Guided Bone Regeneration

Question 1

Ridge Augmentation Techniques

Answer 1

• Distraction Osteogenesis
  
  • high risk of infection & failure
• Guided Bone Regeneration (GBR)
• Block Autograft
• Block Allograft
• Ridge Split Techniques
• Combination

Question 2

GBR vs GTR

Answer 2

• GBR
  
  • on edentulous ridges
• GTR
  
  • around teeth

Question 3

Guided Bone Regeneration

Answer 3

• Use barrier membranes to direct growth of new bone & soft tissue
  
  • sites w/insufficient volumes or dimensions
  • used for fxn, esthetics, or restoration
• Based on Guided Tissue Regeneration (GTR) principles
• Introduced by Dahlin
  
  • rats
  • 1988

Question 4

GBR Regeneration Process

Answer 4

1. Blood Clot
2. Angiogenesis
   
   1. develop new blood vessels
3. Granulation Tissue
4. Osteogenic cells migrate
   
   1. periphery→center
5. Deposits woven bone
6. Lamellar bone forms
7. Remodeling
   
   1. resembles bone growth

Question 5

GBR: PASS Principle

Answer 5

• Primary Closure
  
  • periosteal releasing incision
  • remove membranes after 4-6 mos
• Angiogenesis (Blood Flow)
  
  • formation of new BVs
• Stability
  
  • Suture and anchor membrane and flaps
• Space Maintenance
  
  • membrane b/w bone graft and gingiva

Question 6

What is the Principle of Combination Therapy

Answer 6

• Membrane
  
  • provides barrier
• Graft
  
  • scaffold
  • space maintenance

Question 7

Ideal Membrane Characteristics

Answer 7

• Biocompatible
• Cell Occlusiveness
• Tissue Integration
  
  • protect blood clot
  • wound stabilized
• Space making
  
  • for progenitor cells
• Manage Clinical
• Facilitate migration and proliferation of progenitor cells
• Bacterial infection resistant

Question 8

Types of Barrier Membranes

Answer 8

• Non-Resorbable
  
  • ePTFE, dPTFE
    
    • socket grafting)
  • Millipore
    
    • Cellulose acetate
  • Titanium
• Resorbable:
  
  • Collagen
  • Synthetic: PLA, PGA, PLGA
  • ADM

Question 9

New Membranes

Answer 9

• Alginate
• New degradable copolymers
• Hybrid or nanofibrous membranes
• Amniotic membranes

Question 10

Porosity Principle

Answer 10

• Porosity
  
  • 50-100 um → Bone ingrowth
  • > 100 um (101-150)→ High vascular tissue
  • > 150 um→ Bone with osteons

Question 11

GBR: Other Principles

Answer 11

• Thin layer of soft-tissue ingrowth
  
  • under the membrane
  • initial blood clot shrinks→air entrapped or membrane micromovement
• Micromovement:
  
  • Fibrous Tissue

Question 12

Osteogenesis

Answer 12

• cells in graft form new bone

Question 13

Osteoinduction

Answer 13

• Chemical Process
• BMPs convert neighboring cells→ osteoblasts→form Bone
  
  • BMPs=molecules in graft

Question 14

Osteoconduction

Answer 14

• Physical Effect
• Graft Matrix forms scaffold
  
  • outside cells penetrate the graft → form new bone

Question 15

Osteopromotion

Answer 15

• Materials that support:
  
  • wound healing
  • tissue regeneration
• do not initiate de novo tissue formation

Question 16

Autograft

Answer 16

• Same person
• intraoral or extraoral
  
  • tuberosity, chin, ramus, calvarium, tibia, iliac crest
• osteogenesis
• osteoconduction
• osteoinduction

Question 17

Allograft

Answer 17

• From a different person
• DFDBA, DFBA, Puros
• Osteoinductive
• Osteoconductive

Question 18

Xenograft

Answer 18

• From a different species
• Bovine (Bio-Oss), Horse (Equimatrix)
• Osteoconductive

Question 19

Alloplasts

Answer 19

• Synthetic
• GEM21
• osteoinductive
• osteoconductive

Question 20

Growth Factors

Answer 20

• GFs
  
  • rhBMP2
  • PDGF-BB
  • FGF2
• Controversial Evidence
  
  • Rapid Clearance→ insufficient GF conc in bone defects
  • Deliver w/supra-physiological non-standard doses → therapeutic efficacy

Question 21

Neo-osteogenesis

Answer 21

• de novo bone formation beyond genetic skeletal envelope
• achieved by applying GBR principle

Question 22

Factors that Influence GBR Success

Answer 22

• Patient Factors
  
  • smoking
• Excessive Swelling
• Passive Flap tension
• Cortical Penetration
• Defect morphology
  
  • length
  • angle
• Membrane fixation
• Materials used
• Horizontal Augmentation
  
  • predictable and successful
• Vertical Augmentation
  
  • More challenging
  • Less than horizontal gain
  • Decreased implant success & survival

Question 23

Block Graft

Answer 23

• Block Graft vs GBR
  
  • Greater Ridge Width Gain
  • Lower Implant Success
• Block Graft vs Autogenous Particular Graft
  
  • Greater:
    
    • bone to implant contact
    • Bone Fill
  • Less Mean height Gain

Question 24

Khoury’s Split Bone Block Technique

Answer 24

• Bone Block + GBR

Question 25

Ti-Mesh Membranes

Answer 25

• Titanium Meshes
• used w/particulate bone for large defects
• oxide layer promotes
  
  • cell colonization
  • differentiation of osteogenic lines
• Not mainstrem
  
  • technique sensitive
  • Cost

Question 26

Alveolar Ridge Split (ARS)

Answer 26

• Aka:
  
  • alveolar corticotomy
  • ERE-edentulous ridge expansion
• Splits crest cortical bone
  
  • creates horizontal dimensions for immediate or delayed implant placement
• can be combined with GBR
• Only D3 or D4 bone Types

Question 27

Alveolar Ridge Split: 4 Anatomical Requirements

Answer 27

• Minimal horizontal bone width= 2 mm
• Minimal Vertical Bone Height=10 mm
• No concavity
• Horizontal osteotomes ≥ 1mm from tooth