Incorporation of an antibacterial and radiopaque monomer in to dental resin system

Objectives. The purpose of this study was to prepare antibacterial and radiopaque dental resin through adding one polymerizable quaternary ammonium compound with iodine as counter anion into Bis-GMA/TEGDMA (50/50, wt/wt) dental resin system, and evaluate the degree of monomer conversion, mechanical properties, radiopacity, and antibacterial effectiveness of the polymer. Methods. 2-Dimethyl-2-dodecyl-1-methacryloxyethyl ammonium iodine (DDMAI) (3 wt.% and 5 wt.%) was added into a Bis-GMA/TEGDMA (50/50, wt/wt) resin system with CQ (0.7 wt.%) and DMAEMA (0.7 wt.%) as photoinitiation system. Degree of monomer conversion (DC) was determined by FT-IR analysis. The flexural strength (FS) and flexural modulus (FM) of the polymer were measured using a three-point bending set up. Radiographs were taken to determine the radiopacity of the polymer, and aluminum step-wedge (0.5-4 mm) was used as calibration standard. A single-species biofilm model with Streptococcus mutans as the tests organism was used to evaluate the antibacterial property of the polymer. Bis-GMA/TEGDMA without DDMAI was used as control material in all of the tests. Results. ANOVA analysis revealed that there was no significant difference in DC between polymer with and without DDMAI (p > 0.05). Polymer with 3 wt.% DDMAI had higher FS than the control material (p < 0.05), while polymer with 5 wt.% DDMAI had comparable FS with the control material (p > 0.05). Though average FM of control material was lower than that of 3 wt.% DDMAI containing polymer and higher than 5 wt.% DDMAI containing polymer, but the differences were statistically insignificant. By increasing the quantity of DDMAI, the radiopacity of the polymer increased. Of the three formulations, the polymer with 5 wt.% DDMAI inhibited biofilm the formation of the clinically relevant young biofilm. Significance. Incorporation of DDMAI into resin system could endow it with radiopacity and antibacterial effectiveness, and these two properties seem to be improved with increasing the quantities of DDMAI. (C) 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.