|Budget Amount *help
¥6,600,000 (Direct Cost : ¥6,600,000)
Fiscal Year 1992 : ¥1,100,000 (Direct Cost : ¥1,100,000)
Fiscal Year 1991 : ¥5,500,000 (Direct Cost : ¥5,500,000)
To investigate the bonding-mechanism of bioactive ceramics, the interface between bioactive ceramics and bone were studied by scanning and transmission electron microscopy (TEM). The materials used are apatite-wollastonite-containing glassceramic (A-W GC), Bioglass<@D1(] SY.encircled2.[)@>D1-type glass (Bioglass), Ceravital<@D1(] SY.encircledR.[)@>D1-type glassceramic (KGS), hydroxyapatite (HA), Calcite, and beta-Tricalcium phosphate (TCP).
Particles of these materials ranging between about 100mu and 300mu were implanted into rat tibiae. The specimen of Bioglass, Ceravital and A-W GC after implanted in 8 weeks demonstrated that materials bondedto bone through a collagen-free later consisting of fine apatite crystals distinct from that in bone, which was designated "intervening apatite layer". Crystals in this apatite layer and those of bone were intermingled at their interface, suggesting chemical bonding. Apatite crystals like intervening apatite layer on the surface were formed into g
lassy phases in the surfaces of these three materials, A-W GC, Bioglass and KGS. This apatite layer was not observed in theinterface bone and A-W GC prepared three days after implantation but it was formed in that prepared seven days after implantation. Apatite layer was formed in the surface of A-W GC facing to bone marrow tissues.
In HA, an intervening apatite layer was much less distinct and sometimes absent.
In Calcite and TCP, no intervening apatite layer was not observed and two materials showed direct contact with bone. The surfaces of the implants became rough due to degradation and bone grew into the finest surface irregularities. However, we were unable to demonstrate any continuity of crystals between the resorbable implants and bone by high-resolution TEM.
These results revealed that there is some difference in bonding mechanisms between surface active ceramics like A-W GC, Bioglass and KGS, and bioresorbable ceramics like Calcite and TCP and that HA showed intermediate type of bonding mechanism between surface active ceramics and bioresorbable ceramics. Less