Injectable Thermo-Responsive Dentine Matrix Hydrogel for Enhancing Dentine Regeneration

This study aimed to develop an injectable thermo-responsive composite paste based on digested dentine matrix extract (DDME) for dentine regeneration, with potential applications in vital pulp therapy.

An injectable PLGA-PEG-PLGA/DDME paste was developed and characterized using FTIR. The injectability and self-curing behavior of the composite were evaluated. Its biocompatibility and odontogenic potential were assessed in vitro using human dental pulp cells (hDPCs). Dentine-forming capacity was investigated in an in situ rat model. The effect of the paste on protein expression in hDPCs was examined by label-free proteomic analysis, and the underlying mechanism of DDME-induced odontogenesis was screened. Data were analyzed using Student's t-test and one-way analysis of variance.

The PLGA-PEG-PLGA/DDME paste exhibited excellent injectability and temperature-dependent self-curing. Rheological analysis confirmed shear-thinning behaviour and enhanced viscoelastic properties compared to Water/DDME controls. PLGA-PEG-PLGA significantly improved the handling characteristics of DDME while preserving its bioactivity. In vitro, the paste supported human dental pulp cell viability, migration and odontogenic differentiation, upregulating RUNX2, DMP-1, DSPP and ALP, and enhancing mineralized nodule formation. In situ evaluation in a rat dentine defect model demonstrated that the paste promoted the formation of dentine bridges. Proteomic analysis revealed mTOR signalling as a key pathway, and inhibition experiments with rapamycin confirmed its role in mediating DDME-induced odontogenesis.

The PLGA-PEG-PLGA/DDME composite paste is a promising injectable biomaterial for dentine regeneration, with mTOR modulation offering a potential strategy to optimize outcomes.