title: Effect of light-curing methods on resin cement Knoop hardness at different depths.
abstract: This study evaluated, using Knoop hardness test, the polymerization depth of Rely-X dual-cured resin cement activated by chemical reaction alone (control group) or by chemical/physical mode with light curing through a 1.5-mm-thick ceramic layer (HeraCeram). Bovine incisors had their buccal surface flattened and hybridized. On this surface, a rubber mould (5 mm diameter; 1 mm high) was bulk filled with cement. Either a polyester strip or a 1.5-mm-thick disc of the veneering material was seated over this set. Light curing was performed with either conventional halogen light (QTH; XL2500) for 40 s, light-emitting diode (LED; Ultrablue Is) for 40 s or xenon plasma arc (PAC; Apollo 95E) for 3 s. In a control group, cement setting occurred by chemical reaction alone. After storage dry in dark (24 h/37 degrees C), the specimens (n=5) were sectioned for hardness (KHN) measurements at three depths in a microhardness tester (50 gf load/15 s). Data were submitted to ANOVA and Tukey's test (alpha = 0.05). Rely-X cement presented higher Knoop hardness values when the QTH and LED LCUs were used, compared to the control group and PAC. Light curing with PAC resulted in lower hardness compared to the control group. Cement hardness was significantly lower in deeper regions.
authors.affiliation: Dental Materials Area, Department of Restorative Dentistry, School of Dentistry of Piracicaba, State University of Campinas, Piracicaba, SP, Brazil. sinhoret@fop.unicamp.br
authors.forename: Mário Alexandre Coelho
authors.initials: MA
authors.lastname: Sinhoreti
authors.forename: Izabella Paola
authors.initials: IP
authors.lastname: Manetta
authors.forename: Rubens Nisie
authors.initials: RN
authors.lastname: Tango
authors.forename: Nelson Tetsu
authors.initials: NT
authors.lastname: Iriyama
authors.forename: Rafael Leonardo Xediek
authors.initials: RL
authors.lastname: Consani
authors.forename: Lourenço
authors.initials: L
authors.lastname: Correr-Sobrinho
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry; D000818:Animals; D002417:Cattle; D055117:Curing Lights, Dental; D003624:Darkness; D003776:Dental Porcelain / Q000737:chemistry; D006244:Hardness; D055115:Light-Curing of Dental Adhesives / Q000379:methods*; D008422:Materials Testing; D011108:Polymers / Q000737:chemistry / Q000528:radiation effects; D017680:Potassium Compounds / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry* / Q000528:radiation effects; D055116:Self-Curing of Dental Resins / Q000379:methods; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors
chemical_list: D000538:Aluminum Silicates; D011108:Polymers; D017680:Potassium Compounds; C528569:Rely-X; D019279:Resin Cements; D003776:Dental Porcelain; C016447:feldspar