Factors Asociated With Root Canal Ledging During Instrumentation

Copyright C Munksgaard 2000

Endod Dent Traumatol 2000; 16: 229–231
Printed in Denmark . All rights reserved

Endodontics &
Dental Traumatology
ISSN 0109-2502

Factors associated with root canal ledging
during instrumentation
Kapalas A, Lambrianidis T. Factors associated with root canal
ledging during instrumentation. Endod Dent Traumatol 2000;
16: 229–231. C Munksgaard, 2000.Abstract – The purpose of this study was to identify the presence
of a ledge in 141 cases treated in an undergraduate clinic and in 103
cases treated by endodontists, and to identify the clinical factors
associated with ledging. A total of 626 root canals were examined
and the factors analyzed were canal location, tooth number and
canal curvature. The results indicated that 51.5% of the canalstreated by students had been ledged, whereas the percentage was
33.2% for intact pulp cavities treated by endodontists and 40.6% in
cases of endodontic retreatment. Canal location was found to have
an effect on the incidence of ledging as the mesiobuccal, mesiolingual and distal buccal root canals exhibited a significantly higher
ledge incidence rate than the distal and palatal root canals. Canalcurvature was the most significant variable affecting the incidence
of ledging.

Among the complications most commonly observed
during root canal instrumentation is the deviation
from the original canal curvature resulting in the formation of a ‘‘ledge’’. Ledging may exclude the possibility of achieving a round preparation reaching the
working length, resulting in incomplete instrumentationand obturation of the root canal. Consequently,
there may be a causal relationship between ledging
and treatment failure (1). The main iatrogenic errors
associated with ledging are:
1. Inadequate access cavity preparations
2. False estimation of the root canal direction
3. Erroneous length determination of the root canal
4. Use of straight steel instruments in severely curved
root canals5. Failure to use the instruments in sequential order
6. Attempt to retrieve broken instruments or filling
material during endodontic retreatment
7. Attempt to prepare calcified root canals (2).
Only few data are available regarding the frequency of ledge formation and the clinical factors associated with its occurrence. Greene & Krell (3) have
examined radiographically cases treated bythird-year
dental students in an attempt to associate ledging with
clinical factors such as tooth number, canal location,

A. Kapalas, T. Lambrianidis
Department of Endodontology, School of Dentistry,
Aristotle University of Thessaloniki, Greece

Key words: canal preparation; ledging
Theodor Lambrianidis, 17 Ag. Sofias Str,
546 22 Thessaloniki, Greece
Accepted November 25, 1999

workinglength, the master apical file (MAF) size and
root canal curvature. They found that 46% of the
canals had been ledged and this percentage increased
significantly in teeth where the root canal curvature
exceeded 20æ. Canal curvature, tooth number and canal location were also found to be main variables associated with ledge formation (3). Stadler et al. (4)
have compared the results of twoinstrumentation
techniques in a study comprising 520 roots and recorded a total of 52 incidents of lateral deviation. The
incidence of ledging and instrument breakage was
more frequent when the reaming technique was used,
whereas root perforation and overfilling occurred
more often with the filing technique.
In a study of endodontic retreatment, Bergenholtz
et al. (5) have examined 660 teeth that wereto be
retreated for either technical reasons or the presence
of periapical radiolucencies. They found that 25% of
the root canals retreated for technical reasons and
11% retreated because of the presence of periapical
pathosis were obstructed at the level of the previous
root filling. Ledging may possibly have had a significant correlation with these cases.
Most available studies fail to...