effect of non-eugenol based, calcium hydroxide based and ... - AOSR

EFFECT OF NON-EUGENOL BASED, CALCIUM
HYDROXIDE BASED AND RESIN BASED SEALERS ON
THE RETENTION OF FIBER POSTS LUTED WITH A RESIN
CEMENT- AN IN VITRO STUDY.
Satyanarayana Reddy*, Ramya Raghu*, Gautham*
ABSTRACT
Background: The aim of the study was to compare the effect of non-eugenol based sealer (Nogenol), calcium hydroxide
based sealer (SealApex) and resin based sealer (EndoREZ) on the retention of prefabricated fiber posts luted with a resin
cement.
Methods: 40 extracted single rooted upper anterior teeth were decoronated and root canals were filed, cleaned and shaped
with gates glidden drills and stainless steel hand K-files. Teeth were then divided into 4 groups of 10 specimens each. Group
1 was obturated with gutta percha without a sealer and served as a control. The other three groups were obturated with guttapercha
and either a non-eugenol based sealer, a calcium hydroxide sealer or a resin sealer. Ten mm deep post spaces were
prepared with peeso reamers and prefabricated fiber posts were cemented with Rely X–ARC resin cement. Following 48
hours of storage, specimens were mounted in metal tubes with acrylic resin and the posts were removed in tensile mode using
an Instron testing machine at 1mm/min with data recorded in kilograms.
Results: Using 1-way ANOVA and Bonferroni tests, Group 4 demonstrated significantly greater mean retention strength
values than Group 1 and 2 ((P

Satyanarayana Reddy et al.
and this is regarded as the most severe drawback because it
leads to the loss of the tooth itself. 7
For all these reasons, fiber posts were developed. They
demonstrate an elasticity modulus (MOE) similar to that of
dentin. Initially carbon fiber posts were designed, but due
to their esthetic limitations they were followed by quartz
fiber posts and glass fiber posts. 7
In contrast to metallic posts, non-metallic tooth colored
posts have several advantages: 3,6
- Dentin-like shade
- Physical properties and modulus of elasticity similar
to that of dentin
- Ability to be bonded to the radicular dentin
- Easy retrieval in case of failure
- Lack of corrosion
Retention of the post is the major factor influencing the
survival of the restoration and, to aid in this a luting cement
is employed. 4 Traditionally, zinc phosphate cement has
been the gold standard for post cementation, but studies
have shown that newer resin based cements have superior
properties and demonstrate significantly increased post
retention when compared with zinc phosphate cement. 4
It has been reported that resin-based luting cements are
presently the choice of many clinicians for their strength,
adhesion and ease of use. 4
Many studies have compared the retention of pre-fabricated
posts using different cements but not many have evaluated
the effect of root canal sealers on post retention.
Endodontic sealers are used in conjunction with
obturating materials to serve as luting and sealing agents. 8
Traditionally, sealers containing eugenol were popular,
but in recent times non-eugenol based sealers are gaining
popularity due to their better antimicrobial and sealing
properties. 5,9 Also, they are specially useful while using
resin cements for luting posts. This is because numerous
studies have shown that eugenol can inhibit polymerization
of resin cements. 3,10 Studies have also shown that eugenol
reduces the bond strength of resin cements to dentin
thereby negatively influencing the retention of posts luted
with resin cements. 3,5,10-12
Hence, whenever resin luting cements are employed, noneugenol
based sealers are preferred. 3,5,12
Nogenol, a non-eugenol based sealer has been available
for many decades now, primarily to overcome the irritating
potential of eugenol. 13 It is an extension of the non-eugenol
periodontal dressing. Essentially, eugenol is substituted
by chlorothymol and vegetable oil. 13 Calcium hydroxide
based sealers have been available for the past 2 decades. 13
Studies have reported that they have good sealing property
when compared with other sealers including the traditional
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zinc oxide eugenol sealers probably due to their expansion
upon setting. 5
Urethane dimethacrylate (UDMA) is one of the monomers
forming the organic matrix of composite resins. Recently,
it has been incorporated into an endodontic resin sealer and
is marketed as EndoREZ. 14 This sealer is reported to be
biocompatible, with hydrophilic characteristics and capable
of achieving a satisfactory seal. 14,15 Also EndoREZ has
demonstrated extensive penetration into dentinal tubules
similar to epoxy resin sealers. 16 Due to its hydrophilic
properties it can be used in slightly moist canals thereby
overcoming the problem of obtaining a completely dry
dentinal surface within the root canal. 14,17
At present, there are not many studies reporting the
influence of non-eugenol sealers like Nogenol, SealApex
and EndoREZ on the retention of pre-fabricated fiber posts
luted with resin cements.
Hence, the purpose of this in vitro study was to compare
the effect of Nogenol (non-eugenol sealer), SealApex
(calcium hydroxide sealer) and EndoREZ (resin sealer) on
the retention of pre-fabricated fiber posts luted with resin
cement.
MATERIALS AND METHODS:
The details of the materials used in this study are given in
Table 1. 40 human single rooted maxillary anterior teeth that
were freshly extracted were used for the study. The teeth
were decoronated at the cemento-enamel junction using
carborundum disks rotating at slow speed in a micromotor
straight hand piece. The canals were cleaned and shaped
using Gates Glidden drills for coronal flaring and stainless
steel hand K-files. 3% NaOCl and EDTA gel (Rc-Prep)
were used during canal preparation. The size of master
apical file was kept constant at 40. The final irrigation was
done with 17% EDTA to remove the smear layer.
The teeth were divided into 4 groups, each containing 10
teeth.
- Group 1 was obturated with gutta-percha without a
sealer and served as a control.
- Group 2 were obturated with gutta-percha and a calcium
hydroxide based sealer (SealApex)
- Group 3 were obturated with gutta-percha and noneugenol
based sealer (Nogenol)
- Group 4 were obturated with gutta-percha and resin
based sealer (EndoREZ)
Post space preparation upto the coronal 10mm of each root
canal using size1-4 Peeso reamers. The canals were dried
followed by acid etching and application and light curing
of dentin bonding agent. Rely X-ARC resin cement was
used to lute the fibre posts according to the manufacturer’s
instructions (Figure 1).

After this, the roots were gently notched using a
carborundum disk and the specimens were mounted into
1 cm diameter metal tubes using acrylic. Dental surveyor
was used in mounting the specimens to enable subsequent
post removal in a direction parallel to the long axis of the
posts (Figure 2). A customized metal framework was made
to support acrylic resin around the notches on the coronal
part of the fiber posts (Figure 3). This apparatus facilitated
the removal of the posts in tensile mode.
The specimens were secured and the posts were extracted
using vise clamps mounted in a universal testing machine
(Instron machine) operated in a tensile mode at 1mm/ min
until the posts were dislodged from the canals (Figure 4).
Data was recorded in kilograms and subsequently examined
using ANOVA and Bonferroni tests.
Figure 1: Prefabricated fiber post luted into the canal
Figure 2: Mounting the specimens with surveyor to
ensure parallelism
Non-eugenol, calcium hydroxide and resin sealers: Retention of fiber posts
Table 1: List of materials used in the study
Armamentarium Manufacturer
Nogenol root canal sealer GC America Inc., Alsip, IL 60803
SealApex Sybron Endo, Glendora, California 91740
EndoRez Ultradent, South Jordan, UT 84095 USA.
Rely X-ARC (A3 shade) 3M ESPE
Single bond (Adper) 3M ESPE, St. Paul, MN 55144 USA
Light curing unit – 2500 3M ESPE, USA
17% EDTA - Rc Prep Premier dental products, Canada
37% ortho phosphoric acid (H3PO4) 3M ESPE, 3M Dental products
Surveyor Shin Precision industrial Co.
Instron testing machine Model 5566, Instron Corp, Canton, Massachusetts, SMS,
SS-35N, SAE
Figure 3: Metal sleeve attached to the coronal part of
the fiber post.
Figure 4: Post gripped using vise clamps in an Instron
testing machine.
RESULTS:
All the specimens were subjected to tensile force using an
Instron universal testing machine and the load at which
fracture occurred was recorded in kilograms (kgs) as
shown in Table-2. No root or post fractures occurred in any
of the samples during testing. Mean tensile bond strengths
of all the groups tested is presented in Table-3 along with
the standard deviation. Visual inspection of the cemented
surface of the dislodged post showed resin cement over
the surface with failure appearing to occur at the root-resin
cement interface. Analysis of variance technique (one-way
ANOVA) was used to evaluate the difference among 4
67

Satyanarayana Reddy et al.
groups as shown in Table-4. Normal plot of the data on
tensile bond strength indicated that the observations had
come from normal distribution. Hence, to carry out test
of equality of mean tensile bond strength for the four
groups, Post Hoc test with multiple comparisons using
Bonferroni procedure was carried out with SPSS software.
The test results are presented in Table-5. This gave a value
of P

Table 4: One-way ANOVA test
Table 5: Post Hoc Tests with multiple comparisons using Bonferroni procedure
+ Suggestive significance (P value: 0.05

Satyanarayana Reddy et al.
As fiber posts are a relatively recent addition to the
endodontic armamentarium, there are only a few studies
on the effect of sealers or their constituents on the retention
of glass fiber posts luted with resin cement. In case a post
is required for restoring the endodontically treated tooth,
following obturation post space should be prepared by
removing the core filling material and endodontic sealer
from the canal walls. 15 Traditionally, eugenol based
sealers have been widely employed. 5 With the current shift
towards using resin cements for post cementation,
elimination of eugenol is important as it has considerable
radical scavenging properties and inhibits composite
polymerization. 5 Several researchers have reported that the
presence of eugenol substantially decreased the retention
of posts cemented with resin cement. 5 Thus, the general
recommendation is to avoid using eugenol-containing
sealers prior to bonding procedures in endodontics. 12
Therefore, in the present study non-eugenol sealers such
as Nogenol (non-eugenol based), SealApex (calcium
hydroxide) and a recently developed adhesive sealer
EndoREZ (resin based) were employed. Since it is well
known that eugenol inhibits the polymerization of resin
cements it was assumed that the use of non-eugenol sealant 5
– Nogenol would enhance the retention of fiber post. But
the results of this study showed that Group III (Nogenol)
showed least retention among all groups tested (17.17 ±
13.59). This was even lower than Group I (Control) where
no sealer was used (17.89 ± 3.72). This is in accordance
with the observations of a previous study that there may be
a component in Nogenol that overcomes the benefit of the
non-eugenol setting mechanism. 10 Thus it may be inferred
that Nogenol is not recommended as a sealer in teeth
requiring pre-fabricated posts luted with resin cements. 10
According to the results, Group I (Control group without
sealer) showed higher mean retention strength values than
even Group III (Nogenol). This suggests that the residual
sealer does have a definite effect on bond strength of resin
cements. This is in accordance with the study by Hagge
MS et al. 12
Group II (Seal Apex) performed better than both Group
III (Nogenol) and Group I (Control). This is similar to the
results of and Hagge MS et al. 12 This suggests that calcium
hydroxide sealer residue does not have any inhibitory effect
on the polymerization of resin cements. 12
The results of the present study showed that posts luted
with resin cements were most retentive when EndoREZ
(Group IV) was used as the sealer. This is in accordance
with the prevois study which reported higher post retention
values with a resin sealer. 3 Researchers have also reported
that resin sealers increased the retention of pre-fabricated
fiber posts luted with resin cement. 18 They attributed this to
the greater compatibility between the resin sealer and the
adhesive system used for post cementation as it was not
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possible to completely remove the sealer from the canal walls. 18
EndoREZ is a first generation methacrylate resin based
root canal sealer, similar to many restorative resins. 19 It
has additives to make it hydrophilic to facilitate its use in
the wet environment of root canal system. 14,17 It has been
reported to have good flow and penetrability into dentinal
tubules thereby providing good bond strength to radicular
dentin. 14,17 It may thus be postulated that some residues
of this cement may have remained within dentinal tubules
even after post space preparation.
The resin cement used in the present study is Rely-X-ARC,
a dual cure cement. 20 This is also methacrylate based. 20
Previous studies 4 have revealed that this cement provides
superior retention for fiber posts when compared with other
resin cements. This has been attributed to its superior resin
tag and hybrid layer formation and excellent wettability of
dentinal walls. 4 Since both, the sealer (EndoREZ) and the
resin cement (Rely-X-ARC) are methacrylate based, the
compatibility between them could be the major factor for
maximum retention values for posts in Group IV.
When fiber posts and resin luting systems are used to
restore endodontically treated teeth, the adhesive bonding
to dentin is based on micromechanical retention created
on the demineralized surface by resin tag formation. 21 For
optimal post retention it is critical to have clean canal walls
free from smear layer after post space preparation. 3,22,23
In this study, acid etching was done as it was part of the
cementation protocol with resin cements, which could
have removed the smear layer to some extent.
In vitro tensile bond strength testing may not be truly
representative of the highly differing intraoral conditions.
At best they only provide an indication of the possible
clinical performance of the materials tested. For this
reason, further clinical studies are necessary to validate the
findings of the present study. 3
CONCLUSION:
The future emphasis in endodontics will focus on obtaining
a ‘monoblock’ within the root canal in which the obturating
material, sealer cement, root canal dentin as well as the post
and core will form a single cohesive unit. In time to come,
adhesive sealers and fiber posts will become the norm.
The following conclusions can be drawn from the present
study:
1. Presence of a sealer is bound to affect the retention
of fiber posts luted with resin cement, either positively
or negatively.
2. Nogenol (non-eugenol based sealer) produced the least
retentive values among the three tested sealers.
3. SealApex (calcium hydroxide based sealer) did not
influence the adhesive bonding of fiber posts.

4. EndoREZ (resin based sealer) demonstrated the
highest retention values for fiber posts luted with resin
cements.
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Non-eugenol, calcium hydroxide and resin sealers: Retention of fiber posts
Correspondence:
Dr. Ramya Raghu
Dept of Conservative dentistry and Endodontics,
Bangalore Institute of Dental sciences,
5/3, Hosur road, Near Lakkasandra Bus stop, Bangalore 560027.
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