Papers by Keyword: Hydroxyapatite Film

Abstract: This study aimed to create a thick hydroxyapatite (HAp) film on the surface of a human tooth by using a newly developed powder jet deposition (PJD) device for dental handpieces, and sought to examine the microstructural and mechanical properties of the resulting HAp film. The film was evaluated on three-dimensional view, surface roughness, Vickers hardness, and bonding strength before and after artificial aging through thermal cycling (555°C) for 500 cycles (30 sec for each cycle, 20 sec of dwell time).The HAp particles in the deposited film were densely packed, and the HAp films three-dimensional microstructure and its rough surface were maintained after thermal cycling. There was no significant difference in either the HAp films Vickers hardness or the bonding strength between the film and the enamel substrate before and after thermal cycling. The HAp films created in this study demonstrated excellent microstructural and mechanical properties even after the application of thermal stress. We demonstrated the possibility of using a new type of powder jet deposition (PJD) method we developed to form a new type of interface between the tooth and biomaterials. Consequently, we propose the use of this method in new dental treatments.

Abstract: Ag-doped hydroxyapatite films were deposited on a ZrO2 substrate using r.f. magnetron sputtering to improve the bioaffinity and mechanical properties of the hydroxyapatite. The resulting hydroxyapatite films exhibited a variation in their microstructure and mechanical properties relative to the Ag content. The variation in the (Ca, Ag)/P ratios suggested that some of the Ca2+ ions in the hydroxyapatite were replaced with Ag+ ions. After annealing at 800oC, the hydroxyapatite films showed a microstructure with crystalline nano-grains, whereas the Ag-doped hydroxyapatite films revealed the formation of crystallites embedded in the amorphous matrix. The hydroxyapatite films showed an average roughness of about 3~4nm, very smooth surface, and dense microstructure. The hardness and modulus of the films decreased with an increasing Ag content.