Abstract
Introduction
The aim of the present study was to investigate the influence of root canal preparation
size and taper of middle mesial (MM) canals on fracture resistance of mandibular molars.
Methods
Fifty-five mandibular molar teeth having an MM canal were selected based on the cone-beam
computed tomographic analysis. After the decoronation and distal root separation procedure,
the lengths of the mesial roots were standardized to 13 mm. The specimens were randomly
distributed into 5 groups (n = 11). Mesiobuccal and mesiolingual canals were prepared up to size 30.06 using VDW.ROTATE
rotary files (VDW, Munich, Germany). The MM canal was prepared up to size 25.04, 25.06,
30.04, and 30.06, respectively. No preparation was done in the MM canal in the control
group. After the irrigation protocol, the canals were obturated with the single-cone
technique. A thin layer of silicone-coated specimens was embedded in acrylic resin
and subjected to a fracture strength test by a universal testing machine. A vertical
force was applied to the roots until they fracture. Statistical analysis was performed
with 1-way analysis of variance and post hoc Duncan tests (P = .05).
Results
There was no significant difference between group 25.04 and the control group, but
the fracture strengths of these groups were found to be significantly higher than
that of groups 25.06, 30.04, and 30.06 (P < .05).
Conclusions
Within the limitations of this study, we concluded that increasing the apical diameter
and taper in the MM canal reduces the fracture strength of mandibular molar teeth.
Among the tested instrumentation sizes, fracture strength decreased significantly
when greater than 25.04 instrumentation sizes were chosen.
Key Words
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Article info
Publication history
Published online: June 08, 2021
Identification
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© 2021 American Association of Endodontists.
