W6 - Surgical Implantology - Tulio Flashcards
How can temp crowns be used for preprosthetic surgery
Different contours of temp crowns can be used to reshape soft tissues
- Correct future emergence profiles
What are factors for planning proshetic design? (process) (5)
Aesthetics
Perio health
Tissue reconstruction
Support, stability, retention needs
Strategies to achieve proper bone augmentation (5)
- GBR
- Bone block grafts
- Distraction osteogenesis
- Sinus lift
- Transposition of IAN
Absolute contraindications of implant placement
Recent radiotherapy pt of head/neck (angiogenesis affected, difficult to heal, fragile bone)
Principle of GBR (4)
Exclude soft tissue
space maintenance
clot stabilization
Bone particles placed for regeneration
Advantages and disadvantages of GBR
Pros:
Graft availability
Good for horizontal bone defects
Cons:
Decreased osteoinduction
Low predictability in vertical defects
Lack of tissue integration with titanium reinforced membranes
What happens if an implant is placed when there is severe bone loss
Long implant screw
crown will appear very long
- May require pink porcelain
- Unaesthetic
- Unstable
What are the 2 sinus lift techniques
Lateral technique
Transalveolar technique aka summers technique
Need at least 6mm of bone to place implant and graft for summers technique, otherwise do lateral technique
How does smile change as you age? (3)
- More of lower teeth shown
- Loose collagen and tension in skin (not as elastic)
- Smile curves more downwards
What are partial contraindications for implants? (2)
- Osteoporosis (fragile bone- if you drill bone it will be soft. Healing will be delayed- reduced osseointegration)
- Uncontrolled diabetes
How to do GBR (4)
Perforate surface to create bleeding from base of bone
Mix bone particles
Place membrane on top to isolate soft tissues out
Suture
What is the lateral sinus lift (4 steps)? Indication?
Indicated when there is pneumatisation of mx sinus
- Buccal window made in posterior mx bone
- Careful elevation of sinus epithelium
- Place bone graft without perforating membrane
- Wait 4-5 months and place implant
What can happen to lip if prosthesis is too far B?
Lip can evert
What factors influence whether pts condition is relative or absolute contraindication for implants?
Type of prosthesis
Age of patient
Location of prosthesis (ex. 16 and 26 bone is porous- avoid implant placement if pt has osteoporosis)
What is the purpose of having titanium reinforced skeleton for GBR?
Maintains size and shape to prevent tissue shrinkage
What can happen if membrane is not placed in bone defect?
Soft tissue occupies defect and collapses
More fibour tissue rather than bone
What are the types of membranes? (3)
Natural polymer
Synthetic polymer
Metal
What are bioactive molecules? Downside?
BMP-2
Triggers bone formation and increases angiogenesis
- Expensive
What are hemiderivates? (graft) Challenge?
Autologous growth factors obtained from blood after centrifugation (ex. PRF)
- can make graft more biocompatible and triggers more bone formation
Challenge: biological variability, difficulty tailoriing degradation rate
What is the basic concept of bone tissue engineering
Relies on combination of cells, engineering materials (scaffold) and suitable biochemical factors to repair damaged tissues and organs
What can scaffolds be made of?
Bioceramics: Bi-calcium Phosphate (BCP), hydroxyapatite
Polymers:
(natural- collagen fibrin, cellulose) or Synthetic (PCL, PEG)
Then do surface modification (coat with CaPO4) to trigger bone formation
Can do this to avoid need for autogenous bone graft.
What is the role of cells on bone tissue engineering?
MSC’s proliferate and differentiate into osteoblasts and fibroblasts
What are autologous bone blocks used for?
Can be used for large defects (rather than using particular bone graft)
What are tissue bank bone block grafts? (2)
- Sterilized and preserved
- Retains osteoconductive properties
What is the issue with screws being placed on tissue bank bone blocks?
More bone is placed than necessary as the bone resorbs substantially
Bone graft is screwed into place and will protrude out of bone block graft and can impinge on soft tissues as bone resorbs
What is transalveolar/summer sinus lift?
Used when there is some height of bone but not enough
- Drill across alveolus from top
- Push membrane of sinus up
- Place bone graft
- Place implant
Example of cells used in tissue engineering (3)
MSC
Osteoblast
Endothelial progenitor cell
What is the role of biochemical factors in bone tissue engineering
Stimulate cellular response
Differentiate MSCs in bone cells lineage
Angiogenesis
Ex. BMP-2
Advantages of Bone Tissue engineering (4)
Biocompatibility
Space maintenance
Good for Vertical bone defects
Good tissue integration
Challenges of Bone tissue engineering
Tailoring degradation rate
Soft tissue engineering
