This document discusses several potential errors that can occur during root canal preparation including zipping, elbow formation, ledging, perforation, stripping, outer widening, apical blockage, damage to the apical foramen, and instrument breakage. Zipping occurs when an instrument straightens inside a curved canal, over-enlarging the outside and under-preparing the inside of the curve. Elbow formation describes a narrow region at the point of maximum curvature caused by irregular widening. Ledging can occur when inflexible instruments are used rotationally, creating a platform on the outside of a curve that blocks the apical portion.

1. Errors During Bio-mechanical
Preparations
INDIAN DENTAL ACADEMY
Leader in continuing Dental
Educationwww.indiandentalacademy.com

2. Iatrogenic Damage Caused By Root
Canal Reparation
Weine et al. and Glickman & Dumsha have
described the potential iatrogenic damage
that can occur to roots during preparation
with conventional stainless steel
instruments and included several distinct
preparation errors
www.indiandentalacademy.com

3. Errors discussed are
• Zip
• Elbow
• Ledge
• Perforation
• Stripping and strip perforation
• Outer widening
• Apical blockage
• Damage to the apical foramen
• Instrument breakage
www.indiandentalacademy.com

4. Zip formation
Zipping of a root canal is the result of the
tendency of the instrument to straighten
inside a curved root canal.
This results in over-enlargement of the canal
along the outer side of the curvature and
under-preparation of the inner aspect of the
curvature at the apical end point.
www.indiandentalacademy.com

5. www.indiandentalacademy.com

6. Zip Formation
The main axis of the canal is transported, so
that it deviates from it’s original axis.
The terms straightening, deviation,
transportation are also used to describe this
type of irregular defect.
The terms ‘teardrop’ and ‘hour-glass shape’
are also used to describe the resulting shape
of the Zipped apical part of the root canal.
www.indiandentalacademy.com

7. Elbow Formation
Creation of an Elbow is associated with
zipping and describes a narrow region of
the root canal at the point of maximum
curvature as a result of the irregular
widening that occurs coronally along the
inner aspect and apically along the outer
aspect of the curve.
www.indiandentalacademy.com

8. www.indiandentalacademy.com

9. Elbow Formation
The irregular conicity and insufficient taper
and flow associated with the elbow may
jeopardize cleaning and filling the apical
part of the root canal.
www.indiandentalacademy.com

10. Ledging
Ledging of the root canal may occur as a result of
preparation with inflexible instruments with a
sharp, inflexible cutting tip particularly when used
in a rotational motion.
The ledge will be found on the outer side of the
curvature as a platform which may be difficult to
bypass as it is frequently associated with blockage
of the apical part or the root canal.
www.indiandentalacademy.com

11. The
occurrence of
ledges was
related to the
design of
instruments
no. 40
www.indiandentalacademy.com