Abstract
Background
An additional canal found in the mandibular first molar (M1M) is the middle mesial
canal (MMC), which is often missed during root canal treatment. In this study, the
prevalence of MMC in M1M on cone-beam computed tomography (CBCT) images was evaluated
in 15 countries, along with the effect of some demographic factors on its prevalence.
Methods
Deidentified CBCT images were scanned retrospectively, and the ones including bilateral
M1Ms were included in the study. A written and video instruction program explaining
the protocol to be followed step-by-step was provided to all observers to calibrate
them. The CBCT imaging screening procedure consisted of evaluating three planes (coronal,
sagittal, and axial) after a 3-dimensional alignment of the long axis of the root(s).
The presence of an MMC in M1Ms (yes/no) was identified and recorded.
Results
In total, 6304 CBCTs, representing 12,608 M1Ms, were evaluated. A significant difference
was found between countries (P < .05). MMC prevalence ranged from 1% to 23%, and the overall prevalence was 7% (95%
confidence interval [CI]: 5%–9%). No significant differences were found between the
left and right M1M (odds ratio = 1.09, 95% CI: 0.93, 1.27; P > .05) or between genders (odds ratio= 1.07, 95% CI: 0.91, 1.27; P > .05). As for the age groups, no significant differences were found (P > .05).
Conclusions
The prevalence of MMC varies by ethnicity, but it is generally estimated at 7% worldwide.
Physicians must pay close attention to the presence of MMC in M1M, especially for
opposite M1Ms, due to the prevalence of MMC being significantly bilateral.
Key Words
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Article info
Publication history
Published online: February 28, 2023
Publication stage
In Press Corrected ProofIdentification
Copyright
© 2023 Published by Elsevier Inc. on behalf of American Association of Endodontists.
