Please use this identifier to cite or link to this item:
metadata.dc.type: article
Title: Effect of light curing units post cured time and shade of resin cement on knoop hardness
Authors: Reges, Rogério Vieira
Costa, Ana Rosa
Correr, Américo Bortolazzo
Piva, Evandro
Rontani, Regina Maria Puppin
Sinhoreti, Mário Alexandre Coelho
Correr Sobrinho, Lourenço
Abstract: The aim of this study was to evaluate the Knoop hardness after 15 min and 24 h of different shades of a dual-cured resin-based cement after indirect photoactivation (ceramic restoration) with 2 light-curing units (LCUs). The resin cement Variolink II (Ivoclar Vivadent) shade XL, A2, A3 and opaque were mixed with the catalyst paste and inserted into a black Teflon mold (5 mm diameter x 1 mm high). A transparent strip was placed over the mold and a ceramic disc (Duceram Plus, shade A3) was positioned over the resin cement. Light-activation was performed through the ceramic for 40 s using quartz-tungsten-halogen (QTH) (XL 2500; 3M ESPE) or light-emitting diode (LED) (Ultrablue Is, DMC) LCUs with power density of 615 and 610 mW/cm2, respectively. The Koop hardness was measured using a microhardness tester HMV 2 (Shimadzu) after 15 min or 24 h. Four indentations were made in each specimen. Data were subjected to ANOVA and Tukey’s test (a=0.05). The QTH LCU provided significantly higher (p<0.05) KHN values than the LED LCU. When the post-cure times were compared for the same shade, QTH and LED at 24 h provided significantly higher(p<0.05) KHN values than at 15 min. It may be concluded that the Knoop hardness was generally dependent on the LCU and post-cure time. The opaque shade of the resin cement showed lower Knoop hardness than the other shades for both LCUs and post-cure times.
Keywords: Knoop hardness
Dental ceramic
Resin cement
Light-curing unit
Publisher: Dental Foundation of Ribeirão Preto
Citation: REGES, R. V. ; COSTA, A. R. ; CORRER, Américo Bortolazzo ;PIVA, Evandro ; CORRER, A.B. ;RONTANI, R. M.P. ; SINHORETI, Mário Alexandre Coelho ; CORRER-SOBRINHO, L. . Effect of light curing units, postcured time and shade of resin cement on knoop hardness. Brazilian Dental Journal (Impresso), v. 20, p. 410-413, 2009.
Issue Date: 2009
Appears in Collections:Departamento de Odontologia Restauradora: Artigos de periódicos

Files in This Item:
File Description SizeFormat 
Effect of light-curing units, post-cured time and shade of resin cement on knoop hardness.pdf227,95 kBAdobe PDFThumbnail

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.