title: Effect of light-curing method and cement activation mode on resin cement knoop hardness.
abstract: OBJECTIVE
  To evaluate the Knoop hardness (KHN) of the resin cement Enforce activated by chemical/physical mode or physical mode solely; light-cured directly or through a 1.5 mm thick ceramic disc (HeraCeram) on shade DD2.
  
  
  METHODS
  Light-curing was carried out using a conventional quartz tungsten halogen light (QTH) (XL2500) for 40 seconds at 700 mW/cm(2); light-emitting diodes (LED) (Ultrablue Is) for 40 seconds at 440 mW/cm(2); and Xenon plasma arc (PAC) (Apollo 95E) for 3 seconds at 1600 mW/cm(2). Bovine incisors had their buccal faces flattened and hybridized. A mold was seated on these surfaces and filled with cement. A disc of the acid-etched and silanized veneering material was seated over this set for light-curing. After dry storage (24 hours at 37 degrees C), specimens (n= 10) were sectioned for KHN measurements performed in a microhardness tester (50 gf load for 15 seconds). Data were submitted to ANOVA and Tukey's test (alpha= 0.05).
  
  
  RESULTS
  The highest KHN values were obtained with LED, for both dual-cured and light-cured cement. The lowest KHN value was obtained with light-cured PAC. Light-curing with QTH resulted in hardness values similar to PAC in dual-cured groups.
  
  
  CONCLUSIONS
  Light-curing through HeraCeram can influence resin cement hardness.
authors.affiliation: Department of Restorative Dentistry, Piracicaba Dental School-UNICAMP, Sao Paulo, Brazil.
authors.forename: Rubens Nisie
authors.initials: RN
authors.lastname: Tango
authors.forename: Mário Alexandre Coelho
authors.initials: MA
authors.lastname: Sinhoreti
authors.forename: Américo Bortolazzo
authors.initials: AB
authors.lastname: Correr
authors.forename: Lourenço
authors.initials: L
authors.lastname: Correr-Sobrinho
authors.forename: Guilherme Elias Peçanha
authors.initials: GE
authors.lastname: Henriques
mesh_terms: D000096:Acetone / Q000737:chemistry; D000134:Acid Etching, Dental; D000818:Animals; D002417:Cattle; D002516:Ceramics / Q000737:chemistry; D001840:Dental Bonding; D003764:Dental Materials / Q000737:chemistry* / Q000528:radiation effects; D003776:Dental Porcelain / Q000737:chemistry; D003801:Dental Veneers; D003804:Dentin / Q000648:ultrastructure; D006244:Hardness; D008029:Lighting / Q000295:instrumentation*; D008422:Materials Testing; D011109:Polymethacrylic Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry* / Q000528:radiation effects; D012821:Silanes / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors
chemical_list: D003764:Dental Materials; C103503:EnForce-Sure Cure; D011109:Polymethacrylic Acids; D019279:Resin Cements; D012821:Silanes; C444444:prime and bond 2.1; D003776:Dental Porcelain; D000096:Acetone