[Implants with plasma spray coatings of hydroxyapatite: an experimental study in alveolar bone]

Sintered hydroxyapatite ceramic can be coated to a titanium core by means of a high temperature plasma spray procedure. The biological response of alveolar bone to an implant with such a coating of hydroxyapatite was evaluated in an animal experimental study. The results indicated that the plasma spray coating gave a very strong and direct bonding to cortical alveolar bone. The shear strength between bone and ceramic was greater than the shear strength between ceramic and titanium. From a radiological, macroscopic and microscopic point of view the conclusion could be drawn that the biological properties of a plasma spray coating of hydroxyapatite are the same as the properties of bulk hydroxyapatite ceramic. The outermost layer of the hydroxyapatite coating appeared to be unstable under the experimental conditions.