C-shaped Canal System in Mandibular Second Molars Part III: The Morphology of the Pulp Chamber Floor

By Min Y, Fan B, Cheung GS, Gutmann JL, Fan M

Date: 01/2006
Journal: JOE


To investigate the morphology of pulp chamber floors in mandibular second molars with a C-shaped canal system. N= 44 extracted second MD molars with C-shaped canal morphology in a Chinese population


  • Teeth were scanned by Micro CT
  • The most superior part of pulp chamber floor (line X) was used to analyze the shape of the pulpal floor and canal orifice. Fig 1
  • The pulp chamber floors were reconstructed using 3-D software and classified into 4 types. Fig 2
  • Canal configurations were classified into 5 types. Fig. 3

Most highlighted Results:

  1. 91% of the pulp chamber floors within 3 mm below the CEJ
  2. 86% had the C-shaped orifices. Not all teeth with the C-shaped canal had a C-shaped pulpal floor.
  3. In type II & type IV orifices were similar to those in mandibular 2nd molars with separated roots. There were no significant differences in canal configurations at the different levels.
  4. In type I &type III orifices, There were significant differences among canal configurations at different levels. Continuous C and MB-D canals, from the orifice to the coronal portion, basically retained their shape. In the middle and apical portions of the canal, changed to two canals.

Clinical Significance:

Assist the clinician in the prediction and location of c-shaped canals below the visible orifice.  


Fig 1

Type I:  continuous C-shaped orifice (18 %)

Type II: dentin fusion between the peninsula-like floor and buccal pulp chamber wall, forming one or two mesial orifice(s) and a distal orifice (36%)

Type III: dentin fusion between the peninsula-like floor and the mesial pulp chamber wall, forming a large mesiobuccal- distal (MB-D) orifice and a small mesiolingual orifice (31 %)

Type IV: teeth did not have a C-shaped floor configuration (13 %)

Fig 3

C1: continuous C-shaped canal

C2: MB-D canal and an ML canal

C3a: M canal and a D canal

C3b: MB, an ML, and a D canal

C4: single round or oval canal