Dental Implants and Bone Augmentation Flashcards
What are the 4 parts of an implant?
crown
abutment screw
abutment
implant
What are the 3 types of implant materials?
- titanium alloys
- zirconium
- tantalum
Who discovered Osseointegration? How did they do this?
P.I. Branemark from Sweden in 1952
- titanium chambers inserted in a rabbit femur became firmly fixed to the bone and could not be removed
- living bone could become so fused with the titanium oxide layer of the implant that the two could not be separated without fracture
- fractures occurred between bone and bone (not bone and implant)
Define osseointegration
- a direct functional and structural connection between living bone and the surface of a load carrying implant
- a process whereby clinically asymptomatic rigid fixation of alloplastic materials is achieved and maintained in bone during functional loading
What is the minimum bone thickness required for an implant (F-L: faciolingual)?
2 mm facial bone thickness
What happens if the bone thickness is not 2 mm?
- increased frequency and extend of vertical bone loss
- resorption following integration which may expose implant surface (i.e., esthetic problem)
What is the minimum bone thickness required for an implant (M-D: mesodistal)?
1.5 mm between implant and tooth
3 mm between implants
What is guided bone regeneration?
surgical procedure that utilizes barrier membranes to mechanically exclude the undesirable soft tissues from growing into the osseous defect, allowing only osteogenic cells from the parent bone to repopulate the wound space
What are the guided bone regeneration (GBR) principles?
Primary closure
Angiogenesis
Support
Stability
What is angiogenesis?
decortication and regional acceleratory phenomenon (RAP)
- allows bleeding from marrow spaces, quicker revascularization
- vascular ingrowth may promote neogenic bone formation
- increases regional accelerated phenomeonon (RAP)
- improves graft union
Describe support/membrane fixation
- micro-motion soft tissue layer under the membrane
- inadequate stabilization, loss of wound space-fibrous encapsulation
- suturing of the flap can displace the graft
- tacking membrane reduces graft collapse by 50% following suturing
- fixation increases grafting success
What are the recommended support/membrane fixation systems?
- meisinger master pin
- self tapping miniscrews (pro-fix osteogenics)
What is osteoconduction?
provide space and substratum for the cellular and biomechanical events progressing to bone formation
What is osteogenesis?
direct transfer of vital cells to the area that will regenerate new bone
What is the problem with autograft bone grafts?
because its from yourself you will see lots of resorption
-35-51% horizontal resorption
- 81% volume loss over 2 years
What happens if you add autogenous bone to bone substitutes?
- produces greater gain
- shows less graft volume reduction in the longer term
Bone grafts release 43 different growth factors including
- TGFB1 and 2
- osteoblast stimulating factor I
- BMP
What are the types of defect characteristics?
- horizontal
- vertical
- combinations (both horizontal and vertical
- intrabony defect (in the bone)
- extrabony defect (outside the bone)
What are the horizontal expectations for particulate bone grafts (GBR), autogenous bone grafts, and ridge splits?
Describe the defect characteristic
- bone graft heals from outside in
- regenerative capacity comes from the existing bony walls
- 4 wall defect = rapid bone formation
- 1 wall defect = slow bone formation
- success = volume stability and time
What do you do if you have a 2-3 wall small defect?
fixation not always necessary, collagen membrane
What do you do if you have a large defect?
membrane fixation, consider non-resorbable membrane, consider growth factors, 50:50 AB:DBBM
Describe d-PTFE membrane
*nonresorpable
- dense polytetrafluoroethylene (teflon)
- pore size <0.3 micrometers, bacterial size is 1-5 micrometers
- can be left exposed to oral environment
- when fixed, offers excellent stabilization to underlying graft
Where is a block graft taken from?
symphysis, ramus/external oblique ridge
What are the vertical augmentation options?
- guided bone regeneration (GBR)
- block/only graft
- distraction osteogenesis
- interpositional graft
What are the 2 sinus elevation approaches?
- vertical approach
- lateral approach (gains more bone)
What is the vertical sinus elevation approach?
uses the osteotome technique
- percussion and hyperextension of the neck can dislodge otoliths and induce vertigo
- difficult to asses membrane tears
What is the lateral window technique?
- 6-9 months of healing depending on size of graft
- longer it heals, more bone available
