title: Effect of thermal cycling and disinfection on colour stability of denture base acrylic resin.
abstract: OBJECTIVE
  The purpose of this study was to investigate the effect of thermal cycling and disinfection on the colour change of denture base acrylic resin.
  
  
  METHODS
  Four different brands of acrylic resins were evaluated (Onda Cryl, QC 20, Classico and Lucitone). All brands were divided into four groups (n = 7) determined according to the disinfection procedure (microwave, Efferdent, 4% chlorhexidine or 1% hypochlorite). The treatments were conducted three times a week for 60 days. All specimens were thermal cycled between 5 and 55°C with 30-s dwell times for 1000 cycles before and after disinfection. The specimens' colour was measured with a spectrophotometer using the CIE L*a*b* system. The evaluations were conducted at baseline (B), after first thermal cycling (T1 ), after disinfection (D) and after second thermal cycling (T2 ). Colour differences (ΔE) were calculated between T1 and B (T1 B), D and B (DB), and T2 and B (T2 B) time-points.
  
  
  RESULTS
  The samples submitted to disinfection by microwave and Efferdent exhibited the highest values of colour change. There were significant differences on colour change between the time-points, except for the Lucitone acrylic resin.
  
  
  CONCLUSIONS
  The thermal cycling and disinfection procedures significantly affected the colour stability of the samples. However, all values obtained for the acrylic resins are within acceptable clinical parameters.
authors.affiliation: Department of Dental Materials and Prosthodontics, Faculty of Dentistry of Araçatuba, UNESP - Univ Estadual Paulista, Araçatuba, São Paulo, Brazil.
authors.forename: Marcelo C
authors.initials: MC
authors.lastname: Goiato
authors.forename: Daniela M
authors.initials: DM
authors.lastname: Dos Santos
authors.forename: Gabriella T
authors.initials: GT
authors.lastname: Baptista
authors.forename: Amália
authors.initials: A
authors.lastname: Moreno
authors.forename: Agda M
authors.initials: AM
authors.lastname: Andreotti
authors.forename: Lisiane C
authors.initials: LC
authors.lastname: Bannwart
authors.forename: Stefan F C
authors.initials: SF
authors.lastname: Dekon
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D000891:Anti-Infective Agents, Local / Q000737:chemistry; D002710:Chlorhexidine / Q000737:chemistry; D003116:Color; D019551:Dental Disinfectants / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry*; D003819:Denture Bases; D003820:Denture Cleansers / Q000737:chemistry; D004203:Disinfection / Q000379:methods*; D006801:Humans; D006997:Hypochlorous Acid / Q000737:chemistry; D008422:Materials Testing; D008872:Microwaves / Q000627:therapeutic use; D016877:Oxidants / Q000737:chemistry; D013053:Spectrophotometry / Q000295:instrumentation; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors
chemical_list: D000180:Acrylic Resins; D000891:Anti-Infective Agents, Local; D019551:Dental Disinfectants; D003764:Dental Materials; D003820:Denture Cleansers; D016877:Oxidants; C488492:QC 20 (denture base resin); C539103:onda cryl; C040291:Lucitone; D006997:Hypochlorous Acid; D002710:Chlorhexidine