Objective: To compare the reduction of residual dentine thickness of two different post preparation
methods on the mandibular second molars with a C-shaped root canal configuration.
Methods: A total of 26 extracted right mandibular second molars with a C-shaped root canal
configuration were selected and paired based on similar canal morphology. Each of the
paired teeth was randomly allocated to the heat and ultrasonic instruments group (HU group)
or Peeso Reamer (Mani, Utsonomiya, Japan) group (PR group) (n = 13) and received post
preparation with different instruments after the same endodontic treatment. The reduction of
residual dentine thickness and the minimal remaining dentine thickness at the apical sections
at 4 or 7 mm below the cementoenamel junction (CEJ) were recorded. The data were analysed
using an independent samples t test (α = 0.05).
Results: The reduction of residual dentine thickness for the HU group was less than that for the
PR group in the two sections. Moreover, at the section 7 mm below the CEJ, the teeth reduction
of the distolingual wall in the HU group (0.022 ± 0.007 mm) was significantly lower than that
in the PR group (0.101 ± 0.013 mm) (P < 0.01).
Conclusion: Using heat and ultrasonic instruments to perform post preparation could follow
the original canal configuration to save more tooth structure in the remaining root canal wall,
minimise the reduction of residual dentine thickness and decrease the incidence of root canal
perforation.
Keywords: C-shaped canal, mandibular second molars, post preparation, teeth reduction
