Root Canal Madibular Molar Anatomy

micro-CBCT Study

My analysis of Wolf JOE 2016 for mesial root

• 55% are fairly straight forward like 2-2-1/1 or 1-2-2/2
• 7% are doable with a little luck like 2-1-1/2 or 1-1-1/2
• 38% are nearly impossible to completely access all canals like 2-1-1/3 or 2-2-2/4

Distal root is much better

• 73% are fairly straight forward like 2-2-1/1 or 1-1-2/2
• 12% are doable with a little luck like 2-1-1/2 or 1-1-1/2
• 15% are nearly impossible to completely access all canals like 1-1-1/3 or 1-1-2/3

Why there are teeth that you can never totally clean.

de Pablo JOE 2010  Systemic review 41 studies

• Third root = 13% but strongly correlated with the ethnicity ie great variance
• Three canals 61%, 4 canals 36%, and 5 canals in 1%
• Mesial root = 2 canals 94%, 3 canals 2.3% The most common canal system configuration was Vertucci type IV (52.3%), followed by type II (35%)
• Distal root revealed type I configuration 62.7%, type II (14.5%) and IV (12.4%)
• Isthmus communications = 55% on mesial and 20% on distal root.  What is an isthmus and what is a canal?  Depends on age likely.  In the young it is a canal in the elderly an isthmus

Brazil study molars 74% 2R3C 12% 2R4C 11% 2R2C 3% 1R2C

• first molars 1.7% C shape

If single distal canal then about 60% have mesial canals that join Gen Dent Lamia 2016

Middle Mesial Canal

There is an entire post on the mid mesial canal.

Distal Root

Worldwide 37% of distal roots have a second canal. This varies greatly by region and ethnicity though, as 60% of Egyptians have a second distal canal and only 16% of Venezuelans do. Martins JOE 2022

76%-13%-8%-3% 1-2-3-4 canals in distal root of two rooted molars.  100 extracted Brazilian teeth micro-CT JOE 2015 Filpo-Perez   Interestingly 13% had canal systems not in Vertucci classification and are IMHO very complex.

G through N are unclassified shapes (although ignoring some minor isthmus connections many would fall into Vertucci system)

Radix root

The radix root is much more prominent in the Asian population. Less than 1% of Venezuelans have a radix root but 22% of Chinese have one. Martins JOE 2022

Korean study Radix root. March 2012  Stats show Koreans have high radix rate and high rate of consistency between bilateral sides. Also radix roots have a correlation with complex root canal configuration of mandibular 1st premolar. Wu JOE 2017

• 2R2C 23%
• 1R1C 4%
• bilateral 2R2C was 18%
• bilateral 1R2C was 3%

Korean population study Kim 2013 JOE Dec shows 3/4 have 2 roots, 1/4 have 3 roots – 50% have 4 canals.

Lower molar root canal anatomy

First molar = Systemic Review with 41 studies and almost 19k molars. de Pablo 2010 JOE

• 3 roots 13% and is strongly correlated with ethnicity.
• 3 canals 61%, 4 canals 36%, and 5 canals 1%.
• Mesial root = 2 canals 94% and 3 canals 2%. Vertucci type IV (52%), type II (35%).
• Distal root = type I 63%, type II (14%) and IV (13%).
• Isthmus communications 55% on mesial root and 20% on distal root.

Silva 2013 JOE Brazil study molars 54%=2R3C 32%=2R2C 4%=1R1C 3.5%=1R2C 3.5%=3R4C=Radix 2%=1R3C 1%2R4C

• second molars 3.5% C shape

If single distal canal then about 60% have mesial canals that join Gen Dent Lamia 2016

C shaped canal of lower molars

14% worldwide but much higher in China at 44% von Zuben JOE 2017

1. Type I merging = all canals merge into one apical formen
2. Type II symmetric = meisal and distal symmetrical canals viewed from BL
3. Type III asymmetric = meisal and distal canals asymmetrical viewed from BL