title: Influence of energy density of different light sources on Knoop hardness of a dual-cured resin cement.
abstract: The purpose of this study was to evaluate the Knoop hardness of a dual-cured resin-based luting cement irradiated with different light sources as well energy density through a ceramic sample. Three light-curing unit (LCUs) were tested: tungsten halogen light (HAL), light-emitting diode (LED) and xenon plasma-arc (PAC) lamp. Disc-shaped specimens were fabricated from a resin-based cement (Enforce). Three energy doses were used by modifying the irradiance (I) of each LCU and the irradiation time (T): 24 Jcm(-2) (I/2x2T), 24 Jcm(-2) (IxT) and 48 Jcm(-2) (Ix2T). Energy doses were applied through a 2.0-mm-thick ceramic sample (Duceram Plus). Three groups underwent direct irradiation over the resin cement with the different LCUs and a chemically-activated group served as a control. Thirteen groups were tested (n=10). Knoop hardness number (KHN) means were obtained from cross-sectional areas. Two-way ANOVA and the Holm-Sidak method were used for statistical comparisons of activation mode and energy doses (alpha=5%). Application of 48 J.cm(-2) energy dose through the ceramic using LED (50.5+/-2.8) and HAL (50.9+/-3.7) produced significantly higher KHN means (p<0.05) than the control (44.7+/-3.8). LED showed statistically similar performance to HAL. Only HAL showed a relationship between the increase of LCU energy dose and hardness increase.
authors.affiliation: Department of Restorative Dentistry, Dental School, Federal University of Pelotas, Pelotas, RS, Brazil. piva@ufpel.edu.br
authors.forename: Evandro
authors.initials: E
authors.lastname: Piva
authors.forename: Lourenço
authors.initials: L
authors.lastname: Correr-Sobrinho
authors.forename: Mario Alexandre Coelho
authors.initials: MA
authors.lastname: Sinhoreti
authors.forename: Simonides
authors.initials: S
authors.lastname: Consani
authors.forename: Flávio Fernando
authors.initials: FF
authors.lastname: Demarco
authors.forename: John Michael
authors.initials: JM
authors.lastname: Powers
mesh_terms: D055117:Curing Lights, Dental; D003776:Dental Porcelain; D006219:Halogens; D006244:Hardness; D008422:Materials Testing; D019279:Resin Cements / Q000737:chemistry* / Q000528:radiation effects*; D055116:Self-Curing of Dental Resins; D012666:Semiconductors; D014978:Xenon
chemical_list: D006219:Halogens; D019279:Resin Cements; D003776:Dental Porcelain; D014978:Xenon