Bioinspired smart dentin ECM-chitosan hydrogels for dentin-pulp complex regeneration

Abstract

Objectives: Approximately two-thirds of the world's population suffers from dental caries, and clinical treatment of the resulting lesions varies from dental fillings to devitalization. Despite recent advances in regenerative endodontic therapy, scaffolds intended for the regeneration of the dentin-pulp complex with innate odontogenic potential and microarchitecture similar to these dental tissues are still scarce. Taking advantage of the physio-biological properties of demineralized dentin extracellular matrix (ECM), we developed a functional hydrogel that combines insoluble molecules of dentin with chitosan.

Methods: Dentin powder obtained from extracted teeth was partially demineralized with acetic acid. Demineralized dentin and chitosan powder were separately dissolved in acetic acid to form suspensions that were then mixed in volume ratios of 25/75 or 50/50 (v/v %). The extrudability and gelation time of hydrogel precursors were assessed. Three-dimensional constructs were fabricated following pre-hydrogels pH-adjustment, injection into custom-made molds and incubation at 37 °C. Constructs were characterized for infrared spectral analysis, relative sol-gel fraction, degree of porosity, flexural elastic modulus, in-vitro biodegradability, in-vitro bioactivity, antimicrobial properties against Enterococcus faecalis and biocompatibility for OD-21 cells.

Results: For most of the tested properties, the two proposed hydrogels showed differences, but regardless of these differences, both materials presented morphology, biomechanical attributes, cytocompatibility, and antibacterial properties to serve as dental pulp cell-inducing scaffolds.

Conclusions: Dentin ECM-chitosan hydrogels exhibited in-vitro bioactivity, biocompatibility, and antimicrobial properties to be considered as promising candidates for application as injectable scaffolds for dentin-pulp complex regeneration.

Clinical significance: Extracellular matrices (ECMs) from native tissues have long been considered ideal scaffolds for tissue regeneration. Here, we describe the physicochemical, mechanical, and biological attributes of newly developed hydrogels derived from the functionalization of demineralized dentin ECM with chitosan. The proposed dentin-ECM-chitosan hydrogels have demonstrable microarchitecture, biophysical characteristics, biocompatibility, and antibacterial capacity to produce cell-inducing scaffolds for use in regenerative dentistry.

Keywords: Antimicrobial; Biocompatibility; Bioinspired functional materials; Chitosan; Dentin extracellular matrix; Scaffolds; Smart hydrogels.