| Summary: | Background: Irradiation sources have
been used to reduce the total in-office bleaching time. However, little is
known about the effects of the light irradiation bleaching systems on the
restorative materials. This in vitro
study evaluated the microhardness of 6 different restorative materials during
office bleaching procedures with blue light emitted diode and diode laser
photoactivation.Materials and Methods: FiltekTM supreme
(nanofilled), Tetric EvoCeram (nanohybrid), Tescera ATL (ormocer), Clearfill
Majesty Esthetic (nanofilled), Durafill VS (microfilled) and IPS Empress II
(ceramic) restorative materials were selected in this study. Twenty specimens,
10 mm in diameter and 2 mm thick, were fabricated from each material using a
Teflon mold. All specimens were randomly assigned to two groups (n=10). Group 1
received two topical applications of 35% hydrogen peroxide and was
photoactivated using blue light emitted diode (800 mW/cm2) for 20s.
Group 2 received topical application of 46% hydrogen peroxide using diode laser
(wavelength 980 nm, average power 7 watt, energy setting 200 J, continuous
mode) for 30s. Baseline and after bleaching microhardness measurements were
taken with a Vickers hardness tester that was used with a 300 g for the
porcelain and 100 g for the composite and ormocer specimens, the
dwell time was 30 s for all groups. Data were analyzed statistically, with
one-way-analysis of variance (ANOVA), post-hoc Tamhane's T2 and independent t
tests.Results: After application of both
office bleaching agents, microhardness of all restorative materials tested were
significantly decreased (p<.05). However, Tetric EvoCeram composite resin
material showed the least microhardness value (p<.05).
Conclusion: Blue light emitted diode
and diode laser activation hydrogen peroxide office bleaching agents have
similar effects on the reduction of microhardness of restorative materials. The
data of this study revealed that after bleaching, nanofilled (FS, CME),
microfilled (Df) specimens demonstrated lower changes in microhardness values
than nanohybrid (TEC) composite material.
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