Hydroxyapatite-paste is Capable of Decreasing the Permeability of Hypersensitive Dentin

Objectives: Various agents are currently available for the treatment of hypersensitive dentin, however, their long term therapeutic effectiveness in are still questionable. This study will introduce a new technique capable of occulding dentinal tubules with calcium phosphate deposits.
Methods: Hydroxyapatite powder was mixed with 25 % phosphoric acid to form a paste which was applied on dentin having patent dentinal tubules orifices (treated with EDTA, 2 minutes). The dentin permeability was measured before/after the application of the hydroxyapatite paste using a split chamber device. The top and the fractured dentin surfaces were examined with scanning electron microscope (SEM). Moreover, the chemical nature of the compounds formed on top of dentin surface was examined using the SEM equipped with energy-dispersive X-ray spectroscope (EDS) and FTIR/ATR (Attenuated Total Reflectance Fourier Transform Infrared) technique. The Mann–Whitney test (p < 0.05) was used to compare the effects of using the hydroxyapatite paste on dentin permeability before/after its application.
Results: The application of the hydroxyapatite paste to dentin significantly decreased dentin permeability (p < 0.05). Hydroxyapatite paste was able to occlude patent dentinal tubule orifices with a layer of calcium-phosphate compounds.

Conclusions: Hydroxyapatite paste has a high potential as an agent for the treatment of Dentin hypersensitivity