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.
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.