bone grafts and implantology

Question 1

4 causes of bone loss

Answer 1

congenital

traumatic

pathology

natural

Question 2

types of bone graft

5

Answer 2

autogenous

xenograft

allograft

alloplastic

bone bioengineering

Question 3

autogenous bone grafts

Answer 3

intra-oral: chin, ramus, tuberosity, coronoid process

extra-oral: hip and calvarium

Question 4

xenograft bone graft

Answer 4

deproteinised bone matrix (Bio-Oss)

Question 5

allograft bone graft

Answer 5

irradiated sterilised freeze dried bone blocks

Question 6

alloplastic bone graft

Answer 6

natural sources and synthetic materials (Proplast, HA, TCP, TCS)

Question 7

bone bioengineering bone grafts

Answer 7

growth factors - bone morphogenic proteins (BMP)

Question 8

2 important principles of bone grafts

Answer 8

osteoconduction

osteoinduction

Question 9

osteoconduction

Answer 9

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

Question 10

osteoinduction

Answer 10

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

Question 11

3 ways graft can be applied for ridge augmentation

Answer 11

onlay

interpositional

sinus lift

Question 12

onlay graft

Answer 12

material on top of something only (no matter type of matter)

Question 13

interpositional graft

Answer 13

between 2 pieces of bone

Question 14

interpositional graft

Answer 14

between 2 pieces of bone

Question 15

sinus lift graft

Answer 15

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

Question 16

4 surgeries for ridge augmentation

Answer 16

application of bone grafts

inferior dental nerve retraction or laterlisation

distractoin osteogenesis

zygomatic implants

Question 17

when to do a inferior dnetal nerve retraction/lateralisatoin

Answer 17

when nerve is very superficial and would be perforated if implant placed

Question 18

where can bone be harvested for graft

autogenos bone graft
4

Answer 18

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

Question 19

augmentation of bone for implants aims to…

Answer 19

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 *

Question 20

basic principles of distraction osteogenesis

Answer 20

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

Question 21

4 indications for zygomatic implants

Answer 21

• 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

Question 22

BMPs are

Answer 22

bone morphogenic proteins

cytokines

Question 23

bone bioengineering stages

Answer 23

• 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