title: Effect of thickness of indirect restoration and distance from the light-curing unit tip on the hardness of a dual-cured resin cement.
abstract: This study evaluated the Knoop hardness and polymerization depth of a dual-cured resin cement, light-activated at different distances through different thicknesses of composite resin. One bovine incisor was embedded in resin and its buccal surface was flattened. Dentin was covered with PVC film where a mold (0.8-mm-thick and 5 mm diameter) was filled with cement and covered with another PVC film. Light curing (40 s) was carried out through resin discs (2, 3, 4 or 5 mm) with a halogen light positioned 0, 1, 2 or 3 mm from the resin surface. After storage, specimens were sectioned for hardness measurements (top, center, and bottom). Data were subjected to split-plot ANOVA and Tukey's test (alpha=0.05). The increase in resin disc thickness decreased cement hardness. The increase in the distance of the light-curing tip decreased hardness at the top region. Specimens showed the lowest hardness values at the bottom, and the highest at the center. Resin cement hardness was influenced by the thickness of the indirect restoration and by the distance between the light-curing unit tip and the resin cement surface.
authors.affiliation: Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil.
authors.forename: Andréia Bolzan
authors.initials: AB
authors.lastname: de Paula
authors.forename: Rubens Nisie
authors.initials: RN
authors.lastname: Tango
authors.forename: Mário Alexandre Coelho
authors.initials: MA
authors.lastname: Sinhoreti
authors.forename: Marcelo Corrêa
authors.initials: MC
authors.lastname: Alves
authors.forename: Regina M
authors.initials: RM
authors.lastname: Puppin-Rontani
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002417:Cattle; D003188:Composite Resins / Q000737:chemistry*; D055117:Curing Lights, Dental; D003738:Dental Cements / Q000737:chemistry*; D003743:Dental Enamel / Q000737:chemistry / Q000187:drug effects; D003793:Dental Restoration, Permanent / Q000379:methods*; D006244:Hardness; D055115:Light-Curing of Dental Adhesives / Q000379:methods*; D019279:Resin Cements / Q000737:chemistry*; D018709:Statistics, Nonparametric
chemical_list: D003188:Composite Resins; D003738:Dental Cements; C444701:Filtek Z250; D019279:Resin Cements