Accuracy of working length measurement: electronic apex locator versus cone-beam computed tomography
Abstract
International Endodontic Journal
‘Accepted Article’, doi: 10.1111/iej.12140
Aim
To compare the accuracy of working length (WL) determination using the Raypex 6® electronic apex locator and cone-beam computed tomography (CBCT).
Methodology
A
total of 150 extracted human teeth were decoronated and randomly
assigned to 5 groups (n=30). WL was measured with the Raypex 6®
at both the “constriction” and the “apex” marks, under dry conditions
(group 1) or with 2.5% NaOCl, distilled water or Ultracain®
(groups 2 to 4). The radiological WL (group 5) was calculated from
bucco-lingual and mesio-distal CBCT sections. Differences between
electronic, CBCT measurements and actual length (AL) were calculated.
Positive and negative values respectively indicate measurements falling
short or long of AL. Two-way-ANOVA and the Bonferroni and Welch tests
were used to compare mean differences among groups. The χ2
and Fisher exact tests were used to compare percentages of precise, ±0.5
mm and ±1.0 mm of the AL measurements among the experimental groups.
Statistical analysis was performed at α=0.05.
Results
Mean
differences with respect to AL ranged from 0.26 mm to -0.36 mm, and
from 0.05 to 0.18 mm, respectively, for the electronic measurements at
the “constriction” mark and “apex” mark. CBCT measurements were an
average of 0.59 mm shorter than AL. Percentages of electronic
measurements falling within ±0.5 mm of the corresponding AL referred to
the “apex” mark were greater than at the “constriction” mark, but the
differences were only significant in group 4 (with Ultracain®).
Percentages of CBCT measurements falling within ±0.5 mm of AL (46.7%)
were significantly lower than electronic measurements, regardless of the
condition of the root canal. In 30-38.5% of the measurements taken at
the “apex” mark, and in 3.4%- 13.3% of those at the “constriction” mark,
the file tip extended beyond the foramen.
Conclusions
Electronic measurements were more reliable than CBCT scans for WL determination. The Raypex 6® was more accurate in locating the major foramen than the apical constriction under the experimental set up.
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