Gritsch K, Souvannasot S, Schembri C, Farge P, Grosgogeat B. Influence of light energy
and power density on the microhardness of two nanohybrid composites. Eur J Oral Sci
2008; 116: 77–82. 2008 The Authors. Journal compilation 2008 Eur J Oral Sci
Kerstin Gritsch1, Sourasith Souvannasot1,2, Catherine Schembri1, Pierre Farge3,4, Brigitte
Grosgogeat1,4 1Laboratoire des Multimatriaux et Interfaces, UMR CNRS 5615, Universit de Lyon, Universit Claude Bernard Lyon1, Facult dOdontologie, Lyon Cedex; 2Laboratoire des Matriaux Polymres et des Biomatriaux, UMR CNRS 5223, Universit de Lyon, Universit Claude Bernard Lyon1, Villeurbanne Cedex; 3Dpartement de Formation et Centre de Recherche en Biologie Humaine, Universit de Lyon, Universit Claude Bernard Lyon I, Lyon Cedex; 4Hospices Civils de Lyon, SCTD, Lyon Cedex, France
The purpose of this study was to investigate the role of light parameters on nanohybrid
composite curing. Two nanohybrid resins were cured by two light-emitting diode
(LED) devices and by one quartz-tungsten-halogen (QTH) device using different
combinations of energy density and power density (8 J cm)2 and 400 mW cm)2;
8 J cm)2 and 1,000 mW cm)2; 16 J cm)2 and 400 mW cm)2; and 16 J cm)2–
1,000 mW cm)2). The effects of these combinations on polymerization were assessed
by measuring the Vickers microhardness. Data differed for the two composites and
varied according to the light parameters and the nature of the curing device. For both
resins, an energy density of 16 J cm)2 yielded the best microhardness values at both
the top and the bottom of the sample, independently of the power density. When using
a lower energy density of 8 J cm)2, a modulated power density was required to achieve
proper curing at the bottom of the sample: 8 J cm)2 and 400 mW cm)2 induced
greater values at the bottom surface. At an energy density of 16 J cm)2, the power
density was not relevant (no significant differences were found between 400 and
1,000 mW cm)2), except when the emission spectra of the light-curing units (LCUs)
did not match exactly with the absorption spectra of the photoinitators included in the
resins (greatest values with 16 J cm)2 and1,000 mW cm)2). These results suggest that
above a certain energy density threshold, the power density may not significantly
influence the polymerization kinetics.
Grosgogeat1,4 1Laboratoire des Multimatriaux et Interfaces, UMR CNRS 5615, Universit de Lyon, Universit Claude Bernard Lyon1, Facult dOdontologie, Lyon Cedex; 2Laboratoire des Matriaux Polymres et des Biomatriaux, UMR CNRS 5223, Universit de Lyon, Universit Claude Bernard Lyon1, Villeurbanne Cedex; 3Dpartement de Formation et Centre de Recherche en Biologie Humaine, Universit de Lyon, Universit Claude Bernard Lyon I, Lyon Cedex; 4Hospices Civils de Lyon, SCTD, Lyon Cedex, France
The purpose of this study was to investigate the role of light parameters on nanohybrid
composite curing. Two nanohybrid resins were cured by two light-emitting diode
(LED) devices and by one quartz-tungsten-halogen (QTH) device using different
combinations of energy density and power density (8 J cm)2 and 400 mW cm)2;
8 J cm)2 and 1,000 mW cm)2; 16 J cm)2 and 400 mW cm)2; and 16 J cm)2–
1,000 mW cm)2). The effects of these combinations on polymerization were assessed
by measuring the Vickers microhardness. Data differed for the two composites and
varied according to the light parameters and the nature of the curing device. For both
resins, an energy density of 16 J cm)2 yielded the best microhardness values at both
the top and the bottom of the sample, independently of the power density. When using
a lower energy density of 8 J cm)2, a modulated power density was required to achieve
proper curing at the bottom of the sample: 8 J cm)2 and 400 mW cm)2 induced
greater values at the bottom surface. At an energy density of 16 J cm)2, the power
density was not relevant (no significant differences were found between 400 and
1,000 mW cm)2), except when the emission spectra of the light-curing units (LCUs)
did not match exactly with the absorption spectra of the photoinitators included in the
resins (greatest values with 16 J cm)2 and1,000 mW cm)2). These results suggest that
above a certain energy density threshold, the power density may not significantly
influence the polymerization kinetics.
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