Vol 21 No. 1

J Bagh College Dentistry Vol.21(1), 2009 The effect of dowel …
retentive values was also attributed to the serrated
surface of the Euro post. The superior retentive
abilities of parallel sided design of the post over
tapered design in resisting tensile, shear, and
torque forces, and the serrations at the surface of
the post as well as the use of adhesive resin
cement for luting the post, all these factors will
greatly improved the retention of the post inside
the root canal. This finding is in agreements with
that obtained by Colley et al (5) , Johnson and
Sakamura (6) , Love and Purton (7) , Purton et al (8) ,
and Cohen et al (9) , but disagrees with the findings
of Stockton and Williams (10) who revealed that
the serrated C-post (parallel design) required
significantly more tensile force to dislodge them
than Para post (Plus post). The serrations at the
surface of the fiber post would significantly
increase the retention of the post inside the canal,
also with the findings of Drummond (11) who
found that there was no significance difference in
the retention of the fiber post versus stainless steel
Para post. All the tapered dowels could easily be
removed after the cement seal was broken, and
they came out cleanly with no cement attached.
The bond between the cement and the dowel was
the failure site, while in the parallel sided design
posts could not be removed from the tooth after
the fracture of the cement bond. Tensile forces
greater than the forces required to break the
cement bond were required to remove the parallelsided
dowels, once removed. The parallel sided
dowels were coated with cement as were the
dentinal walls of the prepared canals, thus failure
site with in the cement. The serrations on the
parallel sided dowels served as a mechanical
locking device for the cement and prevent failure
of the cement dowel bond.
Post length has a pronounced effect on post
retention .In this study although the retentive
values of group Ι (Easy post 10mm depth) were
higher than that of group ΙΙ (Easy post 5mm
depth) but still its statistically not significant, this
may be due to the fact that an increase in the
bonded post surface area 50% most likely
influenced the increased in the retentive strength.
There was no significant difference in the
retentive values of group ΙΙΙ (Euro post 10mm
depth) and group ΙV (Euro post 5mm depth) this
may due to that nearly the same number of
retentive spirals engaged the canal wall. The
results of this study are in agreement with that of
Rovatti et al (12) , Purton and Payne (13) and Borer
et al (14) , but disagree with that of Standlee et al
(15) , who claimed that the more deeply the dowel
were placed in their dentin canals the more
retentive they became. The result of Johnson and
Sakamura (6) who stated that an increase in length
of the dowel from 7 to 11mm lead to increase in
the retention by 30%.
Increasing the post depth must be well with in
the constraints of root length, canal morphology,
root diameter in the apical area, and the
maintenance of an endodontic apical seal.
However, the influence of post length on retention
should not be over emphasized and the temptation
to compromise the apical seal of a root filling by
increasing post length should be resisted. Each
tooth must be evaluated on an individual basis by
the dentist before its restored with a post.
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