Tissue Specific Binding and Remineralization of Tooth Surfaces by Peptides

Objectives:

The Dentin phosphoprotein (DPP) plays an important role in the initial mineralization of dentin matrix during development by regulating the nucleation of hydroxyapatite. The purpose of this study was to examine the binding of unphosphorylated synthetic peptides, composed of variations on the DPP-derived repeated sequence Asp-Ser-Ser (DSS), to specific tooth structures and study the ability of these peptides to recruit CaHPO4 to demineralized tooth surfaces; toward the goal of developing novel means of diagnosing and treating early caries.

Methods:

Extracted teeth were sectioned and incubated in a solution of fluorescein-labeled peptide.Control samples were prepared without peptide. Sections, including those containing carious lesions, were imaged after peptide treatment by Confocal Laser Scanning Microscopy to detect binding. To study the abilities of these peptides to induce remineralization, demineralized surfaces were exposed to peptide and crystal growth was assayed by scanning electron microscopy.

Results:

Peptides containing the sequence (DSS)n showed the highest binding activity. (DSS)8, (DSS)6, and (DSS)4 showed tissue-specific binding, primarily to the mantle dentin. (DAA)8 showed a reversed pattern of binding, primarily to the root tip dentin and cortical enamel. Peptide (DSS)8 showed strong staining of carious lesions or artificially demineralized enamel, with little or no binding of surrounding healthy enamel. In remineralization assays, significant crystal growth occurred in demineralized enamel sections exposed to (DSS)8, which correlates with the specific binding of this peptide to the demineralized portions.

Conclusions:

The bright staining of carious lesions by peptides along with the low levels of binding to surrounding healthy enamel indicates that labeled (DSS)n peptides can be effectively used to identify dental lesions. Significant crystal growth and early nucleation in demineralized enamel exposed to (DSS)8 reveals the ability of these peptides to specifically induce mineral nucleation on degraded enamel surface and suggests their potential usefulness in the treatment of early caries.