bone grafts and implantology

Question 1

Name the 4 causes of bone loss

Answer 1

Congenital
Traumatic
Pathology
Natural

Question 2

What are the 4 types of bone graft?

Answer 2

Autogenous - derived from patients own bone
Xenograft - derived from a different species, typically animals
Allograft - derived from a human donor that is not the patient
Alloplastic - composed of synthetic materials

Question 3

Where are autogenous bone grafts often taken from?

Answer 3

Intra-oral - chin, ramus, tuberosity, coronoid process
Extra-oral - iliac crest in hip and calvarium (top of skull)

Question 4

What is often used for xenograft?

Answer 4

Deproteinised bone matrix (Bio-Oss)

Question 5

What are the principles of grafting?

Answer 5

Osteoconduction - the concept of scaffold that supports the bone forming cells
Osteoinduction - osteogenesis is induced through the recruitment of immature cells (UMC) for bone formation

Question 6

Name 4 local sites used for bone grafts

Answer 6

Chin
Ramus
Tuberosity
Coronoid process

Question 7

Name 2 distant sites used for bone grafts

Answer 7

Iliac crest - most common donor site
Calvarium

Question 8

What is Bio-Oss used for?

Answer 8

To minimise resorption

Question 9

What is a bone mill used for?

Answer 9

Crushes bone into multiple small pieces so it can be used as a putty into areas of defect

Question 10

What is applied after Bio-Oss?

Answer 10

Guided tissue regeneration membrane

Question 11

What is an interpositional graft?

Answer 11

Bone graft applied between the inner and outer cortex to increase bone width

Question 12

What does the site of bone graft depend on?

Answer 12

Patient preference
Availability of bone based on CBCT
Position of mental foramen and inferior alveolar nerve
Size of bone needed

Question 13

What process do you want to happen after placing an implant?

Answer 13

Osteointegration

Question 14

What is distraction osteogenesis?

Answer 14

Cutting the bone (osteotomy), separating it to create a gap and then stretching the soft tissue to form bone from within

Question 15

What is nerve lateralisation?

Answer 15

Putting a suture around the inferior alveolar nerve and moving it laterally so an implant can be placed without any damage to the nerve

Question 16

What are the steps of distraction osteogenesis?

Answer 16

Osteotomy
Latency - waiting for inflammatory cells to come into the area and for soft tissue healing
Distraction (lengthening)
Consolidation - leave device in to hold bone in place
Remodelling

Question 17

How is lengthening carried out in distraction osteogenesis?

Answer 17

Using a device, a key is turned so that there is 1mm movement per day, 0.5mm in the morning, 0.5mm in the afternoon
The vector of movement needs to be considered ie - vertically, buccally or lingually

Question 18

Why is 1mm the max movement per day in distraction osteogenesis?

Answer 18

Any more would result in fibrous healing

Question 19

What are the 4 indications for zygomatic implants?

Answer 19

Severe maxillary atrophy
Sinus pneumatization (increase in volume)
Avoids harvesting of bone graft
Hemimaxillectomy

Question 20

What is Bone Morphogenic Protein (BMPs)? and how does it work?

Answer 20

Active osteoinductive factors, extra-cellular protein that is stored in bone matrix
Contains cytokines 15BMP, BMP2, BMP4 and BMP7 to induce bone formation
Converts UMCs into osteoblasts, stimulating angiogenesis