Acid-Assisted Consolidation of Silver Alloys for Direct Fillings
Abstract
Silver-rich metal powders cold-welded by consolidation have been investigated as possible direct dental filling material. The surface of the silver powder must undergo an acid treatment to remove existing contaminants and prevent formation of new surface contaminants during consolidation. This study was designed to investigate the effect of the acid treatment on the strength of the consolidated alloy, its reactivity with the surrounding tooth structure, and its reactions with certain cavity liners. This study investigated the effects of pH and concentration of fluoboric acid on the flexural strength of silver powder consolidated into rectangular beams in a partial 4 x 4 design. The study also assessed, by visible and scanning electron microscopy, what effect the acid-treated powders had on dentin that had been pre-coated with different cavity liners. Mean flexural strengths for beams consolidated using dental hand instruments were in the range (77.0 plus or minus 9.28) MPa to (166.1 plus or minus 17.6) MPa, where the quoted uncertainties are standard uncertainties (i.e., one standard deviation estimates). ANOVA indicated that fluoboric acid pH was highly significant (p less than 0.0001) with lower pH values resulting in higher flexural strength. Concentration alone was not a significant factor for flexural strengths, but there was a significant interaction between concentration and pH (P is less than 0.0001). Microscopy revealed that the acid-treated silver powder demineralized approximately 2 microns of dentin when used with no liner. The use of copal or polyamide varnishes eliminated most of this demineralization, but the use of a dentin adhesive liner resulted in some dislodgment and breakdown of the adhesive film by the acid. The results of this study indicate that this silver powder when treated with dilute fluoboric acid at a pH of approximately 1.0 can result in a filling material with strength equivalent to currently used conventional amalgam.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1998
- Accession Number
- ADA530477
Entities
People
- Anthony A. Guiseppetti
- Frederick C. Eichmiller
- Kathleen M. Hoffman
- Michael M. Wray
- Rangall J. Avers