Bone bonding mechanism of β‐tricalcium phosphate

Abstract

It has been proposed that the formation of a surface apatite layer in vivo on surface active ceramics is an essential condition for chemical bonding between ceramics and bone tissue. To clarify the difference in bone‐bonding mechanisms between surface active ceramics and bioresorbable ceramics, two experiments were performed using plates of dense β‐tricalcium phosphate (β‐TCP). First, plates of β‐TCP were implanted subcutaneously in rats for 8 weeks. Surface change due to bioresorption was observed with scanning electron microscopy. Formation of the apatite layer on the surface was investigated using thin‐film x‐ray diffraction and Fourier transform infrared reflection spectroscopy. Second, plates of β‐TCP were implanted in tibiae of rabbits for 8 and 25 weeks and subjected to the detaching test to measure bone‐bonding strength. β‐TCP bonded strongly to bone. Undecalcified sections of the interface of bone and β‐TCP were examined with SEM‐EPMA. However, by physicochemical methods, no formation of surface apatite layer was observed. These results suggest that β‐TCP bonds to bone through microanchoring between bone and rough surface of resorbed β‐TCP.