This article will discuss; how to use fiber posts more efficient

1. Effect of ascorbic acid, ethanol and acetone on adhesion
between the treated fiber posts and composite resin cores
2012 Nov;4(4):187-91. doi: 10.4047/jap.2012.4.4.187. Epub 2012 Nov 29.
Reza Talebian ALS, DDS, CCRD

2. Contact with the author:
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Reza Talebian ALS, DDS, CCRD
Cosmetic & Reconstructive Dentist at Dental Private Practice
wWw.QueenDent.cO.uK.
email: wWw.QueenDent.cO.uK @gmail.com

3. INTRODUCTION
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Reza Talebian ALS, DDS, CCRD

4. Nowadays, fiber posts are routinely used for adequate
retention of core when significant coronal part of the
tooth has been lost during root canal therapy.
Factors which can participate in long term success of a
post/core restoration include build up material which
is used, type of post and quality of adhesion between
post and core.
Surface treatments of posts are recommended in order
to improve the retention between structures
Reza Talebian ALS, DDS, CCRD

5. Mechanical treatment techniques such as air abrasion
with silica or sandblasting can increase bond strength
between fiber post and resin composite material, but
decrease in post fitness within root canal, due to
modification of post shape.
Chemical treatments lead to greater mechanical
retention by roughening the post surface. Some of
chemical solutions used for post surface treatments are
potassium permanganate, Hydrofluoric acid, silane
and hydrogen peroxide.
Reza Talebian ALS, DDS, CCRD

6. Dissolution of the resin matrix, breaking epoxy resin
bonds and exposing the fibers is the main function of
hydrogen peroxide, which can provide stronger
adhesion between post surface and resin composite.
The most important problem with use of hydrogen
peroxide is oxygen free radicals accumulation within
post surface micro porosities, due to hydrogen peroxide
degradation. New born oxygens interact with post to
core adhesion procedure. So use of agents which can
neutralize the effect of these oxygen free radicals is
recommended.
Reza Talebian ALS, DDS, CCRD

7. Some of these agents can neutralize oxygen effect by
removing and evaporating it from the surface, such as
ethanol and acetone while some of those have direct
antioxidant properties as reducing agents like ascorbic
acid.
The aim of this study was to evaluate and compare
the effect of ascorbic acid, ethanol and acetone on
bond strength between hydrogen peroxide pre-treated
fiber post to composite resin core.
Reza Talebian ALS, DDS, CCRD

8. Materials and Methods
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Reza Talebian ALS, DDS, CCRD

9. 24 white quartz fiber posts (RTD) with ,maximum 1.8 mm
diameter were selected.
Immersion in 24% hydrogen peroxide solution for 10 minutes at
room temperature and then rinsed under running water for
two minutes and gently air-dried.
Group-1 : control group (no any surface treatment).
Group-2 : treatment with ascorbic acid 10% for 5
minutes.
Group-3 : treatment with ethanol 70% for 5 minutes.
Group-4 : treatment with acetone 70% for 5 minutes.
Rinsing under running water for 2 minuets and then gently
air-dried.
Reza Talebian ALS, DDS, CCRD

10. Core build up was then performed using a light cured
flowable composite.
Each post was positioned upright on a glass slab and
fixed with a drop of sticky wax. A cylindrical matrix
was made with 10 mm in diameter and the length was
equal to the non-tapered portion of the post (6 mm). It
was placed around the post and adjusted so that the
post was positioned exactly in the center.
Reza Talebian ALS, DDS, CCRD

11. Flowable composite was applied on the post in onemillimeter thickness increments and each layer was
cured separately using a halogen light curing unit then
were stored in dionized water at 37°C for 24 hours.
Reza Talebian ALS, DDS, CCRD

12. Reza Talebian ALS, DDS, CCRD

13. 
first two sections parallel to the long axis of the post
and then sections perpendicular to the long axis of the
post were done, resulting in sections containing the
post in the center and composite cores on both ends.
The final sections had 1±0.1mm diameter measured by
a digital caliper.
Reza Talebian ALS, DDS, CCRD

14. 
Each stick was glued to the two free sliding
components of a jig mounted on the microtensile tester.
This set-up was designed to apply pure tensile forces.
Reza Talebian ALS, DDS, CCRD

15. The specimens were loaded at a
crosshead speed of 0.5 mm/min
until failure. Bond strength was
expressed in MPa, by dividing
the load at failure point (N) to
the bonding surface area (mm2).
Reza Talebian ALS, DDS, CCRD

16. 
Failure modes of the samples were assessed using a
stereomicroscope at 20x magnification and recorded as
Cohesive failure (failure in post or core material),
Adhesive failure (failure at the interface of post and
core material),
Mixed failure (adhesive-cohesive failure).
Reza Talebian ALS, DDS, CCRD

17. 
Two randomly selected fractured sticks of each
group were sputter-coated with goldpalladium and assessed with Scanning
electron microscope at different
magnifications.
Reza Talebian ALS, DDS, CCRD

18. Tukey HSD & One-way ANOVA were used for
statistical analysis.
Reza Talebian ALS, DDS, CCRD

19. Results
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Reza Talebian ALS, DDS, CCRD

20. According to statistical analysis; Highest value of bond
strength values in G4 and the lowest in G1.
A higher bond strength values was seen in G3 than G2.
There were honestly meaningful statistical difference
among all of groups (P<0.001).
Under stereomicroscope, all of the failures were adhesive,
between post and core.
SEM assessment was confirmed these results.
Reza Talebian ALS, DDS, CCRD

21. Reza Talebian ALS, DDS, CCRD

22. Reza Talebian ALS, DDS, CCRD

23. Discussion
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Reza Talebian ALS, DDS, CCRD

24. Results of The present study demonstrated that bond
strength in groups 2, 3, 4 has significant difference with
control group.
Ascorbic acid plays role as a reducing agent. Electron
transfer from ascorbate to oxygen free radicals -derived
from hydrogen peroxide degradation- can result in
formation of semi-dehydroascorbate, a more stable
material.
Ascorbic acid + 2O2¯→ H2O + semi-dehydroascorbate
(DHA)
Reza Talebian ALS, DDS, CCRD

25. Higher amount of bond strength in group-3, 4 than other
two groups is probably attributed to higher surface
wetting compared to their effects on removing surface
oxygen free radicals.
The results show that acetone can increase bond strength
even more than ethanol; it can be due to more
evaporating power of acetone in comparison to other
materials used.
Stereomicroscopy and SEM evaluations, both of them,
showed that Adhesive area is the weakest area in
adhesion of fiber post to resin composite core. Although,
presence of more epoxy resin on fiber posts surfaces in
Group4 than control Group after adhesive failure
indicated higher bond strength.
Reza Talebian ALS, DDS, CCRD

26. It seems that flowable composites, due to their
low viscosity, are the choice for core build up
since they provide a more homogenous available
surface and without void for bonding.
For more similarities to the oral conditions, it is
recommended to perform fatigue test in
combination with use of antioxidants. Also, in
this study, one type of fiber post and resin
composite material evaluated, future studies on
other types of fiber post and resin composite
materials are recommended. Clinical trials and
evaluation of aging effect on bond strength is yet
to be evaluated.
Reza Talebian ALS, DDS, CCRD

27. CONCOLUSION
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Reza Talebian ALS, DDS, CCRD

28. Within the limits of this study, it can be
concluded that:
Application of ascorbic acid, ethanol and
acetone can increase microtensile bond
strength of hydrogen peroxide pre-treated
fiber posts to resin composite core.
Use of acetone demonstrated higher increase
in bond strength than the other materials.
Reza Talebian ALS, DDS, CCRD

29. FINISH
Reza Talebian ALS, DDS, CCRD