Antibacterial effect of polyethyleneimine nanoparticles incorporated in provisional cements against Streptococcus mutans

Background: Frequently provisional restorations require long-term permanence in the oral cavity, thus an antibacterial effect is desirable. We hypothesized that this effect may be achieved by incorporating polyethyleneimine (PEI) nanoparticles into provisional cements. Methods: The nanoparticles antibacterial effect incorporated at 0.5%, 1%, and 2% w/w into provisional cement, was studied in vitro. The antibacterial effect against Streptococcus mutans and Enterococcus faecalis was tested using direct contact test. The data was analyzed using the ANOVA test, with the Dun- nett test for multiple pairwise comparisons. Results: A strong antibacterial effect was evident in all test groups after an aging period of 14 days against S. mutans and E. faecalis (p < 0.05). A significant effect was found between study groups 0.5% w/w and 1% w/w group, as well as between study groups 0.5% w/w and 2% w/w for E. faecalis (p < 0.05). No significant difference was found between study groups 1% w/w and 2% w/w. The growth rate graphs depict an effective bacteria inhibition starting from 1% w/w. Conclusion: PEI nanoparticles incorporated at low concentrations in a provi- sional cement exhibit antibacterial effect against S. mutans and E. faecalis for a period of 14 days. The minimum effec- tive concentration suggested is 1% w/w. Clinical implica- tions: Incorporation of nanoparticles may prevent caries and inflammation, and thereby improve the results of the pros- thetic treatment. Further investigation is necessary on the effect on mechanical properties and clinical relevance. V C 2010