Functional recovery of demineralized dentin using a glutamic acid-modified electrospun scaffold: A multimodal in vitro characterization

Background: Dentin remineralization poses a significant challenge in restorative dentistry due to the complex structure and mineral-organic composition of dentin. Electrospun nanofibrous scaffolds present a biomimetic platform to facilitate mineral deposition. Functionalization of the scaffold, achieved through the incorporation of biomolecules like glutamic acid, which mimics non-collagenous proteins, may improve remineralization. Objective: To assess the remineralization potential of a glutamic acid-loaded polycaprolactone/nanohydroxyapatite (PCL/nHA/Glu) scaffold on acid-demineralized dentin, through surface and mechanical characterization. Methods: Nanofibrous scaffolds of PCL/nHA and PCL/nHA/Glu were fabricated and applied to demineralized human dentin discs. The samples were immersed in simulated body fluid for 7, 14, and 28 days. Changes in morphology and composition were analyzed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Surface topography was assessed by atomic force microscopy (AFM), and mechanical properties were evaluated via nanoindentation, with statistical analysis conducted using one-way ANOVA. Results: SEM imaging showed progressive mineral deposition in both scaffold groups, with the PCL/nHA/Glu group demonstrating organized crystallite formation and almost complete tubule occlusion by Day 28. EDS indicated earlier and higher Ca and P incorporation in the PCL/nHA/Glu group. AFM showed significant reductions in surface roughness later, while nanoindentation revealed increased elastic modulus and hardness in the PCL/nHA/Glu group by Day 14, indicating mechanical recovery. Conclusion: Glutamic acid-functionalized scaffolds significantly enhanced the remineralization of demineralized dentin, promoting organized mineral deposition and restoration of mechanical properties. These findings support using amino acid-modified scaffolds in dentin tissue engineering. Clinical significance: Functionalization with amino acids is crucial for mimicking the activity of non-collagenous proteins, transforming passive ion delivery systems into bioactive platforms for dentin regeneration. These scaffolds could serve as alternatives to traditional materials in restorative dentistry, aiding in the treatment of dental caries, dentin hypersensitivity, and enhancing pulp vitality and regeneration.