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study aimed to investigate in an ex vivo model the reduction in patient
radiation dose while maintaining accurate linear measurements by comparing
cone-beam computed tomography (CBCT) scans taken at 360 ͦ versus 180ͦrotation,
with porcine jaw specimens as a reference standard.
scans of 12 sectioned porcine hemi-mandibles at 360 ͦ and 180 ͦ rotations
were taken with standardized clinical exposure parameters. To assess
inter-observer variability, 6 assessors who were blinded to the degree of
rotation took linear measurements of anatomic structures on each scan. The
measurements were repeated after 2 weeks to assess intra-observer
variability. Accuracy of measurement was judged against the corresponding
measurements taken from the porcine jaw specimens.
correlations signaled good to excellent intra-observer and inter-observer
and 0.79–0.98), respectively. Mixed regression analysis found no significant
difference between the measurements from 180ͦor 360 ͦ rotations and no
difference between the 2 rotations and porcine jaw specimens.
A CBCT image
sufficient to make accurate clinical measurements with a reduced radiation
exposure may be obtained by using 180ͦrotation of the CBCT tube head. (J
The aim of this study was to measure the in-vitro micro-shear
bond strength (µSBS) of resin composite (N’Durance®) to a novel tri-calcium silicate cement
(Biodentine™) compared to glass ionomer cement (Fuji IX™) and resin modified
glass ionomer cement (Fuji II LC™) using a self-etch adhesive (Scotchbond™
Universal) in a self-etch mode (SE) and a total etch (TE) mode while aging
the substrates and aging the bond at different time intervals and to identify
the mode of failure.
920, 3×4 mm discs of Biodentine, GIC and RMGIC were prepared and
composite resin bonded using either a SE mode or TE mode. They were divided
into two groups. In the first group the substrate was aged for either
immediate (t=0 min,t=5 min, t=20 min, t=24 Hrs) or delayed time intervals (t=2 wks,
t=1month, t=3 months,t=6 months) before bonding and the immediate bond
strength (t=24 hrs) tested. In the second group, the bonding agent was
applied after either immediate (t=5 min) or delayed (t=2 wks) aging of the
substrate, and the bond tested after aging the bond for different time
intervals (t=2 wks, t=1month, t=3 months,t=6 months). The different modes of
failure were identified using an electron microscope.
A significant difference in the µSBS was
found between Biodentine™, GIC, and RMGIC (P<0.001). No significant
difference was found between the (SE) and (TE) modes (P=0.42). When aging the
substrate, a significant difference was found between the immediate and
delayed time intervals (P=0.009). When aging the bond, there was a significant
difference between 2 weeks, 1 month, 3 months, 6 months for all substrates
regardless whether they were aged for an immediate or delayed time period.
Mode of failure was mostly cohesive within the substrate followed by adhesive
failure at the interface between resin and substrate.
Biodentine™ is weak in its early setting
phase, placing the veneering restoration is best delayed for 2 weeks to allow
proper setting of the material to sufficiently withstand the contraction
forces of the composite resin. A total etch or self-etch adhesive may be