Functionalized silk dental floss as a vehicle for delivery of bioactive minerals and ions to the tooth surface.

Purpose: To enable the commercially available silk dental floss to carry a series of desensitizing, alkalizing, and tooth strengthening pharmacons.

Methods: The hydroxy-groups of the serine and tyrosine residues of the commercial silk dental floss were exposed by degumming, and employed as the chemical anchors for the introduction of carboxy-groups to the surface. The affinity of the silk dental floss to a set of bioactive species was studied by SEM, EDS, and XFS. The acetylated silk was used as a control sample for the experiments elucidating the effect of the surface carboxy-groups on its affinity to a series of pharmacons.

Results: While unmodified silk has affinity to microcrystals of sodium carbonate, some affinity to hydroxyapatite particles and Sr2+, its carboxylation drastically increased the affinity to hydroxyapatite, Sr2+, Ca2+ and K+. The unmodified silk had some affinity to existing hydroxyapatite particles, but did not initiate the growth of hydroxyapatite on the surface. Carboxylation of silk enabled the growth of hydroxyapatite on its surface, and significantly increased its affinity to the existing hydroxyapatite particles. The unmodified silk had significant affinity to Zn2+, which exceeded its acylated derivatives.

Clinical Significance: The ability of the commercial and modified silk floss to carry a series of pharmacons makes them precursors for a series of new versatile materials with a potential for delivering small doses of bioactive agents in a targeted manner.