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 Table of Contents  
Year : 2022  |  Volume : 12  |  Issue : 2  |  Page : 180-185

Root and canal configurations of maxillary molars in a Saudi subpopulation (Southern region): In vivo cone-beam computed tomography study

1 Department of Restorative Dental Sciences, College of Dentistry, Jazan University, Jazan, Kingdom of Saudi Arabia
2 Department of Restorative Dental Sciences, College of Dentistry, King Khalid University, Abha, Kingdom of Saudi Arabia
3 Department of Restorative Dental Sciences, College of Dentistry, King Saud University, Riyadh, Kingdom of Saudi Arabia
4 Department of Restorative Dental Sciences, College of Dentistry, Almajmaah University, Almajmaah, Kingdom of Saudi Arabia
5 General Dental Practitioner, Ministry of Health, Jazan, Kingdom of Saudi Arabia

Date of Submission07-Aug-2021
Date of Decision03-Sep-2021
Date of Acceptance03-Nov-2021
Date of Web Publication20-Apr-2022

Correspondence Address:
Dr. Shilpa Bhandi
Department of Restorative Dental Science, College of Dentistry, Jazan University, Jazan
Kingdom of Saudi Arabia
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/sej.sej_171_21

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Introduction: Knowledge regarding the root canal morphology is a key for successful root canal therapy. Maxillary molars comprise a complex root canal system. Thus, this study aimed to evaluate the root morphology and root canal configurations of maxillary molars using cone-beam computed tomography (CBCT) radiographic analysis in a Saudi subpopulation.
Materials and Methods: The CBCT images of 624 maxillary molar teeth from 208 patient records (age: 28.74 ± 9.56 years) were analyzed using i-Dixel three-dimensional imaging software. Sagittal, axial, and coronal serial sections were used to examine the number of roots, root canal configuration, the number of canals, and differences between the right and left sides. Frequencies and percentages were used to represent the results. Differences between both sides were determined by the Chi-square test, and the significance level was set at P < 0.05 for all statistical tests.
Results: In the first molars, 85.8% of teeth had four canals, 14.2% had three canals, 48.2% mesiobuccal (MB) roots had Vertucci Type IV configuration, and both distobuccal and palatal roots had Vertucci Type I roots. In the second molars, three and four canals were present in 33.6% and 66.4% of the teeth, respectively. All the second molars had Vertucci Type I distobuccal and palatal roots, whereas the MB roots were present in 32.9% of the teeth. No significant difference was found between both sides (P > 0.05) for all parameters.
Conclusions: Wide variations were found among the same population, and the presence of four canals in maxillary molars was commonly observed. Clinicians should be aware of such differences and use available diagnostic tools, such as CBCT and dental operative microscopy.

Keywords: Cone-beam computed tomography, endodontics, maxillary molars, root canal morphology, Vertucci's classification

How to cite this article:
Mashyakhy M, Jabali A, Albar N, AbuMelha A, Alkahtany M, Bajawi H, Alroomy R, Alamri F, Bhandi S. Root and canal configurations of maxillary molars in a Saudi subpopulation (Southern region): In vivo cone-beam computed tomography study. Saudi Endod J 2022;12:180-5

How to cite this URL:
Mashyakhy M, Jabali A, Albar N, AbuMelha A, Alkahtany M, Bajawi H, Alroomy R, Alamri F, Bhandi S. Root and canal configurations of maxillary molars in a Saudi subpopulation (Southern region): In vivo cone-beam computed tomography study. Saudi Endod J [serial online] 2022 [cited 2022 Aug 11];12:180-5. Available from: https://www.saudiendodj.com/text.asp?2022/12/2/180/343551

  Introduction Top

The triad for a successful endodontic treatment involves the shaping and debridement of root canals in all dimensions and obturation.[1] For optimal cleaning and shaping of canals, a three-dimensional (3D) view of the root canal structure is necessary, given that the root canal system (RCS) varies from tooth to tooth.[2] Various methods, such as tooth staining,[3] conventional and digital radiography,[4] radiography using contrast media,[5] and computed tomography (CT), have been used to detect incongruence in root canal morphology.[6]

Vertucci described the maxillary first molar as one of the most complicated teeth in the maxillary arch.[7] Maxillary molars have been a constant topic of speculation due to their complex root canal morphology and are the most extensively studied tooth, especially the internal morphology of mesiobuccal (MB) roots.[8] The MB root commonly presents two main canals, namely MB1 and MB2, with an extremely complex canal system including intercanal communications, loops, accessory canals, and apical ramifications.[9] The inability of an operator to negotiate this complex system can lead to treatment failure.[10] A prospective clinical study showed the highly difficult negotiation of MB2 is in the first and second molars.[11] In maxillary molars, a conventional intraoral periapical radiograph provides a 2D view of the RCS; as a result, the prevalence of undetected MB2 canal is high; the need for a 3D view of the RCS can be satisfactorily fulfilled by cone-beam CT (CBCT).[12]

In a recent systematic review of a worldwide nation representing 24 countries with 15,285 first molars and 8,641 s molars, Martines et al. observed that the prevalence of MB2 reached 69.6% and 39% for the first and second molars, respectively.[13]

In a Saudi subpopulation, several studies evaluated maxillary first molars using conventional in vivo radiographs, in vitro CBCT, and micro-CT,[11],[14],[15],[16],[17] whereas six used in vivo CBCT.[15],[18],[19],[20],[21],[22] Al-Shehri et al.[19] reported that most maxillary first molar teeth (99.7%) had three roots: 94% were separated and 6% were fused. Among the separate-rooted teeth, four canals were prominent (55.6%) followed by another three (40.4%), whereas the most presented internal canal configuration in MB root was Vertucci Type I (35.1%), followed by Types IV (33.3%) and II (24.4%). Three studies were reported about maxillary second molars. They showed the predominance of three roots, whereas the prevalence of MB2 ranged from 12% to 80%.[11],[16],[20] Variations in methodologies and criteria of investigated variables when studying maxillary molars have led to the inconsistency of findings.

The published studies on Saudi subpopulations represent different regions of the country, whereas no research came from the southern region, except for one study that evaluated fused rooted molars and their internal anatomy.[22] Thus, this study aimed to evaluate the number of roots and canals and canal configurations of the maxillary first and second molars in a Saudi Arabian subpopulation (southern region) using in vivo CBCT.

  Materials and Methods Top

Sample selection

In the present study, CBCT radiographic images of 208 Saudi patients were collected from databank archives, College of Dentistry, Jazan University at Jazan City, for different diagnostic purposes. Of the 208 patients, 100 male and 108 female patients with mean age of 28.74 ± 9.56 years were included. All CBCT scans were collected retrospectively; the patients were not exposed to X-ray for this study. An ethical approval given by the Institute Ethical Committee was attained before commencing the study (Reference#: CODJU-19682). A total of 624 maxillary molars (330 first and 294 second maxillary molars) were analyzed. Teeth with complete root development and apical closure were included in this study, and root canal-treated teeth, fused roots, resorbed roots, and calcified canals were excluded. Distorted/unclear CBCT radiograph images were excluded.

Radiographic image evaluation

The CBCT machine (3D Accuitomo 170, MORITA, Japan) with 90 kV, 5–8 mA, 17.5 s exposure time, and 0.25 mm voxel-size features was used. Morita's i-Dixel 3D software imaging program was used for the processing of CBCT radiographs. Axial, coronal, and sagittal radiographical segments were acquired for maxillary molars to appraise the external and internal teeth structure. In this study, the number of roots, the number of canals, and canal configurations was assessed in accordance with the Vertucci's classification.[15] Right and left molars differences were also considered. For the consistency of measurements, with an interval of 4 weeks, one observer (an endodontist) evaluated 30% of the samples. The results from Cohen's kappa test showed an agreement between the observations with 88.5% and ±9.5% asymptotic standard error.

Statistical analysis

The data collected were uploaded in a software program for Windows (SPSS V25; IBM, Chicago, IL) for statistical analysis. The results were presented as percentages and frequencies. The differences between both sides (right and left) can be determined using the Chi-square test (contingency coefficient). P < 0.05 was considered significant in all tests.

  Results Top

All maxillary first molars had three separated roots. However, 283 (85.8%) and 47 (14.2%) teeth had four and three canals, respectively [Figure 1]. Nearly half of the teeth (48.2%, n = 159) had Vertucci Type IV MB roots [Figure 2] and [Figure 3]. The canal configuration in distobuccal and palatal roots in all teeth (100%) had Vertucci Type I configuration [Table 1] and [Figure 3].
Figure 1: Axial cone-beam computed tomography sections: (a and b) Maxillary first and second molars with four canals, respectively; all mesiobuccal roots showed mesiobuccal two canals (arrows)

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Figure 2: Axial cone-beam computed tomography sections of maxillary first molar at different levels of the roots: (a) At coronal level of the roots scan shows two canals in mesiobuccal and one canal in DB and palatal roots, (b) At middle level of the roots scan shows two canals in mesiobuccal and one canal in DB and palatal roots, (c) At apical level of the roots scan shows one canal in all roots, with mesiobuccal having Vertucci Type II canal configurations, while DB and P have Type I

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Table 1: Frequency of the number of roots, the number of canals, and Vertucci type among maxillary first molars

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Figure 3: Coronal cone-beam computed tomography sections of maxillary first molars show: (a) Mesiobuccal root with two canals and Vertucci Type IV, (b) Mesiobuccal root with one canal and Type I Vertucci, (c) DB (green arrow) and Palatal (white arrow) roots with one canal and Type I Vertucci

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All maxillary first molars on both sides had three separated roots. However, more than 80% of teeth on both sides (n = 140 for right side; n = 143 for left side) had four canals, and <15% (n = 24 for right side; n = 23 for left side) had three canals, with statistically insignificant difference (P = 0.876). With respect to Vertucci root configuration in the MB root, an insignificant difference was observed between both sides (P = 0.743). High number of teeth on both sides was associated with Vertucci Types I, II, and IV configurations. However, a small number of teeth had Vertucci Types III and V configurations, and two teeth on the left side had Vertucci Type VI configuration. Distobuccal and palatal roots of all teeth in both sides showed Vertucci Type I roots.

Among the 294 maxillary second molars, 292 (99.3%) had separated three roots, and 2 (0.7%) teeth had an extra palatal root (four roots). Among teeth with nonfused roots (n = 292), 98 (33.6%) had three canals and 199 (66.4%) had four [Figure 1]. The distobuccal and palatal roots of all teeth (100%) presented Vertucci Type I configuration. Regarding canal configuration in MB roots, 32.9% (n = 96), 32.5% (n = 95), and 26.4% (n = 77) of teeth had Vertucci Type I, IV, and II configurations, respectively.

All maxillary second molars with three roots (n = 292) were included for the comparison between both sides. Almost two-third of the teeth on both sides had four canals, and about one-third had three canals, with an insignificant difference between both sides (P = 0.711). Similarly, a statistically insignificant difference was present between both sides (P = 0.955) in relation to MB root morphology. A high number of teeth on both sides had Vertucci Type I, II, and IV configurations, and a lesser number had Vertucci Type III, V, and VI configurations. Distobuccal and palatal roots of all teeth on both sides had Vertucci Type I configuration [Table 2].
Table 2: Comparison of right and left sides of maxillary second molars

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  Discussion Top

The second permanent teeth to erupt in the oral cavity is the maxillary first molar followed by the mandibular first permanent molar, making the maxillary first molar susceptible to dental caries and endodontic treatment.[23] The second maxillary molar erupts at the age of 11–13 years, and its anatomy, consisting of deep occlusal grooves, pits, and fissures, makes the tooth more vulnerable to dental caries compared with other molars in the oral cavity.[24] Three roots and four root canals are common in first and second maxillary molars, respectively.[7]

The present study evaluated the number of roots, canals, and canal system configurations in accordance with the most widely used classification (Vertucci's classification) in spite of certain disadvantages.[7] [Table 3] presents the comparison of the current study with other research.
Table 3: Comparison of the present study with other studies

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All maxillary first molars had three roots; 85.8% of the teeth had four canals and 14.2% had three canals. In regard to internal canal configurations, the MB root consisted of 48.2% Type IV and 35.2% Type II Vertucci's classification. The findings of the present study were in agreement with Al-Shehri et al.'s study[19] on the central region of Saudi Arabia in regard to the number of roots only; however, they reported a lesser number for teeth with four canals (55.6%). In addition, the study showed different results regarding internal canal configuration, wherein MB root Vertucci Type I (35.1%) was the most predominant, followed by Types IV (33.3%) and II (24.4%). Another study[20] using the in vivo CBCT of the central region reported similar results based on the number of roots, whereas the number of three canals was higher (73%) and less for four canals (27%). The variation of results may be related to the region where several areas with different subpopulations. Other studies[11],[14],[16],[18],[21] on the same population from different regions utilized various techniques and mainly evaluated the presence of another root canal in MB roots; they reported a range of 23.3% to 86% for MB2, whereas the current findings fell in the higher range. A CBCT worldwide study of the prevalence of second canal in MB roots showed that the prevalence ranged from 48% to 97.6%.[25] Martins et al.[13] recently reported an average of 69.6% MB2 in samples from 24 countries around the world, and this value is lower than our finding. The study covered 41 population groups and showed a wide variety among different populations.

In agreement with a previous in vivo CBCT study[20] on the number of roots in the same population (central region), the number of canals of the maxillary second molars was high for three canals (88%) and low for four canals (12%). Another clinical and radiographic study[11] from the central region reported the presence of 19.7% MB2, which is lower than the current findings. Alfouzan et al.,[16] in a micro-CT study in the central region, observed the high prevalence of MB2 (80%) and MB3 (13.3%). No local study reported canal configurations of the second molar. In a systematic review of 17 populations, the prevalence of MB2 was 39.0%, ranging from 31.1% to 46.9%,[13] which is lower than our findings.

Variations from different populations are well reported in regard to the morphology of MB root,[13],[33] techniques, with CBCT and micro-CT providing accurate, precise, and reliable results. Micro-CT is considered the gold standard in studying root canal morphology, and it provides a higher resolution than CBCT;[16] thus, a higher prevalence of extra canals and other anatomical variations, such as loups, isthmuses, and lateral canals, was observed. However, clinical CBCT offers the best diagnostic information, including gender, location, and ethnicity, which can be missed from in vitro micro-CT, in addition to feasibility and accuracy.

In the present study, the comparison results between right and left sides of maxillary first molars were evaluated as secondary outcomes. No differences were observed between the right and left sides of the maxillary first and second molars in regard to the number of roots, the number of canals, and canal configurations, in agreement with Elhejazi et al.'s study[20] from the central region of Saudi Arabia, Lin et al. on a Taiwanese population and Pan et al. on a Malaysian population.[26],[31]

This study showed wide differences among the same population utilizing the same and various methodologies and worldwide prevalence of MB2.

The main limitations of the present study include the correlation of age and gender to the present morphology. Further studies, including multi centers from different regions in Saudi Arabia, are recommended to find the most accurate prevalence of a second MB canal and its relation to gender and age.

  Conclusions Top

Maxillary molars have high prevalence of four canals, and locating the second canal in MB roots poses a challenge to practitioners. Thus, the limited-field view of CBCT for maxillary molars prior to endodontic treatment is recommended for improved treatment outcomes.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

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  [Figure 1], [Figure 2], [Figure 3]

  [Table 1], [Table 2], [Table 3]


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