. Also, according to Turner et al. (1991) the case was classified as a mandibular two-rooted canine. Turner et al. (1991) standard- ized the observation of the number of roots of the mandibular canines, in which there are one or two roots, where the second one –usually a small, coni- cal-shaped root directed towards lingual surface– is separated from the root trunk at the middle third. These features were sufficient to constitute relia- ble markers to positively identify the individual, despite the absence of radiographs. Systematized Search of the Literature A systematic review of the literature in PubMed (a free-access search engine to MedLine database of The United States National Library of Medicine) was performed through the combination of health science descriptors: “cuspid” and “tooth root”, combined with the Boolean operators: “+” and “&”, which were located in the Medical Subject Headings (MeSH). Publications describing the presence of two-rooted canines were considered, in order to support the discussion of a case report of an individual with deciduous mandibular two- rooted canines. Results Twenty-five publications fill the inclusion criteria, and were classified by year, type of tooth (deciduous or permanent, maxillary or mandibular canines), expression (unilateral or bilateral), sex (female or male), purpose of publication, and other important considerations (Table 1). There was only one report in which a description was performed Figure 1. Deciduous lower two-rooted canines. Buccal view. Figure 2. Deciduous lower two-rooted canines. Lingual view. Figure 3. In alveolar process of the deciduous lower two-roots canines of the mandible is evi- dent the interradicular septum. Figure 4. Postmortem radiography of the de- ciduous lower two-rooted canines. 26 Dental Anthropology 2020 │ Volume 33 │ Issue 01 Table 1. Reports of two-rooted canines in the literature. U=upper, L=lower Authors Year Perma- nent Tooth Expression Gender Number of roots/ canals Objective Considerations Rahmatulla & Wyne 1993 LC Unilateral (right) Female Two roots / two canals Case re- port The description of the distribution in roots canals is performed Heling et al. 1995 LC No report- ing No report- ing Two roots / three canals Case re- port According to the authors this is the first time a mandibular canine three canals Ouellet 1995 LC No report- ing No report- ing Two roots / two canals Descrip- tive study 806 canines were examined 95% of which has a root and 5% two roots Orguneser & Kartal 1998 LC No report- ing No report- ing Two roots / three canals(two apical foramen) Case re- port The description of the distribution in roots canals is performed D´Arcangelo et al. 2001 LC Unilateral (right) Female Two roots / two canals Case re- port The description of root canal treatment is performed in decayed tooth Alapati et al. 2006 UC Unilateral (right) Male One root / two canals Case re- port The description of root canal treatment is performed in decayed tooth Bolla & Ka- vuri 2009 UC Unilateral (left) Female Two roots / two canals Case re- port The description of root canal treatment is performed in decayed tooth Wang et al. 2009 LC Unilateral (right) Female Two roots / two canals Case re- port The description of the distribution in root canals and the root canal treatment in Victorino et al. 2009 LC Bilateral Female Two roots / two canals Case re- port The presentation of a case of bilateral mandibular canines with two canals and Oporto et al. 2010 LC Unilateral (left) Female Two roots / two canals Case re- port The description of root canal treatment is performed in decayed tooth Andrei et al. 2010 LC Unilateral (right) Female Two roots / two canals Case re- port The description of the distribution in root canals is performed Andrei et al. 2011 LC Unilateral (right) Female Two roots / two canals Case re- port The description of the conventional root canal treatment and apical surgery Fonseca et al. 2011 LC Unilateral (left) Male Two canals Case re- port The description of root canals treatment of bifurcation lesion and vertical loss of Bolla & Ka- vuri 2011 UC Unilateral (left) Female One root / two canals Case re- port The description of root canals treatment is performed in decayed tooth Gaikwad 2011 LC Unilateral (left) Female Two roots / two canals Case re- port The description of root canals treatment is performed in decayed tooth Bhardwaj & Bhardwaj 2011 LC Unilateral (right) Female Two roots / two canals Case re- port The description of root canals treatment by recurrent tooth decay due to restora- Moogi et al. 2012 LC Unilateral (right) Female Two roots / two canals Case re- port The description of root canals treatment is performed Ferreira et al. 2012 LC Unilateral (right) No report- ing Two roots / two canals Case re- port Morphological description of the tooth roots for forensic identification is per- Kaul et al. 2012 LC Unilateral (left) Female Two roots / two canals Case re- port Morphological description of the dilacer- ation of the two roots and their respective root canals treatment is performed He et al. 2013 LC Bilateral Male One root / mul- tiples canals Letter to the editor Presentation of a case of bilateral mandib- ular canines with multiple canals, root canals treatment and restoration of ante- rior teeth is performed Ramírez- Sotelo et al. 2013 LC Unilateral (right) Female Two roots / two canals Case re- port Morphological description of roots using computed tomography was performed Fuentes & Borie 2013 LC Bilateral Female Two roots / two canals Case re- port Morphological description of roots using conventional radiography was performed Chawla et al. 2013 UC Unilateral (left) Female One root / two canals Case re- port The description of root canals treatment in decayed tooth is performed Mithunjith.& Borthakur 2013 LC Unilateral (left) Female Two roots / two canals Case re- port The description of root canals treatment in decayed tooth is performed Arora, Nikh- il & Gupta 2013 LC Unilateral (left) Female One root / two canals Case re- port The description of root canals treatment in decayed tooth is performed 27 Dental Anthropology 2020 │ Volume 33 │ Issue 01 for forensic identification purposes; the primary means of description were conventional radiog- raphy and computed tomography. The descrip- tions corresponded to four cases of permanent maxillary canines with left unilateral expression; the other 21 cases were permanent mandibular canines, with right unilateral expression (10 cases); left unilateral expression (9 cases) and bilateral ex- pression (3 cases). Nineteen cases in female and three in male subjects were reported; two-root ex- pression, each root with a canal, was predominant (18 cases). There were no reports in deciduous den- tition. Discussion Usually, the maxillary and mandibular canines are considered as a single-rooted tooth, given the high prevalence of 93.48% of this condition (Oporto et al., 2010), However, Brothwell –cited by Ferreira et al. (2012)– collected several reports on the preva- lence of two-rooted canine expression, finding no population significant differences related to ethnic pattern, bilateral expression, or sexual dimor- phism. According to the literature, the morphologi- cal variation related to the number of roots is 1% to 2% for the maxillary canines, and 1.3% to 15% for the mandibular canines, mainly the two roots and two canals expression with one canal per root (Bolla & Kavuri, 2011). Exceptionally, mandibular two-rooted canines and three canals have been re- ported (Heling et al., 1995), as well as, two-rooted canines, three canals, and two apical foramina (Orguneser & Kartal, 1998), single-rooted canines and two canals (Arora, 2013), and single-rooted canines with multiple canals (He et al., 2014). An- other important feature is that in most cases of ca- nines with two roots these are distributed in a buc- cal and lingual direction (Ferreira et al, 2012); how- ever, in this case report, the roots were distributed in a mesial and distal direction. Thus, most of the reports suggest that canines with two roots corre- spond to a shape abnormality of the tooth during morphogenesis, related to an alteration of the HERS. A tooth root develops from the HERS and around the dental papilla underneath the dental follicle, until it completely cover the papilla in the primary apical foramen (Thomas, 1995). The systematic review of the literature predomi- nantly described canines with more than one root to demonstrate the clinical difficulty of root canal treatment of these teeth after the development of pathological processes (usually caries). This diffi- culty is mainly related to the identification of the longitudinal course of the canals due to superim- posed radiographic images, the narrowness of the canals, complications from filling them, and apical sealing (Bolla & Kavuri, 2009). Radiographic imag- es were used for forensic purposes, in order to identify features that allow the identification of the decedent from the shape, size, and number of roots of the teeth (Senn & Weems, 2013). Thus, Ferreira et al. (2012) reported a case of a mandibular two- rooted canine with two canals in a decomposing set of remains. However, although the victim was not identified by the dental setting, the authors state that given the low prevalence of this dental trait, could eventually become a valuable tool for forensic odontology identification. Conclusions In this case report, it is evident that the study of dental morphological variation from the point of view of dental anthropology –as in the case of bi- lateral expression of mandibular two-rooted ca- nines– constitutes a reliable marker that allows a positive identification of an individual during antemortem-postmortem comparisons in the field of forensic odontology. 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