Detecting silver-containing metal ceramic alloys that discolor porcelain.

R. D. Ringle, J. R. Mackert, C. W. Fairhurst

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Dental laboratories need an internal method to detect silver-containing metal ceramic alloys that stain porcelain. A fiberoptic colorimeter, calculations, and data describe Ag-vapor staining in standard CIE (1976) L*a*b* color space. The color difference value (CDV) of delta L*, delta a*, delta b*, and delta E* for porcelain before and after firing with Pd-Ag alloy, Au-Pt-Pd alloy, and control groups were calculated from L*, a*, and b* values. The CDV for all groups showed a more translucent (-delta L*) porcelain after the second firing. The CDV of porcelain disks exposed to Pd-Ag alloy showed an intense yellow (+ delta b*) stain with slight "greening" (-delta a*). The disks exposed to the Au-Pt-Pd group showed a slight yellow (-delta b*) stain. The delta b* values for the Pd-Ag group were significantly different from the other groups. This color shift (+ delta b) was clearly observed with the unaided eye.

Original languageEnglish (US)
Pages (from-to)563-568
Number of pages6
JournalThe International journal of prosthodontics
Issue number6
StatePublished - Nov 1 1989

ASJC Scopus subject areas

  • Oral Surgery


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