title: [Infinite optical thickness of dentine porcelain of IPS E.max A color series].
abstract: OBJECTIVE
  To determine the infinite optical thickness of dentine porcelain of IPS E.max A color series.
  
  
  METHODS
  Cylindrical dentine porcelain specimens of the IPS E.max A color series were prepared with a diameter of 13 mm and thickness of 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, and 5.0 mm. The chromatic value of all the specimens was determined with CM-5 spectrometer against standard black and white background. The chromatic aberration (deltaE) was calculated by regression equation.
  
  
  RESULTS
  The infinite optical thickness of dentine porcelain of the IPS E.max A color series ranged from 2.341 to 3.333 mm for a deltaE of 1.0, and from 2.064 to 2.904 mm for a deltaE of 1.5. As the chromaticity or thickness increased, the influence by the background color decreased, and the color of specimens became gradually close to the intrinsic color.
  
  
  CONCLUSIONS
  The thickness of the background dentine porcelain specimens must exceed its infinite optical thickness to represent the intrinsic color and avoid the influence by the extrinsic color.
authors.affiliation: Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China. sun_ting1985@hotmail.com
authors.forename: Ting
authors.initials: T
authors.lastname: Sun
authors.forename: Long-quan
authors.initials: LQ
authors.lastname: Shao
authors.forename: Yuan-fu
authors.initials: YF
authors.lastname: Yi
authors.forename: Bin
authors.initials: B
authors.lastname: Deng
authors.forename: Ning
authors.initials: N
authors.lastname: Wen
authors.forename: Wei-wei
authors.initials: WW
authors.lastname: Zhang
mesh_terms: D020099:Coated Materials, Biocompatible / Q000737:chemistry; D003442:Crowns; D003776:Dental Porcelain / Q000737:chemistry*; D017267:Dental Prosthesis Design; D006801:Humans; D017797:Prosthesis Coloring; D019231:Tooth Preparation, Prosthodontic / Q000379:methods*
chemical_list: D020099:Coated Materials, Biocompatible; C508050:IPS e.max Press; D003776:Dental Porcelain