Nano/micro fluorhydroxyapatite crystal pastes in the treatment of dentin hypersensitivity: an in vitro study.

Objectives: Dentin hypersensitivity (DH) is a prevalent problem. This study aimed to formulate a paste using fluorhydroxyapatite (FA) crystals dispersed in different carriers to treat DH. The ability to occlude patent dentinal tubules and to release ions was investigated.
Materials and Methods: Twenty percent FA/sodium alginate, 40% FA/poly(hydroxyethyl methacylate(HEMA)), and 40% FA/poly(DMA-co-MEA) were applied to etched dentin samples and examined with scanning electron microscopy (SEM) to determine the degree of tubule occlusion. Fluoride electrode was used to measure F release and spectroscopy to evaluate Ca and PO4 release. The cytotoxicity of the synthesized poly(DMA-co-MEA) gel was tested. Kruskall-Wallis test was used to test the differences in ion release between the groups.
Results: FA/poly(DMA-co-MEA) paste obstructed up to 80% of the dentinal tubules, while the coverage was up to 70% for FA/poly(HEMA) and less than 50% for FA/sodium alginate. Fluoride and Ca release was the highest for FA/P(HEMA), 7.2 ± 0.7 and 139.8 ± 32.5 ppm, respectively. The highest concentration of PO4 was 46.2 ± 16.4 ppm for FA/Sodium alginate. No statistical significance was found.
Conclusions: FA/Poly(DMA-co-MEA) and FA/poly(HEMA) pastes may offer immediate short-term relief of DH because of their ability to occlude the tubules and adhere to wet dentin surfaces. The release of the F, Ca, and PO4 ions may offer long-term relief by forming a mineral barrier both within the dentinal tubules and on the dentin surface.
Clinical Significance: The tested materials may offer a long-term treatment for DH.