SELF-SETTING, BIOACTIVE, AND BIODEGRADABLE TTCP-DCPD APATITE CEMENT

Tetracalcium phosphate-dicalcium phosphate dihydrate self-setting apat ite cement mixed with low-crystallized seed hydroxyapatite is similar to the host bone in degree of crystallinity. The bonding strength of t his cement with hydroxyapatite-coated titanium rods was twice that wit h noncoated titanium and four times that with stainless steel. Histolo gically, TTCP-DCPD apatite cement incorporated into the tibia of rabbi ts were degraded, absorbed, and replaced by the normal body trabeculae rapidly. The mechanical strength of the cement disk intercalated into a gap made in the rabbit tibiae increased to 73% of that of the norma l tibia at 10 weeks concurrently with the decrease in bone mineral den sity of the disk toward that of the normal tibia, in which bony replac ement of the disk was observed also histologically. These bioactive an d biodegradative characters of this cement are due to the similarity o f its degree of crystallinity to that of the host bone, and could expa nd its clinical applications. (C) 1996 John Wiley & Sons, Inc.