A novel biomaterial derived from the skin secretion of <i>Andrias davidianus</i> for dentinal tubule occlusion

Dentin hypersensitivity is a common challenge for dentists and patients. Occluding dentinal tubules through dentin remineralization is considered an alternative therapeutic approach to manage dentin hypersensitivity. The skin secretion of <i>Andrias davidianus</i> (SSAD) contains various binding functional groups. In this study, SSAD hydrolysate was prepared with tris(2-carboxyethyl)phosphine reduction. Its binding ability to acid-etched dentin, as well as its efficacy in dentin remineralization and tubule occlusion were evaluated. The results demonstrated that SSAD hydrolysate could easily and firmly bind to the surface of collagen fibrils. This hydrolysate could stabilize calcium and phosphorus ions in an amorphous state and induce the accumulation of apatite on the dentin surface. After 4 weeks of incubation in artificial saliva, dentinal tubules treated with 0.5 mg mL^-1 SSAD hydrolysate were evidently sealed by regenerated minerals. The deposited minerals were observed deep within the dentinal tubules (up to 30 ± 5 μm). X-Ray diffraction and energy-dispersive X-ray analyses further confirmed that the regenerated minerals were mainly hydroxyapatite. Sequentially, stable occlusion after acid challenge and significant reduction in dentin permeability were achieved. The microhardness value of the remineralized dentin treated with SSAD hydrolysate was significantly increased. In addition, the proliferation, migration, mineralization, and odontogenic differentiation of human dental pulp stem cells were promoted. Animal experiments indicated that SSAD hydrolysate could also occlude dentinal tubules in the oral environment. In conclusion, our work provides an experimental basis for the potential use of SSAD hydrolysate for treating dentin hypersensitivity.