Root Canal Configuration of the Mandibular First Premolar

By Baisden MK, Kulild JC and Weller RN

Date: 10/1992
Journal: JOE


Purpose: to describe the internal anatomy of the mandibular 1st premolar (shape of the root canal system, canal configuration, level of canal bifurcation).

N= 106 human mandibular left and right 1st premolars


  • Serial transverse sections were made perpendicular to the long axis at 3-mm intervals from CEJ to the apex.
  • Specimens were then placed in 5.25% (NaOCl) for 1 day. Sections were rinsed in phosphate-buffered saline, dried, and mounted using a cyanoacrylate adhesive on a strip of dark plastic film.
  • The sections were then examined with a stereomicroscope and photographed.
  • The slides at each level for each tooth were arranged from the CEJ to the apical-most section and was described and classified according to weine.

Most highlighted Results:

1.The shape of the root canal was predominately oval (51%) or round (40%). Oval at the CEJ, tapers to a round apically.

2.C- shaped canals (4%) were usually associated with the level of bifurcation of Type IV canal configurations and were predominantly located within the buccal canal. C-shaped canals faced the mesial in 11 roots and the distal in 4 roots.

3.The incidence of one canal was 76% (type 1) and two canals 24% (type 2)

4.The level of bifurcation occurs mainly 6 mm (50%) or 9 mm (25%) from the CEJ.

Clinical significance:

Debridement of the root canal system of the mandibular 1st premolar can be very difficult due to the presence of C-shaped canals, Type IV canal configurations, and/or bifurcation of canals located in the apical one half of the root.

Strength: investigating variant anatomic configuration in one study

Weakness: Use of serial sections. At preset, the use of 3-D CBCT would give better determination of canal morphology.