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. 2018 Nov 3;31(1):137–142. doi: 10.1016/j.sdentj.2018.10.005

Evaluation of root canal morphology of mandibular premolars in a Saudi population using cone beam computed tomography: A retrospective study

Hussam Alfawaz a,⁎, Abdullah Alqedairi a, Yousef Hamad Al-Dahman b,c, Asma Suliman Al-Jebaly d, Faisal Abdullah Alnassar e, Sara Alsubait a, Ziyad Allahem a
PMCID: PMC6349998  PMID: 30723367

Abstract

Objective

To investigate the root canal morphology of mandibular first and second premolars using Cone-Beam Computed Tomography (CBCT) in a Saudi population.

Methods

CBCT images of 707 patients, number of roots and canal configuration were identified and categorized according to Vertucci classification. Bilateral symmetry and association between gender and number of roots, as well as gender and root canal configuration were investigated.

Results

Majority of the patients had one root and type I root canal configuration in mandibular first (96.4%) and second premolar (95.6%). All types of canal configurations were observed except Type VII for the mandibular first premolar, and Types VI and VII for the mandibular second premolar. High degree of bilateral symmetry was seen in both mandibular first and second premolars in terms of the number of roots and canal configuration; 93.8% and 97.8%, respectively. There was an association between gender and number of roots (P = 0.04) and gender and root canal configuration in mandibular first premolar (P = 0.030).

Conclusions

Single-root with type I canal configuration was the most prevalent of mandibular premolars in the Saudi population. However, incidence of more than one root with different canal configurations was detected.

Keywords: Root canal morphology, Cone-beam computed tomography, Gender, Mandibular premolars

1. Introduction

A thorough knowledge of root canal morphology is crucial for the success of root canal treatment (RCT) (Vertucci, 2005). Internal root canal complexities are genetically determined and have a definite importance in anthropology, thereby necessitating the identification of root canal morphologies of different ethnic populations (Neelakantan et al., 2010a). Such complexities, including the number of canals in each root, distances of orifices, and canal types, are more difficult to detect (Neelakantan et al., 2010b).

Studies of the internal and external anatomy of teeth have shown that anatomic variations can occur in all types of teeth and can be extremely complex (Vertucci, 2005). Numerous factors contributing to the variations include ethnicity (Gulabivala et al., 2001), age (Neaverth et al., 1987), gender (Sert and Bayirli, 2004), and study design (Neaverth et al., 1987).

Weine et al., 1969, Vertucci, 1984, and Gulabivala et al. (2001) have classified and described the root canal system of human permanent teeth. Vertucci classification is the most commonly used. He classified the root canal configuration into eight categories: Type I (1), Type II (2-1), Type III (1-2-1), Type IV (2), Type V (1-2), Type VI (2-1-2), Type VII (1-2-1-2) and Type VIII (3) (Vertucci, 1984).

Root canal configuration had been identified using different methods such as 2D radiography, root canal staining, hard tissue section, micro-CT and Cone-beam computed tomography (CBCT) scanning. Cone-beam computed tomography scanning is a non-invasive 3D imaging technique. Tachibana and Matsumoto (1990) introduced it in the field endodontics. It provides images of root morphology with more details than those obtained by conventional periapical radiography that will help in improving the endodontic treatment outcomes (Patel et al., 2007).

Cone-beam computed tomography has been used to evaluate the root canal morphology of maxillary premolars and first molar as well as mandibular molars of Saudi population (Alfawaz et al., 2018, Alqedairi et al., 2018, Al-Shehri et al., 2017, Elkady and Allouba, 2013). The root canal morphology of mandibular premolars has not evaluated yet. Therefore, the aim of the study was to investigate the root canal morphology of mandibular first and second premolars using CBCT in the Saudi population.

2. Materials and methods

All procedures performed were in accordance with the ethical standards of the local institutional review board. Seven hundred and seven CBCT images of patients (396 female, 311 male) aged between 16 and 78 years who required routine dental treatment, and were subsequently referred to the Radiology Department were subsequently referred to the Radiology Department of College of Dentistry, King Saud University between 2015 and 2017, were collected. No informed consent was required for this type of study based on institutional review board.

The inclusion criterion was the existence of at least one mandibular first or second premolar with fully developed roots. Exclusion criteria included unclear or distorted CBCT images, previous endodontically treated or initiated teeth, posts or crowns, periapical lesions, and the presence of physiological or pathological process such as root resorption. In total, 391 first mandibular premolar teeth and 343 mandibular second premolar teeth were evaluated in terms of the root number and canal configuration.

The following data was observed and recorded: number of roots, number of canals per root and canal configuration based on Vertucci’s classification. The gender and age of the patients were also recorded.

Two independent endodontists assessed the root and root canal system configuration using the Planmeca Romexis Viewer software (Planmeca, Roselle IL). The CBCT machines used were CS9300 3D digital imaging system (Carestream, USA) with a voxel size of 90–500 μm and Planmeca ProMax 3D (PLANMECA, USA) with a voxel size of ≤200 μm.

To ensure the reliability of the research results, 30 images of CBCT were drawn randomly to measure inter-examiner reliability by recording the root canal numbers and identifying the type of root canal system configuration according to Vertucci’s classification. Intra-examiner reliability was measured using the same images after 1 week. Both inter- and intra-examiner reliability were calculated using Interclass Correlation Coefficient (ICC). Data was analyzed with the chi-square test using SPSS, and the significance was set at a 95% confidence level.

3. Results

For Inter-examiner reliability, the ICC was 0.886 (excellent) for the number of roots and 0.625 (good) for canal configuration. For Intra-examiner reliability, ICC was 1 for the first examiner in regard to number of root and canal configuration and 1 and 0.95 for the second examiner in regard to number of root canal configuration; respectively. The ICC demonstrated that the procedure was standardized for the evaluations and measurements performed by the two observers.

The number of roots recorded in mandibular first and second premolars was up to three roots (Fig. 1). The majority had one root; 96.4% in mandibular first premolar and 95.6% in mandibular second premolars.

Fig. 1.

Fig. 1

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a: The axial plane of CBCT of mandibular Second premolar showing the three roots. b: The coronal plane of CBCT image. c: The sagittal plane of CBCT image.

The frequency and percentage of the number of roots and canal configuration in mandibular first and second premolar teeth are shown in Table 1, Table 2 respectively.

Table 1.

The frequency and percentage of the number of roots and canal configuration in mandibular first premolar teeth.

Number of Roots
One Root Two Roots Three Roots Total
Frequency (%) Female 200 (97.5%) 3 (1.5%) 2 (1%) 205 (100%)
Male 177 (95.2%) 9 (4.8%) 0 (0%) 186 (100%)
Total 377 (96.4%) 12 (3.1%) 2 (0.5%) 391 (100%)
Canal Configuration
Type I (1) Type II (2-1) Type III (1-2-1) Type IV (2) Type V (1-2) Type VI (2-1-2) Type VII (1-2-1-2) Type VIII (3) Total
Frequency (%) Female 180 (87.8%) 7 (3.4%) 8 (3.9%) 1 (0.5%) 3 (1.5%) 0 (0%) 0 (0%) 6 (2.9%) 205 (100%)
Male 164 (88.2%) 7 (3.8%) 4 (2.2%) 7 (3.8%) 3 (1.6%) 1 (0.5%) 0 (0%) 0 (0%) 186 (100%)
Total 344 (88%) 14 (3.6%) 12 (3.1%) 8 (2%) 6 (1.5%) 1 (0.3%) 0 (0%) 6 (1.5%) 391 (100%)
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Table 2.

The frequency and percentage of the number of roots and canal configuration in mandibular second premolar teeth.

Number of Roots
One Root Two Roots Three Roots Total
Frequency (%) Female 164 (95.3%) 6 (3.5%) 2 (1.2%) 172 (100%)
Male 164 (95.9%) 7 (4.1%) 0 (0%) 171 (100%)
Total 328 (95.6%) 13 (3.8%) 2 (0.6%) 343 (100%)
Canal Configuration
Type I (1) Type II (2-1) Type III (1-2-1) Type IV (2) Type V (1-2) Type VI (2-1-2) Type VII (1-2-1-2) Type VIII (3) Total
Frequency (%) Female 155 (90.1%) 6 (3.5%) 0 (0%) 3 (1.7%) 2 (1.2%) 0 (0%) 0 (0%) 6 (3.5%) 172 (100%)
Male 154 (90.1%) 9 (5.3%) 1 (0.6%) 6 (3.5%) 1 (0.6%) 0 (0%) 0 (0%) 0 (0%) 171 (100%)
Total 309 (90.1%) 15 (4.4%) 1 (0.3%) 9 (2.6%) 3 (0.9%) 0 (0%) 0 (0%) 6 (1.7%) 343 (100%)
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Type I was the most prevalent canal configuration in mandibular first premolar and in mandibular second premolar teeth. In mandibular first premolars, 94.7% had one canal apically (type I, II, III), 3.8% had two canals apically (type IV, V, VI) and 1.5% had three canals apically (type VIII). In mandibular second premolars, 94.8% had one canal apically (type I, II, III), 3.5% had two canals apically (type IV,V) and 1.7% had three canals apically (type VIII).

Chi-Square and fisher exact tests for mandibular first premolars demonstrated an association between gender and number of roots (P = 0.046), and gender and root canal configuration (P = 0.030). The prevalence of two-rooted mandibular first premolars in men was higher than that for women, while three-rooted mandibular first premolars were seen in women only (P ≤ 0.05). However, single-rooted mandibular first premolars were the most predominant root morphology in both genders. Interestingly, canal configuration Type VIII was seen in women only (2.9%).

In mandibular second premolars, there was no association between gender and number of roots nor gender and root canal configuration (P > 0.05). However, types II, III, and IV canal configurations were more likely to be observed in men, while types V and VIII were found more frequently in women (P = 0.069).

Among the 210 patients having right and left mandibular first premolar teeth, 93.8% of teeth showed a symmetrical number of roots and canal configuration, while 5.2% showed a symmetrical number of roots, but a different canal configuration, and 0.5% showed a symmetrical canal configuration but a different number of roots. However, 0.5% did not show any type of symmetry.

Among 181 patients where mandibular right and left second premolar teeth were present, 97.8% of teeth showed a symmetrical number of roots and canal configuration, while 1.7% showed a symmetrical number of roots, but a different canal configuration. Only 0.5% lacked any type of symmetry.

4. Discussion

Successful root canal treatment is achieved when all the canals are located, debrided, shaped, disinfected, and obturated completely (Al-Dahman et al., 2018, Nallapati, 2005). Reasons related to the failure of root canal treatment include untreated canals, incomplete disinfection, and inadequate obturation (Gulabivala et al., 2001). Therefore, proper clinical and radiographical examinations are mandatory for successful root canal treatment.

Different techniques have been used for the evaluation and assessment of root canal morphology. Recently, the use of CBCT has been considered an excellent clinical tool for this purpose due to its three-dimensional evaluation of the tooth anatomy (Alfawaz et al., 2018, Alqedairi et al., 2018, Al-Shehri et al., 2017, Patel et al., 2009). In addition, it is more reliable and yielded a high level of reproducibility regardless of changes in tooth positions (Lund et al., 2010, Michetti et al., 2010).

The number of root canals in mandibular first premolar teeth was reported to be one canal in 69.3–86%, two canals in 14–25.5% (Green, 1973, Pineda and Kuttler, 1972, Vertucci, 1978, Zillich and Dowson, 1973), and three canals in 0.5% (Zillich and Dowson, 1973), and 0.4% (Vertucci, 1978). In mandibular second premolar teeth, the number of root canals was reported to be one canal in 97.5% and two canals in 2.5% of the teeth studied (Vertucci, 1978), while the incidence of three root canals was ranging from 0 to 0.4% (Vertucci, 1978, Zillich and Dowson, 1973). Findings of the current study of second premolar fall in the same range of the previous studies while it is different concerning first premolar. This could be attributed to ethnicity and method of evaluation. Moreover, case reports of mandibular second premolars with four and five root canals have been published (Al-Abdulwahhab and Al-Nazhan, 2015, Macri and Zmener, 2000).

In mandibular first premolars, the most predominant root morphology observed in this study was single-rooted (96.4%), followed by double-rooted (3.1%), and then three-rooted (0.5%). The prevalence of two rooted mandibular first premolars was higher in this study when compared to other studies using the clearing method of extracted teeth in Turkey (0%) (Çalişkan et al., 1995), Iran (2%) (Rahimi et al., 2007), and Jordan (3%) (Awawdeh and Al-Qudah, 2008). Investigations of root canal morphology of extracted teeth considered as invasive studies compared to CBCT. A higher prevalence was reported in Caucasians (10.9%) using radiographs (Trope et al., 1986), Egyptian (3.2%) (Alhadainy, 2013), South Asians (6%) (Singh and Pawar, 2014), and South Saudi subpopulations (18%) (Chourasia et al., 2017), where the clearing technique was the method used. Moreover, a study from a Kuwait population using two-dimensional radiographic evaluation reported a high incidence of two rooted mandibular first premolar teeth (15%), however it evaluated a small sample size of twenty teeth (Zaatar et al., 1997). Conventional radiograph does not provide an adequate amount of information when dealing with complicated endodontic cases in clinical practice as the CBCT does. This approach was strongly supported by the American and European association (AAE and AAOMR joint position statement, 2015, European Society of Endodontology, 2014).

The prevalence of three rooted mandibular first premolars (0.5%) was higher in comparison to the study using Radiovisiography on an Indian population (0.2%) (Iyer et al., 2006), and lower than the study of the South Saudi subpopulation (2%) (Chourasia et al., 2017). In general, the occurrence of three rooted canals is rare in mandibular premolars.

Most of the mandibular first premolar teeth had type I canal configuration followed by type II, and type III. Type VIII canal morphologies in which there were three distinct canals were observed in 6 teeth. According to Vertucci’s classification (Vertucci, 1984), type I was more frequent (67.39%) than the other canal configurations. The occurrence of multiple canals in mandibular first premolar teeth was reported in a range from 0.2% to 39.5% (Alhadainy, 2013, Chourasia et al., 2017, Green, 1973, Park et al., 2013, Pineda and Kuttler, 1972, Rahimi et al., 2007, Sert and Bayirli, 2004, Vertucci, 1984, Yoshioka et al., 2004). Velmurugan and Sandhya (2009) reported that the incidence of type II canal configuration was 16.6%, while Parekh et al. (2011) reported an incidence of 5%. Only one study dealing with the morphology of first mandibular premolar of Saudi population was published (Chourasia et al., 2017). The findings of the present study are different from Chourasia et al., 2017 study due to differences of methodology of evaluation and number of teeth.

In mandibular second premolar teeth, the major root morphology observed was single-rooted, followed by two-rooted, then three roots. Moreover, most of these teeth exhibited type I canal configuration, followed by type II, and type VIII. These findings were similar to other studies where the incidence of type I was reported to be 93.63% and 98.5% in a Turkish population, respectively (Çalişkan et al., 1995, Ok et al., 2014). Cleghorn et al have reviewed the morphology of root canal system studies in mandibular second premolars and reported an overall incidence of 91% with one canal and 9% with two canals (Cleghorn et al., 2007).

In comparison to a recent CBCT study in a selected German population, one root was found more prevalent in both mandibular first and second premolars, 90.76% and 98.16%, respectively, and with one canal, 77.9% and 96%, respectively (Bürklein et al., 2017), which coincides with the findings in our study. Also, case reports have been published for two rooted mandibular second premolars with 3 root canals (Al-Attas and Al-Nazhan, 2003), and three roots with three root canals (Alenezi et al., 2015).

Ok et al., 2014, Bürklein et al., 2017 reported that men had significantly more roots and root canals than women in mandibular first premolars. Moreover, Martins et al. (2018) reported that a lower number of roots and higher type I canal configurations were detected in women, while three root canal system configurations were more prevalent in men with few differences found between the two genders. In the current study, there was an association between gender and number of roots (P = 0.046), and gender and root canal configuration (P = 0.030) in mandibular first premolars while there was no association between gender and number of roots nor gender and root canal configuration (P > 0.05) in the second premolars.

Three studies have compared the degree of symmetry in root canal morphology in contralateral premolars (Johnsen et al., 2017, Johnsen et al., 2016, Xu et al., 2016). Two of these studies assessed the symmetry using μ-CT and concluded that contralateral premolars can be viewed as a mirror image of each other on the basis of geometrical analysis (Johnsen et al., 2017, Johnsen et al., 2016). In the other study (Xu et al., 2016), CBCT was used and the results found that few matching contralateral premolars were observed. In our study, however, a high degree of symmetry was seen in both mandibular first and second premolars in terms of the number of roots and canal configuration (93.8% and 97.8%, respectively).

5. Conclusion

Within the limitation of this study, in a Saudi population, the majority of mandibular first and second premolar teeth exhibited a single root with type I canal configuration. However, incidence of more than one root with different canal configurations was detected. Further studies are recommended with a larger sample size for greater representation of a Saudi population. Clinicians should be aware of the complexity of root canal anatomy using the most recent and reliable armamentarium to achieve favorable treatment outcomes.

Ethical statement

The study was independently reviewed and approved by the local institutional review board (No. E-18-3091) at King Saud University and conducted in full accordance with the World Medical Association Declaration of Helsinki.

Acknowledgments

Acknowledgment

The authors thank King Saud University, College of Dentistry Research Center (CDRC) for their support in conducting the study (FR0376), and Dr. Ahmed Qattan (General Practitioner, Thadiq General Hospital, Saudi Arabia) for his efforts in data collection.

Conflicts of interest

The authors have no conflicts of interest relevant to this article.

Footnotes

Peer review under responsibility of King Saud University.

References

  1. AAE and AAOMR joint position statement: Use of cone beam computed tomography in endodontics 2015 update. J. Endod. 41, 1393–1396. [DOI] [PubMed]
  2. Al-Abdulwahhab B., Al-Nazhan S. Root canal treatment of mandibular second premolar with four root canals. Saudi Endod. J. 2015;5(3):196–198. [Google Scholar]
  3. Al-Attas H., Al-Nazhan S. Mandibular second premolar with three root canals: report of a case. Saudi Dent. J. 2003;15(3):145–147. [Google Scholar]
  4. Al-Dahman Y.H., Al-Qahtani S.A., Al-Mahdi A.A., Al-Hawwas A.Y. Endodontic management of mandibular premolars with three root canals: case series. Saudi Endod. J. 2018;8(2):133–138. [Google Scholar]
  5. Alenezi M., Tarish M., Alenezi D. Root canal treatment of three-rooted mandibular second premolar using cone-beam computed tomography. Saudi Endod. J. 2015;5(3):187–190. [Google Scholar]
  6. Alfawaz H., Alqedairi A., Alkhayyal A.K., Almobarak A.A., Alhusain M.F., Martins J.N.R. Prevalence of C-shaped canal system in mandibular first and second molars in a Saudi population assessed via cone beam computed tomography: a retrospective study. Clin. Oral Investig. 2018:1–6. doi: 10.1007/s00784-018-2415-0. Epub ahead of print. [DOI] [PubMed] [Google Scholar]
  7. Alhadainy H.A. Canal configuration of mandibular first premolars in an Egyptian population. J. Adv. Res. 2013;4(2):123–128. doi: 10.1016/j.jare.2012.03.002. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Alqedairi A., Alfawaz H., Al-Dahman Y., Alnassar F., Al-Jebaly A., Alsubait S. Cone-beam computed tomographic evaluation of root canal morphology of maxillary premolars in a Saudi population. BioMed. Res. 2018;2018:1–8. doi: 10.1155/2018/8170620. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Al-Shehri S., Al-Nazhan S., Shoukry S., Al-Shwaimi E., Al-Sadhan R., Al-Shemmery B. Root and canal configuration of the maxillary first molar in a Saudi subpopulation: A cone-beam computed tomography study. Saudi Endod. J. 2017;7(2):69–76. [Google Scholar]
  10. Awawdeh L.A., Al-Qudah A.A. Root form and canal morphology of mandibular premolars in a Jordanian population. Int. Endod. J. 2008;41(3):240–248. doi: 10.1111/j.1365-2591.2007.01348.x. [DOI] [PubMed] [Google Scholar]
  11. Bürklein S., Heck R., Schäfer E. Evaluation of the root canal anatomy of maxillary and mandibular premolars in a selected german population using cone-beam computed tomographic data. J. Endod. 2017;43(9):1448–1452. doi: 10.1016/j.joen.2017.03.044. [DOI] [PubMed] [Google Scholar]
  12. Çalişkan M.K., Pehlivan Y., Sepetçioğlu F., Türkün M., Tuncer S.Ş. Root canal morphology of human permanent teeth in a Turkish population. J. Endod. 1995;21(4):200–204. doi: 10.1016/S0099-2399(06)80566-2. [DOI] [PubMed] [Google Scholar]
  13. Chourasia H., Boreak N., Tarrosh M., Mashyakhy M. Root canal morphology of mandibular first premolars in Saudi Arabian southern region subpopulation. Saudi Endod. J. 2017;7(2):77–81. [Google Scholar]
  14. Cleghorn B.M., Christie W.H., Dong C.C.S. The root and root canal morphology of the human mandibular second premolar: a literature review. J. Endod. 2007;33(9):1031–1037. doi: 10.1016/j.joen.2007.03.020. [DOI] [PubMed] [Google Scholar]
  15. Elkady A., Allouba K. Cone beam computed tomographic analyasis of root and canal morphology of maxillary premolars in Saudi subpopulation. Egyptian Dent. J. 2013;59(7):3419–3429. [Google Scholar]
  16. European Society of Endodontology. Patel S., Durack C., Abella F., Roig M., Shemesh H. European Society of Endodontology position statement: the use of CBCT in endodontics. Int. Endod. J. 2014;2014(47):502–504. doi: 10.1111/iej.12267. [DOI] [PubMed] [Google Scholar]
  17. Green D. Double canals in single roots. Oral Surg. Oral Med. Oral Pathol. 1973;35(5):689–696. doi: 10.1016/0030-4220(73)90037-6. [DOI] [PubMed] [Google Scholar]
  18. Gulabivala K., Aung T.H., Alavi A., Ng Y.L. Root and canal morphology of Burmese mandibular molars. Int. Endod. J. 2001;34(5):359–370. doi: 10.1046/j.1365-2591.2001.00399.x. [DOI] [PubMed] [Google Scholar]
  19. Iyer V.H., Indira R., Ramachandran S., Srinivasan M.R. Anatomical variations of mandibular premolars in Chennai population. Ind. J. Dent. Res. 2006;17(1):7–10. doi: 10.4103/0970-9290.29898. [DOI] [PubMed] [Google Scholar]
  20. Johnsen G.F., Dara S., Asjad S., Sunde P.T., Haugen H.J. Anatomic comparison of contralateral premolars. J. Endod. 2017;43(6):956–963. doi: 10.1016/j.joen.2017.01.012. [DOI] [PubMed] [Google Scholar]
  21. Johnsen G.F., Sundnes J., Wengenroth J., Haugen H.J. Methodology for morphometric analysis of modern human contralateral premolars. J. Comput. Assist. Tomogr. 2016;40(4):617–625. doi: 10.1097/RCT.0000000000000417. [DOI] [PubMed] [Google Scholar]
  22. Lund H., Grondahl K., Grondahl H.G. Cone beam computed tomography for assessment of root length and marginal bone level during orthodontic treatment. Angle Orthod. 2010;80:466–473. doi: 10.2319/072909-427.1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Macri E., Zmener O. Five canals in a mandibular second premolar. J. Endod. 2000;26(5):304–305. doi: 10.1097/00004770-200005000-00016. [DOI] [PubMed] [Google Scholar]
  24. Martins J.N.R., Marques D., Francisco H., Caramês J. Gender influence on the number of roots and root canal system configuration in human permanent teeth of a Portuguese subpopulation. Quintessence Int. 2018;49(2):103–111. doi: 10.3290/j.qi.a39508. [DOI] [PubMed] [Google Scholar]
  25. Michetti J., Maret D., Mallet J.P., Diemer F. Validation of cone beam computed tomography as a tool to explore root canal anatomy. J. Endod. 2010;36:1187–1190. doi: 10.1016/j.joen.2010.03.029. [DOI] [PubMed] [Google Scholar]
  26. Nallapati S. Three canal mandibular first and second premolars: a treatment approach. J. Endod. 2005;31(6):474–476. doi: 10.1097/01.don.0000157986.69173.a6. [DOI] [PubMed] [Google Scholar]
  27. Neaverth E.J., Kotler L.M., Kaltenbach R.F. Clinical investigation (In Vivo) of endodontically treated maxillary first molars. J. Endod. 1987;13(10):506–512. doi: 10.1016/S0099-2399(87)80018-3. [DOI] [PubMed] [Google Scholar]
  28. Neelakantan P., Subbarao C., Ahuja R., Subbarao C.V., Gutmann J.L. Cone-beam computed tomography study of root and canal morphology of maxillary first and second molars in an Indian population. J. Endod. 2010;36(10):1622–1627. doi: 10.1016/j.joen.2010.07.006. [DOI] [PubMed] [Google Scholar]
  29. Neelakantan P., Subbarao C., Subbarao C.V. Comparative evaluation of modified canal staining and clearing technique, cone-beam computed tomography, peripheral quantitative computed tomography, spiral computed tomography, and plain and contrast medium–enhanced digital radiography in studying root C. J. Endod. 2010;36(9):1547–1551. doi: 10.1016/j.joen.2010.05.008. [DOI] [PubMed] [Google Scholar]
  30. Ok E., Altunsoy M., Nur B.G., Aglarci O.S., Çolak M., Güngör E. A cone-beam computed tomography study of root canal morphology of maxillary and mandibular premolars in a Turkish population. Acta Odontol. Scand. 2014;72(8):701–706. doi: 10.3109/00016357.2014.898091. [DOI] [PubMed] [Google Scholar]
  31. Parekh V., Shah N., Joshi H. Root canal morphology and variations of mandibular premolars by clearing technique: an in vitro study. J. Contemp. Dent. Pract. 2011;12(4):318–321. doi: 10.5005/jp-journals-10024-1052. [DOI] [PubMed] [Google Scholar]
  32. Park J.B., Kim N., Park S., Kim Y., Ko Y. Evaluation of root anatomy of permanent mandibular premolars and molars in a korean population with cone-beam computed tomography. Eur. J. Dent. 2013;7(1):94–101. [PMC free article] [PubMed] [Google Scholar]
  33. Patel S., Dawood A., Ford T.P., Whaites E. The potential applications of cone beam computed tomography in the management of endodontic problems. Int. Endod. J. 2007;40(10):818–830. doi: 10.1111/j.1365-2591.2007.01299.x. [DOI] [PubMed] [Google Scholar]
  34. Patel S., Dawood A., Whaites E., Pitt Ford T. New dimensions in endodontic imaging: part 1. Conventional and alternative radiographic systems. Int. Endod. J. 2009;42(6):447–462. doi: 10.1111/j.1365-2591.2008.01530.x. [DOI] [PubMed] [Google Scholar]
  35. Pineda F., Kuttler Y. Mesiodistal and buccolingual roentgenographic investigation of 7,275 root canals. Oral Surg. Oral Med. Oral Pathol. 1972;33(1):101–110. doi: 10.1016/0030-4220(72)90214-9. [DOI] [PubMed] [Google Scholar]
  36. Rahimi S., Shahi S., Yavari H.R., Manafi H., Eskandarzadeh N. Root canal configuration of mandibular first and second premolars in an Iranian population. J. Dent. Res. Dent. Clin. Dent. Prosp. 2007;1(2):59–64. doi: 10.5681/joddd.2007.010. [DOI] [PMC free article] [PubMed] [Google Scholar]
  37. Sert S., Bayirli G.S. Evaluation of the root canal configurations of the mandibular and maxillary permanent teeth by gender in the Turkish population. J. Endod. 2004;30(6):391–398. doi: 10.1097/00004770-200406000-00004. [DOI] [PubMed] [Google Scholar]
  38. Singh S., Pawar M. Root canal morphology of south asian indian mandibular premolar teeth. J. Endod. 2014;40(9):1338–1341. doi: 10.1016/j.joen.2014.03.021. [DOI] [PubMed] [Google Scholar]
  39. Tachibana H., Matsumoto K. Applicability of X-ray computerized tomography in endodontics. Endod. Dent. Traumatol. 1990;6(1):16–20. doi: 10.1111/j.1600-9657.1990.tb00381.x. [DOI] [PubMed] [Google Scholar]
  40. Trope M., Elfenbein L., Tronstad L. Mandibular premolars with more than one root canal in different race groups. J. Endod. 1986;12(8):343–345. doi: 10.1016/S0099-2399(86)80035-8. [DOI] [PubMed] [Google Scholar]
  41. Velmurugan N., Sandhya R. Root canal morphology of mandibular first premolars in an Indian population: a laboratory study. Int. Endod. J. 2009;42(1):54–58. doi: 10.1111/j.1365-2591.2008.01494.x. [DOI] [PubMed] [Google Scholar]
  42. Vertucci F.J. Root canal morphology and its relationship to endodontic procedures. Endod. Top. 2005;10(1):3–29. [Google Scholar]
  43. Vertucci F.J. Root canal anatomy of the human permanent teeth. Oral Surg. Oral Med. Oral Pathol. Oral Radiol. Endod. 1984;58(5):589–599. doi: 10.1016/0030-4220(84)90085-9. [DOI] [PubMed] [Google Scholar]
  44. Vertucci F.J. Root canal morphology of mandibular premolars. J. Am. Dent. Assoc. 1978;97(1):47–50. doi: 10.14219/jada.archive.1978.0443. [DOI] [PubMed] [Google Scholar]
  45. Weine F.S., Healey H.J., Gerstein H., Evanson L. Canal configuration in the mesiobuccal root of the maxillary first molar and its endodontic significance. Oral Surg. Oral Med. Oral Pathol. Oral Radiol. Endod. 1969;28(3):419–425. doi: 10.1016/0030-4220(69)90237-0. [DOI] [PubMed] [Google Scholar]
  46. Xu J., Shao M.Y., Pan H.Y., Lei L., Liu T., Cheng L., Hu T., Dummer P.M.H. A proposal for using contralateral teeth to provide well-balanced experimental groups for endodontic studies. Int. Endod. J. 2016;49(10):1001–1008. doi: 10.1111/iej.12553. [DOI] [PubMed] [Google Scholar]
  47. Yoshioka T., Villegas J., Kobayashi C., Suda H. Radiographic evaluation of root canal multiplicity in mandibular first premolars. J. Endod. 2004;30(2):73–74. doi: 10.1097/00004770-200402000-00002. [DOI] [PubMed] [Google Scholar]
  48. Zaatar E.I., Al-Kandari A.M., Alhomaidah S., Al-Yasin I.M. Frequency of endodontic treatment in Kuwait: radiographic evaluation of 846 endodontically treated teeth. J. Endod. 1997;23(7):453–456. doi: 10.1016/s0099-2399(97)80302-0. [DOI] [PubMed] [Google Scholar]
  49. Zillich R., Dowson J. Root canal morphology of mandibular first and second premolars. Oral Surg. Oral Med. Oral Pathol. 1973;36(5):738–744. doi: 10.1016/0030-4220(73)90147-3. [DOI] [PubMed] [Google Scholar]

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