Histopathology of Ceramic Disease

Objectives: If a ceramic implant is implanted in a bony bed, the continuity of the bone structure around the implant is interrupted and an interface is created, between the graft and the surrounding bone. In case of a press-fit implantation, a static stress deforms the bone according to its stiffness. In case of a stiff hydroxyapatite (HA) implant, the bed is deformed and a strain-adapted bone remodelling occurs, in case the press-fit fails, fibrous encapsulation and bone resorption is described. Since HA granulated material is still the golden standard in dental bone augmentation the purpose of the study was to evaluate the histopathology in an animal experiment, in which ceramic implants in a non-pressfit situation caused fibrous encapsulation and inflammation.
Methods: Contact healing of a ceramic implants was studied in 16 giant rabbits using an standardized animal model of the trochlea of the distal femur. In the center of the patellar groove, a 4.55-mm-large ceramic cylinder was inserted into a 4.50-mm-large defect; both were created using a wet-grinding surgical procedure with diamond-coated instruments. 2 animals of the series with a follow up of 22 months and 2 years failed with respect to a press-fit insertion and developed "ceramic disease". The histopathology of stable and loose fixations were evaluated with high resolution of thin sections.
Results: "Ceramic disease" could be defined by its interface ceramic-to-bone. A dense fibrous tissue intermixed with foreign body giant cells was dominating the histology. The high-resolution of thin section revealed the path of resorption of single hydroxyapatite particles.
Conclusions: Hydroxyapatite implants have to be combined with particles providing damping properties.