Root Canal Morphology of Permanent Three-rooted Mandibular First Molars: Part III—An Odontometric Analysis

By Gu Y, Zhou P, Ding Y, Wang P, Ni L.

Date: 01/2012
Journal: JOE


•Purpose: Quantitatively analyze level furcation, root apex, wall thickness, diameter and taper of the root canals in 3 rooted mandibular 1st  molar. •N=20 – 3 rooted mandibular 1st molars).

Inclusion criteria: intact roots, native Chinese.

Exclusion criteria: previously instrumented, immature roots, caries apical to CEJ.


•Teeth were cleaned with 5% NaOCl and ultrasonic scaler.  Then scanned at fixed resolution using micro CT.

•Level of root apex: distance from apex to proximal CEJ. Level of furcation: distance from lowest point of furcation to proximal CEJ (M, D furcation) were measured. Wall thickness in B,L,M and D.  Maximum canal diameter was calculated if BL/MD  ratio >2 canal is considered oval. root canal tapers of the apical, middle, and coronal portions.

Most highlighted Results:

1.Root apex level is higher in DL root compared to DB and M roots, while distal furcation is significantly lower than mesial one with an average of 1 mm.

2.B, L wall thickness is more than M,D in all canals.

3.The distal wall of the M root and the mesial wall of the D root are the thinnest zones

4.DL canal was rounder and had the smallest (BL/MD) measurements than the other 3 canals.

5.BL taper is greater than the MD for each canal except the middle portion of the DL canal.

*(M:mesial, D:distal, B: buccal, L:lingual)