Influence of the curing mode on the degree of conversion of a dual-cured self-adhesive resin luting cement beneath ceramic.
OBJECTIVE
To evaluate the effect of the delayed photoactivation and ceramic barrier on the degree of conversion (DC) of self-adhesive resin cement.


METHODS
Circular specimens (5 mm in diameter × 1 mm in thickness) of the RelyX U-100 resin cement were made using the following curing protocols (n = 10): (G1) 40 s beneath a IPS Empress II ceramic; (G2) 40 s of direct photocuring; (G3) 80 s beneath the ceramic; (G4) 80 s of direct photocuring; (G5) self-curing; (G6) 5 min in the absence of light (self-curing) followed by transceramic photocuring for 40 s; (G7) 5 min in the absence of light (self-curing) followed by transceramic photocuring for 80 s. All the specimens were photoactivated by LED (800 mW/cm(2)). After 24 h of dry storage, the DC was measured by FTIR, on the top surface of the specimens. Data were submitted to one-way ANOVA and Tukey test (p ≤ 0.05).


RESULTS
Direct photocuring with no ceramic interposition, regardless of the curing time (40 s and 80 s) promoted the highest conversion mean (56.79 ± 1.19 and 59.98 ± 2.93, respectively) and the 5 min delay time for the transceramic photocuring presented a similar mean compared to the immediate transceramic photocuring. The DC was influenced by the ceramic barrier, decreasing the conversion values (49.72 ± 1.91 for 40 s and 52.36 ± 2.50 for 80 s), with no statistical difference from the groups with the previous 5 min of photoactivation delay. The self-cure only showed the worst DC values.


CONCLUSIONS
Direct photocuring provided a higher degree of conversion for the self-adhesive resin cement. The delayed light activation did not influence the degree of conversion for the resin cement tested.
Department of Restorative Dentistry, Piracicaba Dental School, State University of Campinas, São Paulo, Brazil. edujcsj@gmail.com
Eduardo José
EJ
Souza
Boniek Castillo Dutra
BC
Borges
Dayane Carvalho Ramos Salles
DC
Oliveira
William Cunha
WC
Brandt
Ronaldo
R
Hirata
Emmanuel João Nogueira Leal
EJ
Silva
Mário Alexandre Coelho
MA
Sinhoreti
D002516:Ceramics; D055117:Curing Lights, Dental; D003738:Dental Cements; D017550:Spectroscopy, Fourier Transform Infrared
D003738:Dental Cements