Scanning electron microscopic evaluation of the effect of different root‑end resection methods in the crack formation in root canals filled with mineral trioxide aggregate or calcium‑enriched mixture cement

Abstract

Background: There is some concern that root resection may alter the surface features and
crack formation of the previously set orthograde material. The aim of this in vitro study was to
evaluate the crack formation in orthograde mineral trioxide aggregate (MTA) and calcium‑enriched
mixture (CEM) plugs after root resection.
Materials and Methods: This in vitro study was conducted on 170 extracted human maxillary
anterior teeth. The teeth were randomly divided three experimental (n = 50) and control (n = 20)
groups. In Group 1, after root canal treatment, half of the roots were cut with a bur, and the other
half with an ultrasonic cutter. In Groups 2 and 3, after the 4‑mm CEM and MTA plugs were placed
and set, the root ends of half of the samples were cut with a bur and the other half by an ultrasonic
cutter. The prevalence of cracks in the dentin and orthograde apical plugs of MTA and CEM was then
assessed by scanning electron microscopy. Data were analyzed using the McNemar’s, Chi‑square,
and Fisher’s exact tests at P ≤ 0.05 level of significance.
Results: In general, the prevalence of crack in dentin in Groups 2 and 3 was significantly higher
than in the plug (P < 0.05). There was no significant difference in the prevalence of dentin crack in
the studied groups (P > 0.05). The prevalence of crack in dentin was lower when the bur was used
to cut off the end of the root, although the difference was not significant. The prevalence of crack
in the plug was similar in CEM and MTA.
Conclusion: Based on the results of this study, the prevalence of crack in dentin is always significantly
higher than its prevalence in the plug, and the prevalence of crack in the plug was similar in CEM
and MTA; then, when there is an orthograde access to the root canal and surgery is likely in future,
MTA and CEM can be placed in an orthograde technique and it just resects the root during surgery.
Key Words: Dentine, pulp canal, retrograde obturation, root canal, ultrasonic surgery