Antibacterial efficacy of GIC containing propolis 432 surface occurs with the formation of acquired sali- vary pellicle on the surface and adherence of bac- teria the acquired pellicle.37 A sucrose-mediated mechanism is a main route that facilitates bacte- rial adherence to surfaces. S. mutans is capable of synthesizing mainly glucans from sucrose, which promotes a high adhesion and eventually contrib- utes to the formation of dental bioﬁlm.12 Because of the fact that the bacteria in bioﬁlms are more resistant than their planktonic forms, the MIC does not provide information on the efﬁcacy of an- timicrobial agents against infections involving bio- ﬁlms. In vitro bioﬁlm assays can easily be used as a relevant model for testing the antiplaque proper- ties of the oral restorative materials. Duarte et al31 showed that subinhibitory con- centration of EEP was used to evaluate its action on bioﬁlm formation. According to our bioﬁlm for- mation assay, the GICs containing EEP developed less biomass on their surface than the convention- al GIC. Although the dry bioﬁlm weights were not signiﬁcantly different on each EEP concentration, the bacterial density was lower in the GIC contain- ing 50% EEP. The result means the concentration is important in terms of the bacterial load on den- tal bioﬁlm. In general, GICs containing EEP with each concentration showed a potential antibacte- rial and anti-GTFs activity in vitro, but more EEP concentration is essential to reduce S. mutans in bioﬁlms. EEP solutions have been widely used commer- cially on the market as toothpaste, mouth wash etc. However, it is still an unofﬁcial drug in phar- macy. A further step should be taken to verify if a sufﬁcient dose to kill the target microorganisms can be reached within the oral cavity, without caus- ing major local or systemic adverse effects. Even though we studied on the cariogenic microorgan- ism, S. mutans, more studies with other bacterial strains which take place for the dental bioﬁlm for- mation are still needed. The effective antimicrobial activity of propolis gives hope in the treatment of oral cavity diseases. CONCLUSION This is the ﬁrst report that evaluated antibacte- rial efﬁcacy of propolis containing GIC on S. mutans. By the results of this preliminary study, it can be concluded that GIC containing propolis would be a promising material for restoration. Reduction in European Journal of Dentistry bacterial counts obtained by placing GIC in a cav- ity probably due to the release of ﬂuoride, is not reliable; therefore, antibacterial GICs containing propolis provides an alternative approach. How- ever, further studies should be performed on its physicochemical aspects to know how the pres- ence of EEP interferes with the mechanical and adhesive properties of GIC. REFERENCES 1. Kumazawa S, Hamasaka T, Nakayama T. Antioxidant ac- tivity of propolis of various geographic origins. Food Chem 2004;84:329-339. 2. Kujumgiev A, Tsvetkova I, Serkedjieva Y, Bankova V, Chistov R, Popov S. Antibacterial, antifungal and antiviral activity of propolis of different geographic origin. J Ethnopharmacol 1999;64:235-240. 3. Russo A, Cardile V, Sanchez F, Troncoso N, Vanella A, Garbarion JA. Chilean propolis: antioxidant activity and antiproliferative action in human tumor cell lines. Life Sci 2004;76:545-558. 4. Drago L, Mombelli B, De Vecchi E, Fassina MC, Tocalli L, Gismondo MR. In vitro antimicrobial activity of propolis drug extract. J Chemother 2000;12:390-395. 5. Takaisi-Kikuni NB, Schilcher H. Electron microscopic and microcalorimetric investigations of the possible mecha- nism of the antibacterial action of a deﬁned propolis prov- enance. Planta Med 1994;60:222-227. 6. Santos FA, Bastos EM, Uzeda M, Carvalho MA, Farias LM, Moreira ES, Braga FC. Antibacterial activity of Brazilian propolis and fractions against oral anaerobic bacteria. J Ethnopharmacol 2002;80:1-7. 7. Park YK, Koo H, Abreu JA, Ikegaki M, Cury JA, Rosalen PL. Antimicrobial activity of propolis on oral microorganisms. Current Microbiology 1998;36:24-28. 8. Koo H, Rosalen PL, Cury JA, Ambrosano GM, Murata RM, Yatsuda R, Ikegaki M, Alencar SM, Park YK. Effect of a new variety of Apis mellifera propolis on mutans streptococci. Current Microbiology 2000;41:192-196. 9. Koo H, Rosalen PL, Cury JA, Park YK, Ikegaki M, Sattler A. Effect of Apis mellifera propolis from two Brazilian re- gions on caries development in desalivated rats. Caries Res 1999;33:393-400. 10. Koo H, Pearson SK, Scott-Anne K, Abranches J, Cury JA, Rosalen PL, Park YK, Marquis RE, Bowen WH. Effects of apigenin and tt-farnesol on glucosyltransferase activity, bioﬁlm viability and caries development in rats. Oral Micro- biol Immunol.2002;17:337-343.