rde Restorative Dentistry & Endodontics Restor Dent Endod 2234-7658 2234-7666 The Korean Academy of Conservative Dentistry 10.5395/rde.2018.45.e1 rde-45-e1 Research Article The prevalence of radix molaris in the mandibular first molars of a Saudi subpopulation based on cone-beam computed tomography AL-AlawiHassan 1 Al-NazhanSaad 2 * Al-MaflehiNassr 3 AldosimaniMazen A. 4 ZahidMohammed Nabil 5 ShihabiGhadeer N. 6 Dental Department, Ministry of Health Endodontist, Huraymala General Hospital, Riyadh, Saudi Arabia Department of Restorative Dentistry-Endodontics, College of Dentistry, Riyadh Elm University, Riyadh, Saudi Arabia Department of Preventive Dental Sciences-Biostatistics, College of Dentistry, King Saud University, Riyadh, Saudi Arabia Department of Oral Medicine and Diagnostic Sciences, College of Dentistry, King Saud University, Riyadh, Saudi Arabia Department of Preventive Dental Sciences, College of Dentistry, Prince Sattam Bin AbdulAziz University, Al Kharj, Saudi Arabia General Practitioner, Riyadh, Saudi Arabia Correspondence to Saad Al-Nazhan, BDS, MSD Professor, Department of Restorative Dentistry-Endodontics, College of Dentistry, Riyadh Elm University, Riyadh 11681, Saudi Arabia. E-mail: saad.alnazhan@riyadh.edu.sa 02 2020 04 02 2020 45 1 e1 17072019 25092019 01102019 Copyright © 2020 The Korean Academy of Conservative Dentistry 2020 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract Objectives

The purpose of this study was to determine the incidence of radix molaris (RM) (entomolaris and paramolaris) in the mandibular first permanent molars of a sample Saudi Arabian subpopulation using cone-beam computed tomography (CBCT).

 Materials and Methods

A total of 884 CBCT images of 427 male and 457 female Saudi citizens (age 16 to 70 years) were collected from the radiology department archives of 4 dental centers. A total of 450 CBCT images of 741 mature mandibular first molars that met the inclusion criteria were reviewed. The images were viewed at high resolution by 3 examiners and were analyzed with Planmeca Romexis software (version 5.2).

 Results

Thirty-three (4.5%) mandibular first permanent molars had RM, mostly on the distal side. The incidence of radix entomolaris (EM) was 4.3%, while that of radix paramolaris was 0.3%. The RM roots had one canal and occurred more unilaterally. No significant difference in root configuration was found between males and females (p > 0.05). Types I and III EM root canal configurations were most common, while type B was the only RP configuration observed.

 Conclusions

The incidence of RM in the mandibular first molars of this Saudi subpopulation was 4.5%. Identification of the supernumerary root can avoid missing the canal associated with the root during root canal treatment.

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(A) Cone-beam computed tomography (CBCT) images of mandibular first molar showing 4 canals (arrow). (B) CBCT showing disto-buccal root with one canal (arrow). (C) Separated distal roots with one canal each (arrow).

(A) Cone-beam computed tomography (CBCT) images of mandibular first molar showing disto-lingual root bilateral entomolaris (arrow). (B) Bilateral separated roots with one canal (arrow).

Prevalence of supernumerary root in mandibular first molar

Author/reference Origin Incidence (%) Evaluation method
Curzon and Curzon [4] Mongoloid Keewatin Eskimo (Canada) 27 In vitro (extracted teeth)
Reichart and Metah [5] Thai (Thailand) 19.2 In vitro (extracted teeth)
Walker [6] Chinese (Hong Kong) 15 In vitro (extracted teeth)
Younes et al. [7] African (Egypt) 0.7 In vitro (extracted teeth)
  Asian (Saudi Arabia) 2.3  
Zaatar et al. [8] Kuwait 2.7 In vivo (periapical radiographs)
Sperber and Moreau [9] Senegal 3.1 In vitro (extracted teeth)
Al-Nazhan [10] Saudi Arabia 5.97 In vivo (periapical radiographs)
Ahmed et al. [11] Sudan 3 In vitro (extracted teeth)
Schäfer et al. [12] Germany 0.7 In vivo (periapical radiographs)
Al-Qudah and Awawdeh [13] Jordan 3.9 In vitro (extracted teeth)
Song et al. [14] Korea (Mongoloid origin) 33.1 In vivo (periapical radiographs)
Zhang et al. [15] China 29 In vivo (CBCT)
Demirbuga et al. [16] Turkey 2.06 In vivo (CBCT)
Mukhaimer and Azizi [17] Palestine 3.73 In vivo (periapical radiographs)
Rodrigues et al. [18] Brazil 2.58 In vivo (CBCT)
Rahimi et al. [19] Iran 3.00 In vivo (CBCT)
Gupta et al. [20] Haryana (North India) 13.00 In vivo (periapical radiographs and CBCT)

CBCT, cone-beam computed tomography.

Total number of evaluated cone-beam computed tomography images

Dental center Grand total Total fit criteria
Male Female Total
Riyadh Elm University 105 160 265 82
King Saud University 134 135 269 193
Prince Sattam Bin Abdulaziz University 144 81 225 116
Uranus Dental Center 44 81 125 59
Total 427 457 884 450

Number of roots of mandibular first molar in relation to sex and jaw side

Sex Jaw side Total No. of patients Total No. of teeth No. of roots
1 2 3
Male Bilateral 165 330 0 326 (44.0%) 4 (0.5%)
  Unilateral 87 87 0 77 (10.4%) 10 (1.4%)
Female Bilateral 126 252 1 (0.1%) 245 (33.1%) 6 (0.8%)
  Unilateral 72 72 0 59 (8.0%) 13 (1.8%)
Total   450 741 1 (0.1%) 707 (95.4%) 33 (4.5%)

Number and percentages of patients with entomolaris (distolingual root) and paramolaris (mesiobuccal root) in mandibular first molars according to sex and jaw side (n = 741)

Sex Jaw side Total No. of patients Total No. of teeth Radix molaris
Entomolaris Paramolaris
Male Bilateral 2 4 4 (0.5%) 0
  Unilateral 10 10 8 (1.1%) 2 (0.3%)
  Total 12 14 12 (1.6%) 2 (0.3%)
Female Bilateral 3 6 6 (0.8%) 0
  Unilateral 13 13 13 (1.8%) 0
  Total 16 19 19 (2.6%) 0
Grand total   28 33 (4.5%) 31 (4.2%) 2 (0.3%)

Morphology of the distolingual root (entomolaris) based on Song et al. [30] classification. (n = 741)

Sex Jaw side Total No. of patients Total No. of teeth Song et al. [30] classification
Type I Type II Type III Small type Conical type
Male Bilateral 2 4 0 2 2 0 0
  Unilateral 8 8* 2 2 3 1 0
  Total 10 12 2 4 5 1 0
Female Bilateral 3 6 2 2 2 0 0
  Unilateral 13 13 7 2 3 1 0
  Total 16 19 9 4 5 1 0
Grand total   26* 31 (4.2%) 11 (1.5%) 8 (1.1%) 10 (1.3%) 2 (0.3%) 0

* The other 2 teeth of 2 patients were type B of Carlsen and Alexandersen [29] classification.