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A.-M. LE BELL, L.
LASSILA, and P. VALLITTU, University of Turku, Finland
Objectives: The aim of this study was to compare bonding of two
different fiber-reinforced composite (FRC) posts in root canal
dentin discs. Serrated titanium posts served as reference.
Methods: Prefabricated carbon FRC posts with cross-linked polymer
matrix and individually formed FRC posts with interpenetrating
polymer network (IPN) matrix were compared. The crowns of
extracted third molars were removed and post spaces (diameter: 1.5
mm) were drilled, etched and bonded. The posts were treated with
dimethacrylate resin for 3 minutes and light-polymerized. A
dual-polymerizing composite resin cement was used for cementing.
After 26 days in water storage the samples were thermocycled
(6000x) and cut into discs of thicknesses: 1, 2 and 4 mm (n=
8/group). Push-out force was measured by pushing the post from one
end. Assessment of the failure mode was made by two independent
operators under a stereomicroscope (1= adhesive failure between
post and cement, 2= cohesive failure of post-system, 3= adhesive
failure between cement and dentin). Results: The push-out force
increased with increased height of dentin disc in all groups
(ANOVA, p< 0.001 ). The individually formed FRC posts showed a
trend for highest push-out force in all heights of dentin discs:
66.6 N (1 mm), 154.1 N (2 mm) and 371.1 N (4 mm) although the
difference was not statistically significant. None
of the individually formed FRC posts showed adhesive failures
between the post and the cement whereas 54 % of the prefabricated
carbon FRC posts and 79 % of the titanium posts showed either
complete or partly adhesive failure between post and cement.
Conclusions: There was no difference in push-out force between the
posts. However,
contrary to the other posts, there were no adhesive (cement-post)
failures with the individually formed FRC posts, suggesting better
interfacial adhesion of cement to post in this group.
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