title: Resin-based luting agents and color stability of bonded ceramic veneers.
abstract: BACKGROUND
  The type of resin-based luting agent might influence the color stability of ceramic veneers.
  
  
  OBJECTIVE
  The purpose of this study was to investigate the effects of resin-based agents and aging on the color stability of ceramic veneers bonded to enamel.
  
  
  METHODS
  Ceramic disks were cemented to bovine enamel disks with 4 resin-based luting agents (n=10): dual-polymerizing cement (RelyX ARC), light-polymerizing cement (RelyX Veneer), flowable composite resin (Filtek Z350 Flow), or composite resin preheated for 30 minutes at 60°C (Filtek Z350 XT). CIE L*, a*, and b* color coordinates were measured 24 hours after cementation (baseline) with a color spectrophotometer and reevaluated after 10,000 and 20,000 thermal cycles. Color variation was calculated by using CIELab (ΔE*(ab)) and CIEDE2000 (ΔE00) methods. Then 95% confidence intervals were calculated for color variation means between baseline and 10,000 thermal cycles and between 10,000 and 20,000 thermal cycles. The 95% confidence intervals were also calculated for the means of individual color coordinates (L*, a*, and b*).
  
  
  RESULTS
  The dual-polymerizing cement had the highest color variation among all luting agents. No significant differences were found in color variation among the light-polymerizing materials. All agents showed ΔE*(ab)>3.46 and ΔE00>2.25 after 20,000 thermal cycles. Variations in L*, a*, and b* coordinates were material dependent. The dual-polymerizing agent was yellowish and reddish after aging.
  
  
  CONCLUSIONS
  The dual-polymerizing cement had higher color variation than the light-polymerized materials when used for bonding ceramic veneers to enamel. Flowable and preheated composite resins had similar color stability to that of light-polymerizing resin-based cement.
authors.affiliation: Graduate student, Graduate Program in Dentistry, Federal University of Pelotas, Pelotas, Brazil.
authors.forename: Júlia R
authors.initials: JR
authors.lastname: Almeida
authors.affiliation: Private practice, Pelotas, Brazil.
authors.forename: Gabriela U
authors.initials: GU
authors.lastname: Schmitt
authors.affiliation: Doctoral student, Graduate Program in Dentistry, Federal University of Pelotas, Pelotas, Brazil.
authors.forename: Marina R
authors.initials: MR
authors.lastname: Kaizer
authors.affiliation: Professor, Graduate Program in Dentistry, Federal University of Pelotas, Pelotas, Brazil.
authors.forename: Noéli
authors.initials: N
authors.lastname: Boscato
authors.affiliation: Professor, Graduate Program in Dentistry, Federal University of Pelotas, Pelotas, Brazil. Electronic address: moraesrr@gmail.com.
authors.forename: Rafael R
authors.initials: RR
authors.lastname: Moraes
mesh_terms: D000818:Animals; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002417:Cattle; D002516:Ceramics / Q000737:chemistry*; D003116:Color; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003743:Dental Enamel / Q000033:anatomy & histology; D003764:Dental Materials / Q000737:chemistry*; D003801:Dental Veneers; D055115:Light-Curing of Dental Adhesives / Q000295:instrumentation; D008422:Materials Testing; D011092:Polyethylene Glycols / Q000737:chemistry; D058105:Polymerization; D011109:Polymethacrylic Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry*; D055116:Self-Curing of Dental Resins / Q000295:instrumentation; D013053:Spectrophotometry / Q000295:instrumentation; D013997:Time Factors
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D011109:Polymethacrylic Acids; C462240:RelyX ARC; D019279:Resin Cements; C533204:filtek Z350; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate