Bone grafting and Implantology Flashcards
What is a Dental implant?
titanium screw inserted into bone (heals via osteointegration)
-> crown inserted on top after healing
What is the minimum amount of healthy bone required for a normal dental implant?
10mm
What are the types of bone loss?
- Congenital- born without sufficient bone levels (CLP, hypodontia)
- Traumatic
- Pathology
- Natural- physiological, occurs with age
What are the types of bone grafts?
Autogenous- IO/EO
Xenograft (from animals)- as deproteinised bone matrix (bio-oss)
Allograft- irradiated sterilised freeze dried bone blocks
Alloplastic- natural sources and synthetic materials (HA, proplast, TCP, TCS)
Bone bioengineering- bone growth factors (bone morphogenic protein)
What are the intraoral sites for autogenous bone grafts?
Chin
Tuberosity
Ramus
Coronoid process
What are the EO sites for autogenous bone grafts?
Hip
Calvarium
What are the 2 different strategies in bone grafting?
Osteoconduction- replace tissue with scaffold that supports bone forming cells
-> higher risk of infection and loss
Osteoinduction- If material itself can stimulate bone formation- induces undifferentiated mesenchymal cells to change into osteoblasts (form bone)
What are the different means of bone augmentation?
Application of grafts- onlay, interpositional, sinus lift
Inferior dental nerve retraction/lateralisation
-> moving nerve during procedure into a new position
Distraction osteogenesis
Zygomatic implants
What is an onlay graft?
When grafting material is applied on top of bone
What is an interpositional graft?
When graft is applied between 2 pieces/tables of bone
-> increases bone height
-> covered with bio-oss and guided tissue regeneration membrane
Why may a sinus lift be used?
If maxillary sinus occupies most of bone in area of the maxilla you want to place implant (don’t want to perforate)
Relocate sinus lining/membrane upwards and then graft underneath
What are the steps in a sinus lift?
Expose outer cortex
Lift sinus mebrane
Apply bone graft
Add bio-oss (xenographic)
Cover everything with guided tissue regeneration membrane
How is a bone graft from chin harvested and used for bone augmentation?
Harvest bone from chin if not enough bone in maxilla
Raise mucoperiosteal flap, cut outer table of mandible with surgical drill or surgical saw (stay away from mental nerves), take this bone and put in maxilla (reconstruct deficient bone in this region)
Some can be done with LA but most with GA
Insert implant when healed
-> same principles apply to outer cortex of mandible (good graft site due to thickness)
What part of the hip bone is used in grafts? When is this used?
Medial cortex of the ileac crest
If massive bony deficiency
Why is harvesting bone from the skull a good option?
Cortical membranous bone- less chance of infection or resorption is less
What is the use of the milling machine when doing bone augmentation?
Produces putty stage used to augment deficient bone
What are the steps in in inserting an implant
Sequence of drills go through bone and then widening
-> Pilot drill, widening drill, then size of drill which is compatible with implant
Load dental implant (pure titanium)
Apply healing cap
After 4-6 months it is ready to receive crown (should last 20 years- success rate is over 90%)
What is the issue with bone in hypodontia patients?
Can be deficient- thin and lacking in height
What is done to augment bone in hypodontia patients?
Bone augmentation and orthognathic surgeries may both be required
-> graft is taken from chin and covered with GTRM and titanium foil
Which condition can result in loss of bone and need for augmentation before placing implants?
Central giant cell granuloma
What is the advantage of distraction osteogenesis?
Allows bone lengthening/augmentation without using grafts
-> can be in multiple directions- vertical, horizontal, medial, lateral
Can prevent damage of mental nerve
How is distraction osteogenesis carried out?
Cut bone (osteotomy)
Wait until blood clot forms at site
Using distractor device stretch callous between pieces of bone to allow lengthening process to happen (allows remodelling process and bone formation- lengthen callous at rate of 1mm per day)
-> Leave double the lengthening time to allow bone to consolidate after you have achieved desired length
When is retraction of IAN considered?
If you cannot augment or use distraction osteogenesis
What are the indications for zygomatic implants?
Severe maxillary atrophy
Sinus is large or patient does not want sinus lift
Avoid harvesting of bone graft
-> patient may not want this
Hemimaxillectomy (due to cancer)- patient is missing large parts of their maxilla
For retention of a denture
What are the different about zygomatic implants?
They are longer- around 55mm
What is BMP? What is its use in implantology?
Cytokine which responds to trauma within bone and cause osteoinduction
-> convert UMCs into osteoblasts AND stimulate angiogenesis
Can be injected into area you want to augment to stimulate bone augmentation
Which BMPs induce osteogenesis?
BMP2, 4, 7
When may bioengineering using BMPs be utilised?
On patients with CLP who are receiving surgery at a young age
-> other bone augmentation surgeries deemed inappropriate due to age
