|Year : 2016 | Volume
| Issue : 4 | Page : 397-404
C-shaped mandibular primary first molar diagnosed with cone beam computed tomography: A novel case report and literature review of primary molars' root canal systems
Gozde Ozcan, Ahmet Ercan Sekerci, Fatma Kocoglu
Department of Maxillofacial Radiology, Faculty of Dentistry, Erciyes University, Kayseri, Turkey
|Date of Web Publication||29-Sep-2016|
Department of Maxillofacial Radiology, Faculty of Dentistry, Erciyes University, 38039 Kayseri
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Knowledge of the different anatomical variations in root canal system of dedicious dentition will improve the practice of the pediatric dentists. The teeth with C-shaped root canal configurations are definitely a problem in endodontic treatment. Dentists who are specialists of endodontics must have adequate knowledge about various root canal morphologies of primary tooth that have a tendency for rapid progression of dental caries to achieve a technically satisfactory outcome. This report presents an extraordinary case of unusual tooth morphology involving the mandibular first primary molar with a C-shaped configuration which has not yet been reported.
Keywords: C-shaped, primary molar, root canal morphology
|How to cite this article:|
Ozcan G, Sekerci AE, Kocoglu F. C-shaped mandibular primary first molar diagnosed with cone beam computed tomography: A novel case report and literature review of primary molars' root canal systems. J Indian Soc Pedod Prev Dent 2016;34:397-404
|How to cite this URL:|
Ozcan G, Sekerci AE, Kocoglu F. C-shaped mandibular primary first molar diagnosed with cone beam computed tomography: A novel case report and literature review of primary molars' root canal systems. J Indian Soc Pedod Prev Dent [serial online] 2016 [cited 2021 Apr 20];34:397-404. Available from: https://www.jisppd.com/text.asp?2016/34/4/397/191438
| Introduction|| |
Thorough clinical knowledge of the primary tooth morphology is a prerequisite for successful root canal treatment in clinical dentistry, especially for root canal treatment and dental traumatology.
The primary dentition has numerous functions and it is important in a child's development. However, due to mineralized structure of primary teeth, they are more susceptible to advance of caries than permanent teeth. In that case, endodontic therapy of a primary tooth with decay is the only way to heal and retain it commonly. However, the root and canal anatomy of primary teeth is rarely reported because of the scarcity of intact primary teeth without root resorption, the knowledge in morphology, and variation of the root canal systems of primary teeth is the basic provision of detecting the treatment technique.
Successful root canal therapy consists of thorough biomechanical instrumentation and chemical debridement, followed by hermetic obturation of the root canal system. However, the complexity of the root canal anatomy presents clinical challenges and difficulties that often jeopardize the primary goal of such therapy. Therefore, variations in the root canal systems and characteristic features in different races should be recognized before or during endodontic treatment. 
C-shaped root canal system is a single, ribbon-shaped orifice with an arc of 180° or more [Figure 1]. In permanent dentition, most often, the C-shape of the pulp chamber is used to describe the mandibular second molars, the maxillary first molars and the maxillary second molars. As primary teeth exhibit morphologic differences from the permanent teeth both in size and in general internal and external design, a comprehensive understanding of the root and the root canal morphology is of utmost importance. 
|Figure 1: Classification of the canal configuration of the modified Melton's method. (C1) The shape is an uninterrupted "C" with no separation or division. (C2) The canal shape resembles a semicolon resulting from a discontinuation of the "C" outline. (C3a) Two separated canals. (C3b) Three separated canals. (C4) Only one round or oval canal. (C5) No canal lumen can be observed (which is usually seen near the apex only)|
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To gather this knowledge, different techniques were used which either destroyed or altered the tooth structure, thus precluding further studies on the same teeth. Computed-based techniques have been popularly used for studying root canal morphology.  Cone beam computed tomography (CBCT), one of these methods, potentially provides the clinician with the ability to observe an area in three different planes with a practical tool for noninvasive and three-dimensional reconstruction imaging for use in endodontic applications and morphologic analyses. The combination of sagittal, coronal, and axial CBCT images eliminates the superimposition of anatomic structures. Root morphology can be visualized in three dimensions, as the number of root canals and their convergence or divergence from each other. From this point, CBCT has been suggested to assist in identifying root canal systems. 
The aim of this article is to present a primary mandibular molar with C-shaped root canal diagnosed incidentally during the examination of CBCT images taken to evaluate mandibular right incisor with talon cusp and to perform a literature review of primary molars' root morphology and root canal systems.
| Case Report|| |
An 8-year-old girl was referred to the Department of Oral and Maxillofacial Radiology for the evaluation of lower right central incisor with talon cusp. The patient's medical history and family history were not contributory. General examination did not reveal any abnormality. On clinical examination, the patient's oral hygiene was moderate with mild crowding of the teeth in the maxillary and mandibular anterior regions. Intraoral examination revealed a linear cusp-like structure on the lingual aspect of mandibular permanent right central incisor. The tooth had a talon cusp on the lingual side. On close examination of the involved tooth, a well-delineated accessory cusp was observed. Despite the presence of grooves, there was no discernible separation between the two. All the other teeth did not show any developmental abnormality. As the talon cusp caused occlusal disharmony, CBCT was obtained to examine the relationship with root canal system. CBCT investigation indicated that there was a connection between the pulp chambers [[Figure 2] - yellow-lined arrows]. The parents of the patient did not prefer any contouring of the crown, so she was advised periodic follow-up.
|Figure 2: Three-dimensional (a), sagittal (b) and axial (c) (yellow-lined arrow) tomographic view of talon cusp on the right mandibular central incisor; cone beam computed tomography axial section of maxillary arch at cervical and apical third level of primary first molar with C-shaped canal (c and d), sagittal (e), and coronal (f) sections and three-dimensional (g) view (white-lined arrow)|
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During the examination of CBCT images, diagnosis of a C-shaped mandibular primary first molar was also noticed. Axial slices of the mandible were obtained at different levels to determine the canal morphology [[Figure 2] - white-lined arrows]. The tooth root showed one root canal orifice with C-shaped canal that extended from the cervical third up to the apex, thus categorizing the root canal system as a Melton type I C-shaped anatomy.
| Discussion|| |
To successfully perform a root canal treatment on a primary tooth, an intimate knowledge of the internal and external morphology of each primary teeth is required.  A thorough knowledge of the dental anatomy of primary dentition is essential for all treatment aspects. The major cause of failure of pulpectomy is an inability to recognize and therefore adequately treat all the canals of the root canal system. 
Reported studies related to root and root canal morphology of human primary molars were shown in [Table 1] and [Table 2]. In primary mandibular molars, two canals in the mesial root and one canal in the distal root comprised the most commonly observed anatomical configuration. ,,, The internal and external morphology of the primary mandibular first molar closely resembles the primary mandibular second molar.  In Gaurav et al.'s  study, the mesial root of all the primary mandibular molars had two canals, i.e. mesiobuccal (MB) and mesiolingual, and the distal root showed the presence of two canals in 20% of the samples and presence of one canal in the remaining 80% of the samples. The findings are in accordance with the findings of Aminabadi et al.,  Zoremchhingi et al.,  Hibbard and Ireland  who found more than one canal in 25%, 40%, and 20% of distal root, respectively. In the present report, mandibular primary first molar had C-shaped root canal system.
Maxillary primary first and second molars have been described as having three divergent and separated roots. ,, However, studies demonstrated that the incidence of fusion between palatal and distobuccal (DB) roots in maxillary primary first molars was reported with a high ratio by 29%,  53.5%,  77.7%,  and 40%.  In a study by Wang et al.,  most maxillary primary molars had one canal for each root with two canals in distobuccally-palatally fused roots, and three of 18 (17%) maxillary primary molars demonstrated communication between the MB and DB root canals. This result was also comparable with the report by Zoremchhingi et al.  reported that 37.5% of the maxillary first primary molar had a similar root canal communication. Besides, in the maxillary first molars, the incidence of a double canal system in the MB root was reported in 6.7%,  7.4%,  and 35%  of the samples, and in the DB root, it was reported in 3.7%  of the specimens.
A study reported by Goodacre  has found that the mean lengths of the MB, DB, and palatal roots of the maxillary primary first molars were 8.8, 8.2, and 7.8 mm, respectively, and in the maxillary primary second molars, the mean lengths were 10.8, 9.7, and 10.8 mm, respectively. In a study by Fumes et al.,  the mean lengths of the MB, DB, and palatal roots of the maxillary first molars were 7.9, 6.7, and 5.9 mm, respectively, and in the maxillary second molars, the mean lengths were 8.5, 6.5, and 7.4 mm, respectively. In mandibular primary first and second molars, while Goodacre  reported that the lengths of the mesial and distal roots were 10.5 and 8.9 mm and 11.4 and 10.5 mm, respectively, the mean lengths reported by Fumes et al.  were 7.3 and 6.4 mm and 8.5 and 8.9 mm, respectively.
In primary mandibular molars, the morphology of double ribbon-shaped canal system has been reported to range from 24% to 100% in the mesial root and from 22.2% to 60% in the distal root. , In the study by Wang et al.,  the palatal roots of maxillary second primary molars and ribbon-shaped root canals were observed, but were only a few. In their study, it was noted that the number of ovoid- and ribbon-shaped root canals equally occurred at the cervical level in maxillary primary molars. In the mandibular molars, the flat-oval shape occurred more frequently than the oval shape at the middle level. Despite all these reports, we have not encountered any study about C-shaped primary tooth.
| Conclusion|| |
This study showed a new variation of root canal system in a primary molar. CBCT provides effective and accurate clues and knowledge of variations in the root canal morphology, which would help clinicians to obtain a thorough understanding of the variations in root canal morphology of primary molars to overcome the issues.
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Conflicts of interest
There are no conflicts of interest.
| References|| |
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[Figure 1], [Figure 2]
[Table 1], [Table 2]