Active chitosan hydrogel loaded with polydopamine-coated regeneration silicon for advanced treatment of root caries

Root caries are primarily caused by cariogenic bacteria, posing a significant threat to the oral health of older adults. Due to the lesion's anatomical location and the moist microenvironment, clinical management is challenging and recurrence rates remain high. In order to address this unmet clinical need, we developed an activated chitosan hydrogel loaded with polydopamine-coated regeneration silicon (PDA-Regesi-CS) for early intervention in root caries. In this formulation, chitosan provides potent antibacterial activity, regeneration silicon promotes cementum remineralization, and polydopamine enables durable wet-adhesion properties. In vitro experiments demonstrated that the hydrogel significantly inhibited the growth of Streptococcus mutans, Actinomyces viscosus, Lactobacillus acidophilus, Candida albicans, and a four-species mixed bacterial culture, achieving biofilm inhibition and mature biofilm eradication rates exceeding 92%. Furthermore, it effectively promoted the remineralization of demineralized cementum, with nano-hardness reaching 33.54 kgf/mm² after 28 days. In vivo rat model experiments further validated its superior efficacy in early root caries treatment, showing a low Doff score of 0.2 and surface mineral density of 1.31 g/cm³ on exposed root surfaces. Collectively, these findings demonstrate the promising potential of the PDA-Regesi-CS hydrogel as a targeted therapeutic intervention for the early management of root caries, but further evaluation of its clinical translational feasibility is still needed.