Synthesis of novel chlorhexidine spheres with controlled release from a UDMA–HEMA resin using ultrasound

Abstract

ObjectiveEstablish the release kinetics of new chlorhexidine particles incorporated in a dental resin, and with the application of ultrasound. MethodsSpherical chlorhexidine particles (SCP) were synthesized (5wt%), freeze dried and incorporated into UDMA–HEMA resins. Chlorhexidine diacetate (CDP) (5wt%) was similarly incorporated in separate resins. Resin discs were immersed in deionized water, and a release profile established (650h). Ultrasound was used to trigger chlorhexidine (CHX) release from the resin discs at specific durations (10–30s) and time intervals (1–425h). Chlorhexidine content was determined by UV–vis absorption. The chlorhexidine particles/polymer composites were characterized using TGA, SEM, and confocal microscopy. ResultsSCP exhibited structures with high chlorhexidine content (90–95%), and a Mean (SD) diameter of 17.2 (2.5)μm which was significantly (p<0.001) smaller than the CDP crystals at 53.6 (33.7)μm. The SCP discs had a lower (7.7%) CHX release compared to the CDP group (16.2%). Ultrasonication of the resin discs with increasing durations (10–30s) resulted in higher drug release rates. CDP release rates (CHX) over 650h were: 23.5% (10s), 42.6% (20s), 51.2% (30s), and for SCP (CHX) were; 9.8% (10s), 12.3% (20s), and 14.0% (30s). SEM/confocal microscopy revealed CDP discs exhibited dissolution associated with the particle surface and SCP from the interior. SignificanceChlorhexidine spheres incorporated in a dental resin demonstrated a responsive and lower CHX release. Ultrasound enhanced CHX release and is useful in clinical situations where the drug is required on demand to treat severe or persistent infections.