44. Regenerative therapy.Guided tissue regeneration

Question 1

Guided Tissue Regeneration (GTR)

Answer 1

• Regenerating periodontal structures lost due to periodontal disease=>
• Barrier membranes direct growth of new bone and periodontal ligament=>
• On root surface previously exposed due to disease

Question 2

Restitutio ad integrum” in the context of GTR

Answer 2

• Complete restoration of periodontal tissue to original state=>
• Formation of alveolar bone, functionally aligned periodontal ligament, and new cementum

Question 3

Materials used for barrier membranes in GTR

Answer 3

• Non-absorbable materials=>
• Polytetrafluoroethylene (PTFE)
• Expanded polytetrafluoroethylene (e-PTFE)=>
• Often reinforced w/ titanium
• Perforated titanium foil
• Bioabsorbable materials=>
• Natural materials=>Collagen membranes from porcine or bovine origin
• Synthetic materials=> Polylactic acid, copolymers of polylactic acid, polyglycolic acid, PEG

Question 4

Requirements for barrier membrane materials in GTR

Answer 4

• Biocompatibility=>No adverse tissue reactions
• Barrier function=>allowing passage of desirable gases and nutrients
• Tissue integration=>Should permit tissue growth into, but not through, membrane
• Maintain space for tissue ingrowth
• Easy to trim and place

Question 5

Characteristics of non-absorbable membranes

Answer 5

• Do not provoke tissue reactions
• Second surgical procedure for removal
• Porous and non-porous options=>titanium foil w/ specific thickness and perforations

Question 6

Characteristics and complications of bioabsorbable membranes

Answer 6

• More compatible than non-absorbable membranes
• Avoid need for second surgery to remove membrane
• Complications=>early degradation, epithelial downgrowth, premature loss of material

Question 7

Synthetic bioabsorbable membranes

Answer 7

• Polylactate acid and its copolymers
• Polyglycolic acid and its copolymers
• Polyglactin (Vicryl)
• PEG

Question 8

Natural bioabsorbable membranes

Answer 8

• Porcine origin=>Jason membrane and Collprotect membrane
• Bovine origin=>Geistlich Bio-Gide®

Question 9

Types of bone replacement grafts used in GTR

Answer 9

• Autologous grafts (autografts)=>patient’s own body
• Isografts=>genetically identical species
• Allografts=>different individuals of same species
• Xenografts=>different species
• Synthetic grafts (alloplasts)=> synthetic materials
• Composite grafts=>combination of different graft materials

Question 10

Autografts

Answer 10

• Same individual
• Osteogenic (4 weeks) osteoconductive and osteoinducive (2-4weeks) potential
• Extraoral=>
• Iliac crest, tibia, fibula, ribs
• Intraoral=>
• Chin, exostoses, torus
• Ramus, tuberosity

Question 11

Isografts

Answer 11

• Genetically identical species

Question 12

Allografts

Answer 12

• Same species
• Osteoinductive potential
• DFDBA=>deminineralised freeze dried bone allograft
• FDBA=>freeze dried bone allograft
• Frozen

Question 13

Alloplasts

Answer 13

• Synthetic
• Osteoconductive
• Hydroxyapatite
• Calcium phosphate cements(CPC)
• Beta-tricalcium phosphate(TCP)
• Biphasic alloplastic materials
• Bioactive glasses
• Synthetic polymers

Question 14

Xenografts

Answer 14

• Different species
• Osteoconductive and osteoinducive potential
• Bovine derived
• Porcine derived
• Coralline calcium carbonate

Question 15

Potential characteristics of bone replacement grafts

Answer 15

• Osteogenesis=>new bone by cells in graft
• Osteoinduction=>new bone through differentiation of mesenchymal cells into osteoprogenitor cells
• Osteoconduction=>new bone by providing a scaffold for bone growth

Question 16

Biologically active regenerative materials used in GTR

Answer 16

• Platelet-derived growth factor (PDGF)
• Transforming growth factor ß1 (TGFß1)
• Fibroblast growth factor (FGF)
• Platelet-rich plasma (PRP)
• Enamel matrix derivative (EMD, such as
• Emdogain®)