title: Detecting silver-containing metal ceramic alloys that discolor porcelain.
abstract: 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.
authors.forename: R D
authors.initials: RD
authors.lastname: Ringle
authors.forename: J R
authors.initials: JR
authors.lastname: Mackert
authors.forename: C W
authors.initials: CW
authors.lastname: Fairhurst
mesh_terms: D003124:Colorimetry; D003722:Dental Alloys / Q000009:adverse effects*; D003776:Dental Porcelain; D012834:Silver / Q000009:adverse effects / Q000032:analysis*
chemical_list: D003722:Dental Alloys; D003776:Dental Porcelain; D012834:Silver