title: Translucency of dental ceramics with different thicknesses.
abstract: BACKGROUND
  The increased use of esthetic restorations requires an improved understanding of the translucent characteristics of ceramic materials. Ceramic translucency has been considered to be dependent on composition and thickness, but less information is available about the translucent characteristics of these materials, especially at different thicknesses.
  
  
  OBJECTIVE
  The purpose of this study was to investigate the relationship between translucency and the thickness of different dental ceramics.
  
  
  METHODS
  Six disk-shaped specimens of 8 glass ceramics (IPS e.max Press HO, MO, LT, HT, IPS e.max CAD LT, MO, AvanteZ Dentin, and Trans) and 5 specimens of 5 zirconia ceramics (Cercon Base, Zenotec Zr Bridge, Lava Standard, Lava Standard FS3, and Lava Plus High Translucency) were prepared following the manufacturers' instructions and ground to a predetermined thickness with a grinding machine. A spectrophotometer was used to measure the translucency parameters (TP) of the glass ceramics, which ranged from 2.0 to 0.6 mm, and of the zirconia ceramics, which ranged from 1.0 to 0.4 mm. The relationship between the thickness and TP of each material was evaluated using a regression analysis (α=.05).
  
  
  RESULTS
  The TP values of the glass ceramics ranged from 2.2 to 25.3 and the zirconia ceramics from 5.5 to 15.1. There was an increase in the TP with a decrease in thickness, but the amount of change was material dependent. An exponential relationship with statistical significance (P<.05) between the TP and thickness was found for both glass ceramics and zirconia ceramics.
  
  
  CONCLUSIONS
  The translucency of dental ceramics was significantly influenced by both material and thickness. The translucency of all materials increased exponentially as the thickness decreased. All of the zirconia ceramics evaluated in the present study showed some degree of translucency, which was less sensitive to thickness compared to that of the glass ceramics.
authors.affiliation: Department of Prosthodontics, School of Stomatology, Fourth Military Medical University, Xi'an, China.
authors.forename: Fu
authors.initials: F
authors.lastname: Wang
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Takahashi
authors.forename: Naohiko
authors.initials: N
authors.lastname: Iwasaki
mesh_terms: D002516:Ceramics / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry; D003776:Dental Porcelain / Q000737:chemistry*; D006801:Humans; D008027:Light; D008422:Materials Testing; D013053:Spectrophotometry; D013499:Surface Properties; D015040:Zirconium / Q000737:chemistry
chemical_list: D003764:Dental Materials; C520133:IPS e.max CAD LT; C508050:IPS e.max Press; C493120:lithia disilicate; D003776:Dental Porcelain; C023506:Glass ceramics; D015040:Zirconium; C028541:zirconium oxide