Nigerian Journal of Clinical Practice

ORIGINAL ARTICLE
Year
: 2019  |  Volume : 22  |  Issue : 11  |  Page : 1611--1616

Anatomical analysis of permanent mandibular incisors in a Saudi Arabian population: An in Vivo cone-beam computed tomography study


M Mashyakhy 
 Department of Restorative Dental Sciences, College of Dentistry, Jazan University, Jazan, Saudi Arabia

Correspondence Address:
Dr. M Mashyakhy
Department of Restorative Dental Sciences, College of Dentistry, Jazan University, P.O Box 114, Jazan
Saudi Arabia

Abstract

Aims: To investigate the root canal's anatomy, gender differences, and bilateral symmetry of permanent mandibular incisors using cone-beam computed tomography (CBCT). Materials and Methods: A total of 208 patients with 822 well-developed mandibular incisors were evaluated. CBCT images were retrieved from the database of patients who received treatment in the College of Dentistry and Dental Clinics. The following parameters were evaluated using CBCT: (1) the number of roots; (2) the number of canals; (3) canal configuration according to Vertucci's classification; (4) differences between genders; and (5) bilateral symmetry. Results: Two canals appeared in 26.3% of mandibular central incisors, 30.8% of lateral incisors, and 28.6% of all the 822 mandibular incisors. In the teeth with two canals, Type III configuration was dominant. There were no statistically significant differences found between the central and lateral incisors (P = 0.449). There were gender differences in central incisors, while lateral incisors showed none. Slight bilateral asymmetries appeared in central and lateral incisors in relation to some canals and canals configurations. Conclusion: CBCT can be of great use in locating the second canal and determining canal configuration in mandibular incisors. Knowledge of bilateral asymmetry can be of clinical significance when the clinician is treating contralateral teeth in the same patient.



How to cite this article:
Mashyakhy M. Anatomical analysis of permanent mandibular incisors in a Saudi Arabian population: An in Vivo cone-beam computed tomography study.Niger J Clin Pract 2019;22:1611-1616


How to cite this URL:
Mashyakhy M. Anatomical analysis of permanent mandibular incisors in a Saudi Arabian population: An in Vivo cone-beam computed tomography study. Niger J Clin Pract [serial online] 2019 [cited 2022 May 18 ];22:1611-1616
Available from: https://www.njcponline.com/text.asp?2019/22/11/1611/270857


Full Text



 Introduction



A thorough understanding of root canal anatomy and morphology is essential for accurate diagnosis and successful management of root canal disease.[1],[2] Moreover, knowledge about the complexity of the root canal system (RCS) is of utmost importance for understanding the principles and complications of cleaning and shaping the RCS.[3] Several studies have evaluated the root canal morphology of central and lateral mandibular incisors. Mandibular incisors are unique as the canals can have different cross-sectional shapes: round and long oval. Wu et al.[4] found that the canal might vary along the course of the tooth, and long oval canals are relatively common (occurring in at least 25% of the teeth).[4] Another study classified the cross-sectional root canal configurations as round, oval, long oval, flattened, or irregular.[5] Most permanent mandibular incisors have one root and one canal; however, a small percentage may have a second canal, lateral canal, or apical deltas.[6]

Vertucci [7] in his study found that 70% and 75% of the central and lateral incisors, respectively, had one canal with one foramen. Miyashita et al.[8] reported 87.6% of mandibular incisors had single canals from the pulp chamber to the apex. Another study found that 79% of central and lateral mandibular incisors had one major canal with one apical foramen.[9] Different techniques have been used to study the root canal morphology of permanent mandibular anterior teeth. These techniques include direct microscopic observation, canal staining, clearing technique, modified canal staining and clearing, horizontal sectioning and macroscopic observation, stereomicroscopy root clearing, conventional radiography, contrast-enhanced radiography, and spiral computed tomography.[3],[10] Cone-beam computed tomography (CBCT) has been introduced into dental imaging and provides a non-invasive three-dimensional (3-D) evaluation of dental and maxillofacial structures that overcomes the limitations of the 2-D radiography.[11],[12],[13] CBCT is considered a valid diagnostic method and can be used to detect additional roots, canals, and different canal configurations.[6],[11],[12],[13],[14],[15]

Two recently published studies used in vivo CBCT in a large number of teeth from Israeli and Caucasian populations. The first study reported two root canals in 40.5% and 37.9% of mandibular central and lateral incisors, respectively, with Vertucci Type III canal configuration being the most prevalent.[16] The other study reported two root canals in approximately 30% of both mandibular central and lateral incisors, with Vertucci Type III configuration being dominant.[17] In a Saudi Arabian population and Al-Fouzan et al.[18] evaluated 80 extracted mandibular incisors using clearing techniques; they reported the incidence of two canals to be 30%. The results of this study were in agreement with previous studies in the same group of teeth from different populations, but the information was inconclusive, particularly when the gender and location of teeth in the jaw were unknown, in addition to the small sample size.

Upon a literature search, the previously mentioned study is the only one available in a Saudi Arabian population. Therefore, the aims of this in vivo CBCT study are to evaluate the morphology of the mandibular incisors, gender differences, and bilateral symmetries in a Saudi Arabian population.

 Subjects and Methods



A total of 822 mandibular central and lateral incisors (410 central and 412 lateral incisors) were evaluated. These teeth were screened from CBCT radiographs of 208 subjects; of these 100 (48%) were male and 108 (52%) were female with a mean age of 28.74 ± 9.56 years (median = 26 years) ranging from 17─59 years. CBCT images were retrieved from the database of College of Dentistry, Jazan University, Jazan, Saudi Arabia from 2016 to 2017 after the Institute's ethical research approval was granted. Mandibular central and lateral incisors with fully developed roots and closed apices were included in the study. Root canal-treated, calcified, resorbed, or distorted teeth on CBCT images were excluded. The CBCT machine used in this in vivo retrospective study was 3D Accuitomo 170 (MORITA, Japan) with the following scanning parameters: 90 Kv, 5–8 mA, 17.5-s exposure time, and 0.25-mm voxel size. All CBCT images were processed and reconstructed using Morita's i-Dixel 3D imaging software. Serial axial, coronal, and sagittal sections were acquired to evaluate external and internal morphology of maxillary molars. The same Endodontist assessed the CBCT images twice, with a 5-week interval in between each assessment.

For reliability, one observer (the author) evaluated 30% of the total sample twice with an interval period of 5 weeks. Results of Cohen's Kappa test revealed an almost perfect agreement between observations with a value of 85.8% and asymptotic standard error of ±9.8%.

The following parameters were evaluated:

Number of roots, number of canals, and canal configurations according to Vertucci [7] classificationDifferences between gendersBilateral symmetry.

Statistical analysis

The collected data were introduced to the Statistical Package of Social Sciences software program for Windows (SPSS V25; IBM, Chicago, IL), coded, and analyzed. The results were expressed as frequencies and percentages with a 95% confidence interval. The Z-test was used to determine differences in the independent proportions. A Chi-square test was used to determine the differences between both genders (male and female) and both locations (right and left). A Cohen's Kappa test was used for bilateral symmetry; the Kappa test was also used for intra-rater reliability. The level of significance for all statistical tests was set at P value < 0.05.

 Results



Mandibular central incisors had a higher frequency than that of mandibular lateral incisors of teeth with one root (100% versus 99.5%), one canal (73.7% versus 69.2%), and Vertucci Type I (73.7% versus 69.2%). The prevalence of the second canal in mandibular central and lateral incisors was 26.3% and 30.8%, respectively, with prevalence of Type III Vertucci canal configuration [Figure 1] and [Figure 2]. There were no significant differences found between central and lateral incisors (P = 0.449, P = 0.165, and P = 0.065, respectively).{Figure 1}{Figure 2}

Mandibular central incisors

A total of 410 mandibular central incisors (right and left) were evaluated. All teeth (100%) had one root. Out of the total sample, there were 302 (73.7%) teeth that had one canal and 108 (26.3%) teeth that had two canals. Similarly, 302 (73.7%) teeth had Vertucci Type I and 108 (26.3%) teeth had Vertucci Type III [Table 1].{Table 1}

Regarding differences between males and females, both genders had all their mandibular central incisors with one root. For the single canals in one tooth, females had more (170 representing 79.4% of teeth in females) than males (132 teeth, representing 67.3% of teeth in males). However, for the teeth with two canals, males had more than females. The difference was statistically significant (P = 0.007). Similarly, there was a significant difference (P = 0.007) with Vertucci classification between both genders with the same percentages applied [Table 2].{Table 2}

For bilateral symmetry, out of 208 participants, 205 (98.6%) participants had bilateral (both right and left sides) mandibular central incisors. In general, bilateral symmetry for the number of roots was 100%, while it was 91.2% for the number of canals, and 91.2% for Vertucci classification.

All participants (100%) had one root in both the left and right sides, 142 (69.3%) participants had one canal in both sides, and 45 (21.9%) participants had two canals on both sides. Similarly, significant symmetry of Vertucci Types was found with the same percentages applied [Table 3].{Table 3}

Mandibular lateral incisors

A total of 412 mandibular lateral incisors (right and left) were evaluated; 410 (99.5%) teeth had one root, and only two (0.5%) teeth had two roots. Teeth with one canal and one foramen accounted for 285 (69.2%) teeth, while 127 (30.8%) teeth were found with two canals. Four out of the 127 teeth with two canals have two separate canals with two foramina. Vertucci Type I appeared in 285 (69.2%) teeth, while 123 (29.8%) teeth had Vertucci Type III, and only four (1.0%) teeth had Vertucci Type V [Table 4].{Table 4}

Among the 214 female teeth, 213 (99.5%) teeth had one root and one tooth (0.5%) had two roots. Similarly, among 198 teeth in males, there were 197 (99.5%) teeth with one root, and there was only one tooth (0.5%) with two roots. There was no significant difference observed (P = 1.000). In total, 152 (71.0%) teeth in females and 133 (67.2%) in males had one canal, while 62 (29.0%) teeth in females and 65 (32.8%) teeth in males had two canals; there was no significant difference (P = 0.455). Regarding Vertucci classification, 133 (67.2%) teeth in males had Vertucci Type I, 63 (31.8%) teeth had Vertucci Type III, and only two (1.0%) teeth had Vertucci Type V. In females, 152 (71.0%) teeth had Vertucci Type I, 60 (28.0%) teeth had Vertucci Type III, and only two (1.0%) teeth had Vertucci Type V. There was no significant difference across gender (P = 0.698) [Table 5].{Table 5}

Out of 204 (98.1% of the study population) participants with both right and left mandibular lateral incisors, 202 (99.0%) participants had one root in both sides. Bilateral symmetry for the number of canals was 85.8% (P < 0.001), where 127 (62.3%) participants had one canal in both sides, and 48 (23.5%) participants had two canals in both sides. For Vertucci classification, bilateral symmetry was 85.3% (P < 0.001), where 127 (62.3%) participants had Vertucci Type I in both sides, 46 (22.5%) participants had Vertucci Type III, and one (0.5) participant had Vertucci Type V in both sides [Table 6].{Table 6}

 Discussion



Various methods have been used to evaluate the root canal configuration of central and lateral mandibular incisors. Green used staining and grinding methodology to investigate 500 mandibular incisors and found that 21% of the central and lateral mandibular incisors had one major canal with one apical foramen.[9] Vertucci [7] utilized decalcification and dye injection into the pulp space techniques to evaluate 200 central and lateral mandibular incisors; he reported that a single canal with one foramen was identified in 70% of the mandibular central incisors, 27% had two canals with one apical foramen, and 3% had two canals with 2 apical foramina. Although 75% of lateral incisors had a single canal with one foramen, 23% had two canals with one apical foramen, and 2% had two canals with two apical foramina.[7] In a Turkish population, one study showed that 67.5% of central mandibular incisors and 63.0% of lateral mandibular incisors had more than a single canal in 400 mandibular incisors, using demineralization and staining method.[19] In the present in vivo CBCT study, we found variations in the results compared with previous studies, where one canal with one foramen appeared in 73.7% mandibular central incisors and 69.2% in mandibular lateral incisors. Two canals (26.3% and 30.8%) were for central and lateral incisors, respectively, with Type III canal configurations.

Our findings are in agreement with a study done in the same Saudi Arabian population by Al-Fouzan et al.[18] using clearing and dye injection technique to examined 80 extracted human mandibular incisors. They found that 70% of the samples had one main canal and one main apical foramen corresponding to Vertucci Type I, while the remaining 30% had two canals with Type III canal configuration.[18] These findings are in contrast to those in a study conducted in a Turkish population that showed a high prevalence of a second canal in mandibular central and lateral incisors (68% and 63%, respectively).[19]

CBCT is a valuable addition to the study and is an excellent tool to expand our understanding of root canal morphology; it helps the clinician to identify all canals in a given tooth and even to project the smallest access cavity possible before endodontic treatment.[20] It is also useful for detecting additional roots and canals anatomy.[11],[12],[13],[14] The main advantages of using in vivo CBCT in prevalence and anatomy studies, apart from its high resolution, it provides information about genders and allows for the investigation of teeth in the jaws. In a CBCT study of 2,351 mandibular incisors, Martins et al. reported that approximately 30% of both teeth had two root canals were, with Vertucci Type III dominant when two canals present,[17] which is not in agreement with our findings. In a CBCT study of 1,200 teeth from a Chinese population, the prevalence of one canal in the mandibular central and lateral incisors was 84.29% and 72.64%, respectively,[21] which is higher prevalence than our results. In an Israeli population, 1,472 central mandibular incisors and 1,508 lateral mandibular incisors were evaluated using in vivo CBCT; the authors reported that 59.5% of central mandibular incisors and 62.1% of lateral mandibular incisors had a single canal.[16]

The present study also addressed gender differences. In central incisors, males had a significantly higher number of two canals than that of females, while lateral incisors no differences on gender. Our findings are in agreement with a study conducted in a Caucasian population,[17] in which males had a higher prevalence of having more than one canal when than that of females. In addition, in a Chinese population, the analysis of gender differences in mandibular incisors revealed that males had a significantly higher prevalence of a second canal.[22]

Bilateral symmetry was also investigated in our study. With regard to the number of roots, we found the symmetry in central and lateral incisors to be 100% and 99%, respectively, while the numbers of canals were 91.2% and 85.8%, respectively. This finding aligns with a previously published study that was conducted in a Turkish population using in vivo CBCT, which reported symmetries in central and lateral incisors in 100% and 99.8%, respectively, and in regard to number of roots and 94.8% and 89.8%, respectively in number of canals.[23] Another in vivo CBCT study conducted in an Israeli population also studied the bilateral symmetry in mandibular incisors. They reported that the incidence of having more than one canal in central and lateral mandibular incisors was 69.8% and 68.7%, respectively.[16] Knowledge about the presence of bilateral symmetry and asymmetry in the same patient could be of clinical significance when a clinician is treating bilateral teeth.

Missed canals were associated with endodontic failure; knowledge about the prevalence of another canal, location, and configuration is of great importance from a clinical perspective as it can aid clinicians in successfully treating dental diseases.[24] Mandibular incisors present with different cross-sections, including round, long oval, long oval flattened, and irregular shapes across the length of the root.[4],[5] Cleaning and shaping such anatomy with oval and long oval canals is challenging in practice.[25] During instrumentation of oval canals with rotary files, canals left with unprepared parts work as a debris retention area with providing a good environment for bacteria.[26],[27],[28],[29],[30],[31],[32] Conventional radiography is an essential clinical tool in endodontic therapy. However, radiographs are two-dimensional (2-D) images and, in the case of complicated anatomy, using conventional radiography alone may not be sufficient for collecting all of the required details.[3] CBCT helps the clinician to identify root canal anatomy and, consequently, prepares them with the needed armamentarium and techniques for managing cases of complicated anatomy, such as the presence of extra tooth canals.

 Conclusion



Within the limitations of this study, permanent mandibular incisors presented with second canals in about 28.6% of cases with Type III canals configurations. Mandibular central incisors showed a significant difference between genders with regard to some canals and canals configurations, while lateral incisors did not. Slight bilateral asymmetries were present in both mandibular incisors, which could be of clinical significance in case of treating contralateral teeth in the same individual.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

1Krasner P, Rankow HJ. Anatomy of the pulp-chamber floor. J Endod 2004;30:5-16.
2Vertucci FJ. Root canal morphology and its relationship to endodontic procedures. Endod Topics 2005;10:3-29.
3Verma GR, Bhadage C, Bhoosreddy AR, Vedpathak PR, Mehrotra GP, Nerkar AC, et al. Cone beam computed tomography study of root canal morphology of permanent mandibular incisors in Indian subpopulation. Pol J Radiol 2017;82:371-5.
4Wu MK, R'Oris A, Barkis D, Wesselink PR. Prevalence and extent of long oval canals in the apical third. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2000;89:739-43.
5Jou YT, Karabucak B, Levin J, Liu D. Endodontic working width: Current concepts and techniques. Dent Clin North Am 2004;48:323-35.
6Saati S, Shokri A, Foroozandeh M, Poorolajal J, Mosleh N. root morphology and number of canals in mandibular central and lateral incisors using cone beam computed tomography. Braz Dent J 2018;29:239-44.
7Vertucci FJ. Root canal anatomy of the human permanent teeth. Oral Surg Oral Med Oral Pathol 1984;58:589-99.
8Miyashita M, Kasahara E, Yasuda E, Yamamoto A, Sekizawa T. Root canal system of the mandibular incisor. J Endod 1997;23:479-84.
9Green D. Double canals in single roots. Oral Surg Oral Med Oral Pathol 1973;35:689-96.
10Boruah LC, Bhuyan AC. Morphologic characteristics of root canal of mandibular incisors in North-East Indian population: An in vitro study. J Conserv Dent 2011;14:346-50.
11Zhang R, Yang H, Yu X, Wang H, Hu T, Dummer PM. Use of CBCT to identify the morphology of maxillary permanent molar teeth in a Chinese subpopulation. IntEndod J 2011;44:162-9.
12La SH, Jung DH, Kim EC, Min KS. Identification of independent middle mesial canal in mandibular first molar using cone-beam computed tomography imaging. J Endod 2010;36:542-5.
13Levin A, Shemesh A, Katzenell V, Gottlieb A, Ben Itzhak J, Solomonov M. Use of cone-beam computed tomography during retreatment of a 2-rooted maxillary central incisor: Case report of a complex diagnosis and treatment. J Endod 2015;41:2064-7.
14Shemesh A, Levin A, Katzenell V, Ben Itzhak J, Levinson O, Zini A, et al. Prevalence of 3- and 4-rooted first and second mandibular molars in the Israeli population. J Endod 2015;41:338-42.
15Sert S, Bayirli GS. Evaluation of the root canal configurations of the mandibular and maxillary permanent teeth by gender in the Turkish population. J Endod 2004;30:391-8.
16Shemesh A, Kavalerchik E, Levin A, Ben Itzhak J, Levinson O, Lvovsky A, et al. Root canal morphology evaluation of central and lateral mandibular incisors using cone-beam computed tomography in an Israeli population. JEndod 2018;44:51-5.
17Martins JNR. Root and root canal morphology of the permanent dentition in a Caucasian population: Acone-beam computed tomography study. IntEndodJ2017:1013-26.
18Al-Fouzan KS, AlManee A, Jan J, Al-Rejaie M. Incidence of two canals in extracted mandibular incisors teeth of Saudi Arabian samples. Saudi Endod J 2012;2:65-9.
19Sert S, Aslanalp V, Tanalp J. Investigation of the root canal configurations of mandibular permanent teeth in the Turkish population. IntEndod J 2004;37:494-9.
20Michetti J, Maret D, Mallet JP, Diemer F. Validation of cone beam computed tomography as a tool to explore root canal anatomy. J Endod 2010;36:1187-90.
21Han T, Ma Y, Yang L, Chen X, Zhang X, Wang Y. A study of the root canal morphology of mandibular anterior teeth using cone-beam computed tomography in a Chinese subpopulation. J Endod 2014;40:1309-14.
22Lin Z, Hu Q, Wang T, Ge J, Liu S, Zhu M, et al. Use of CBCT to investigate the root canal morphology of mandibular incisors. Surg Radiol Anat 2014;36:877-82.
23Kayaoglu G, Peker I, Gumusok M, Sarikir C, Kayadugun A, Ucok O. Root and canal symmetry in the mandibular anterior teeth of patients attending a dental clinic: CBCT study. Braz Oral Res 2015;29:1-7.
24Karabucak B, Bunes A, Chehoud C, Kohli MR, Setzer F. Prevalence of apical periodontitis in endodontically treated premolars and molars with untreated canal: A cone-beam computed tomography study. J Endod 2016;42:538-41.
25Paque F, Ganahl D, Peters OA. Effects of root canal preparation on apical geometry assessed by micro-computed tomography. J Endod 2009;35:1056-9.
26De-Deus G, Barino B, Zamolyi RQ, Souza E, Fonseca A Jr, Fidel S, et al. Suboptimal debridement quality produced by the single-file F2 ProTaper technique in oval-shaped canals. J Endod 2010;36:1897-900.
27Paque F, Balmer M, Attin T, Peters OA. Preparation of oval-shaped root canals in mandibular molars using nickel-titanium rotary instruments: Amicro-computed tomography study. J Endod 2010;36:703-7.
28Siqueira JFJr, Alves FR, Almeida BM, de Oliveira JC, Rôças IN. Ability of chemomechanical preparation with either rotary instruments or self-adjusting file to disinfect oval-shaped root canals. J Endod 2010;36:1860-5.
29Paque F, Peters OA. Micro-computed tomography evaluation of the preparation of long oval root canals in mandibular molars with the self-adjusting file. J Endod 2011;37:517-21.
30De-Deus G, Souza EM, Barino B, Maia J, Zamolyi RQ, Reis C, et al. The self-adjusting file optimizes debridement quality in oval-shaped root canals. J Endod 2011;37:701-5.
31Metzger Z, Teperovich E, Zary R, Cohen R, Hof R. The self-adjusting file (SAF). Part 1: Respecting the root canal anatomy--Anew concept of endodontic files and its implementation. J Endod 2010;36:679-90.
32De-Deus G, Barino B, Marins J, Magalhães K, Thuanne E, Kfir A. Self-adjusting file cleaning-shaping-irrigation system optimizes the filling of oval-shaped canals with thermoplasticized gutta-percha. J Endod 2012;38:846-9.