Bone graft Alloplast in Periodontics in Dentistry.

#dental #alloplast #bonegraft

1. ALLOPLAST

2. GRAFT It is a viable tissue/organ that after removal from donor site is implanted/transplanted within the host tissue, which is then repaired, restored and remodelled

3. CLASSIFICATION OF BONE GRAFT  Based on the origin: 1. Autografts: where in the bone is obtained from the same individual. 2. Allografts: which are obtained from different individuals of same species. 3. Xenografts: meaning bone obtained from different species usually bovine or porcine origin. 4. Alloplasts : which are synthetic graft materials/bone substitutes.

4. ALLOPLAST • It is also known as synthetic bone graft material or bone substitute or inert biologic fillers • An alloplast is a synthetic, inorganic, biocompatible bone grafting material which serves as a scaffold for bone growth through osteoconduction

5. PROPERTIES 1. Biocompatibility 2. Minimal fibrotic reaction 3. The ability to undergo remodeling and support new bone formation 4. Similar strength comparable to cortical/ cancellous bone 5. Similar modulus of elasticity comparable to bone 6. Osteogenic potential  7. Resorbable

6. CLASSIFICATION   Absorbable: Ceramics Beta tricalcium phosphate Hydroxyapatite Calcium sulfate Calcium carbonate Non absorbable: Porous hydroxyapatite Dense hydroxyapatite Bioglass Calcium-coated polymer of hydroxyethyImethacrylate and polymethyl methacrylate

7. ADVANTAGES • Absence of antigenicity • No potential for disease transmission • Unlimited supply • Osteoconductive property

8. DISADVANTAGES • The synthetic grafts work as inert scaffolds with no osteogenic or osteoinductive potential. • Most of the synthetic grafts get encapsulated with fibrous connective tissue and stop stimulating bone growth. • The resorption rate is either very high or very slow.

9. Hydroxyapatite (HA)   Hydroxy apatite is a surface-active material which reacts with its biological surroundings through the exchange of Calcium and Phosphate ions present in the material. These ions trigger bio mineralization to form the regenerative crystals through primary and secondary nucleation to form genetically determined hard tissues. HA acts a matrix to facilitate the in growth of normal hard tissues into the bone defect and helps in bone regeneration.

10. Tri calcium phosphate (TCP) It is biological filler which is partially resorbable and allows bone replacement. Conversion of the graft is pivotal for regeneration, first serving as a scaffold and then permitting replacement with the bone. It is a calcium phosphate that is mixed with naphthalene at high temperatures. As the composite cools, naphthalene evaporates forming a porous calcium phosphate structure.

11. Hard Tissue Replacement polymer (HTR) Non resorbable, biocompatible micro porous composite of poly methyl methacrylate, poly hydroxylethyl methacrylate and calcium hydroxide.  It does not produce inflammatory or immune response in contact with bone or soft tissue.

12. Bio- active glass Certain types of glasses and ceramics composed primarily of Si02-CaO-Na20-P205 have been widely used in conjunction with medical and dental implants.  They develop a layer of hydroxy-carbonate apatite on their surface following exposure to body fluids. When exposed to tissue fluids, bioactive glasses are covered by a double layer composed of silica gel and a calcium-phosphorous rich (apatite) layer. 

13. The calcium phosphate-rich layer promotes adsorption and concentration of proteins utilized by osteoblasts to form a mineralized extra cellular matrix.  It has been theorized that these bioactive properties guide and promote osteogenesis allowing rapid formation of bone

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