ORIGINAL RESEARCH An agar diffusion study comparing the antimicrobial activity of Nanoseal with some other endodontic sealers Ali Burak Aal-Saraj, BDS; Zaihan Ariffin, BDS, GDCD, DCD; and Sam’an Malik Masudi, DDS, MS Restorative Unit School of Dental Science, Science University of Malaysia, Kelantan, Malaysia Keywords agar diffusion, antimicrobial activity, endodontic sealer, micro-organism. Correspondence Dr Zaihan Ariffin, School of Dental Sciences, Science University of Malaysia, Health Campus, 16150 Kubang Kerian, Kelantan, Malaysia. Email: zaihan@kck.usm.my doi:10.1111/j.1747-4477.2010.00241.x Abstract The aim of this study was to evaluate the antimicrobial activity of a new experimental nano-hydroxyapatite epoxy resin-based sealer (Nanoseal) with several other commercially available sealers; AH26, Tubliseal, Sealapex and Roekoseal against Enterococcus faecalis, Pseudomonas aeruginosa, Streptococcus mutans, Streptococcus sobrinus and Escherichia coli for up to 7 days. Agar diffusion was used in this study. Fifty Muller-Hinton agar plates were prepared and divided into five experimental groups (n = 10), for each micro-organism. Another 10 agar plates were used as positive and negative controls. Endodontic sealers were tested against each micro-organism. Inhibition zones produced were recorded. The results of this study showed that all test materials exhibited inhibition zones towards the tested micro-organisms for 7 days except for Roekoseal, which showed no inhibition zones. Nanoseal and AH26 exhibited similar zones of inhibition. Significant difference was found between Nanoseal and the other tested sealers (P < 0.001). Introduction Orthograde endodontic treatment can be summarised as a series of procedures for cleaning, shaping and filling of the root canal system (1). The elimination of as many microbes as possible in an infected pulp canal is one of the main objectives of root canal treatment (2). In this respect, endodontic sealers with antimicrobial properties can be advantageous (3). Endodontic sealers should have antimicrobial activity or at least they should not encour- age microbial growth of residual micro-organisms (4,5). Sealers that possess optimum antimicrobial and flow ability properties might eliminate micro-organisms not removed by chemo-chemical preparation (6). Recently, the School of Dental Sciences, Universiti Sains Malaysia, has prepared a new experimental endo- dontic sealer (Nanoseal). This sealer is similar to various epoxy resin-based sealers, but with a different filler. The aim of this study was to evaluate the antimicro- bial activity of a new experimental nano-hydroxyapatite epoxy resin-based sealer (Nanoseal) compared with some commercial sealers (AH26, Tubliseal, Sealapex, and Roekoseal) against a number of facultative anaerobes. Materials and methods Research materials The sealers used in this study were: • Nanoseal-experimental nano-hydroxyapatite sealer (epoxy resin-based, School of Dental Sciences, USM, Malaysia) • AH26-silver free (epoxy resin-based, Dentsply De Trey GmbH, Germany) • Tubliseal (zinc oxide eugenol-based, SybronEndo, CA, USA) • Sealapex (calcium hydroxide-based, SybronEndo, MI, USA) • Roekoseal (polydimethylsiloxane-based, Roeko/ Colte’ne/Whaledent, Langenau, Germany) All sealers were prepared in strict compliance according to the manufacturers’ instructions. Aust Endod J 2012; 38: 60–63 60 © 2010 The Authors Australian Endodontic Journal © 2010 Australian Society of Endodontology