Peptide-Guided Remineralization of Dental Hard Tissues

Objectives: Demineralization is the main cause of many dental disease where mineral content of dental hard tissue is lost due to imbalance in the oral environment. Despite numerous attempts to restore lost tissues through remineralization, chemically stable and structurally functional new mineral layer has not been successfully accomplished. The aim of this study has been to develop materials and methods to remineralize enamel, dentin and cementum to restore the lost tissue structure and function.
Methods: Extracted human teeth were used in this study. Formulations were developed using a 15-amino acid remineralizing sequence, called amelogenin derived peptide, shADP5, that was derived from human amelogenin. Carious lesions were artificially formed separately on enamel and the root surfaces of extracted teeth. Remineralization was carried out at different concentrations of shADP5 with Ca/PO₄ ions. Ca/PO₄ or fluoride only samples were used for comparison. Detailed structural, compositional and mechanical characterization was performed using optical microscopy, SEM and micro/nanoindentation using cross-sectional samples exposing interface between the remineralized layer and underlying tooth surface. Statistical analyses were done using student’s t-test, p<0.05 was considered significant.
Results: The SEM images revealed new mineral layers formed on the teeth of peptide-treated group with thickness in the range of 5-10±2.0µm within 0.5-1hr. Hardness and elastic modulus measured on the peptide-treated mineral layers ranged up to 2.3±0.2GPa and 48.8±4.7GPa, respectively, which compared favorably to healthy dentin. Most significantly, cross-sectional analyses indicated that the newly formed mineral penetrated into the underlying dental tissues forming an integrated interface, similar in structure and function to dentin-enamel junction and dentin-cementum junction. No-peptide comparison groups produced non-continuous amorphous inorganic deposits.
Conclusions: This research demonstrated successful remineralization of demineralized enamel, dentin and cementum in formulations containing the key ingredients of shAD5/Ca/PO₄. These results provide design criteria for future practical materials and methods towards developing clinical and daily-use products.