Development of ion-loaded polyethylene glycol-based biomaterials for the controlled mineral occlusion and antibacterial sealing in dentinal tubules

Dentinal tubule exposure leads to dentin hypersensitivity and pulp bacterial invasion. This study aimed to evaluate polyethylene glycol (PEG) derivatives, varying in different molecular weights (MWs) and functional groups, to achieve deep dentinal tubule occlusion and concurrent antimicrobial activity under the neutral, non-destructive conditions. PEG derivatives were synthesized, ion-loaded, and characterized. In vitro ion permeation and precipitation actions were assessed across various pH levels by human dentin slices and turbidity assays. The sealing depth and crystal phase of the precipitates were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. Furthermore, the materials' biocompatibility, biomineralization potential, and antibacterial activity were evaluated. Low MW PEG exhibited ideal nanoscopic size and charge neutrality. Both MW and functional group modifications affected ion permeation and controlled crystallization. Among the materials, PEG 200 group achieved the superior dentinal tubule sealing depth. However, both the caprolactone (CL) and acrylic acid (AAC) terminal modifications significantly compromised the sealing depth. For biocompatibility, PEG and PEG-CL demonstrated excellent cytocompatibility, whereas the introduction of AAC resulted in cytotoxicity. Regarding antimicrobial performance, Low MW PEG and AAC group showed broad-spectrum antimicrobial efficacy. PEG derivatives with low MW are the most promising candidates, demonstrating excellent biocompatibility and deep dentinal tubule sealing via strontium phosphate-related crystallization under the neutral conditions. While functional groups like AAC offer superior crystal control and antibacterial properties, the associated reduced penetration depth and cytotoxicity necessitate further optimization for clinical application.