bone grafts and dental implant procedures.pptx

Bone Grafts and Dental Implants These are viruses belonging to family retroviridae.
These possess an enzyme reverse transcriptase, which prepares a DNA copy from RNA genome.
Presence of an enzyme reverse transcriptase is a characteristic feature of this family.

1. Bone grafts Dr P arvati

2. What is graft? What are bone grafts? Types of bone grafts Applications of bone grafts. Biologic concept of using bone grafts Bone grafts application in periodontical defects Factors affecting the bone grafts

3. Types of bone grafts – 1. Based on nature of bone – Cancellous Chips Cortical Powder Cortico-cancellous Marrow graft 2. Based on source – Autogenous Allogenic/ Allograft / Homograft Isogenic Xenograft/ Heterograft Composite graft Alloplast

4. 3. Based on vascularity – A. Non- vascularised B. Vascularised Pedicle Microvascular free transfer 4. Based on donor site – Iliac crest – from ant., post. Ilium or trephine grafts Rib – full thickness, split Calvarial – full thickness, split Fibula etc. 5. Based on function – Bridging / inlay graft – inserted into a recess created across the defect Contour / onlay graft – placed along existing bone

5. Principles of bone grafting – 1 . Harvest from familiar site. 2. Avoid contaminated site. 3. Contour the graft to fit the defect. 4. Absolute immobilization. 5. Ensure adequate blood supply to graft. 6. Do not have graft exposed. 7. Assess graft take periodically.

6. To increase in the clinical bone fill To preserve and augument the bone for future implant Placement Formation of functional PDL Rationale of bone grafts

7. Biologic concept of using bone grafts Contains bone forming cells[ Osteogenesie ] Serve as scaffold for bone formation[ Osteoconduction ] Matrix of bone grafting material contains bone inductive substances[ Osteoinduction ]

8. Osteoconduction Formation of bone by osteoblasts from the margins of the defect on the bone graft material’ Osteoconductive material facilitate bone formation by bridging the gap between the existing bone and a distant location that otherwise would not be occupied by bone.

9. Osteoinduction Cell mediators at the defect[BMP] Stimulation of osteoprogenitor cells Osteoblasts New bone formation

10. Bone Morphogenic Proteins(BMPs) Bone formation by induction at ectopic sites – Urist (1965) BMPs - Group of growth factors and cytokines known for their ability to induce the formation of bone and cartilage. Originally, seven such proteins were discovered.(BMP-2 to BMP-7) - TGF- β proteins family Since then, thirteen more BMPs have been discovered, bringing the total to twenty.

11. Osteogenesis Osteoblasts in the transplanted bone having adequate blood supply and cellular viability. Forms new centers of ossification within the grafts.

12. Use of bone grafts in periodontal defects Autografts Allografts / Homografts Isografts Xenografts / Heterografts Alloplasts

13. Autografts Used in intrabony defects Promotes bone healing through osteogenesis and osteoconduction Can be harvested from intraoral or extraoral donor sites.

14. Autografts from intraoral sites Maxillary tuberosity Exostoses Extraction site Edentulous ridges Mandibular sympysis Osteoplasty osteostomy sites

15. Bone harvested from intraoral sites are Osseous coagulum Bone blend Intra oral bone marrow transplants Bone swaging

16. Osseous coagulum it’s the mixture of bone dust and blood. Bone blend Autoclaved capsule and pestle Its predetermined site and packed in to the defe

17. Bone swaging Existence of an edentulous area adjacent to the defect from which bone is pushed in to contact with the root surface without fracturing the bone at its site.

18. Autografts from the extra oral site

19. Allografts Frozen cancellous illiac bone and marrow Cryopreserved bone from the head of femur Freeze dried bone allograft Dimineralised FDBA

20. FDBA Osteoconductive Cortical bone is deflated and cut in to pieces washed with ab alcohol deep frozen freeze dried and vaccum sealed.

21. DFDBA Decalcified with hcl and washed in sodium phosphate buffer and vaccum sealed and to expose the bone inducing agent. More osteoinductive proteins More osteogenic proteins than FDBA Disadvantage

22. Xenografts ABB[ Anorganic bovine bone] its an osteoconductive . Its architecture similar to human bone. Boplant calf bone Kiel bone calf/ox bone

23. Alloplasts Synthetic inorganic inert material They act as defect fillers Biocompatible Oteogenic potential resorbable in long run absorbable and non absorbable Ex:Bioceramics,Beta Tricalcium phosphate,Hydroxyapetite .

24. Factors affecting bone graft incorporation or resorption – 1.Graft factors – a. Embryological origin – - Membranous bone retain bony mass more than endochondral bone - Endochondral bone show fibrous replacement. b. Nature of bone in graft – - Cancellous bone - large amount of marrow spaces - early revascularization - encorporate better than cortical bones. - Cancellous bone retain some viable bone cells.

25. c. Revascularisation of graft – d. Size of graft – e. Harvest technique – - Atraumatic technique – better take. - Avoid excessive heat while using rotary instruments. - Graft to be placed immediately at recipient site for better take.

26. f. Presence of periosteum – - Reduces reorption & improves incorporation. - Emphasised role of periostium in bone regeneration. { Reid, McCarthy & Kobler (1981), Thaller , Kim & Kawamoto (1989) } Burstein et al (1995) – Three layers of periosteum – Inner – Cambium layer Middle – Osteogenic reserve cells Outer – Vascular network of arterioles & venules Outer layer responsible for early re-vascularization.

27. 2. Recipient factor – a. Age – younger the age better the take b. Recipient site – Graft in contact with bone Vascularity 3. Fixation of graft – Rigid fixation – faster graft healing Wire fixation – fibrous union