Surgical Aspects of Implants Flashcards
What is pre-implant surgery?
Surgery done prior to implant going in to ensure environment is suitable for implant
Usually augmentation - bone will have dissolved away and will need to be replaced
Why do pre-implant surgery?
Too little bone to support implant in an acceptable position
Too much bone (rare) - ridge reduction
Why reduce the ridge?
Bone of poor quality (too thin - if reduce ridge = bone gets thicker)
Additional restorative space
Augmentation techniques?
Sinus lift Block graft Guided bone regeneration Ridge split Zygomatics Use of narrow/short implants
Types of augmentation?
Autograft - pinch a bit of bone (bone shaving) from somewhere else on the same patient
Allograft - get bone from someone else
Xenograft - get bone from an animal
Inorganic material - beta TCP and HAP (hydroxyapatite) (used for religious region)
What is osseoinduction?
Promotes bone formation
What is osseoconduction?
A scaffold
What techniques increase the bone width?
Guided bone regeneration
Ridge split
Block graft
Narrow/angled implants
What techniques increase bone height?
Onlay graft (still a block graft) (does not work very well) Inlay graft Osseodistraction Short implants/all on 4 Zygomatic implants
What are the principles/stages of bone augmentation?
Plan - Diagnostic wax up - Stents
Raise flap and distress surface (evaluate and stimulate graft site)
= angiogenesis created (new BVs created) = path for new BVs to supply new bone
= also allows graft to integrate into bone without cortical plate being in the way = osseogenesis (bone formation)
Fix graft
Leave 3-6 months for angiogenesis and osseogenesis (if larger bone regeneration = leave for longer)
Inadequate width by a small amount - guided bone regeneration is done: what is the function of the membrane that overlies the particulate?
Membrane protects particulate to stabilise it and protect fibroblasts from flap passing into articulate as it is remodelled into bone
How is guided bone regeneration done?
Take scrapings of bone and blood = large surface area of bone that will release cytokines and blood has inflammatory mediators = blood is osseoinductive
Why distress the bone before placing the implant?
Drill before implant is in around it = decortication/distressing of bone = angiogenesis and osseogenesis
How is dual layer guided bone regeneration completed?
Internal layer with bone chips = can be dissolved
External layer with scaffold which cannot be dissolved and will protect the underlying layer and blood to cause bone to form around the scaffold
Aims of the dual layer guided bone regeneration technique?
Bone chip s- osseoinductive
Bone substitute - osseoconductive (prevent it being dissolved)
Absorption of bone-conditioned blood makes bone substitute osseoinductive
Membrane over top to prevent soft tissues contacting and resorbing grafted material
Inadequate width of bone if small to moderate amount - manage with ridge split osteotomy - what is this?
Opening bone and making it broader
Moderate to large amount inadequate width of bone - Buccal onlay graft - what is this?
Distress bone
Block graft and membrane on top
Particulate around it to help support it when it seal
Where is bone for grafts most commonly taken from?
Mandibular symphysis
Mandibular ramus
Mandibular symphysis grafts?
Mental nerve damage Reduced sensitivity over chin Scarring in buccal sulcus - fraenal tags Chin ptosis Apicectomy of anteriors or necrose them by removing the blood supply
Inadequate height of bone - occlusal onlays?
Large amount of bone needed from hip or rib = poor bone quality
Inadequate heigh of bone - how to deal with localised defects?
Osseodistraction
Osseodistractor attached to basal bone and screwed in and expands the bone over a couple of weeks
What can you do with inadequate bone height when risk of nerve damage?
Mandibular inadquate height = reposition the nerve to avoid damaging it when a bone graft needed
BUT still big risk of nerve damage
