Use of microcomputed tomography for the evaluation of canal filling quality depending on the part of root canal*

Introduction. High-resolution microcomputed
tomography (microCT) is an emerging technology
with several applications to endodontics. Aim of the
study: To analyse in detail root canal fillings in the
apical third, in the middle and coronal thirds in in
vitro conditions with the use of microCT. Material
and methods. Eighty single roots were prepared with
the “step-back” technique or with a Pro File system
using the “crown-down” technique. Each main group
was divided into two subgroups and obturated with
either cold lateral (CL) condensation or thermoplastic
(Th) compaction with System B and Obtura II. The
distribution of voids (number and volume) was assessed
by means of microCT. Results. In the apical third of the
root canal, in total over three times more external voids
(e-voids) (598) with a greater volume than internal
voids (i-voids) (167) were found. In the middle third
the numbers of i-voids (664) and e-voids (651) were
similar. The mean volume of i-voids was higher among
root canals filled using CL condensation as compared
to Th compaction (p=0.001). The greatest number of
i-voids (3872) and e-voids (1888) were found in the
coronal third. The mean volume of i-voids was higher
among root canals filled using CL condensation as
compared to those filled by means of Th compaction
(p=0.001). Conclusions. Irrespective of the obturation methods, the most hermetically filled part of the root
canal was the apical third while the coronal third
was the least hermetically filled part. E-voids with a
greater volume predominated in the apical part, while
numerous small i-voids were detected closer to the
crown.