Patient Bill Of Rights Root Canal Anatomy Of The Permanent First Molar

Nestor Cohenca, D.D.S., FIADT


Root Canal Anatomy Of The Permanent Mandibular First Molar. Clinical Implications And Recommendations

The world of endodontics has incorporated new technologies, instruments and materials in the past decade. Among them, operating microscopes, digital radiography, cone beam computed tomography (CBCT), 3D nickel titanium files, sonic and ultrasonic instruments and new irrigation delivery systems. However, despite all these improvements, the overall outcome, especially of non-surgical endodontics, has not increased significantly. Why? If we think critically, there are two important factors directly related to prognosis on which our advancements were limited: predictable eradication of microorganisms and access to the full anatomy of the canal system in which they might be harbored.

The mandibular first molar is the more frequently endodontically treated tooth. In a study by Swartz et al, the success rate of endodontically treated teeth was 87.79%, demonstrating the mandibular firs molar a significant lower success rate of 81.48%. It is well accepted that a unique cleaning and shaping technique is not suitable for all cases. Therefore, the endodontist should be able to fully understand the tooth morphology and root canal configurations in order to select the most appropriate treatment modality for a particular case and increasing the healing rate.

Number of roots

Review of the literature revealed a strong correlation between the presence of a third root in 13% of teeth and the ethnicity of the patients, particularly Asians, Mongolians and Eskimos. This macrostructure was term radix entomolaris with high variation regarding the coronal, mesio-distal plane. When the position of this third root was buccal, it is called radix paramolaris. Its shape and curvature are highly variable. Several radiographic exposures are required to clearly observe the presence of additional roots. Treating a mandibular first molar without initial off-angle radiographs could lead to third roots go unnoticed (Fig 1). Initially, a file located in the extra root, may give the appearance of a perforation. To prevent mishaps, it is advisable to choose a small and highly flexible instrument when treating the apical portion.

Number of root canals

In a systematic review compiling data on 4,745 mandibular first molars, three canals were present in 61.3%, followed by 4 canals in 35.7% of cases and 5 canals in almost 1% (Fig 2). However, in vivo studies performed by endodontists demonstrated the presence of 4 canals in 45% of the treated cases. Five canals were found in 0.8% of the samples while case reports have demonstrated the possibility of six and even 7 root canals.


  1. The number of roots in the first mandibular molar is directly related to the ethnicity of the population studied.
  2. The instrumentation of the third root requires a different access and the use of small and flexible instruments, considering the curvature at the apical third.
  3. Mesial roots present 2 canals on a regular basis, adopting 2-2 and 2-1 as the most frequent configurations. A third canal might be present in 2.6% of the population.
  4. The most common configuration in the distal root is 1-1 (62.7%), followed by 2-1 (14.5%) and 2-2 (12.4%).
  5. Access modifications are required in order to find extra roots and/or canals.
  6. The presence of isthmuses reaches 55% in the mesial root and 20% in the distal. This anatomical configuration should be taken into consideration during endodontic treatment as well as during periapical surgery.

Nestor Cohenca, DDS, FIADT

Diplomate. American Board of Endodontics

PS. Full references available per request.

I am delighted to share my experience. Dr. Cohenca performed a root canal Treatment From the moment I arrived, the care and attention provided by the entire team were outstanding. Dr. Cohenca ensured that I was comfortable and well-informed throughout the procedure. The pre-operative care was thorough, making me feel at ease and confident in the treatment plan. I highly recommend Dr. Cohenca and their practice to anyone seeking top-notch dental care. Their dedication to patient comfort and successful outcomes is truly commendable.

S.M. Google

Dr. Cohenca might look like a regular endodontist, but in reality he is a magician. Knowledgeable and personable, he created a great atmosphere. With expert hands, he delivers the best dentist experience that you can live through. The staff lives up to the expectations and the office gives you a sense of harmony. You won't be disappointed. Thank you Dr.

C.O. Yelp

I have no words enough to say how wonderful he is, very gentle, professional, is an incredible human and good heart. Simply the best in the world.!

D.C. Google

We had the greatest experience with Dr Cohenca. He explained everything ahead so clearly and kept giving details during the treatment, so my daughter felt calm and relaxed. The stuff is friendly and supportive, Loved this place, surely recommend it

I.O. Google

Entire process was quick, professional and better than expected. Thank you Dr. Cohenca and your entire team.

S.K. Google


Total Reviews


Average Rating

privacy We respect your privacy
* All information subject to change. Images may contain models. Individual results are not guaranteed and may vary.