(IV) Porous Ceramics
The concept behind nearly inert, micro-porous bioceramics (type2) is the ingrowths of tissue into pores on the surface or throughout the implant. The increased interfacial area between the implant and the tissues result in an increased inertial resistance to movement of the device in the tissue. The interface is established by the living tissue in the pores. This method of attachment is often termed biological fixation. It is capable of withstanding more complex stress states than type1 implants, which achieve only morphological fixation.
The limitation associated with type2 porous implants is that, for tissue to remain viable and healthy, it is necessary for the pores to be greater than 100 to
150m in diameter. The large …show more content…
(V) Bioactive Glasses and Glass-Ceramics
Another approach to the solution of the problems of interfacial attachment is the use of bioactive materials (type3). The concept of bioactive materials is intermediate between resorbable and bioinert.
Certain compositions of glasses, ceramics, glass-ceramics, and composites have been shown to bond to bone. These materials are also called bioactive ceramics.
Some, even more specialized compositions of bioactive glasses, will bond to soft tissues as well as bone. A common characteristic of such bioactive materials is a modification of the surface that occurs upon implantation. The surface forms a biologically active hydroxycarbonate apatite (HCA) layer, which provides the bonding interface with tissues. The HCA phase that forms on bioactive implants has the same chemical structure as the mineral phase in bone, and is therefore responsible for interfacial bonding.
The bonding results in an interface that resists substantial mechanical forces.
Bonding to bone was first demonstrated for a range of bioactive glasses, which contained specific amounts of SiO2, CaO, and P2O5. These glasses contained less than
60 mol% SiO2, high contents of Na2O, and CaO, and had a high CaO/ P2O5
The concept behind nearly inert, micro-porous bioceramics (type2) is the ingrowths of tissue into pores on the surface or throughout the implant. The increased interfacial area between the implant and the tissues result in an increased inertial resistance to movement of the device in the tissue. The interface is established by the living tissue in the pores. This method of attachment is often termed biological fixation. It is capable of withstanding more complex stress states than type1 implants, which achieve only morphological fixation.
The limitation associated with type2 porous implants is that, for tissue to remain viable and healthy, it is necessary for the pores to be greater than 100 to
150m in diameter. The large …show more content…
(V) Bioactive Glasses and Glass-Ceramics
Another approach to the solution of the problems of interfacial attachment is the use of bioactive materials (type3). The concept of bioactive materials is intermediate between resorbable and bioinert.
Certain compositions of glasses, ceramics, glass-ceramics, and composites have been shown to bond to bone. These materials are also called bioactive ceramics.
Some, even more specialized compositions of bioactive glasses, will bond to soft tissues as well as bone. A common characteristic of such bioactive materials is a modification of the surface that occurs upon implantation. The surface forms a biologically active hydroxycarbonate apatite (HCA) layer, which provides the bonding interface with tissues. The HCA phase that forms on bioactive implants has the same chemical structure as the mineral phase in bone, and is therefore responsible for interfacial bonding.
The bonding results in an interface that resists substantial mechanical forces.
Bonding to bone was first demonstrated for a range of bioactive glasses, which contained specific amounts of SiO2, CaO, and P2O5. These glasses contained less than
60 mol% SiO2, high contents of Na2O, and CaO, and had a high CaO/ P2O5