title: The effect of repeated firings on the color change and surface roughness of dental ceramics.
abstract: OBJECTIVE
  The color of the ceramic restorations is affected by various factors such as brand, thickness of the layered the ceramic, condensation techniques, smoothness of surface, number of firings, firing temperature and thickness of dentin. The aim of this study was to evaluate the color change and surface roughness in dental porcelain with different thicknesses during repeated firings.
  
  
  METHODS
  Disc-shaped (N=21) metal-ceramic samples (IPS Classic; Ivoclar Vivadent; Shaar, Liechtenstein) with different thickness were exposed to repeated firings. Color measurement of the samples was made using a colorimeter and profilometer was used to determine surface roughness. ANOVA and Tukey tests with repeated measurements were used for statistical analysis.
  
  
  RESULTS
  The total thickness of the ceramics which is less than 2 mm significantly have detrimental effect on the surface properties and color of porcelains during firings (P<.05).
  
  
  CONCLUSIONS
  Repeated firings have effects on the color change and surface roughness of the dental ceramics and should be avoided.
authors.affiliation: Department of Prosthodontics, Faculty of Dentistry, Ankara University, Ankara, Turkey.
authors.forename: Fehmi
authors.initials: F
authors.lastname: Gonuldas
authors.affiliation: Dental Clinic, Antalya, Turkey.
authors.forename: Kerem
authors.initials: K
authors.lastname: Yılmaz
authors.affiliation: Department of Prosthodontics, Faculty of Dentistry, Ankara University, Ankara, Turkey.
authors.forename: Caner
authors.initials: C
authors.lastname: Ozturk
keywords: Color change; Dental ceramics; Repeated firings; Surface roughness