Allograft
Xenografts
and
Non bone graft material
Allograft
are obtained from other individuals of the same species.
obtained from mostly cortical bones
within 12 hours of the donor's death - Cut- washed with absolute alcohol
and then Deep Frozen. It can be either demineralized or not.
When we compare freeze-dried bone allograft (FDBA)
with
demineralized freeze dried bone allograft (DFDBA)
- FDBA is considered osteoconductive whereas
- DFDBA is considered osteoinductive
In DFDBA demineralization is done in cold, dilute HCl - which expose BMP
(bone morphogenetic protein)
DFDBA therefore has higher osteogenic potential than FDBA
DFDBA from cortical bone is better than cancellous DFDBA
Disadvantages of allograft
- since they are foreign to the patient - can produce immune response - which is avoided by deep freezing, radiation and chemical treatment.
- although highly rare - viral transmission is possible therefore numerous steps are taken to prevent it, including chemical treatment.
Xenografts
which are grafts obtained from other species.
œ calf bone
treated by detergent reactions catalyzed and freeze treatment
œ Kiel bone
calf bone + denatured with 20% of hydrogen peroxide
œ anorganic bone
ox bone when treated with ethylene diamine to remove the organic content
(All these three are historical which are not in use now.)
Bio-oss
Bovine derived, anorganic bone currently in use.
It is anorganic - since the organic content has been removed, but trabecular pattern and porosity is retained. It helps in clot stabilisation and revascularization.
Bio-oss combination with Bio-guide (resorbable membrane)
- Helps in the prevention of Migration of fibroblast and connective tissue in to graft
Bio-oss in combination with p 15 - cell binding polypeptide
- enhances bone regeneration
Non bone graft material
include
sclera, dura, cartilage, cementum, dentin, plaster of paris, plastic materials and ceramics,
coral derived materials also.
- Cartilage can act as a scaffold.
- Plaster of Paris is porous and prevents flap necrosis.
But neither of them substitutes bone graft purpose completely.
- Plastic material is composed of polymethylmethacrylate. It is biocompatible and non-resorbable. It showed defect-fill, but no evidence of the new attachment.
- Coral derived bone graft materials include
natural Coral
and
Coral derived porous hydroxyapatite
both are biocompatible but slow resorption is a disadvantage.
Calcium Phosphate bio materials -
they are osteoconductive and hence act as scaffold & have excellent tissue biocompatibility.
Two types include
hydroxyapatite
- non resorbable
- calcium phosphate ratio is 1.67
tricalcium phosphate
- Ca:P is 1.5
- partially bioresorbable
Bioactive glass consists of
Sodium, calcium Salts, phosphates and the Silicon dioxide.
When contacts tissue fluid the glass particles are coated with hydroxy carbonate apatite - And incorporate organic ground substance proteins like glycosaminoglycans and attracts osteoblasts.