bone grafts and implantology Flashcards
4 causes of bone loss
congenital
traumatic
pathology
natural
types of bone graft
5
autogenous
xenograft
allograft
alloplastic
bone bioengineering
autogenous bone grafts
intra-oral: chin, ramus, tuberosity, coronoid process
extra-oral: hip and calvarium
xenograft bone graft
deproteinised bone matrix (Bio-Oss)
allograft bone graft
irradiated sterilised freeze dried bone blocks
alloplastic bone graft
natural sources and synthetic materials (Proplast, HA, TCP, TCS)
bone bioengineering bone grafts
growth factors - bone morphogenic proteins (BMP)
2 important principles of bone grafts
osteoconduction
osteoinduction
osteoconduction
concept of scaffold that supports the bone forming cells
if replacing a peice of bone with something that acts as scaffold only
* higher risk of infction and loss
osteoinduction
osteogenesis is induced through the recruitment of immature cells (UMC) for bone formation
- if replace a piece of bone with something that can stimulate bone foramtion
- better
Bone morphogenetic protein can stimulate bone formation
3 ways graft can be applied for ridge augmentation
onlay
interpositional
sinus lift
onlay graft
material on top of something only (no matter type of matter)
interpositional graft
between 2 pieces of bone
interpositional graft
between 2 pieces of bone
sinus lift graft
underneath or layer cavity
e.g. maxillary sinus occupies most of bony space but require more physical bone for implant placement, so lift sinus lining up and place bone graft
* allows bone heigh to be sufficient for implant, as before would perforate sinus lining abd cause infection
4 surgeries for ridge augmentation
application of bone grafts
inferior dental nerve retraction or laterlisation
distractoin osteogenesis
zygomatic implants
when to do a inferior dnetal nerve retraction/lateralisatoin
when nerve is very superficial and would be perforated if implant placed
where can bone be harvested for graft
autogenos bone graft
4
INTRA ORAL
* chin
* outer cortex of mandible (thick here)
EXRA ORAL
* iliac crest of hip (if need a large amount, pt will need GA)
* calvarium (outer table of skull)
best type of graft
augmentation of bone for implants aims to…
increase height or width of bone (or both) as otherwise compromise foundation
*bone graft, cover up with guided tissue membrane or titanium foil, weight 3-4months before inserting implant
sequence of drills to widen cavity to reach size needed for implant placement *
basic principles of distraction osteogenesis
Osteotomy (location and direction) -cut bone
Latency – wait for blood clot to form at site
Distraction
* Vector, rate and rhythm (v controlled)
* Stretch callus inside between two pieces of bone to allow lengthening process to happen
* 1mm a day
* can have multi-directional movement (vertical, medial, lateral)
Consolidation
Remodelling
*timely - need cooperation (distract, consolidate and remodel phase)
Can be used to gain height over mental foramen so implant not cut mental nerve and cause loss in sensation*
lengthen bone without any graft
4 indications for zygomatic implants
- Sever maxillary atrophy
- Sinus pneumotization
- Avoid harvesting of bone graft (sinus lift)
- Hemimaxillectomy (no maxilla due to cancer)
Insert behind maxillary sinus, higher entry
Build superstructure on top
BMPs are
bone morphogenic proteins
cytokines
bone bioengineering stages
- Active osteoinductive factors, extra cellular protein and stored in bone matrix
- 15 BMPs, BMP2, BMP4, BMP7 induce bone formation
- Convert UMCs (immature cells) into osteoblasts, stimulate angiogenesis
*trauma – release cytokines, some are BMP, call cells on body to form osteoblasts and bone
* theory that you can inject BMP to make bone - mimic trauma process *
used for cleft lip and palate
