In vitro antibacterial effects of glass- ionomer cement containing ethanolic extract of propolis on Streptococcus mutans Nursen Topcuoglu1 Fatih Ozan2 Mustafa Ozyurt3 Guven Kulekci1 ABSTRACT Objective: The aim of this study was to evaluate the antibacterial property of glass-ionomer ce- ment (GIC) containing propolis against Streptococcus mutans and its effect on the in vitro S. mutans bioﬁlm formation. Methods: Ethanolic extract of propolis (EEP) was prepared at two concentrations as 25 and 50%. Three different experimental GIC disks were prepared using pure liquid and liquid solutions diluted with 25 and 50 percent of EEP concentrations. Minimum inhibitory concentration (MIC) of EEP on the growth of S. mutans ATCC 25175 was determined by using agar dilution method. Agar diffusion test and an in vitro S. mutans bioﬁlm assay for GIC disks with and without EEP were performed. Results: MIC values of Turkish propolis for S. mutans ATCC 25175 was found as 25 µg/mL. Experi- mental GICs containing propolis exhibited inhibition zones and their dry bioﬁlm weights were less than the pure GIC. The bacterial density was lower in the GIC containing 50% EEP. Conclusions: A distinct antibacterial and antibioﬁlm efﬁcacy of propolis containing GIC on S. mu- tans has been observed. Although further research is needed to show clinical results, antibacterial GIC containing propolis would be a promising material for restoration. (Eur J Dent 2012;6:428-433) Key words: Propolis; Streptococcus mutans; glass-ionomer cement; bioﬁlm formation; antibacte- rial effect 1 Department of Microbiology, Faculty of Dentistry, Istanbul University, Istanbul, TURKIYE 2 Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Abant Izzet Baysal University, Bolu, TURKIYE 3 Department of Microbiology and Clinical Microbiology, Gülhane Military Medical Academy, Haydarpasa Training Hospital, Istanbul, TURKIYE Corresponding author: Dr. Nursen Topcuoglu Istanbul Universitesi, Dishekimligi Fakultesi, Mikrobiyoloji Bilim Dalı, 34093, Capa, Istanbul, TURKIYE Tel/Fax: +90 212 4142595 Email: nursentopcuoglu@yahoo.com INTRODUCTION Over the last few decades, a worldwide in- crease has been observed in the use of natural products for pharmacological purposes. Propo- lis, which is a natural product widely consumed in the folk medicine since ancient times, is a serious candidate to be added to topical formulations due to its antioxidant properties.1 Besides antioxidant activity, epidemiological studies have also detect- ed that propolis has many pharmacological prop- 428 European Journal of Dentistry