title: Influence of particle size distribution of dental opacifier on the color of titanium opaque porcelain.
abstract: OBJECTIVE
  To investigate the effect of particle size distribution of opacifier tin dioxides (SnO(2)) on the color of dental opaque porcelain for pure titanium by spectrophotometer.
  
  
  METHODS
  Sixteen groups of opaque porcelain powders were prepared by combining four grain size SnO(2) with four pigments (no pigment, yellow, coral pink and grey). Five porcelain discs (13 mm diameter and 2mm thickness) for each powder were fired. K/S ratios and L*a*b* values of specimens were obtained by a spectrophotometer. The maximum color differences (ΔE(max)) caused by grain size of SnO(2) in each pigment group were determined using the CIELAB and the CIEDE2000 formulas. The L*a*b* values in each pigment group were compared by MANOVA and the ΔE(max) of different pigment groups were subjected to one way ANOVA.
  
  
  RESULTS
  With SnO(2) grain size increasing, the L* values decreased, and both a* and b* became more chromatic consistently in each pigment group (p<0.001). The ΔE(max) in all pigmented groups were above the 50:50% perceptibility thresholds, with ΔE(max) in yellow group greater than the acceptability thresholds. Significant difference was found in the ΔE(max) of four pigment groups regardless of the color formula (p<0.001).
  
  
  CONCLUSIONS
  15 wt% SnO(2) with median particle size ranging from 0.85 μm to 20.75 μm caused significantly perceptible color differences in the pigmented titanium opaque porcelains used in this study.
authors.affiliation: Department of Prosthodontics, School of Stomatology, Fourth Military Medical University, Xi'an, China.
authors.forename: XingXing
authors.initials: X
authors.lastname: Li
authors.forename: Pei
authors.initials: P
authors.lastname: Zhang
authors.forename: JianFeng
authors.initials: J
authors.lastname: Yang
authors.forename: TianWen
authors.initials: T
authors.lastname: Guo
mesh_terms: D003116:Color; D003124:Colorimetry; D003776:Dental Porcelain; D008027:Light; D008422:Materials Testing; D016876:Metal Ceramic Alloys; D010316:Particle Size; D017797:Prosthesis Coloring; D013053:Spectrophotometry; D017971:Tin Compounds; D014025:Titanium
chemical_list: D016876:Metal Ceramic Alloys; D017971:Tin Compounds; D003776:Dental Porcelain; D014025:Titanium; C045358:stannic oxide