A Cone-Beam Computed Tomography Scanning of the Root Canal System of Permanent Teeth among the Moscow Population

Background Successful endodontic treatment requires a significant knowledge of root canal anatomy. The aim of this study was to evaluate the root and root canal number of permanent teeth among the Moscow population using cone-beam computed tomography (CBCT) scanning. Materials and methods 300 CBCT images of subjects were analyzed to study the anatomy of roots and root canal system of each tooth. The collected data were analyzed using IBM SPSS statistics software 22.0 version. Results The maxillary incisors and canines had one root with one canal in 100%. Maxillary premolars had one root with one or two canals and two roots with two canals, while mandibular premolars were single-rooted with one or two canals. Maxillary first and second molar had three separated roots, and the prevalence of four canals was more often in first molars. Mandibular molars had two roots with different number of canals. Conclusion The root canal system varies greatly among populations and even in different individuals within the same population; thus, using CBCT scanning is an effective technique in investigating the root canal system.


Background
e success of endodontic treatment depends on the precise knowledge of root and root canal anatomy, which is an important challenge due to the complexity of the root canal system and the anatomical variations [1,2]. is knowledge helps the clinicians in endodontic treatment planning and decreases the percent of endodontic treatment failure. Many studies have been conducted to determine the anatomy and morphology of root canal system using different techniques [3][4][5][6][7][8][9]. Recently, with the development of cone-beam computed tomography (CBCT) technique, it became possible to study the anatomy of teeth, due to the high-quality threedimensional (3D) images obtained from CBCT. is image allows studying the anatomy of the jaws, the morphology of teeth, and their root canal system [3]. Many studies have used this technique to find out the anatomy of root canal system especially in the molar regions [3,6,8].
Root canal morphology has been classified using different ways by several investigators in the literature [10][11][12]. Weine et al. [12] classified it into four types depending on the pattern of division of the main root canal of a tooth along its course from the floor of the pulp chamber to the root apex. Vertucci [10] also classified the root canal morphology in a more descriptive manner into eight types. is classification has been widely used by many researchers to classify the canal system of different teeth.
It is known that the number of teeth roots and the anatomy of root canal system vary among the world population, and to date, there are still no studies about the anatomy of roots and root canals in Russian Federation, where dental practitioners still use the data obtained from foreign authors on the anatomy of root canals in planning the endodontic treatment. e aim of this study was to investigate the anatomy of root and root canal system among the Moscow population using CBCT technique.

Materials and Methods
300 subjects aged 20-70 years were enrolled in this study, from those attending the diagnostic center (LLC Zolotoye Secheniye) for 3D radiological scanning in the period between January 2017 and November 2017. e study protocol was approved by the Ethics Committee in People's Friendship University of Russia (RUDN University), Moscow, Russia. A written consent was signed by all subjects, including who participated in this study. CBCT images were taken using a 3D eXam ® dental tomography scanner (KaVo, Biberach, Germany) with standard exposure settings (23 * 17 cm field of view; 0.3 mm voxel size; 110 kv; 1.6-20 s) and were viewed by three examiners in a semidark room using I-CAT viewer software (version 10, Hatfield, England). All teeth were evaluated in axial, coronal, and sagittal planes, and the number of roots and the number of canals in each tooth were recorded. e presence of additional canals especially in the molar regions was recorded.

Statistical Analysis.
Data were processed using the software (SPSS v 22 for win, IBM, Chicago, IL), and descriptive data were processed to analyze the percentage of roots and root canals in each tooth.

Results
300 CBCT scans of 300 subjects with mean age of 49.91 ± 14.01 were analyzed. All the maxillary incisors had one root with 100% and one canal with 100%. First and second maxillary molars had three roots with 100%, and third molar recorded one root in 33.7% and three roots in 47.9%. Data for maxillary teeth including the number of roots and root canals are shown in (Table 1).
For mandibular teeth, data were the following: central and lateral incisors and canines showed one root and one canal in 99.4%, 99.2%, and 99.8%, respectively. First molars had two roots in 100%, and second molars had one root in 0.5% and two roots in 99.5%. Data for mandibular teeth are shown in (Table 2).

Discussion
e knowledge of the anatomy of the root canal system is the gold standard in successful endodontic treatment, and studying root and canal morphology has endodontic and anthropological significance. is study evaluated the roots and root canal system among the Moscow population using CBCT scanning. e advantages of CBCT scanning are its high accuracy, minimal distortion, and 3D visualization. Moreover, it is a nondestructive technique and can provide specific data [3].
When analyzing the anatomy of the maxillary anterior teeth, 510 central incisors, 500 lateral incisors, and 540 canines were recorded, and one root with one canal was identified in 100% of cases. ese data are comparable with the results obtained from other studies on the anatomy of central incisors in USA [10], Mexico [11], Turkey [13], and Chennai urban [14]. e presence of two canals in lateral incisors was found in 13.7% of cases in a study by Calişkan et al. (Turkey) [13], in 9.5% of cases by Sert and BayirliIn (Turkey) [15], and in 2% in a study by Jain et al. (Chennai urban) [14]. e prevalence of two canals in canines was 3.9%, 2-4%, 4%, and 18.4% in studies by Calişkan et al. [13], Sert and Bayirli [15], Jain et al. [14], and Amardeep et al. [16] respectively. is difference in results could be attributed to the evaluation method, sample size, and racial differences.
According to the current study, the anatomy of root canals of maxillary first premolar was variable, two roots were identified in 91.3% of cases and 8.7% of cases were one rooted, and the first premolar recorded one root and two canals in 2.6% and one canal in 6.1% of cases. Similar data obtained in the studies of Bulut [17] recorded one canal in 82.1% of the cases and two canals in 17.8%. e maxillary first molar was analyzed by all researchers in detail by the number of canals in each root. ree separated roots were identified in 100% of cases. e number of canals varied from 3 to 5. e four-canal root system occurred in 59.8% of cases, and the localization of the two canals takes place more often in the mesiobuccal root (MB) and also occurred in the distobuccal root (DB e maxillary third molar in our study was defined as single-rooted in 47.9% and three-rooted in 52.1%, and the system of root canals could consist of one, two, three, or more canals as shown in (Table 1). Similar results were found in a study of Sidow et al. (USA) [40], in which, it was found 15% of third molars had one root and 45% had three roots, and the number of canals ranged from 1 to 6 in teeth with one root and 2 to 5 in teeth with 3 roots. A study by Tomaszewska et al. (Poland) [41] reported the one-rooted maxillary third molar in 38.5% of cases and 61.5% were three-rooted. e prevalence of one, three, and four canals were 23.1%, 46.1%, and 15.4%, respectively. Singh and Pawar (India) [42] found three-canal system of maxillary third molar in 43% of cases and four-canal system in 5%.
In this study, for mandibular teeth, it was identified in central and lateral incisors and canines, one canal in 99.4%, 99.2%, and 99.8%, respectively, and two canals in 0.6%, 0.8%, and 0.2% of cases, respectively. ese findings are consistent with other studies, where one canal was recorded in central incisors in 99.7% in Madeira and Hetem (Brazil) [43] and 99% in Walker (China) [44]. For lateral incisors, studies have reported the presence of 2 canals in 1.3% (Mexico) [11], 0.8% (Brazil) [43], and 1% (China) [44]. e presence of 2 canals in canines was 20.48% and 20.4% in studies by Rahimi [16]. e mandibular first premolar was found as singlerooted in 100% of cases. One canal was found in 89.2%, and two canals in 10.8% of cases. is coincides with the results of Bulut (Turkey) [17] When analyzing the structure of the root canal system of the mandibular second molar, it was defined to be a two-, three-, and four-canal systems. 82.2% of cases had three canals. e most similar data were found in Celikten et al. e mandibular third molar was revealed as two-rooted in most cases (80%), and the canal system could have twoand three-canals, and these results agreed with other studies of the anatomy of third molar, as in Kuzekanani et al. (Iran) [64] where 73% of cases had 2 roots, and a study by Sidow et al. (USA) [40], where 77% of two roots were defined.

Conclusions
e root canal system varies greatly among populations and regions and even in different individuals within the same population, and using CBCT scanning is an effective technique in investigating the root canal system.

Data Availability
e data used to support the findings of this study are included within the article.

Conflicts of Interest
e authors declare that they have no conflicts of interest.