GC EUROPE Kalore - Manual (Page 16)

16
Contraction Stress (MPa)
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Esthet-X HD † TPH3 † KALORE Premise † Filtek Supreme †
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GC Kalore technical manual
Independent Testing of Shrinkage Stress - OHSU
Independent testing of shrinkage stress using a Bioman stress measurement device was
conducted by Dr. Ferracane at OHSU School of Dentistry. This test uses a cantilever load-cell (500
kg) fitted with a rigid integral clamp, with a circular steel rod (10 mm diameter x 22 mm long)
held vertically and perpendicular to the load-cell axis by the end of the cantilever. A removable,
horizontal glass plate was placed underneath the rod and held rigidly in position by a Bioman
clamp during testing. the lower end of the steel rod was sand-blasted, and the surface of the
glass plate was silanated (but not sandblasted). An uncured composite sample 5 mm in diameter
and 0.8 mm in thickness (representing a bonded to non-bonded surface area (C-factor) of ~3) was
then introduced between the glass plate and the vertical rod to form an uncured specimen-disk.
The composite sample was then light-cured from below for 40 seconds at 800 mW/cm2. The
load-signal from the cantilever cell was amplified and the signal was acquired by a standard
computer. the registered load (in newton, n) was then divided by the disk area in order to
obtain the stress values (MPa). Subsequently, as in other studies using this methodology, the raw
stress data were treated by a “correction factor” of four in order to relate the data to a low
compliance system (such as a human tooth cusp). measurements were performed for five minutes
after curing. testing was performed in this manner for five samples of each composite tested.
After each evaluation, the Bioman
clamps were removed and the set
resin sample/glass-plate/metal piston
was removed and carefully examined
for any signs of debonding. if
debonding occurred (which was rare),
the debonded sample was excluded
from the test results. Data was
analyzed by the ANOVA/Tukey’s test to
compare the composites (p<0.05). It
was found that the polymerization
contraction stress of KALORE was
significantly lower than for all other
composites tested (Fig. 13).
Independent Testing – Indiana University School of Dentistry
independent testing of shrinkage stress was also conducted by Dr. Platt at indiana university
School of Dentistry. A tensometer was used to measure polymerization contraction stress. The
tensometer consists of a rectangular beam (10 mm in width and 40 mm in height) made of
stainless steel with a Young’s modulus of 193 GPa that is clamped horizontally on the beam
holder. During testing, the tensile force generated by the bonded shrinking composite sample
deflects the cantilever beam. this deflection is measured with a linear variable differential
transformer (lVDt), and the contraction stress is obtained by dividing the measured tensile force
by the cross-sectional area of the sample. to perform the test, a composite sample was placed
between two quartz rods positioned vertically in the tensometer. the top rod was connected to
the cantilever beam at a distance of 12.50 cm from the beam holder, and the bottom quartz rod
was used to complete the assembly to the tensometer and to guide the light from the curing unit
to the sample. the lVDt was positioned 23 cm from the sample assembly at the free end of the
cantilever beam.
Figure 13. contraction stress of tested composites.
a, b, c differences are not statistically significant within each letter.