Curved canals

Curves in the roots have a high risk of getting peforated during cleaning and shaping and this section clears out the various doubts regarding preserving or eliminating the curves and the different techniques in dealing with the curves.

 

1. Why is the use of reamers inadvisable in the canals curved in the apical third?

By moving reamers in the apical curves, an unwanted “hourglass effect” is produced with consequent enlargement and displacement of the foramen along with creating notches and ledges in the external wall of the curve all of which will complicate the preservation of the curve.

Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 504 

2. Why are the curves of the apical third not straightened?

The apical curves must never be straightened even minimally since doing so will displace the apical foramen from its original position and altering its shape. This is a serious error that will lead to treatment failure.

Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 502 

3. What are double curves or bayonet curves?

Double curves are found in the middle third frequently in U/L second premolars characterized corono apically, by the presence of first curve directed mesially and the second curve distally.

Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 506 

4. What is the significance of double curves?

Double curves are most difficult to be preserved but straightening will lead to displacement of the foramen. The first is maintained as much as possible to prevent thinning of the root that can lead to lateral perforation/ stripping. To maintain the second curve which is more apically placed, rules stated for the curves of apical third have to be followed.

Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 506 

5. How are the curves in the apical, middle and the coronal thirds of a canal managed generally?

The curves of the apical third are preserved, those of the middle third are blunted and smoothed during routine canal preparation and curves of the coronal third must be eliminated before commencing normal cleaning and shaping.

Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 509 

6. Why do problems occur during reconstruction of endodontically treated molars?

The mesial roots of lower molars and mesio buccal roots of upper molars that are curved have a high risk of perforation since they are completely inadequate to receive the retentive posts sufficiently. So anticurvature filing can safeguard against these risks.

Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 513