Volume 4, Issue 1 (3-2019)                   J Res Dent Maxillofac Sci 2019, 4(1): 30-35 | Back to browse issues page


XML Print


Download citation:
BibTeX | RIS | EndNote | Medlars | ProCite | Reference Manager | RefWorks
Send citation to:

Shakeri F, Azizi H, Razian F, Haghanifar S, Hoshyari N. Prevalence of Mid-Mesial Canal and Isthmuses in Mandibular First and Second Molars in an Iranian Population. J Res Dent Maxillofac Sci 2019; 4 (1) :30-35
URL: http://jrdms.dentaliau.ac.ir/article-1-233-en.html
1- Post-graduate student, Department of Endodontics, Dental Faculty
2- Dentist
3- Assistant professor, Department of Oral and Maxillofacial Radiology, Dental Faculty
4- Assistant professor, Department of Endodontics, Dental Faculty, Mazandaran University of Medical Sciences, Sari, Iran , narjeshoshyari@rocketmail.com
Full-Text [PDF 338 kb]   (1028 Downloads)     |   Abstract (HTML)  (3646 Views)
Full-Text:   (885 Views)



Abstract


Background and Aim: It is essential to know the internal root canal anatomy to reach a successful root canal debridement and a subsequent successful root canal obturation. Due to the importance of knowing the complexity of mid-mesial (MM) canals and isthmuses and how to deal with these anatomic variations, in this study, we examined the incidence and prevalence of the MM canal and isthmuses in mandibular first and second molars.
Materials and Methods: In this cross-sectional study, cone-beam computed tomography (CBCT) records of patients presenting for diagnostic purposes to a radiology center in the city of Sari were used. A total of 207 mandibular first molars (81 males and 126 females) and 235 mandibular second molars (94 males and 140 females) were examined. Data were entered into SPSS 16 software. Descriptive data were presented using frequency percentage with the significance level of less than 0.05.
Results: Among the mandibular first molars that were examined in the study population, the prevalence of the MM canal was reported to be 2.5% in males and 4% in females. Similarly, the prevalence of the MM canal in the mandibular second molars was reported to be 2.1% in males and 3.6% in females. Also, the prevalence of isthmuses was 81.2% (males) and 78.9% (females) in the first molars and 78.7% (males) and 70.7% (females) in the second molars.
Conclusion: Based on the results of this study, it is important for dentists to be familiar with the root canal anatomy and to consider the referral of complex cases to endodontists.
Keywords: Cone-Beam Computed Tomography, Anatomic Variation, Root Canal, Mandible, Molar
 

Introduction


In order to reach a successful root canal debridement and a subsequent successful root canal obturation, it is essential to know the internal root canal anatomy. (1) It is necessary to know unusual root canal anatomies and their differences. It has been proven that the presence of a conical root canal with a single apical foramen is an exception and not a rule. (2)
Root formation initiates with the apical proliferation of the epithelial cells of the Hertwig epithelial root sheath (HERS). (3) Epithelial cell distribution and proliferation are determined genetically, and the distribution pattern determines whether the root canal is wide or narrow, direct or curved, and long or short. (4)
Various forms of root canal anatomy can occur in the first and second mandibular molars. The third canal in the mesial root of mandibular molars is the mid-mesial (MM) canal. (5)
Since the time that Vertucci and Williams reported the presence of the MM canal in mandibular molars for the first time, several case reports have been presented on additional canals in the mesial root. (6) Although several authors agree on the presence of three orifices in the mesial root of mandibular molars, only a small number of them have reported the presence of three distinct independent root canals. (7)
There is a probability for the presence of an isthmus in every dental root that contains two root canals. Isthmuses may contain necrotic debris, tissue remnants or organic layers that can support the growth of microorganisms and can lead to root canal treatment failure, especially in maxillary and mandibular molars. (8)
Cone-beam computed tomography (CBCT) is a new technology that was first introduced in 1982 for angiography and later for maxillofacial imaging. (9) CBCT systems have recently been introduced for imaging the hard tissues of the maxillofacial region. CBCT is capable of providing accurate images below the limit of millimeters with lower scan times and a lower dose, and its three-dimensional (3D) information of root morphology, pulp chamber, and root canals is more accurate than that rendered by intraoral radiography. CBCT can be used to evaluate the number and the morphology of root canals and their path along the root in all three dimensions prior to endodontic treatments. (10)
Due to the importance of knowing the complexity of MM canals and isthmuses and how to deal with these anatomic variations, in this study, we examined the prevalence of MM canals and isthmuses in mandibular first and second molars.


Materials and Methods



In this cross-sectional descriptive study, we used the CBCT images of patients who referred to a maxillofacial radiology center in the city of Sari for diagnostic and therapeutic purposes. A total of 207 CBCT images (81 males and 126 females) of first mandibular molars and 235 CBCT images (94 males and 140 females) of second mandibular molars were evaluated in terms of the prevalence of the MM canal and isthmuses.
The inclusion criteria for CBCT images of mandibular second molars were as follows:

  1. No apical lesion,

  2. No previous root canal treatment,

  3. Fully developed root apices,

  4. No deep carious lesion,

  5. No root canal calcification or resorption,

  6. High-quality CBCT images of second molars.

High-resolution CBCT images were taken by an oral and maxillofacial radiologist using Cranex 3D (Soredex, Helsinki, Finland) with the following exposure settings: voxel size=130 µm, milliampere (mA)=6, kilovoltage peak (kVp)=89, and field of view (FOV)=6×8 cm. The CBCT images were processed using OnDemand3D™ Dental software (Cybermed, Seoul, South Korea).
Data were evaluated by a general dentist and an endodontist; in case of no consensus, an oral and maxillofacial radiologist evaluated the images. Data were entered into SPSS 16 software (SPSS Inc., Chicago, IL, USA). Descriptive data were presented using frequency percentage with the significance level of less than 0.05.
 
  
Results



The prevalence of the MM canal in the mandibular first molars according to gender is shown in Table 1. The prevalence of the MM canal in the mandibular first molars was 2.5% in males and 4% in females.
The prevalence of the MM canal in the mandibular second molars according to gender is shown in Table 1. The prevalence of the MM canal in the mandibular second molars was 2.1% in males and 3.6% in females.
The prevalence of isthmuses in the mandibular first molars according to gender is shown in Table 2 (81.2% in males and 78.2% in females). According to Table 2, the prevalence of isthmuses in the mandibular second molars was 78.7% in males and 70.7% in females.
Table 1: Prevalence of the mid-mesial (MM) canal in the first and second molars
Table 2: Prevalence of isthmuses in the first and second molars



Discussion



Several researchers have examined the morphological features of mandibular molars. In previous articles, the presence of a third canal in the mesial roots of mandibular molars has been evaluated as the presence of an MM canal or an isthmus. However, there is still debate on the prevalence of MM canals and isthmuses in the mesial roots of mandibular molars.

Related studies have been performed using various techniques. (6-8,11,12) Transparency procedures and radiography were the most common methods; the limitations of these methods in the field of diagnosis have been mentioned in these articles. (12-17) Other methods include decalcification, histologic evaluation, stereomicroscopic analysis, scanning electron microscopy (SEM), micro CT, and CBCT (11-13,18,19) with different results.

The prevalence of the MM canal has been reported to be 0.82% to 37.5%. (20-23) The differences in the results can be due to the study design, sample size, and ethnicity.

In several studies, genetics has been considered as a predisposing factor, while other studies have found no such correlation. (21)

In this study, we evaluated the prevalence of the MM canal in the mesial roots of mandibular molars in an Iranian population.

The limitations of study tools in the evaluation of the anatomic features of teeth lead to various interpretations. The advancements of imaging methods have made it possible to produce non-destructive 3D images in vivo with the aid of CBCT. (22) For this reason, in this study, we evaluated the prevalence of the MM canal in the mesial roots of mandibular molars using CBCT.

In our study, the prevalence of the MM canal was 2.5% (males) and 4% (females) in the mandibular first molars and 2.1% (males) and 3.6% (females) in the mandibular second molars. 

Versiani and colleagues examined the prevalence of the MM canal in Turkish and Brazilian populations. (12) They reported that the prevalence of the MM canal was higher among the Brazilian population (22.1%) compared to the Turkish population (14.8%), which is higher compared to our results (3.5%).

In a CBCT study by Nosrat et al, the MM canal was observed in 0.26% of the lower molars. (15) It was claimed that the inadequate cut-off thickness and the low spatial resolution of CBCT were the causes of the low reported prevalence. (15)

The MM canal orifice is located in the developmental groove between the mesiobuccal orifice and the mesiolingual orifice, and it is often covered by dentin shelves that should be removed using an ultrasonic tip under light and magnification. (24,25)

In our study, the prevalence of isthmuses was 81.2% (males) and 78.9% (females) in the first molars and 78.7% (males) and 70.7% (females) in the second molars.

In their study on the prevalence of isthmuses in the mesial roots of mandibular first molars, Teixeira et al reported the incidence of isthmuses to be high. (25) Isthmuses were observed with a higher incidence at the apical third of the root; some of the isthmuses were complete and some were incomplete. (25)

Von Arx reported a prevalence of 83% for isthmuses, which was close to our results. (21)
In 2017, Tahmasbi et al studied the prevalence of isthmuses in the mesial roots of mandibular molars in a CBCT study; they reported a prevalence of 64.7% for isthmuses. (11) Since the methodology of the mentioned study was similar to ours, the difference in the results may be due to the different study populations.

Type of Study: Original article | Subject: Radiology

References
1. Martins JN, Marques D, Silva EJ, Caramês J, Versiani M. Prevalence Studies on Root Canal Anatomy Using Cone-beam Computed Tomographic Imaging: A Systematic Review. Journal of endodontics. 2019 Mar;45(4):372-86. [DOI:10.1016/j.joen.2018.12.016] [PMID]
2. Abou-Rass M, Frank AL, Glick DH. The anticurvature filing method to prepare the curved root canal. J Am Dent Assoc. 1980 Nov;101(5):792-4. [DOI:10.14219/jada.archive.1980.0427] [PMID]
3. Luan X, Ito Y, Diekwisch TG. Evolution and development of Hertwig's epithelial root sheath. Dev Dyn. 2006 May;235(5):1167-80. [DOI:10.1002/dvdy.20674] [PMID] [PMCID]
4. Hamamoto Y, Nakajima T, Ozawa H, Uchida T. Production of amelogenin by enamel epithelium of Hertwig's root sheath. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 1996 Jun;81(6):703-9. [DOI:10.1016/S1079-2104(96)80077-1]
5. Bhosale S, Balasubramanian A, Maroli R, Jayasree S. Middle Mesial Canal: A Common Finding-A Report of Three Cases. J Contemp Dent. 2014 Sep;4(3):152. [DOI:10.5005/jp-journals-10031-1086]
6. Vertucci FJ, Williams RG. Root canal anatomy of the mandibular first molar. J N J Dent Assoc. 1974 Spring;45(3):27-8.
7. Holtzmann L. Root canal treatment of a mandibular first molar with three mesial root canals. Int Endod J. 1997 Nov;30(6):422-3. [DOI:10.1111/j.1365-2591.1997.tb00735.x] [PMID]
8. Gu L, Wei X, Ling J, Huang X. A microcomputed tomographic study of canal isthmuses in the mesial root of mandibular first molars in a Chinese population. J Endod. 2009 Mar;35(3):353-6. [DOI:10.1016/j.joen.2008.11.029] [PMID]
9. Srinivasan VM, Chintalapani G, Duckworth EA, Kan P. Advanced cone-beam CT venous angiographic imaging. Journal of neurosurgery. 2018 Jul;129(1):114-20. [DOI:10.3171/2017.2.JNS162997] [PMID]
10. Lin Z, Hu Q, Wang T, Ge J, Liu S, Zhu M, Wen S. Use of CBCT to investigate the root canal morphology of mandibular incisors. Surg Radiol Anat. 2014 Nov;36(9):877-82. [DOI:10.1007/s00276-014-1267-9] [PMID]
11. Tahmasbi M, Jalali P, Nair MK, Barghan S, Nair UP. Prevalence of Middle Mesial Canals and Isthmi in the Mesial Root of Mandibular Molars: An In Vivo Cone-beam Computed Tomographic Study. J Endod. 2017 Jul;43(7):1080-3. [DOI:10.1016/j.joen.2017.02.008] [PMID]
12. Versiani MA, Ordinola-Zapata R, Keleş A, Alcin H, Bramante CM, Pécora JD, Sousa-Neto MD. Middle mesial canals in mandibular first molars: A micro-CT study in different populations. Arch Oral Biol. 2016 Jan;61:130-7. [DOI:10.1016/j.archoralbio.2015.10.020] [PMID]
13. Chavda SM, Garg SA. Advanced methods for identification of middle mesial canal in mandibular molars: an in vitro study. Endodontology. 2016;28(2):92-96. [DOI:10.4103/0970-7212.195425]
14. Azim AA, Deutsch AS, Solomon CS. Prevalence of middle mesial canals in mandibular molars after guided troughing under high magnification: an in vivo investigation. J Endod. 2015 Feb;41(2):164-8. [DOI:10.1016/j.joen.2014.09.013] [PMID]
15. Nosrat A, Deschenes RJ, Tordik PA, Hicks ML, Fouad AF. Middle mesial canals in mandibular molars: incidence and related factors. J Endod. 2015 Jan;41(1):28-32. [DOI:10.1016/j.joen.2014.08.004] [PMID]
16. Pomeranz HH, Eidelman DL, Goldberg MG. Treatment considerations of the middle mesial canal of mandibular first and second molars. J Endod. 1981 Dec;7(12):565-8. [DOI:10.1016/S0099-2399(81)80216-6]
17. Gupta S, Sinha DJ, Gowhar O, Tyagi SP, Singh NN, Gupta S. Root and canal morphology of maxillary first premolar teeth in north Indian population using clearing technique: An in vitro study. J Conserv Dent. 2015 May-Jun;18(3):232-6. [DOI:10.4103/0972-0707.157260] [PMID] [PMCID]
18. KUTTLER Y. Microscopic investigation of root apexes. J Am Dent Assoc. 1955 May;50(5):544-52. [DOI:10.14219/jada.archive.1955.0099] [PMID]
19. Schäfer E, Diez C, Hoppe W, Tepel J. Roentgenographic investigation of frequency and degree of canal curvatures in human permanent teeth. J Endod. 2002 Mar;28(3):211-6. [DOI:10.1097/00004770-200203000-00017] [PMID]
20. de Pablo OV, Estevez R, Péix Sánchez M, Heilborn C, Cohenca N. Root anatomy and canal configuration of the permanent mandibular first molar: a systematic review. J Endod. 2010 Dec;36(12):1919-31. [DOI:10.1016/j.joen.2010.08.055] [PMID]
21. von Arx T. Frequency and type of canal isthmuses in first molars detected by endoscopic inspection during periradicular surgery. Int Endod J. 2005 Mar;38(3):160-8. [DOI:10.1111/j.1365-2591.2004.00915.x] [PMID]
22. Sert 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 Jun;30(6):391-8. [DOI:10.1097/00004770-200406000-00004] [PMID]
23. Kontakiotis EG, Tzanetakis GN. Four canals in the mesial root of a mandibular first molar. A case report under the operating microscope. Aust Endod J. 2007 Aug;33(2):84-8. [DOI:10.1111/j.1747-4477.2007.00068.x] [PMID]
24. Fabra-Campos H. Three canals in the mesial root of mandibular first permanent molars: a clinical study. Int Endod J. 1989 Jan;22(1):39-43. [DOI:10.1111/j.1365-2591.1989.tb00503.x] [PMID]
25. Teixeira FB, Sano CL, Gomes BP, Zaia AA, Ferraz CC, Souza-Filho FJ. A preliminary in vitro study of the incidence and position of the root canal isthmus in maxillary and mandibular first molars. Int Endod J. 2003 Apr;36(4):276-80. [DOI:10.1046/j.1365-2591.2003.00638.x] [PMID]

Add your comments about this article : Your username or Email:
CAPTCHA

Send email to the article author


Rights and permissions
Creative Commons License This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

© 2024 CC BY-NC 4.0 | Journal of Research in Dental and Maxillofacial Sciences

Designed & Developed by: Yektaweb