Multifunctional bilayer scaffold for dental pulp protection and sustained calcium hydroxide release for mineralized tissue regeneration

Abstract

Injury to the mineralized tissues that protect the dental pulp can lead to pulp exposure and inflammation, necessitating the use of biologically active materials capable of preserving pulp vitality. While current biomaterials such as mineral trioxide aggregate (MTA) are widely used in vital pulp therapy (VPT), their high cost, challenging handling, and lack of structural flexibility highlight the need for alternatives. Here, we introduce a multifunctional bilayer scaffold composed of a polycaprolactone (PCL) film and a PCL/poly(ethylene oxide) (PCL/PEO) blend loaded with calcium hydroxide (CH), designed to provide both cytoprotection and mineralized tissue regeneration. The scaffold features a compact PCL layer, acting as a barrier to protect the pulp from external cytotoxic agents, and a CH-loaded fibrillar PCL/PEO electrospun layer, aimed at promoting odontoblastic differentiation through sustained calcium ion release. The bilayer structure demonstrated mechanical stability and a degradation profile suitable for clinical application. The release mechanism relies on gradual fiber degradation and CH dissolution. In vitro, the fibrillar layer enhanced calcium ion release, supported dental pulp stem cell adhesion and viability, and stimulated mineralized matrix formation. The compact layer preserved cell viability even in the presence of glass ionomer cement. In vivo, the bilayer scaffold elicited a comparable inflammatory response and expression of dentinogenesis and angiogenesis markers relative to MTA, although it did not attain the same level of mineralized tissue formation. Overall, our results indicate that this multifunctional bilayer scaffold offers a cost-effective, dual-purpose alternative to current materials, with potential for further optimization of its tissue regeneration capabilities prior to clinical implementation.