Research and Education In vitro evaluation of the shear bond strength and bioactivity of a bioceramic cement for bonding monolithic zirconia
The Journal of Prosthetic Dentistry
Available online 17 July 2019
Statement of problem
Adhesive
cementation is the most common bonding strategy for zirconia
restorations. Although cementation with a bioactive luting agent has
been proposed as an alternative, how the bond strength compares is
unclear.
Purpose
The
purpose of this in vitro study was to evaluate shear bond strength
after cementing a monolithic zirconia ceramic to human dentin with a
bioceramic cement, compare it with a traditional cement, and evaluate
its bioactive properties.
Material and methods
A
total of 120 dentin specimens and 120 Y-TZP (BruxZir) cylindrical
specimens were used. Zirconia and dentin specimens were randomly divided
into 8 study groups (n=15) based on 2 luting cement types (a bioceramic
cement or glass ionomer cement as control), 2 airborne-particle
abrasion protocols (50 μm or 110 μm), and 2 water storage durations (24
hours or 30 days). After the shear bond strength test using a universal
machine at a crosshead speed of 1 mm/min, fracture patterns were
evaluated under a stereomicroscope and a scanning electron microscope.
Strength values were statistically analyzed with a 3-factor ANOVA model
(α=.05). Bioactivity was evaluated in simulated body fluid (SBF).
Results
The
control glass ionomer cement achieved significantly greater shear bond
strength compared with the tested bioceramic cement. Mean bond strength
values ranged from 2.52 MPa to 5.23 MPa for the bioceramic cement tested
and from 4.20 MPa to 6.61 MPa for the control cement. The duration of
water storage played a significant role in the bond strength, with
groups stored for 30 days reaching higher bond strength values, whereas
the particle size of airborne-particle abrasion did not have a
significant effect. Failure types were primarily mixed. No apatite
formation was recorded on the surface of the specimens even after 30
days of immersion in SBF.
Conclusions
The evaluated cement did not develop apatite in SBF, and its bond strength values were below the control glass ionomer cement.
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