Periodontal Regeneration

Question 1

Define regeneration and repair

Answer 1

Regeneration: reconstitution of new periodontium (alveolar bone, PDL, and cementum).

Repair: healing by replacement with epithelial and/or connective tissue that matures to various nonfunctional types of scar tissue is termed new attachment.

Histologically it includes long junctional epithelium, ankyloses, and/or new attachment The ideal goal of periodontal surgical therapy is periodontal regeneration

Question 2

What are reconstructive surgical techniques?

Answer 2

1. Non-bone graft-associated.
2. Graft-associated.
3. Biologic mediator-associated new attachment and regeneration

Question 3

All recommenced in regenerative therapy techniques must have:

Answer 3

1. careful case selection.
2. Complete removal of all irritants on the root surface.
3. Occlusal adjustment or splinting if needed ,is indicated
4. Systemic antibiotics.

Flap design and incisions should follow the description given for flaps used in reconstructive surgery (papilla preservation flap).

Question 4

What are types of guided tissue regeneration?

Answer 4

1. Nonresorbable membrane: e.g. polytetrafluoroethylene (PTFE), PTFE Titanium reinforced Disadvange:
   a. Membrane exposure, which result in no or limited regeneration.
   b. Need for secondary procedure for surgical removal
2. Biodegradable(Resorbable):e.g. Bio-Gide(collagen)

Question 5

What are advantages and disadvantages of Biodegradable(Resorbable):e.g guided tissue regeneration?

Answer 5

Advantages

a. Reduce operatory time More tissue compatibility Increase patient acceptance
b. Elimination of second surgery for barrier removal Reduces risk of loss of regenerated attachment owing to reentry surgery.

Disadvantages

a. Instability of barrier
b. Membrane degradation products can affect the process of tissue regeneration.
c. Risk of cross-infection in membranes of animal origin.
d. Lack of stiffness-collapse of membrane.

Question 6

What classification of bone graft material by origin

Answer 6

Classifications of bone graft material Grafts are either categorized by their origins and function during healing. Categorization by origin include:

1. autografts are bone obtained from the same individual.
2. allografts are bone obtained from a different individual of the same species.
3. xenografts are bone from a different species.

Question 7

Talk about bone allografts

Answer 7

Bone allografts are commercially available from tissue banks. They are obtained from cortical bone within 12 hours of the death of the donor, defatted, cut in pieces, washed in absolute alcohol, and deepfrozen. The material may then be demineralized, and subsequently ground and sieved to a particle size of 250 to 750 μm and freeze-dried. Finally, it is vacuum-sealed in glass vials. Numerous steps are also taken to eliminate viral infectivity. e.g. Freeze-Dried Bone Allograft(FDBA), Demineralized Freeze-Dried Bone Allograft(DFDBA).

Studies provided strong evidence that DFDBA in periodontal defects results in significant probing depth reduction, attachment level gain, and osseous regeneration.

The combination of DFDBA and GTR has also proved to be very successful.

Question 8

Talk about xenografts

Answer 8

Currently, an anorganic, bovine-derived bone marketed under the brand name Bio-Oss (Osteohealth) has been successfully used both for periodontal defects and in implant surgery.

Both allografts and xenografts are foreign to the patient and, therefore, have the potential to provoke an immune response. Attempts have been made to suppress the antigenic potential of allografts and xenografts by radiation, freezing, and chemical treatment.

Question 9

Talk about osteogenic, osteoinductive, or osteoconductive potential.

Answer 9

Osteogenesis refers to the formation or development of new bone by cells contained in the graft.

Osteoinduction is a chemical process by which molecules contained in the graft (e.g., bone morphogenetic proteins) convert the neighboring cells into osteoblasts, which in turn form bone.

Osteoconduction is a physical effect by which the matrix of the graft forms a scaffold that favors outside cells to penetrate the graft and form new bone.

All grafting techniques require presurgical scaling, occlusal adjustment as needed, and exposure of the defect with a full-thickness flap. The flap technique best suited for grafting purposes is the papilla preservation flap because it provides complete coverage of the interdental area after suturing). The use of antibiotics after the procedure is generally recommended.

Question 10

Talk about tissue engineering wiry biologic mediators

Answer 10

In wound healing, the natural healing process usually results in tissue scaring or repair. By using Tissue engineering ——> tissue regeneration

Question 11

Tissue engeneering is the manipulation of one or more of the three elements:

Answer 11

1. Signaling molecules: platelete derived growth factor (PDGF), bone morphogenic protein(BMP).
2. Scaffold or supporting material e.g. CaPo4, collagen.
3. Cells e.g. osteoblast, fibroblast.

Successful tissue engineering requires interplay among three components: Implanted & cultured cells that will create new tissue; Biomaterial to act as scaffold or matrix to hold cells; Biological signaling molecules that instruct cells to form desired tissue type.