Enhanced antimicrobial properties of POSS-modified composite resin with chlorhexidine-loaded bioactive glass

The aim of this study was to develop a novel antibacterial dental composite resin by loading chlorhexidine (CHX) onto bioactive glass (BG 45S5) and incorporating it into a resin matrix containing cage-type polyhedral oligomeric silsesquioxane (POSS) nanomonomers.

CHX was loaded onto the surface of BG 45S5 using a blending method to obtain experimental groups with different CHX concentrations. Experimental composite resins were prepared by incorporating 20 wt% CHX-loaded BG 45S5 and 40 wt% SiO₂ as inorganic fillers into a matrix containing 4 wt% POSS nanomonomer. Materials characterization were performed using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), with analysis of double-bond conversion. Mechanical properties were evaluated using a universal testing machine, and fracture mechanisms were analyzed by SEM. In vitro drug release was assessed to determine chlorhexidine release behavior. Biocompatibility was evaluated using CCK-8 assays, acute oral systemic toxicity tests, and oral mucosal irritation tests. Antimicrobial activity was assessed using bacterial growth assays, agar plate counting, and the plate diffusion method.

Increasing chlorhexidine concentration resulted in particle agglomeration, reduced double-bond conversion rate, and decreased mechanical strength. Compressive strength of C₂ differed significantly from that of C₀ (p < 0.05), whereas flexural strength showed no significant difference (p > 0.05). At a chlorhexidine loading concentration of 2 %, the composite resin demonstrated acceptable mechanical properties. In vitro drug release demonstrated an initial rapid release phase followed by a sustained and slower release. Furthermore, CCK-8 assays showed that C₂ maintained comparable cell viability to C₀ at 24, 48, and 72 h (p > 0.05). In vivo evaluations revealed no significant systemic toxicity or oral mucosal irritation. C₂ exhibited significant antibacterial activity compared with C₀ (p < 0.05).

Incorporation of 2 % CHX-loaded bioactive glass 45S5 into a POSS-modified composite resin maintained acceptable mechanical performance and provided sustained drug release, biocompatibility, and significant antibacterial activity.

The modified composite resin with a low CHX loading concentration demonstrated antibacterial activity while maintaining acceptable mechanical performance and biocompatibility, suggesting its potential application as a bioactive restorative material.