Rechargeable microbial anti-adhesive polymethyl methacrylate incorporating silver sulfadiazine-loaded mesoporous silica nanocarriers

Objectives. Even though polymethyl methacrylate (PMMA) resin is widely used as a dental material, it has poor microbial anti-adhesive properties, which accelerates oral infections. In this investigation, silver-sulfadiazine (AgSD)-loaded mesoporous silica nanoparticles (AgMSNs) were incorporated into PMMA to introduce long-term microbial anti-adhesive effects and to make PMMA a rechargeable resin. Methods. After characterization of the Ag-MSNs in terms of their mesoporous characteristics and drug loading capacity, the 3 point flexural test and hardness were evaluated in PMMA incorporating Ag-MSNs (0.5, 1,2.5 and 5%). Anti-adhesive effects were observed for Candida albicans and Streptococcus oralis with experimental specimens for up to 28 days and after recharging with AgSD. Results. A typical spherical morphology and high mesoporosity were observed for the MSNs used for loading AgSD. Incorporation of Ag-MSNs into PMMA (0.5, 1, 2.5 and 5%) sustained its flexural strength but increased its surface hardness. Anti-adhesive effects were observed after 1 h of exposure to both microbial species, and the effects accelerated with increasing Ag-MSN incorporation into PMMA. Long-term microbial anti-adhesive effects were observed for up to 14 days, and further long-term (7 days) anti-adhesive effects were observed after reloading the Ag-MSN-incorporated PMMA (aged for 28 days) with AgSD; these effects were largely caused by released silver ions and partially by changes in surface hydrophilicity. No cytotoxicity to keratinocytes was observed. Conclusions. The improved mechanical properties and the prolonged microbial anti-adhesive effects, which lasted after reloading of the drug, suggest the potential usefulness of Ag-MSN-incorporated PMMA as a microbial anti-adhesive dental material.Signcance. Ag-MSN-incorporated PMMA can be used as a microbial anti-adhesive dental material for dentures, orthodontic devices and provisional restorative materials. (C) 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.