Transmission electron microscopy of the interface between bone and pseudowollastonite implant

This paper reports on the structural morphology of the interface in vivo be tween implants composed of bioactive synthetic pseudowollastonite ceramic a nd bone in rat tibias, Thin sections of the interfaces were examined after 6 and 8 weeks of implantation period in a high resolution transmission elec tron microscope up to the lattice plane resolution level, The interfaces developed normal biological and chemical activities and rema ined reactive over the 8-week period. The regions showing direct bone tissu e bonding to the implant contained nanocrystals of hydroxyapatite-like phas e growing epitaxially across the interface in the [002] direction, The nano crystals were also identified in the bone tissue formed in the interfacial area. The reactivity of the implant caused in the first instance formation of an amorphous woven type of bone, which transformed into a crystalline lamellar type containing collagen fibres, The Ca/P ratio of the interfacial region was found to be between 1.67 in the mature bone tissue formed about 5 mum f rom the interface, and 2.06 in the regions right at the interface.