The permanent maxillary second molar: Canal number And configurations in a Tunisian population
By Soumaya Touzi 1, Rim Kallala 1, Faten Khanfir2, Mohamed Romdhane1; Khalfi Mohamed Salah2, Faten Ben Amor 2.
1: Department of Dental Anatomy of the Dentistry Clinic of Monastir, Tunisia;
2: Department of General Anatomy of the Dentistry Clinic of Monastir, Tunisia.
One of the major causes of failure in endodontic treatment is the impossibility of locating and treating the entire root canal system, a result of the lack of knowledge regarding the dental, internal or external anatomy. 1
Maxillary molars are the teeth that contain the greatest number of roots, with diverse shapes and formations, which is why their internal canal system is so variable. 2
Any existing root canals that remain undetected by the operator during the entire course of endodontic treatment are a major threat to the failure of treatment. 3
The aim of the current research was to describe the variations in the root canal anatomy of maxillary first molar in a tunisian population using sectioning.
Materials and Methods
In this study, we used 98 maxillary second molars that have been extracted mainly for periodontal reasons. The teeth were stored in a sodium hypochlorite solution diluted to 5% during 3 days and then washed in running water and dried.
Each tooth is macroscopically examined to determine the number of roots and grinded progressively at the root surface to highlight the path of the root canals.
Canal number and configurations are observed and analyzed using sections:
-Mesio buccal and disto buccal root: bucco-lingual sections
-Palatal root: mesio-distal sections.
1- Number of roots by tooth (Table 1)
2- Number of canals by root (Table 2)
3- Canal configurations (Table 3)
4- Different canal configurations observed at the mesio buccal root (Figures 1, 2)
5- Different canal configurations observed at the disto buccal root (Figure 3)
6- Different canal configurations observed at the lingual root (Figure 4)
Number of roots
In the present study, 93 % of maxillary first molars were 3 rooted. Our results are similar to the findings of Libfeld 4 (90.6%), Neelakantan 5 (93.1%) and Sert 6 (91.27%).
We found 5.8% 2 rooted second maxillary molars. For consulted studies, the percentage was from 0% 5 to 21.86%. 7
We found 1.1% one rooted molars which is close to the majority of studies. 7,4,8,6 Gu Y 7 found larger percentage (14.11%).
We didn’t find 4 rooted second maxillary molars which is similar to the study of Neelakantan.5 Other studies found percentages that do not exceed 1.4% 8 (table 4).
- Mesio buccal root
– Number of canals:
We found in our study that 97.5 % of cases have a single canal and 2.4 % have 2 canals.
The frequencies of 2 canals varied from 19.7% according to Al-Fouzan 9 to 93.7% according to Kulild 10; these results are not consistent with ours. These differences may be due to the variety of the used techniques.
This root can have more than two canals according to Ozcan et al. 11 who reported a case of a maxillary second molar with 3 canals in the mesio buccal root and Caliskan et al. 12 who showed that 16% of second maxillary molars had 3 canals in this root (Table 5).
– Canals configurations:
Our study showed that 97.5 % have type I configuration and 2.5 % have type II configuration. We have not found the types III, IV and V.
There is great variability in the results of literature; the percentage of type I varied from 34%14 to 86,9% 18; type II from 1, 8% 18 to 34% 14 and type III from 0% 14 to 15.6%. 19
For type IV, the results are divergent and span from 0% 19 to 40%. 20 Type V presents 0% for most studies 18, 19, 22, 14, 21 (table 6).
The differences in results may be explained by differences in the number of samples or by heterogeneous populations.
- Disto buccal root
– Number of canals:
In the present study, this root had in 100% of cases one canal whitch agree with the study of Médioni et al. 24
– Canals configurations:
All studies confirmed that the type I is predominant with a percentage that varies from 84.9%5 to 100%. 24 Other configurations have a percentage not exceeding for the type II 2% 23, for the type III 2.4% 5, for the type
IV 4.4% 5, and for the type V 6% 23 (table 7).
- Palatal root
– Number of canals:
In the present study,the palatal root had in 100% of cases only one canal whitch agrees with the findings of Médioni et al. 24 and Sert et al. 6 Neelakantan et al 5 found only 87.7% of this root with one canal. According to all studies, types III and V did not exceed 6% 23, 20, 25 and type IV did not exceed 3.4% 5, 25 and type II was not found.
– Canals configurations:
All studies confirmed that the type I is predominant with a percentage that varies from 87.8%5 to 100%. 24, 6 Other configurations have a percentage not exceeding for the type III 6% 20, 23, for the type IV 3.4% 5, and for the type V 6%.23 the type II is absent for all studies 24, 23, 5, 6, 20, 25 (table 8).
The present study showed that most of maxillary first molars were 3 rooted (93%), 5.8% were 2 rooted and 1.1% presented one root. In the mesio buccal root, the most prevalent configuration was type I (97.5%), type II represented 2.5%. In the disto buccal root and in the palatal root, we found vertucci type I on 100% of cases.
References Pécora JD, Woelfel JB, Sousa Neto MD, Issa EP. Morphologic study of the maxillary molars. Part II: internal anatomy. Braz Dent J 1992; 3: 53-57.  Betancourt P, Navarro P, Cantín M, Fuentes R. Cone-beam computed tomography study of prevalence and location of MB2 canal in the mesiobuccal root of the maxillary second molar. Int J ClinExp Med 2015; 8:9128-34.  Alrahabi M, Zafar MS. Evaluation of root canal morphology of maxillary molars using cone beam computed tomography. Pak J MedSci 2015; 31:426-30.  Libfeld H, RotsteinI.Incidence of four-rootedmaxillary second molars: literaturereview andradiographicsurvey of 1200 teeth. J Endod 1989; 15: 129-31.  Neelakantan.P,Subbarao.C, BDS, Ahuja.R, Subbarao.C.V, and Gutmann.J.L. Cone-Beam Computed Tomography Study of Root and Canal Morphology of Maxillary First and Second Molars in an Indian Population, Journal Of Endodontic 2010; 36: 1622-07.  Sert.S, Sahinkesen.G,Topcu.F T .Eroglu .S E and OktayE.A.Root canal configurations of third molar teeth. A comparisonwith first and second molars in the Turkish population. Aust Endod J 2011; 37: 109–17.  Gu.Y ,Wang.W , Ni.L.Four-rooted permanent maxillary first and second molars in a northwestern Chinese population, Archives Of Oral biology 2015 ;60: 811–7.  Peikoff MD, Christie WH, FogelHM. The maxillary second molar: variations in the number of roots and canals. Int Endod J 1996; 29: 365-9.  Al-Fouzan.KS,Ounis.HF,Merdad.K and Al-Hezaimi.K.Incidence of canal systems in the mesio-buccal roots of maxillary first and second molars in Saudi Arabian population. Aust Endod J 2013; 39: 98–101.  Kulild JC, Peters DD. Incidence and configuration of canal systems in the mesiobuccal root of maxillary first and second molars. J Endod 1990; 16:311-7.  Ozcan E, Aktan AM, Ari H.A case report: Unusual anatomy of maxillary second molar with 3mesiobuccal canals. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009;107:
43-6. Holderrieth S, GernhardtCR. Maxillary molars with morphologic variations of the palatal root canals: a report of four cases. J Endod 2009;35:1060-5.  Weller RN, Hartwell GR. The impact of improved access and searching techniques on detection of the mesiolingual canal in maxillary molars. J Endod 1989; 15: 82–3.  Singh C, Sikri VK, Arora R. Study of root canals and their configuration in maxillary second permanent molar. Indian J Dent Res 1994; 5:3-8.  Stropko JJ. Canal morphology of maxillary molars: clinical observations of canal configurations. J Endod 1999; 25: 446-50.  Alavi AM, Opasanon A, Ng YL, Gulabivala K .Root and canal morphology of Thai maxillary molars. Int Endod J 2002; 35: 478–85  Domark JD, Hatton JF, Benison RP, Hildebolt CF. An ex vivo comparison of digital radiography and cone-beam and micro computed tomography in the detection of the number of canals in the mesiobuccal roots of maxillary molars, J Endod 2013 ;39:901-5.  ] Rwenyonyi CM, Kutesa AM, Muwazi LM, BuwemboW. Root and canal morphology of maxillary first and second permanent molar teeth in a Ugandan population. Int Endod J 2007; 40: 679-83. Y-L. Ng, T. H. Aung, A. Alavi& K. Gulabivala. Blackwell Science, Ltd Root and canal morphology of Burmese maxillary molars International Endodontic Journal, 2001;34: 620–30.  Kim Y, Lee SJ, Woo J. Morphology of maxillary first and second molars analyzed by cone-beam computed tomography in a Korean population: variations in the number of roots and canals and the incidence of fusionJournal Of Endodontics2012;38: 1063-8. Calişkan MK, Pehlivan Y, Sepetçioğlu F, Türkün M, Tuncer SS. Root canal morphology of human permanent teeth in a Turkish population. J Endod 1995; 21: 200-4. Yoshioka.T, Kikuchi.I,Fukumoto.Y, Kobayashi.C&Suda.H. Detection of the second mesiobuccal canal in mesiobuccal roots of maxillary molar teeth ex vivo. International Endodontic Journal 2005; 38:124–8.  Weng.X L,Yu,S.B,Zhao.SL,Wang.HG,Mu.T,Tang.RY,Zhou.XD,Root Canal Morphology of Permanent Maxillary Teeth in the Han Nationality in Chinese Guanzhong Area: A New Modified Root Canal Staining Technique. Journal Of Endodontics 2009; 35: 651–6.  Médioni E, Vené G. Anatomie endodontique fondamentale et clinique. Encycl Med Chir (Paris, France), Stomatologie Odontologie, 23-050-A-05, 1994, 10p.  Altunsoy M, et al. Root canal morphology analysis of maxillary permanent first and second molars in a Southeastern Turkish population using cone-beam computed tomography, Journal of Dental Sciences 2014;20: 1-7.