Lecture 5 - OMFS (Exam2): Surgical Reconstruction of Maxillofacial Defects

- Pathological Conditions

- Trauma

- Infection

- Congenital and Acquired Deformities

What are 4 Causes of Maxillofacial Defects:

osteogenesis

the formation and development of bone:

osteoinduction

the process of stimulating osteogenesis Recruitment of mesenchymal cells from surrounding bed that further differentiate (bone may even grow or extend into an area where is not normally found):

chemotaxis - mitosis - differentiation

What are the 3 phases of osteoinduction:

osteoconduction

the act of providing a physical matrix or scaffolding suitable for deposition of new bone. An in-growth process from recipient bed into structure of graft:

the amount of transplanted cells that survive the grafting procedure

The Two-Phase Theory of Osteogenesis states:

-Initially from the transplanted cells in the graft that proliferate and form new osteoid. The amount of bone regenerated during this phase depends on :

diffusion of nutrients from the surrounding graft bed

The Two-Phase Theory of Osteogenesis states:

-The amount of bone regenerated during this phase depends on the amount of transplanted cells that survive the grafting procedure. The cells depend on :

T-Lymphocytes

If graft is between different individuals or species, the graft will be recognized as a foreign substance and will mount an intense response . It is a cell-mediated response by_______

true

t/f: Tissue typing is common place for organ transplantation, but never for bone grafts

- true

- false

10cc

for each 1cm defect, we need ______cc cancellous bone

- 1cc

- 10cc

- 100cc

- 1000cc

decrease

radiotherapy or excessive scarring from trauma or infection will _____ the vascularity

Allogeneic Grafts

graft taken from another individual of the same species:

osteogeneic cells

allograph materials are treated to destroy any remaining ________ in the graft

phase II

allograph materials provide hard tissue matrix for _____ induction

Xenogeneic Grafts

Graft tissue taken from another species (animal source):

greater

Xenogeneic Grafts have _______ antigenic dissimilarity than allogeneic

Xenogeneic Grafts

ID the type of graft:

-Advantages: Do not require another site of operation in the host (donor site) & a large quantity of bone can be obtained

-Disadvantages: Do not provide viable cells for phase I osteogenesis & must be rigorously treated to reduce antigenicity

Autogenous Grafts

What is the Gold Standard for Bone Grafting Materials:

- Allogenic Grafts

- Xenogenic Grafts

- Alloplastic material

- Autogenous Grafts

Low resorption rate

All of the following is true about xenografic demineralized bone EXCEPT:

- Has osteoinductive potential (contains BMPs)

- Poor physical characteristics

- Low resorption rate

demineralized bone

-Has osteoinductive potential (contains BMPs)

-Poor physical characteristics

-High resorption rate

deproteinated bone

-Crystalline carbonated apatite

-Free of antigenicity

-Osteoconductive material

-Overall porocity: 70-75 % (space left for regeneration of new bone

-Undergoes remodeling (osteoclass indentified on Bio-Oss surface)

Allogenic Grafts

hydroxyapatite is what type of grafting material?

- Allogenic Grafts

- Xenogenic Grafts

- Alloplastic material

- Autogenous Grafts

Autogenous Grafts

Graft tissue taken from the same person:

Autogenous Grafts

- is the most ideal bone graft material

-No immunologic response

-more cells survive the transplation because of the access they have to nutrients in the surrounding graft bed

-supplies living, immunocompatible bone cells essential to phase I osteogenesis

angle of mandible

all are autogenous graft donor sites available in intra-oral regions except?

- angle of mandible

- mentum (chin)

- retromolar area

- mandibular tori

- maxillary tuberosity

Posterior iliac crest

Which location can you obtain the MOST ccs of autogenous bone material:

- Anterior iliac crest

- Posterior iliac crest

- Calvarium

- Single rib

- Tibia

4, 2

Cancellous bone from ilium: __ times the ostoegenic cellularity of cortical bone and ___ times that of other cancellous sources

incision technique

all the following will decrease vascularity of recipient site except:

- radiotherapy

- incision technique

- excessive scarring from trauma

- infection

complex

for intraoral grafting, options for types of graft include all the following except:

- particulate

- block

- complex

- combination

Restoration of Aesthetics

All of the following are Goals & Principles of Mandibular Reconstruction, EXCEPT:

- Restoration of Continuity

- Restoration of Aesthetics

- Restoration of Alveolar Bone Height

- Restoration of Osseous Bulk

-Control of residual mandibular segments

-A good soft tissue bed for the bone graft

-Immobilization of the graft

-Aseptic environment

-Systemic antibiotics

What are the Surgical Principles of Maxillofacial Bone-Grafting Procedures:

soft tissues

All bone grafts need to be covered on all sides by ______ to avoid contamination and to provide the nutrients necessary for revascularization of the graft

excised

Areas of dense scars should be ____ until healthy tissue is encountered

false

t/f: Incisions should be designed so that they can be closed over the graft

- true

- false

true

t/f: More successful grafting of large defects are done extraorally vs intraorally

oral cavity

You want to avoid perforation into the ______ while performing an extraoral approach

complete return to adequate function with appropriate aesthetic results

A successful reconstruction =

maxillary reconstruction

________ cases are best solved with a surgical obturator

- maxillary reconstruction

- mandibular reconstruction

-avoid contamination

- provide necessary nutrients for revascularization and consolidation of the graft

why do bone grafts need to be covered by soft tissues?

30 - 50 cc

About how much bone can you get from the Anterior iliac crest?

- 30 - 50 cc

- 60 - 80 cc

- 20 - 25 cc

- 10 - 15 cc

- 15 - 40 cc

60 - 80 cc

About how much bone can you get from the Posterior iliac crest?

- 30 - 50 cc

- 60 - 80 cc

- 20 - 25 cc

- 10 - 15 cc

- 15 - 40 cc

20 - 25 cc

About how much bone can you get from the Calavrium?

- 30 - 50 cc

- 60 - 80 cc

- 20 - 25 cc

- 10 - 15 cc

- 15 - 40 cc

10 - 15 cc

About how much bone can you get from a single rib?

- 30 - 50 cc

- 60 - 80 cc

- 20 - 25 cc

- 10 - 15 cc

- 15 - 40 cc

15 - 40 cc

About how much bone can you get from a tibia?

- 30 - 50 cc

- 60 - 80 cc

- 20 - 25 cc

- 10 - 15 cc

- 15 - 40 cc

fibula

iliac crest

scapula

Free grafts can be obtained from what locations: