UvA

Introduction: The aim of this study was to explore the
influence of retreatment procedures on the appearance
of defects on the root canal walls. Methods: Two
hundred mandibular premolars were divided into 4
groups. One group was left unprepared. The rest of
the teeth were prepared with ProTaper files up to size
F4 and filled with gutta-percha and AH26. One group
was left filled and received no further treatments. The
filling material was removed from the remaining teeth
either with ProTaper retreatment files or with Hedstr€om
files. Roots were then sectioned and inspected under
a microscope. Data were analyzed with the nominal
regression test (a = 0.05). Results: No defects were
observed in the unprepared group. Retreatment groups
showed significantly more defects than the initial treatment
group (P < .05).There was no difference between
the appearance of defects after retreatment with
Hedstr€om files and ProTaper retreatment files. The remaining
dentin thickness and level of the root did not
significantly influence the appearance of defects.
Conclusions: Retreatment procedures result in more
defects than initial treatment. When assessing the
outcomes of endodontic retreatment, the substantial
damage to the root canal walls should be considered.