Dopamer: A bioactive polydopamine-containing glass-ionomer cement with mineralizing and antibacterial properties

Objective

To develop and characterize a novel bioactive polydopamine (PDA)-containing glass-ionomer cement (Dopamer) with enhanced mechanical, antibacterial, and mineralization properties for use as a restorative dental material.

Methods

Dopamer was developed by coating fluoroaluminosilicate glass particles with polydopamine (PDA) via dopamine polymerization in alkaline solution. The PDA-coated glass particles were then mixed with a polyacrylic polymer. Mechanical properties were assessed through compressive strength, flexural strength, and Vickers microhardness testing using standardized specimens. Fuji XI and Herculite composite resin were used as the control groups. The adhesion to dentin was evaluated using shear bond strength test. Mineralization potential was investigated using Raman spectroscopy and scanning electron microscopy (SEM) to detect apatite formation on the surface and at the dentin-material interface. Cytocompatibility was evaluated using viability and proliferation assays on human dental pulp stem cells (DPSCs). Antibacterial activity against Streptococcus mutans was examined using both colony-forming unit (CFU) counts and live/dead bacterial staining assays on biofilms formed on the material surfaces. Additionally, odontogenic differentiation was examined using gene expression analysis. An in vivo mice molar pulp capping model was used to assess tertiary dentin formation and inflammatory response after placement of the material. All quantitative data were analyzed using one- or two-way ANOVA followed by Tukey’s post hoc test, with significance set at p < 0.05. Kruskal-Wallis Test was utilized to evaluate pulp inflammation scores analysis.

Results

Dopamer exhibited significantly enhanced (p < 0.001) mechanical properties, including improved compressive strength, flexural strength, and microhardness, compared to the conventional glass-ionomer cement (GIC). Shear bond strength to dentin also improved significantly (p < 0.05), demonstrating stronger adhesion. In vitro analyses confirmed in situ mineral formation and dentin mineralization capacity of Dopamer. Raman spectroscopy and SEM-EDS analyses revealed extensive mineral deposition at the interface between Dopamer and dentin, including calcium phosphate-rich layers suggestive of hydroxyapatite formation. Moreover, antibacterial testing demonstrated that Dopamer significantly (p < 0.001) inhibited Streptococcus mutans colonization compared to control (p < 0.001), reducing the risk of recurrent caries. Biocompatibility assays revealed high viability of DPSCs cultured on Dopamer, comparable to or better than the control groups. Dopamer also significantly upregulated odontogenic markers in vitro. In vivo studies showed formation of a continuous layer of tertiary dentin beneath the placed Dopamer, with minimal inflammatory response indicating excellent biocompatibility and regenerative potential.

Significance

By combining enhanced mechanical strength, mineralization capacity, and antibacterial properties, Dopamer addresses critical limitations of existing glass-ionomer dental restorative materials, offering a bioactive, durable solution for restorative dentistry. This multifunctional material represents a promising advancement in dental restoration, supporting both clinical performance and long-term oral health.