title: Development of casting investment preventing blackening of noble metal alloys Part 2. Application of developed investment for type 4 gold alloy.
abstract: The objective of this study was to evaluate the efficacy of the developed investment for the prevention of blackening of a cast Type 4 gold and to analyze the oxides on its surface in relation to the blackening of the alloy. The experimental investments were prepared using a gypsum-bonded investment in which boron (B) or aluminum (Al) was added as a reducing agent. A Type 4 gold alloy was cast into the mold made of the prepared investment. The effect of the additives was evaluated from the color difference (deltaE*) between the as-cast surface and the polished surface of the cast specimen. B and Al were effective to prevent the blackening of a Type 4 gold alloy and the color of the as-cast surface approached that of the polished surface with increasing B and Al content. The prevention of the blackening of the gold alloy can be achieved by restraining the formation of CuO.
authors: Department of Dental Materials Science, School of Dentistry at Niigata, The Nippon Dental University 1-8 Hamaura-cho, Niigata City, Niigata, 951-8580, Japan.
authors: Akira
authors: A
authors: Nakai
authors: Kiyoshi
authors: K
authors: Kakuta
authors: Shin-ichi
authors: S
authors: Goto
authors: Katuma
authors: K
authors: Kato
authors: Atushi
authors: A
authors: Yara
authors: Hideo
authors: H
authors: Ogura
mesh_terms: D000535:Aluminum / Q000737:chemistry; D000704:Analysis of Variance; D001895:Boron / Q000737:chemistry; D002133:Calcium Sulfate / Q000737:chemistry; D003116:Color; D003300:Copper / Q000737:chemistry; D003734:Dental Casting Investment / Q000737:chemistry*; D003775:Dental Polishing; D004577:Electron Probe Microanalysis; D006047:Gold Alloys / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D010087:Oxides / Q000737:chemistry; D019163:Reducing Agents / Q000737:chemistry; D013499:Surface Properties
chemical_list: D003734:Dental Casting Investment; D006047:Gold Alloys; D010087:Oxides; D019163:Reducing Agents; D003300:Copper; D000535:Aluminum; D001895:Boron; C030973:cupric oxide; D002133:Calcium Sulfate