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ICP > Implants > Flashcards

Implants Flashcards

1
Q

Titanium biocompatibility

A 
•	Tough, light and durable 
•	TiO2 surface 
•	Low corrosion 
•	Biocompatible 
•	Bioinert or bioactive?
•	Osseointegrating 
•	Biointeraction?
o	Protein absorption 
o	Calcium phosphate deposition
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2
Q

Osseointegration from clinical perspective

A

3 month healing period - can be shorter in mandible as more dense bone
Avoid micro-movement
Can wear prosthesis on top but need to relieve to avoid pressure on implant
Check check stability with radiofrequency analysis (RFA)

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3
Q

Cement retained vs screw retained

A

Cement retained:
+ Better aesthetics
+ No chipping of access hole
- Associated with peri-implantitis due to cement

Screw retained:
+ Reduced risk peri-implantitis
- Chipping of access hole
- Less aesthetic

Screw retained less aesthetic due to screw hole - can be covered with composite but margins eventually stain. In anterior region this can be overcome by using Omnigrip driver which allows placement of screwdriver into curved channel at 25degrees

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4
Q

Types of implant bridges (3)

A

Multi-unit abutments
Fixture level screw retention
Cement retained bridge

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5
Q

Multi-unit abutment bridges

A

+ Allows engagement of internal channel
- Expensive (£180 per abutment)

Divergent implants placed, multi-unit abutment slots on implants, bridge slots on top of abutments and all screwed in through screw hole
(Implant/screw in bone, abutment (crown prep shaped) sits in screw, bridge fits on top of abutment and screwed on)

Having abutments is advantageous as if any issues with implant, can separate components and identify problem without messing around with implant in bone

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6
Q

Fixture-level screw retention

A

+ Avoids cost of multi-unit abutments

  • Does not fully engage internal connection
  • Stress on screws
  • Bridge sits above implants, then crews pass through crown into implant channel. No anti-rotational device
    Wouldn’t work for just one crown as presence of multiple screws/sites prevents crowns spinning
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7
Q

Cement retained

A

+ Engages with internal connection
+ Similar to standard crown and bridge work in terms of fit
Basically same part/mechanism as multi-unit abutments but final crown is cemented on instead of screw retained

  • Cant be unscrewed - any problems, whole thing need to come off
  • Risk of cementitis
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8
Q

Types of implant retained dentures

A

Local abutments
Ball attachments
Milled bar
Magnets

Denture retained good for maintaining OH as comes in and out

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9
Q

Implant retained denture - local abutments

A

Standard implants allow divergence of 17 degrees
If implants more divergent than this - extended male range allows 30 degrees of divergence
Range can go up to 60 degrees divergence however if this is case - should rethink implant placement

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10
Q

Implant retained denture - ball attachments

A

Retain denture via ball attachments

Different colours correspond to different degrees of stiffness

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11
Q

Implant retained denture - milled bar

A

+ Greater stability

  • requires more implants
  • at least 15-17mm height needed
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12
Q

Implant retained denture - magnets

A
  • Usually solution for poor implant position
  • Dont provide much retention

+ able to compensate for significant angulation
+ able to provide low profile if limited vertical space

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13
Q

Guided tissue regeneration

A
  • Collagen is the most widely used membrane material today
  • Typically derived from bovine (e.g. Geistlich) or porcine (e.g. Nobel Biocare) sources
  • Small risk of adverse reaction and theoretical risk of disease transmission with possibility of religious or ethical objection
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14
Q

Flap design (2)

A

Papilla sparing/Sclar:
+ doesn’t raise flap papilla to papilla - avoids recession
+ scarring hidden at point of mucogingival junction

Sulcal incision:
+ avoids scarring
- risk of papilla recession

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15
Q

Implant diameters

A

Narrow platform - maxillary 2
Regular platform - maxillary 1
Wide platform - molars

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16
Q

Cover screw vs healing abutment

A

Cover screw screwed onto implant then gum stitches over so implant completely buried - protects from external environment, good when concerns about healing e.g. diabetes or case when GBR used. Requires second surgery at later date to change cover screw for healing abutment then further few weeks healing

Healing abutment - transmucosal. Gum heals as collar around tooth

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17
Q

How does the surface of a titanium dental implant differ from the bulk material?

A
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18
Q

List the materials properties of titanium implants that are associated with good clinical performance

A
19
Q

Name a synthetic bone graft substitute
Which material is currently most widely used as a membrane for GTR
Which surgeon scientist is credited with birth of implantology

A

** Branemark pioneered careful surgery and patient selection, whilst early implants didn’t

20
Q

Pre-planning: things to consider

A 
Patients desires/expectations 
Medical history 
Social history 
Clinical examination 
Case-specific considerations
Radiographic examination
21
Q

Patients desires/expectations

A

Problem in their own words - don’t assume implants only option to satisfy expectations
Patient priority - functional/aesthetic
Patient understanding of risks and timescale involved, smile line etc

22
Q

Medical history

A

Bisphosphonates
Steroids - alone no, but can compound effect of bisphosphonates
Diabetes
Immunosupressants
Radiotherapy - if area has undergone more than 60 Grays = higher risk implant failure & osteoradionecrosis - IMRT
Bone diseases - Paget’s, osteoporosis
Bleeding tendencies
Generally, only absolute contraindication is bisphosphonates/denosumab

23
Q

Social history

A

20-300% increased risk of implant failure if smoker
Heavy smoker 15/day
Non-smokers failure risk is 3% failure
So max risk for smokers is 9%
However need to be warned of risks and consented
Is not an absolute contraindication but is for providing on NHS
Variation in practitioner acceptance

24
Q

E/O examination:

ab

A

Skeletal profile

Smile line - high (upper lip above cervical line), medium (papillary line visible), low (papillary line covered by lip)

25
Q

I/O:

cdef

A

c - horizontal and vertical space requirements
Horizontal - at least 3mm between implants, 1.5mm between implant-tooth
Vertical - screw retained = 5mm, cement retained = 7mm
Minimum 15-17mm if milled bar

d - access
Should be able to fit 2 fingers between opposing dentition for access for surgery

e - perio status
BoP, pocketing, review previous perio/recession
Hx of perio increases risk of peri-implantitis
Active disease contraindication for implants

f - 3D assessment of available bone/dimensions
Mesiodistal clinical space and surgical space
Apices of teeth - esp. after ortho if teeth been tilted and roots converge apically
Buccolingual - check by palpating, ridge map (w/callipers) or CBCT to assess buccal-lingual dimension
Vertical - 4mm safety margin for IDN (renton)

26
Q

Pre-implant surgery - ?

A

To little bone to support implant in acceptable position
Too much bone - ridge reduction
Done if bone poor quality, make additional restorative space, remove knife edge ridges

27
Q

Types of augmentation

A

Autograft - from self
Allograft - from donor
Xenograft - from animal
Inorganic material - HAP, bet TCP

28
Q

Osseoinductive vs osseoconductive

A

Inductive - promotes/induces bone formation
Conductive - acts as scaffold for bone formation. Will need something osseoinductive around it to induce the formation

E.g. osseoinductive - bone chips taken from pt
E.g. osseoconductive - bovine particulate (xenograft). Will need addition of other things to induce bone

29
Q

Techniques for WIDTH: (5)

A

Guided bone regeneration
Ridge split
Block graft
Narrow/angled implants

Taking study models and waxing up additional thickness needed for bone allows you see whether you’ll need small amount, moderate amount or large amount. This will influence what operation is done

30
Q

Techniques for HEIGHT:

A 
Onlay graft 
Inlay graft 
Osseodistraction 
Short implants/all on 4
Zygomatic implants
31
Q

Inadequate width - small amount:

A

GUIDED BONE REGENERATION
Common and popular
Can be undertaken at same time as implant placement and done in GDP
Works by tricking natural bone into thinking its fractured
Normal fracture site - week 1 haematoma formation + release of inflammatory mediators such as IL-1, IL-6 & proteins e.g. BMP-2, PDGF, TGF-b (cytokines) which induce bone callus formation
Bone chips have large SA releasing these cytokines + introduce osteoblasts into area as matrix for new bone formation
Chips taken from pt = gold standard osseoinductive agent
Bovine derived mineral less soluble than grafted bone chips so combination of these ensures osseoinduction without risk of area resorbing later on
Week 17 - remodeling

32
Q

Dual layer GBR technique

A

Bone chips - osseoinductive
Bone substitute e.g. Creos/Bio-oss - osseoconductive
Absorbtion of bone-conditioned blood makes bone substitute osseoinductive
Membrane over top to stop soft tissue contacting and resorbing graft material

Dual layer GBR - flap raised, bur holes aside implant to allow neovascularisation of bone layer as it heals, layer of bone chips on outside layer of implant (layer 1) then bovine particulate (layer 2). Bovine particulate compressed to allow blood from chips to saturate particulate so inflammatory mediators carried into area, membrane over top then close.

33
Q

Inadequate width: small-mod amount

A

RIDGE SPLIT OSTEOTOMY
Trapdoor incision - incision across top of ridge then 2 lateral relieving incisions - care not to damage mental nerve
Then follow with standard drilling protocol but size of final osteotomy is undersized compared to width of implant allowing bone to be levered outwards - larger implant in smaller hole - ‘ridge split’

34
Q

Inadequate width - mod-large amount

A

BUCCAL ONLAY GRAFT
Bone placed on top of buccal plate - bone harvested either from mandibular symphsis or ramus. Can take from iliac crest if large amount needed but poorer quality

Get recipient site ready to take bone, bur holes to promote angiogenesis over healing period.
Make incision in donor site, harvest bone using saggital saw. Screw hole made in recipient site and trauma screw used to screw donor bone into site.

35
Q

Risk of mandibular symphysis graft:

A

Reduced sensitivity over chin
Scarring in buccal sulcus - fraenal tags
Chin ptosis - reduce risk by strapping chin
Damage to incisor/canine region - can accidentally apicect these teeth

Do incision through lower lip, leaving border of muscle above incision to allow muscle-muscle suturing - reduce risk of ptosis
Ensure cuts are below incisor region and leave 5mm safety margin to leave adequate blood supply for lower incisors
When block taken - divide into 2 to reduce risk of fracture if whole piece lifted out as one

36
Q

Inadequate height

A

OCCLUSAL ONLAY GRAFT
If whole mandible is edentulous and significant bone needed
Ring of bone used like polo and ‘onlay’ onto ridge, screw into place

37
Q

Inadequate height: localised defect

A

OSSEODISTRACTION
Cut made in bone to split bone then osseodistractor used with activator on top. Activator twisted which moves two pieces of bone apart
Favoured to occlusal onlay graft as, as bone moves, moves mucosa with it

38
Q

Inadequate height: maxilla

A

SINUS LIFT

Flap raised, piezo used to cut trap door, floor of sinus lifted, particulate bone graft layer

39
Q

Inadequate height: mandibular canal

A

NERVE REPOSITION
Mandibular canal can get in way of grafting so can lateralise inferior alveolar nerve to move it out the way so graft can be placed
Post-op testing to ensure no loss of sensation

40
Q

Alternatives:

All on 4 & zygomatic implants

A

All on 4: placing implants at an angle posteriorly to avoid structures like mental nerve or maxillary antrum. Implants emerge further back so can place prosthesis further back

Zygomatic implants - when no posterior bone at all in maxilla can get support from zygomatic bones plus combination of anterior traditional implants

41
Q

Failure modes of implants:

A

Mechanical/material
Biological
Appearance and function

42
Q

Mechanical/material failures:

A 
Fractured porcelain 
Fractured bridgework 
Screw loosening 
Fractured abutment 
Fractured implant - rare 
Worn/broken clips - common 
Worn attachments - common
43
Q

Biological failures

A 
Plaque/calculus 
Gingival inflammation 
Gum recession 
Peri-implantitis 
Failure of implant to integrate 
Pocketing
Bleeding 
Pus exudate 
Bone loss
Tooth movement
Damage to nerves/teeth
44
Q

Aesthetic and functional failures:

A 
Poor shape
Poor colour
Poor position 
Gum recession 
Black triangles 
Can't chew 
Lisp
Pain and discomfort
Proprioception

ICP (5 decks)

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