Back ground: This in vitro study was carried out to investigate the effect of post space regions (coronal, middle and
apical), Time and the mode of polymerization (dual, self-cured) of the cements used on the bond strength between
translucent fiber post and root dentin by using push-out test.
Materials and Methods: Forty eight extracted mandibular first premolars (single root) were instrumented with ProTaper
Universal system files (for hand use) and obturated with gutta percha for ProTaper and AH26® root canal sealer
following the manufacturer instructions, after 24 hours post space was prepared using FRC postec® plus drills no.3
creating 8 mm depth post space. The prepared samples were randomly divided into two main groups (24 samples
each) according to the used cement (Group M, self-cure, Multilink N) and (Group R, dual cure, Relyx U100). Then
each group was subdivided into three groups (each group contains 8 samples) according to the testing time after
cementation. (g M1: push out test after 24 hour of cementation with Multilink N), (g M2: push out test after one week
of cementation with Multilink N),(g M3: push out test after two weeks of cementation with Multilink N), (g R1: push out
test after 24 hours of cementation with RelyxU100), (g R2: push-out test after one week of cementation with
RelyxU100), (g R3: push out test after two weeks of cementation with RelyxU100). After cementation and incubation
each root was sectioned horizontally into 3 slices (2 mm in thickness) represent the coronal, middle and apical
regions of the post space. Push out bond strength test was performed and measured using a universal testing
machine (Tinius-Olsen) at across head speed of 0.5 mm/min.
Results: showed that regarding the root region, the bond strength values increased significantly apical to coronal
region in both tested cements. For the effect of time, the bond strength values also significantly increased with time
for both tested cements. For mode of polymerization, the self-cured resin cement Multilink N showed higher bond
strength values.
Conclusion: the retention of fiber post was affected by root region, mode of polymerization of the cements used
and time elapsed after cementation of the post |