Study of the effect of a photocurable bioadhesive composite hydrogel for dentin caries management

Conventional invasive restorations for dental caries often leads to healthy tissue loss. This study developed a photocurable composite bioadhesive hydrogel (GelMA-QAS/DMA@HAP) as a minimal invasive surface coating for the management of caries through synergistic antibacterial and remineralization pathways.

Gelatin methacryloyl (GelMA) was functionalized with a C8 alkyl quaternary ammonium salt (QAS) for antibacterial activity and methacryloyl dopamine (DMA, 5 mg/mL) for wet adhesion, followed by the incorporation of 5% (w/v) nano-hydroxyapatite (nHAP). Adhesive performance was evaluated via shear bond strength testing in accordance with ISO/TS 11405. Antibacterial activity against Streptococcus mutans UA159 was assessed using plate counting for planktonic bacteria and live/dead staining coupled with confocal laser scanning microscopy for mature biofilms (n = 3). In vitro tubule occlusion was observed on acid-etched bovine dentin (n = 3). In vivo remineralization was evaluated using a 7-day rat demineralized dentin defect model (n = 5/group), with Vickers microhardness as the primary outcome. Statistical analyses utilized ANOVA or non-parametric equivalents with a significance threshold of p < 0.05.

FTIR and ¹H NMR confirmed successful synthesis. The hydrogel formulation containing 5 mg/mL DMA exhibited the highest shear bond strength among tested groups (p < 0.05). Sustained release of calcium and phosphate ions was maintained over 120 h. The hydrogel significantly inhibited planktonic S. mutans growth (p < 0.01) and reduced the proportion of viable bacteria in mature biofilms to approximately 10% after 24 h of incubation (p < 0.05). In vitro, the hydrogel effectively penetrated and formed mineral plugs within exposed dentinal tubules. In vivo, the Vickers microhardness of treated demineralized defects increased to approximately 30 HV0.01, significantly higher than that of untreated controls (<20 HV0.01) (p < 0.05).

The GelMA-QAS/DMA@HAP hydrogel integrates wet-surface adhesion, contact-active antibacterial properties, and mineral deposition into a single photocurable system. While current evidence is limited to preclinical in vitro assessments and short-term in vivo defect models, this material demonstrates potential as an adjunctive coating strategy for the minimal invasive preservation and management of caries.