A Three-Dimensional Study of Canal Curvatures in the Mesial Roots of Mandibular Molars

By Cunningham CJ, Senia ES.

Date: 04/1992
Journal: JOE



to determine the frequency, degree of curvature, and the configuration of MB and ML root canals of mandibular molars. The effect of coronal flaring on canal curvatures in both dimensions was then investigated. 

•n= 100 mandibular 1st & 2nd molars. Exclusion: incompletely formed apices, 3rd molars, previous endodontic therapy, and teeth with gross decay or large restorations.


  • Both clinical and Proximal views were taken with a #8 K file introduced into the MB & ML canal. 
  • The canal curvatures were calculated for both views using the technique described by Schneider. Fig1
  • The distance from (point a) to (point b) was measured in millimeters for each canal from both views. 
  • 20 teeth were chosen for coronal flaring with Canal Master rotary instruments up to the primary curve. 

Most highlighted Results:

1. 100% of the teeth demonstrated curvatures in the MB and ML canals, both in clinical & proximal view radiographs. 

2.No significant difference in the degree of curvature of a canal seen in a CV  and PV 

3.MB canal demonstrated greater mean curvature in PV and CV than ML in Type II & III and the curvature was more evident in CV and in type II i.e 30 ⁰ curvature in CV of type II MB canal

4. Weine type II morphology demonstrated a greater mean curvature with a wider range and a larger number of secondary curves than Weine type III roots when viewed from the proximal.  

5.The mean distance from (point a) to (point b) was slightly greater in the proximal view for both MB and ML canals. 

6. 21% of the MB canals were longer than the ML canals by an average of 0.75 mm. 

7.Significant Reduction of the arc of curvature, both in CV and PV, was achieved using Canal Master rotary instruments 8.MB root shows greater degree of curvature than other roots in primary and secondary curve.

9. Clinical significance: 

Proximal view curvatures cannot be predicted or estimated from examining a clinical view radiograph.