Biomimetic Dentin Repair: Amelogenin-Derived Peptide Guides Occlusion and Peritubular Mineralization

Objectives: Reproducing an integrated mineral layer that occludes exposed dentin with concomitant peritubular mineralization towards reestablishing structural and mechanical integrity of the tooth with long-term durability has been a significant challenge. Here, we describe a biomimetic treatment that promotes dentin repair using a mineralization-directing peptide, sADP5, derived from amelogenin.
Methods: Exposed human dentin specimens were prepared according to the dentin disc model. Dentin discs with a thickness of ~2 mm were cut from mid-coronal dentin and etched for 30 seconds with a 10% citric acid solution. Specimen were then placed into 0.8 mM sADP5 peptide solution, incubated for 10 minutes, and then transferred into artificial saliva for 1 hour at 37°C. The remineralized layer's structure, composition, and nanomechanical properties were analyzed by cross-sectional scanning electron microscopy imaging, energy-dispersive X-ray spectroscopy, and nanomechanical testing.
Results: The occlusion was achieved through a layer-by-layer peptide-guided remineralization process that forms an infiltrating mineral layer on dentin. The elemental analysis provided calcium and phosphate compositions similar to those in mineral hydroxyapatite. The measured average hardness and reduced elastic modulus values for the mineral layer were significantly higher than those of the demineralized and sound human dentin. The structural integration of the new mineral and underlying dentin was confirmed by thermal aging, between 5-45^oC over 2500 cycles, demonstrating no physical separation. These results showed structurally robust and mechanically durable interface between the interpenetrating mineral layer and underlying dentin and it can withstand long-term mechanical and thermal stresses in the oral environment.
Conclusions: The sADP5 peptide-guided remineralization procedure described herein could provide a foundation for developing highly effective oral care products leading to novel biomimetic treatments for a wide range of demineralization-related ailments and it offers a highly potent long-term solution for dentin hypersensitivity.