Effect of light curing modes on mechanical properties of direct and indirect composites.
OBJECTIVE
To evaluate the degree of conversion (DC), flexural strength (FS) and Knoop microhardness (KHN) of direct and indirect composite resins polymerized with different curing systems.


METHODS
Specimens of direct (Z250, 3M/Espe) and indirect (Sinfony, 3M/Espe) restorative materials were made and polymerized using two light curing units: XL2500 (3M/Espe) and Visio system (3M/Espe). Absorption spectra of both composites were obtained on a FTIR spectrometer in order to calculate the DC. FS was evaluated in a universal testing machine and surface microhardness was performed in a microhardness tester (50gf/15s). DC, FS and KHN data were submitted to two-way ANOVA and Tukey's test (α = 0.05).


RESULTS
Z250 showed higher DC, FS and KHN compared with Sinfony when the polymerization was carried out with XL2500 (p < 0.05). However, there is no statistical difference in DC between the materials when Visio was used (p > 0.05). Visio showed higher DC and KHN for Z250 and Sinfony than the values obtained using XL2500 light curing (p < 0.05). For FS, no significant difference between curing units was found (p > 0.05).


CONCLUSIONS
Even though the Visio system could increase DC and KHN for some direct and indirect composites, compared with the conventional halogen curing unit, a high number of monomers did not undergo conversion during the polymerization.
Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas, Piracicaba, São Paulo, Brazil. catelan@estadao.com.br
Anderson
A
Catelan
Márcia Regina do Espírito
MR
Santo
Lívia Maluf
LM
Menegazzo
João Carlos Silos
JC
Moraes
Paulo Henrique
PH
dos Santos
D000704:Analysis of Variance; D003188:Composite Resins; D055117:Curing Lights, Dental; D008422:Materials Testing
D003188:Composite Resins