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.