Initial curing characteristics of composite cements under ceramic restorations.
PURPOSE
To assess the degree of conversion (DC) of dual-curing composite cements when cured through ceramic-veneered zirconia disks.


METHODS
Portions of mixed cement, either G-CEM LinkForce (GC), Panavia V5 (Kuraray Noritake) or ResiCEM (Shofu), were placed on the ATR crystal of a Fourier Transform Infrared Spectroscope (FTIR; iS50, Thermo Scientific) and squeezed to a 100-µm film thickness using a microscopy cover glass. DC (%) of the composite cements applied in self-curing mode was measured in the dark at 37°C. Following the dual-curing mode, the cements were light-cured directly (positive control) or through a ceramic-veneered zirconia disk (0.5-mm thick zirconia with a 1.0-mm thick veneering ceramic) for 40 sec using two light-curing units (G-Light Prima 2, GC; PenCure, Morita). Per experimental group, 5 tests were conducted to measure DC in self-cure and dual-cure mode (n=5). FTIR spectra of the composite cement films were acquired to determine DC every min up to 30 min. DC of the composite cements was statistically compared using two-way repeated-measures ANOVA (α=0.05).


RESULTS
For all cements investigated, the self-curing mode resulted in significantly lower DC at 10, 20 and 30 min than the light-curing mode. When the composite cements were light-cured through the zirconia disk, DC at 30 min dropped significantly for ResiCem (Shofu), while not for Panavia V5 (Kuraray Noritake) and G-CEM LinkForce (GC).


CONCLUSIONS
Self-curing slows down polymerization but does not reach for all composite cements the highest (light-cured) DC. Ceramic-veneered zirconia-based restorations may affect DC of some composite cements.
['Inokoshi|Masanao|M|', 'Nozaki|Kosuke|K|', 'Takagaki|Tomohiro|T|', 'Okazaki|Yohei|Y|', 'Yoshihara|Kumiko|K|', 'Minakuchi|Shunsuke|S|', 'Van Meerbeek|Bart|B|']
D002516:Ceramics D055117:Curing Lights, Dental D055115:Light-Curing of Dental Adhesives D008422:Materials Testing D019279:Resin Cements
Degree of conversion Zirconia Light-curing unit FTIR, Light spectrometer Luting composite