Abstract
Purpose: The purpose of this in vitro study was to investigate the oral conditions that cause discoloration of 12 mass%Au-Ag-Pd alloy, and to investigate the relation between discoloration and the amounts of volatile sulfur compounds (CH3SH, H2S) and oral microorganisms (Fusobacterium nucleatum, Streptococcus mutans) produced.
Materials and Methods: Casts (5×5×0.46mm) of Au-Ag-Pd, titanium, Co-Cr and Au-Pt alloy were incubated in THB broth for four weeks at 37°C. Oral microorganisms such as Fusobacterium nucleatum or Streptococcus mutans incubated in the THB broth. After incubation, the luminance of thecasts were evaluated and color differences (ΔE*ab) between before and after incubation were calculated according to the CIELab color system. The cast surface was observed using an electron probe X-ray microanalyzer.
Results: 1. Luminance and ΔE*ab of Au-Ag-Pd alloy incubated with Fusobacterium nucleatum showed a marked amount of accretion, and Fusobacterium nucleatum was related to the production of CH3SH, H2S. 2. The casts of Au-Ag-Pd alloy incubated with control and Streptococcus mutans were discolored and discoloration tended to be more marked in THB broth including L-cysteine. 3. The reduced luminance found in the casts of titanium, Co-Cr and Au-Pt alloy was less than that found in Au-Ag-Pd alloy. 4. Qualitative analysis showed that sulfide was produced after four weeks of incubation in Au-Ag-Pd alloy.
Conclusions: The findings indicated in vitro that the production of CH3SH, H2S was related to the discoloration of Au-Ag-Pd alloy. The discoloration of Au-Ag-Pd alloy may also be related to the total oral conditions such as periodontics, halitosis and oral care.
