title: Effect of the amount of thickness reduction on color and translucency of dental monolithic zirconia ceramics.
abstract: OBJECTIVE
  This study investigated the effect of amount of thickness reduction on color and translucency of dental monolithic zirconia ceramics.
  
  
  METHODS
  One-hundred sixty-five monolithic zirconia specimens (16.3 mm × 16.3 mm × 2.0 mm) were divided into 5 groups (Group I to V) according to the number of A2-coloring liquid applications. Each group was then divided into 11 subgroups by reducing the thickness up to 1.0 mm in 0.1-mm increments (Subgroup 0 to 10, n=3). Colors and spectral distributions were measured according to CIELAB on a reflection spectrophotometer. All measurements were performed on five different areas of each specimen. Color difference (ΔE(*) ab) and translucency parameter (TP) were calculated. Data were analyzed using one-way ANOVA and multiple comparison Scheffé test (α=.05).
  
  
  RESULTS
  There were significant differences in CIE L(*) between Subgroup 0 and other subgroups in all groups. CIE a(*) increased (0.52<R(2)<0.73), while CIE b(*) decreased (0.00<R(2)<0.74) in all groups with increasing thickness reduction. Perceptible color differences (ΔE(*) ab>3.7) were obtained between Subgroup 0 and other subgroups. TP values generally increased as the thickness reduction increased in all groups (R(2)>0.89, P<.001).
  
  
  CONCLUSIONS
  Increasing thickness reduction reduces lightness and increases a reddish, bluish appearance, and translucency of monolithic zirconia ceramics.
authors.affiliation: Comprehensive Treatment Center, Seoul National University Dental Hospital, Seoul, Republic of Korea.
authors.forename: Hee-Kyung
authors.identifier: 0000-0002-9079-6086
authors.initials: HK
authors.lastname: Kim
authors.affiliation: Department of Prosthodontics and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea.
authors.forename: Sung-Hun
authors.identifier: 0000-0003-3289-9703
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Department of Prosthodontics and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea.
authors.forename: Jai-Bong
authors.initials: JB
authors.lastname: Lee
authors.affiliation: Department of Prosthodontics and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea.
authors.forename: Jung-Suk
authors.identifier: 0000-0002-9439-1465
authors.initials: JS
authors.lastname: Han
authors.affiliation: Department of Prosthodontics and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea.
authors.forename: In-Sung
authors.identifier: 0000-0002-6780-2601
authors.initials: IS
authors.lastname: Yeo
authors.affiliation: Department of Dentistry, Ajou University School of Medicine, Suwon, Republic of Korea.
authors.forename: Seung-Ryong
authors.identifier: 0000-0003-4176-6865
authors.initials: SR
authors.lastname: Ha
keywords: Color; Dental Prosthesis Coloring; Y-TZP ceramic