Metformin is a promising small molecule for dentin regeneration, but an effective local delivery system for pulp applications has been underexplored. This study encapsulated metformin in poly(lactic-co-glycolic acid) (PLGA) microspheres and incorporated them into calcium phosphate–chitosan cement (CPCC) as a direct pulp-capping material (DPC). Metformin-PLGA microspheres were prepared by double emulsion and mixed with CPCC at a concentration of 0% to 20% by weight. Microsphere morphology, encapsulation efficiency, chemical composition, and physico-mechanical properties were characterized, and compatibility with human dental pulp stem cells (hDPSCs) was evaluated by live/dead assay and SEM. The microspheres were spherical (5.43 ± 0.17 µm) with (51 ± 3.69%) encapsulation efficiency, and FTIR confirmed metformin incorporation. The 15% Met-PLGA-CPCC group showed flexural strength (15.22 ± 1.98 MPa), elastic modulus (4.60 ± 0.73 GPa), and work of fracture (104.96 ± 12.48 J/m²) comparable to or higher than CPCC and MTA, while all Met-PLGA-CPCC groups had shorter setting times ranging from 18 min to 27 min than CPCC (39.15 ± 2.10 min) and MTA (123 ± 4.2 min). Metformin release increased proportionally with Met-PLGA content. hDPSCs exhibited good attachment and high viability on all materials over the evaluated period. In conclusion, Met-PLGA-CPCC provides fast-setting and favorable physico-mechanical properties, sustained metformin delivery, and excellent hDPSC compatibility. These properties support its potential as a bioactive direct pulp-capping material and as a versatile platform for regenerative applications.

Secondary caries and biofilm accumulation remain major causes of failure in provisional crowns and restorations, highlighting the need for multifunctional resin coatings with antibacterial and remineralizing capabilities. This study aimed to develop a novel bioactive and antibacterial resin-based surface coating incorporating 10% dimethylaminododecyl methacrylate (DMADDM), 20% nanoparticles of amorphous calcium phosphate (NACP), and/or 20% calcium fluoride nanoparticles (nCaF₂) within a urethane dimethacrylate/triethylene glycol divinylbenzyl ether (UDMA/TEG-DVBE) matrix. Coatings were evaluated for degree of conversion (DC), flow, shear bond strength, brushing wear resistance (10,000 cycles), and calcium (Ca), phosphate (PO₄), and fluoride (F) ion release up to 70 days. All groups achieved clinically acceptable polymerization, with the lowest DC at 50%. NACP-containing coatings significantly increased shear bond strength to 18.3 ± 2.8 MPa, representing a ~170% increase compared with the experimental control (6.8 ± 2.1 MPa) and exceeding the ISO 10477 minimum threshold of 5 MPa. After brushing simulation, experimental coatings demonstrated low wear depth (0.93–1.19 µm), which was ~40% lower than the commercial control (1.85 ± 0.40 µm). Sustained ion release was achieved for 70 days, with 20% NACP-formula releasing 1.22 mmol/L Ca and 0.90 mmol/L PO₄, while the dual NACP–nCaF₂ formulation provided simultaneous Ca (0.62 mmol/L) and F (0.33 mmol/L) release. The developed coatings demonstrated promising physicochemical properties, bonding performance, wear resistance, and sustained remineralizing ion release, supporting their potential application as therapeutic surface coatings for provisional restorations.

Background: Tooth root caries and periodontal tissue loss remain major challenges in elderly and periodontally compromised patients, while current restorative materials lack combined antibacterial and regenerative properties. Objective: The objective of this study was to develop a novel metformin-containing antibacterial composite for root cavity restorations to prevent recurrent caries and potentially promote periodontal tissue regeneration. Methods: Experimental composites contained 5% dimethylaminohexadecyl methacrylate (DMAHDM), varying metformin concentrations (2.5–15%), and glass fillers. Mechanical and antibacterial properties as well as cytocompatibility toward human periodontal ligament stem cells (hPDLSCs) were investigated. Results: The experimental composites achieved flexural strengths of 67.9 to 50.1 MPa (n = 6), significantly higher than (41.3 ± 3.4 MPa) of commercial control Vitremer (p < 0.05), while maintaining clinically acceptable elastic moduli of 3.7–3.1 GPa. Experimental composites achieved an 8-log reduction in Streptococcus mutans (S. mutans) biofilms and significantly reduced lactic acid production and metabolic activity compared to biofilms on commercial controls. The composite containing 15% metformin demonstrated acceptable cytocompatibility toward hPDLSCs under clinically relevant diluted conditions, matching commercial controls (p > 0.1). Conclusions: These findings suggest that this novel composite possesses potent antibacterial activity, acceptable cytocompatibility, and adequate mechanical properties, making it promising for multifunctional root caries restorations.