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2552
Introduction
Prefabricated fiber posts have been increasingly used for the restoration of endodontically treated teeth
because of their low stiffness being comparable to dentin, their frictionless bonded-post technique (Duret,
Reynaud et al. 1990), less need for extra appointments, and esthetics when using for tooth-colored restoration.
Although previous studies showed that the occurrence of root fractures was rare with the use of fiber posts
(Fredriksson, Astback et al. 1998; Ferrari, Vichi et al. 2000; Akkayan and Gulmez 2002), on the other hand, the
fiber post restoration often failed via dislodging of the bonded posts or “decementation” (Dallari and Rovatti
1996)
.
The failures were found to occur at the resin cement-dentin interface more often than at the post-resin
cement interface (Boschian Pest, Cavalli et al. 2002)
.
Many factors can weaken the adhesion of the fiber post to
the root canal wall, such as
reduced visibility inside the root canal,
endodontic procedures prior to post
cementation, smear layer remnants on canal walls along the post space, the variability of intraradicular dentin,
unfavorable geometry of the root canal system for bonding, and the compatibility of resin cements with dentin
adhesives. Accordingly, the clinicians should therefore circumspectly select the proper bonding technique in order
to obtain the optimal bonding performance to radicular dentin.
Currently, many types of resin cement system that can be used for fiber post bonding are available in
markets. According to the bonding substrate modification, there are three major categories of resin cements
commonly used.
The first one, the “Etch-and-Rinse” system, has phosphoric acid etching that completely
dissolves the smear layer and creates a zone of demineralized dentin, following by penetration of hydrophobic
resins with or without adhesive (i.e. Variolink II
®
; Ivoclar Vivadent).
Conversely, the second system, the “Self-
etch”
system,
uses adhesives containing high concentrations of acidic resin monomers to simultaneously
demineralize and infiltrate the smear layer-covered dentin (i.e. Panavia F 2.0
®
; Kuraray Medical Inc.). Lastly, the
“Self-adhesive” system (i.e. RelyX Unicem, 3M ESPE), does not require any pre-treatment of tooth substrates.
From the previous literature, some studies showed higher bond strengths with the etch-and-rinse system as
compared to the self-etch and self-adhesive resin cements (Goracci, Sadek et al. 2005; de Durao Mauricio,
Gonzalez-Lopez et al. 2007), while Bitter K
et al.
(2006) demonstrated that the self-adhesive resin cement
provided a higher bond strength than the others. Therefore, the bonding effectiveness of each resin-based luting
agent is still a controversial issue. Moreover, the data about capability of new self-adhesive resin cement in the
luting of fiber posts to root canal dentin is still scarce. The aim of this study was therefore, to evaluate the regional
bond strength of fiber posts bonded to root canal dentin using various resin-based luting agents by means of the
thin-slice push-out method.
Materials and methods
Fifteen human single-root premolars, recently extracted for orthodontic reasons, were selected. Teeth
with non-closed apex, caries, restorative or root canal treatment were excluded. A light-cure composite resin was
placed over the root-surface to create a uniform thickness (2 mm) of a wall in order to eliminate any effect of
