Does an additional UV LED improve the degree of conversion and Knoop Hardness of light-shade composite resins?
OBJECTIVE
The purpose of this study was to evaluate the degree of conversion (DC) using FT-Raman spectroscopy and the Knoop hardness (KHN) of composites cured by second and third-generation LED light curing-units (LCU), Radii Cal and Ultralume 5.


METHODS
Three composites (Filtek Supreme XT, Filtek Z350, and Esthet X) were selected for this study. KHN testing (n=10) was performed with 10 indentations for the top (T) and bottom (B) surfaces. For DC (n=10), both the T and B surfaces were analyzed.


RESULTS
For KHN, the three composites differed in hardens. There was a "LCU-surface" interaction, in which Radii Cal showed significantly greater hardens in the B surface. For DC, there was a "composite-surface-LCU" interaction. For the "composite" factor, there was no significant difference between the groups, except for Supreme XT-Radii Cal (T or B surfaces). For the "LCU" factor there was a significant difference for Supreme XT T surface, Ultralume 5 obtained a higher DC. For the Z350 T surface, a significant difference in the DC in which Radii Cal obtained better results. For the "surface" factor, all groups presented T surfaces with a higher DC than the B surfaces, the sole exceptions involved Esthet X-Radii Cal and Z350-Ultralume 5.


CONCLUSIONS
Knowledge regarding composite composition and the characteristics of LCUs are important for effective polymerization.
Department of Restorative Dentistry, Piracicaba Dental School, State University of Campinas (UNICAMP), Piracicaba (SP), BRAZIL.
Maria Cecília Caldas
MC
Giorgi
Flávio Henrique Baggio
FH
Aguiar
Luís Eduardo Silva
LE
Soares
Airton Abrahão
AA
Martin
Priscila Christiane Suzy
PC
Liporoni
Luís Alexandre Maffei Sartini
LA
Paulillo