Atomic Layer Deposition: A Novel Strategy to Remineralize Calcium Hydroxyapatite Matrix

Atomic layer deposition on biomaterials is a newly emerging field of research interest. This thesis focuses on the infiltration of dentin hydroxyapatite with TiO2 via ALD and ability of the as-deposited TiO2 to nucleate mineral ions. We demonstrated that the calcium hydroxyapatite matrix of dentin can be infiltrated with a nanofilm of TiO2 by low temperature atomic layer deposition. Dentin is a high aspect ratio structure having dentinal tubules throughout its depth with pore openings of 1.21 µm diameter on the top surface. Atomic layer deposition (ALD) was performed on teeth samples at 100oC using tetrakis (diethylamino) titanium as a precursor and ozone as an oxidizer to obtain a 42 nm-thick layer of TiO2. Energy dispersive x-ray spectroscopy showed that a nanolayer of TiO2 was deposited on the top surface of the dentin as well as the exposed surface of dentinal tubules throughout their depth. We further confirmed the potential of as-deposited TiO2 nanofilm to nucleate calcium phosphate crystals and remineralize the dentinal matrix. Calcium and phosphorus content of the demineralized dentin was found to increase by a factor of 5 due to nucleation and crystal growth as a result of in vitro biomimetic remineralization process. Atomic layer deposition of calcium phosphate nucleating metal oxide is a promising technique to restore the lost minerals from teeth.