title: Discoloration of various CAD/CAM blocks after immersion in coffee.
abstract: OBJECTIVE
  This study evaluated color differences (ΔEs) and translucency parameter changes (ΔTPs) of various computer-aided design/computer-aided manufacturing (CAD/CAM) blocks after immersion in coffee.
  
  
  METHODS
  Eight CAD/CAM blocks and four restorative composite resins were evaluated. The CIEL*a*b*values of 2.0 mm thick disk-shaped specimens were measured using the spectrophotometer on white and black backgrounds (n= 6). The ΔEs and ΔTPs of one day, one week, and one month immersion in coffee or water were calculated. The values of each material were analyzed by two-way ANOVA and Tukey's multiple comparisons (α = 0.05). The ΔEs after prophylaxis paste polishing of 1 month coffee immersion specimens, water sorption and solubility were also evaluated.
  
  
  RESULTS
  After one month in coffee, ΔEs of CAD/CAM composite resin blocks and restorative composites ranged from 1.6 to 3.7 and from 2.1 to 7.9, respectively, and ΔTPs decreased. The ANOVA of ΔEs and ΔTPs revealed significant differences in two main factors, immersion periods and media, and their interaction except for ΔEs of TEL (Telio CAD, Ivoclar Vivadent). The ΔEs significantly decreased after prophylaxis polishing except GRA (Gradia Block, GC). There was no significant correlation between ΔEs and water sorption or solubility in water.
  
  
  CONCLUSIONS
  The ΔEs of CAD/CAM blocks after immersion in coffee varied among products and were comparable to those of restorative composite resins. The discoloration of CAD/CAM composite resin blocks could be effectively removed with prophylaxis paste polishing, while that of some restorative composites could not be removed.
authors.affiliation: Department of Prosthodontics, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Sasipin
authors.initials: S
authors.lastname: Lauvahutanon
authors.affiliation: Department of Removable Partial Prosthodontics, Division of Oral Health Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.
authors.forename: Maho
authors.initials: M
authors.lastname: Shiozawa
authors.affiliation: Department of Oral Biomaterials Engineering, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Takahashi
authors.affiliation: Department of Oral Biomaterials Engineering, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.
authors.forename: Naohiko
authors.initials: N
authors.lastname: Iwasaki
authors.affiliation: Department of Basic Oral Health Engineering, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.
authors.forename: Meiko
authors.initials: M
authors.lastname: Oki
authors.affiliation: Liaison Center for Innovative Dentistry, Tohoku University Graduate School of Dentistry, Miyagi, Japan.
authors.forename: Werner J
authors.initials: WJ
authors.lastname: Finger
authors.affiliation: Department of Prosthodontics, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Mansuang
authors.initials: M
authors.lastname: Arksornnukit
keywords: CAD/CAM block; Discoloration; Translucency parameter; Water solubility; Water sorption