Bioinspired Peptide-Decorated Tannic Acid for in Situ Remineralization of Tooth Enamel: In Vitro and in Vivo Evaluation

Tooth enamel can be eroded by the local cariogenic bacteria in plaque or nonbacterial factors in the oral environment. The damage is irreversible in most situations. For the etched human tooth enamel to be restored in situ, a salivary-acquired pellicle (SAP) bioinspired tannic acid (SAP-TA) is synthesized. Statherin is one of the SAP proteins that can selectively adsorb onto enamel surface. Peptide sequence DDDEEKC is a bioinspired sequence of statherin and has the adsorption capacity of hydroxyapatite (HAP). TA has abundant polyphenol groups that can grasp Ca²⁺ in saliva to induce the regeneration of HAP crystal. Hence, SAP-TA not only enhances the binding force at the interface of remineralization but also mimics the biomineralization process of tooth enamel. Moreover, ferric ion can coordinate with SAP-TA to form a compact coating that increases the adsorbed amounts of SAP-TA on tooth enamel. Compared with SAP-TA alone, the etched enamels treated with SAP-TA/Fe(III) have a better remineralization effect and mechanical properties (surface microhardness recovery >80% and binding force of 64.85 N) when being incubated in artificial saliva for 2 weeks. In vivo remineralization performance is evaluated in a classical rat caries model. The polarizing microscope and micro-CT results show that SAP-TA/Fe(III) has a good effect on the remineralization process in a real oral environment, indicating that it is a promising repair material for in situ remineralization of enamel.