title: Delayed Light Activation Improves Color Stability of Dual-Cured Resin Cements.
abstract: OBJECTIVE
  To evaluate the color change caused by post-irradiation conversion (ΔE24hand ΔE8 days) and artificial aging (ΔEAGING) of resin cements light activated through ceramics of different opacities immediately and 6 minutes after manipulating the material.
  
  
  METHODS
  Resin cement disks (Allcem and LuxaCore) were light activated through ceramics (without ceramic, e.max HT, LT, and MO) immediately and 6 minutes after the manipulation (n = 10). Spectrophotometry was used to evaluate ΔE24hand ΔE8 daysafter 37˚C-dry-dark-storage for 24 hours and 8 days, and ΔEAGINGafter 60˚C-water-storage for 24 hours. Data were analyzed with three-way ANOVA and Tukey's HSD (α = 0.05).
  
  
  RESULTS
  Regarding the post-irradiation color change, significant differences were found between the cements (p < 0.0001), light activation protocols (p = 0.037), and ceramics (p < 0.001). The immediate activation (16.2 ± 0.1) showed lower ΔE values than the delayed activation (16.5 ± 0.1). Ceramics influenced the ΔE values as follows: MO (14.0 ± 1.2) < LT (14.9 ± 1.2) ≈ HT (15.4 ± 1.2) < control (21.2 ± 1.2). Regarding ΔEAGING, significant differences were found between cements (p < 0.001), light activation (p = 0.006), and ceramics (p < 0.001). The delayed activation (8.4 ± 0.1) showed lower values than the immediate activation (8.9 ± 0.1). Ceramic spacers influenced ΔEAGINGas follows: control (5.6 ± 0.2) < MO (6.6 ± 0.2) < HT (11.0 ± 0.2) ≈ LT (11.5 ± 0.2).
  
  
  CONCLUSIONS
  The delayed light activation resulted in increased color stability, while the ceramic interposition resulted in lower color stability.
authors.affiliation: Department of Operative Dentistry, Endodontics and Dental Materials Bauru School of Dentistry, Bauru, Brazil.
authors.forename: Adilson Y
authors.initials: AY
authors.lastname: Furuse
authors.affiliation: Graduate Program in Dentistry, Universidade Positivo, Curitiba, Brazil.
authors.forename: Lino Oliveira Carvalho
authors.initials: LOC
authors.lastname: Santana
authors.affiliation: Department of Operative Dentistry, Endodontics and Dental Materials Bauru School of Dentistry, Bauru, Brazil.
authors.forename: Fabio Antonio Piola
authors.initials: FAP
authors.lastname: Rizzante
authors.affiliation: Universidade de Sao Paulo Faculdade de Odontologia de Bauru, Bauru, Brazil.
authors.forename: Sérgio Kiyoshi
authors.initials: SK
authors.lastname: Ishikiriama
authors.affiliation: Universidade de Sao Paulo Faculdade de Odontologia de Bauru, Bauru, Brazil.
authors.forename: Juliana Fraga
authors.initials: JF
authors.lastname: Bombonatti
authors.affiliation: Positivo University, Curitiba, Brazil.
authors.forename: Gisele Maria
authors.initials: GM
authors.lastname: Correr
authors.affiliation: Positivo University, Curitiba, Brazil.
authors.forename: Carla Castiglia
authors.initials: CC
authors.lastname: Gonzaga
mesh_terms: D000537:Aluminum Oxide; D003116:Color; D003188:Composite Resins; D003776:Dental Porcelain; D055115:Light-Curing of Dental Adhesives; D008422:Materials Testing; D019279:Resin Cements / Q000528:radiation effects*; D013053:Spectrophotometry; D013499:Surface Properties
chemical_list: C105314:AllCeram; D003188:Composite Resins; C483522:LuxaCore; D019279:Resin Cements; D003776:Dental Porcelain; D000537:Aluminum Oxide
keywords: Resin-based cements; ceramics; color change; delayed light curing