Comparison of Cytotoxicity and Antimicrobial Potentials: Conventional Vs. Copper-loaded Zinc Phosphate Cement

Objectives: The formation of biofilms on the cement gap and the surrounding substrata may lead to secondary caries, which is known as one of the main reasons for the failure of prosthetic restorations. In order to reduce microbial adhesion on luting materials, various antimicrobial additives have been investigated in the past. The aim of the present study was to evaluate the biocompatibility and the antimicrobial effect of a copper-loaded zinc phosphate cement (Hoffmann´s Copper Cement, Hoffmann Dental Manufaktur, Germany) in comparison to a conventional unloaded reference cement (Hoffmann´s Cement normal setting, Hoffmann Dental Manufaktur, Germany).
Methods: Specimens of both materials were produced (10mm in diameter, 1mm thickness) and polished. Half of the samples were stored in aqua dest. for one month. Afterwards, the arithmetic surface roughness and the free surface energy were measured and the surface allocation of copper has been determined. The microbial adhesion has been determined fluorometrically after incubation with Streptococcus sanguinis and Candida albicans. Cytotoxicity was tested by using an ISO 10993-5 conform WST/CCK8 assay on L929 mouse fibroblasts.
Results: There were no significant differences in surface roughness, surface free energy, cytotoxicity, and antibacterial or antifungal activities, nevertheless the observed cytotoxicities on both materials were extremely high. The surface allocation of copper in the copper-loaded cement was low.
Conclusions: The copper-loaded zinc phosphate cement did not exhibit any quantifiable antimicrobial potential. Additionally all other tested parameters were not significantly different to the unloaded cement. These findings may result from the low surface allocation of copper in the copper-loaded phosphate cement.