Influence of different shades and LED irradiance on the degree of conversion of composite resins

The aim of this study was to evaluate the degree of conversion (DC) of two composite resins with different shades that were light cured by light-emitting diodes (LEDs) of different irradiances. Specimens (5 mm ' 2 mm) were prepared with a nanofilled (Filtek Supreme - A2E, A2D, and WE) or microh...

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Bibliographic Details
Published in:Brazilian oral research 2012-03, Vol.26 (2), p.165-169
Main Authors: Gaglianone, Lívia Aguilera, Lima, Adriano Fonseca, Araújo, Larissa Sgarbosa Napoleão de, Cavalcanti, Andrea Nóbrega, Marchi, Giselle Maria
Format: Article
Language:English
Subjects:
Analysis of Variance
Composite Resins - chemistry
Composite Resins - radiation effects
Curing Lights, Dental
Dentistry
DENTISTRY, ORAL SURGERY & MEDICINE
Light
Materials Testing
Phase Transition
Polymerization
Random Allocation
Spectroscopy, Fourier Transform Infrared
Surface Properties
Time Factors
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Summary:The aim of this study was to evaluate the degree of conversion (DC) of two composite resins with different shades that were light cured by light-emitting diodes (LEDs) of different irradiances. Specimens (5 mm ' 2 mm) were prepared with a nanofilled (Filtek Supreme - A2E, A2D, and WE) or microhybrid resin (Opallis - A2E, A2D, and EBleach Low) and were randomly divided into 12 groups (n = 5 each) according to the composite resin and light-curing unit (Elipar FreeLight 2, 1250 mW/cm²; Ultralume 5, 850 mW/cm²). After 24 h, the DC was measured on two surfaces (top and bottom) with Fourier Transform infrared spectroscopy (FTIR). Data were statistically analyzed with two-way ANOVA and Tukey test (a = 0.05). Statistical differences among the surfaces were observed in all experimental conditions, with higher values on the top surface. The microhybrid resin presented the highest DCs for shades A2E and A2D on the top surface. The LED with higher irradiance promoted better DCs. Taken together, the data indicate that the shade of a composite resin and the irradiance of the light source affect the monomeric conversion of the restorative material.
ISSN:1807-3107
1807-3107
DOI:10.1590/s1806-83242012005000002