Prevalence of middle mesial canals and Isthmi in mandibular molars in a subpopulation of Andhra Pradesh: An in vivo investigation using CBCT.


  • Girija S Sajjan Vishnu Dental College
  • Ch Rajashekar Meghana Institute of Dental Sciences
  • K Madhu Varma Vishnu Dental College
  • R Kalyan Satish Vishnu Dental College
  • T  Rishitha St Joseph Dental College and Hospital
  • G Srikanth Vishnu Dental College



CBCT Dental, Operating Microscope, Isthmi, Mandibular Molars, Middle Mesial Canal


Background: Pulp and root canal space is enigmatic and highly complex. Encountering rare has become a norm with the advancements in the technology of materials and types of equipment. The success of the root canal treatment depends on the effective removal of bacteria from the whole pulp space. A high percentage of the missed canal is reported for the failure of Endodontic therapy. Mandibular molars have complex root canal anatomy. Two roots with two canals in mesial root and one to two canals in distal root is a common occurrence.    Nevertheless, the incidence of variation is relatively high, including separate distolingual, mesiobuccal, C-Shaped canals, isthmus, and additional canal in the mesial root. A wide range of the middle mesial canal occurrence, i.e., 3.1 to 46.1%, is reported in the world and 28.3% in North India.

Aim: To identify the prevalence of the true middle mesial canal (MM) and configuration of Isthmi in the mesial root of the mandibular molar in the AP   subpopulation of South India.  

Materials and methods: CBCT of 89 patients were randomly selected from the institutional database. Data entry was performed in Excel, and data analysis was done with the Statistical Package for Social Sciences (SPSS).

Results: Four images (4.5%) revealed Middle Mesial canals with no statically significant occurrence. The frequency of isthmi in the mesial roots was 52.7%.  This showed a considerable presence.

Conclusion: MM canals are 4.5% in a subpopulation of Andhra Pradesh. Isthmuses are very common in the mesial roots of permanent mandibular molars. Isthmus about 58% was seen with Type II configuration that is the presence of two canals without a definite communication.

Author Biographies

Girija S Sajjan, Vishnu Dental College

Professor and Head, Department of Conservative Dentistry and Endodontics, Vishnu dental college, Bhimavaram, Andhra Pradesh, India - 534202.

Ch Rajashekar, Meghana Institute of Dental Sciences

Senior Lecturer, Department of Conservative Dentistry and Endodontics, Meghana Institute of Dental Sciences, Nizamabad, Telangana, India.

K Madhu Varma, Vishnu Dental College

Professor, Department of Conservative Dentistry and Endodontics, Vishnu Dental College, Bhimavaram, Andhra Pradesh, India - 534202.

R Kalyan Satish, Vishnu Dental College

Professor, Department of Conservative Dentistry and Endodontics, Vishnu Dental College, Bhimavaram, Andhra Pradesh, India - 534202.

T  Rishitha, St Joseph Dental College and Hospital

Senior Lecturer, Department of Conservative Dentistry and Endodontics, St Joseph Dental College and Hospital, Eluru, Andhra Pradesh, India.

G Srikanth, Vishnu Dental College

Postgraduate Student, Department of Conservative Dentistry and Endodontics, Vishnu Dental College, Bhimavaram, Andhra Pradesh, India - 534202


Ballullaya SV, Vemuri S, Kumar PR. Variable permanent mandibular first Molar: Review of literature. Journal of conservative dentistry: JCD. 2013;16(2):99.

Garg AK, Tewari RK, Kumar A, Hashmi SH, Agrawal N, Mishra SK. Prevalence of three-rooted mandibular permanent first molars among the Indian population. J Endod. 2010;36(8):1302-6.

Reyhani MF, Rahimi S, Shahi S. Root canal therapy of a mandibular first molar with five root canals: A case report. Iran Endod J 2007;2:110-2.

Pomeranz HH, Eidelman DL, Goldberg MG. Treatment considerations of the middle mesial canal of mandibular first and second molars. J Endod. 1981; 7: 565-8.

Weller RN, Niemczyk SP, Kim S. Incidence, and position of the canal isthmus. Part 1. Mesiobuccal root of the maxillary first Molar. J Endod. 1995;21:380-3.

Pineda F. Roentgenographic investigation of the mesiobuccal root of the maxillary first Molar. Oral Surgery, Oral Medicine, Oral Pathology. 1973;36(2):253-60.

Von Arx T. Frequency and type of canal isthmuses in first molars detected by endoscopic inspection during periradicular surgery. Int Endod J 2005;38:160-8.

Vertucci FJ. Root canal anatomy of the human permanent teeth. Oral Surg Oral Med Oral Pathol 1984;58:589-99.

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; 35: 353-356.

Hsu YY, Kim S. The resected root surface. The issue of canal isthmuses. Dent Clin North Am. 1997;41(3):529-40.

Chavda SM, Garg SA. Advanced methods for identification of middle mesial canal in mandibular molars: An in vitro study. Endodontology. 2016;28(2):92.

de Toubes KM, de Souza Côrtes MI, de Abreu Valadares MA, Fonseca LC, Nunes E, Silveira FF. Comparative analysis of accessory mesial canal identification in mandibular first molars by using four different diagnostic methods. J Endod. 2012;38(4):436-41.

Jacobsen EL, Dick K, Bodell R. Mandibular First Molars with Multiple Mesial Canals. 1994; 20(12): 610-613.

Wang Y, Zheng QH, Zhou XD, Tang L, Wang Q, Zheng GN, et al. Evaluation of the root and canal morphology of mandibular first permanent molars in a western Chinese population by cone-beam computed tomography. J Endod 2010; 36: 1786-1789.

Neelakantan P, Subbarao C, Subbarao CV. 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 canal morphology. J Endod 2010; 36: 1547-1551.

Blattner TC, George N, Lee CC, Kumar V, Yelton CD. Efficacy of cone-beam computed tomography as a modality to accurately identify the Presence of second mesiobuccal canals in maxillary first and second molars: a pilot study. J Endod 2010; 36: 867-870.

Hassan BA, Payam J, Juyanda B, van der Stelt P, Wesselink PR. Influence of scan setting selections on root canal visibility with cone beam CT. Dentomaxillofac Radiol 2012; 41: 645-648.

Nosrat A, Deschenes RJ, Tordik PA, Hicks ML, Fouad AF. Middle mesial canals in mandibular molars: incidence and related factors. J Endod 2015; 41: 28-32.

Ricucci D, Siqueira JF. Biofilms and apical periodontitis: study of prevalence and association with clinical and histopathologic findings. J Endod 2010;36: 1277 88.

Gulabivala K, Aung TH, Alavi A, Ng YL. Root and canal morphology of Burmese mandibular molars. Int Endod J 2001; 34: 359-370.

Chen G, Yao H, Tong C. Investigation of the root canal configuration of mandibular first molars in a Taiwan Chinese population. Int Endod J 2009; 42: 1044-1049.

Karapinar-Kazandag M, Basrani BR, Friedman S. The operating microscope enhances detection and negotiation of accessory mesial canals in mandibular molars. J Endod. 2010;36(8):1289-94.

Mannocci F, Peru M, Sherriff M, Cook R, Pitt Ford TR. The isthmuses of the mesial root of mandibular molars: a micro?computed tomographic study. Int Endod J. 2005;38(8):558-63.

Kim S, Pecora G, Rubinstein RA. The resected root surface and isthmus. In: Color Atlas of Microsurgery in Endodontics. Philadelphia: W.B. Saunders Company; 2001. p. 98-104.

Rubinstein RA, Kim S. Long-term follow-up of cases considered healed one year after apical microsurgery. J Endod 2002;28:378-83.

Bidar M, Sheikhnezmi M, Moradi S. In vitro evaluation of the Presence of second canal in distal root of first and second mandibular molars. J Dent 2006;30:177-82.

Fan B, Pan Y, Gao Y, Fang F, Wu Q, Gutmann JL. Threedimensional morphologic analysis of isthmuses in the mesial roots of mandibular molars. J Endod 2010;36:1866-9.

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;36:276-80.

Kim S, Kratchman S. Modern endodontic surgery concepts and practice: A review. J Endod 2006;32:601-23.

Vera J, Siqueira JF Jr, Ricucci D, Loghin S, Fernandez N, Flores B, et al. One- versus two-visit endodontic treatment of teeth with apical periodontitis: A histobacteriologic study. J Endod 2012;38:1040-52.

Johnson M, Sidow SJ, Looney SW, Lindsey K, Niu LN, Tay FR. Canal and Isthmus Debridement Efficacy Using a Sonic Irrigation Technique in a Closed-canal System. J Endod 2012;38:1265-8.

Sarno MU, Sidow SJ, Looney SW, Lindsey KW, Niu LN, Tay FR. Canal and Isthmus Debridement Efficacy of the VPro Endo Safe Negative-pressure Irrigation Technique. J Endod 2012;38:1631-4.

Susin L, Liu Y, Yoon JC, Parente JM, Loushine RJ, Ricucci D, et al. Canal and isthmus debridement efficacies of two irrigant agitation techniques in a closed system. Int Endod J 2010;43:1077-90.

Jung IY, Seo MA, Fouad AF, Spangberg LS, Lee SJ, Kim HJ, et al. Apical anatomy in mesial and mesiobuccal roots of permanent first molars. J Endod 2005;31:364-8.

Endal U, Shen Y, Knut A, Gao Y, Haapasalo M. A high-resolution computed tomographic study of changes in root canal isthmus area by instrumentation and root filling. J Endod 2011;37:223-7.

de Groot SD, Verhaagen B, Versluis M, Wu MK, Wesselink PR, van der Sluis LW. Laser activated irrigation within root canals: Cleaning efficacy and flow visualization. Int Endod J 2009;42:1077-83.






Original Articles