The plaque‐inhibiting effect of copper amalgam

Abstract

In order to assess whether copper amalgam accumulates less bacterial plaque than silver amalgam, 14 copper amalgam cervical restorations were placed in 10 patients. Control silver amalgam fillings were placed in homologous teeth of the same jaw. To evaluate the amount of plaque, the stained areas on the amalgams were analyzed from photographs with a planimetric method. Further quantitative analyses of plaque growth on copper amalgam were carried out with microbiological methods, for which a new group of 10 patients was selected. Cervical cavities were prepared on both sides of the jaw. Specimens of copper amalgam and silver amalgam restorations were placed on opposite sides. The plaque was collected after 2 and 3 days and cultivated under aerobic and anaerobic conditions on blood agar plates and on Mitis Salivarius Agar. The results of both methods show a very significant inhibition of plaque growth on copper amalgam. These results were confirmed by scanning electron micrographs which showed that copper amalgam only had plaque on small areas. The plaque appeared in band formations arranged irregularly on the surface. Higher magnifications revealed a filamentous structure with predominating coccoid organisms. Scanning electron micrographs also showed that pellicle formation, which is considered to be necessary for bacterial adherence to the surface, took place on both amalgams.

In vitro plaque formation on commonly used dental materials

“…Copper amalgam has also been shown to inhibit plaque formation in vivo (Hyppa & Paunio, 1977). However, recently it has been demonstrated that the new high copper amalgams have little or no inhibitory efl'ect on plaque samples in vitro (Heys et al, 1979).…”

“…Previous in vitro work has found amalgam, especially copper amalgam, to be both cytotoxic (Lierskar, 1974;Takahashi, 1975) and bacteriostatic (McCue, McDougall & Shay, 1951;Shay, Allen & Martz, 1956). Copper amalgam has also been shown to inhibit plaque formation in vivo (Hyppa & Paunio, 1977). However, recently it has been demonstrated that the new high copper amalgams have little or no inhibitory efl'ect on plaque samples in vitro (Heys et al, 1979).…”

Current‐induced effects on growth and adhesion properties of Streptococcus mutans in vitro

“…The antibacterial properties of amalgam alloys have been attributed to combined effects of various bacteriotoxic elements re- leased by the alloys (10)(11)(12)(13). The concentrations of the bacteriotoxic elements (Ag, Hg, Cu) determined in the present sttidy after the 4-h experimental period were iow.…”

Studies on uterine tract infections and the IUCD with special reference to actinomycetes

“…In dentistry, to avoid excessive drilling of cavities in children's teeth, copper cements and filling materials have been used, which, by their bacteriostatic effect may limit caries. Bacterial growth around and underneath dental fillings is a constant problem and compared with other materials, those that contain copper have been shown to reduce bacterial growth and dental plaque formation (Turkheim 1953;Hyppa & Paunio 1977: Bundy et al 1980. Recent Scandinavian work has shown that copper sulphate mouth washes may be a better clinical alternative to chlorhexidine mouth washes in reducing the levels of dental plaque (Wiler & Rolla 1982).…”