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

Introduction: 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.

Methods: 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.

Results: 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).

Conclusions: 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.

Clinical significance: 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.

Antibacterial; Biocompatibility; Chlorhexidine; Dental resin composites; Polyhedral oligomeric silsesquioxane.