Controlled Release of Chlorhexidine from a HEMA-UDMA Resin Using a Magnetic Field

Objectives. To functionalize novel chlorhexidine (CHX) particles with iron oxide (Fe3O4) nanoparticles and control their release kinetics in a dental resin using an external magnetic field. Methods. Fe3O4 nanoparticles were synthesized and incorporated into spherical CHX particles and the powder was freeze dried. Resin disc specimens were produced using a UDMA-HEMA resin mixed with freeze dried spherical Fe3O4-CHX particles (5 wt.%), which were placed into a Teflon mould (10 mm diameter x 1 mm depth) and covered with a Mylar strip. A MACS magnet was left in contact for 0 min (Group 1), 5 min (Group 2) or 10 min (Group 3) and the resin discs subsequently light cured (Bluedent LED pen, Bulgaria) for 60 s per side. The resin discs were immersed in deionized water at various time points up to 650 h. UV-Vis absorbance was used to determine the CHX content. CHX released for each time point was determined. The functionalized CHX particles and resin discs were characterized using TEM, TGA, EDX and SEM. Results. Fe3O4 nanoparticles (20 nm) incorporated into the spherical CHX particles led to a mean (SD) particle size reduction from 17.15 (1.99) mu m to 10.39 (2.61) mu m The presence of Fe(3)O(4 )nanoparticles in the spherical CHX particles was confirmed with SEM, EDX, and TGA. SEM of Group 1 resin discs (no magnetic exposure) showed functionalized CHX spheres were homogeneously distributed within the resin discs. For resin discs which had magnetic exposure (5 or 10 min) the particles started to cluster nearer the surface (Group 2: 43.7%, Group 3: 57.3%), to a depth of 94 mu m. UV-Vis absorbance revealed Group 1 resin discs had a cumulative CHX release of 4.4% compared to 5.9% for Group 2 and 7.4% for Group 3 resin discs, which had magnetic exposure (5, 10 min). Significance. Fe3O4 nanoparticle functionalized CHX spheres demonstrated a magnetic field responsive property. A magnetic field responsive release of CHX may be useful in clinical situations where the drug can be directed to give a tailored release at the site of infection. (C) 2018 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.