Osseointegration - Intro to Implants & ISODs

• Why choose implants:

  • Tissue quality and quantity to support conventional removable prosthodontics inadequate
  • Attempts to replace missing tissue has often led to local tissue derangement leaving the patient in a worse condition (eg., surgery, soft tissue trauma, the removal of tumours)
  • An alternative to edentulism (rather than an alternative to having natural teeth) - especially the conventional lower denture
• Indications for implants:

  • Retention problems (technical problems that can't be corrected by conventional means - dictated by the anatomy)
  • Loading of mucosa (pt may have pain because their mental foramina are v close to the crest of the alveolus - distribute loading through implants to take pressure away from that area)
• Indications for implants:

  • Psychological problems accepting dentures
  • Trauma (physical or surgical)
  • Oncological (tumour removal)
  • Aplasia (failure of tooth development)
  • Adjacent teeth (avoid damage to adjacent teeth)
  • Diastema (difficult to maintain a diastema - could use an implant to replace a tooth to help do that)
  • Pt expectation
  • Biological cost
• Contraindications for implants:

  • Few absolute contraindications, many relative
  • Smoking
  • Contributes to periodontitis and thereby peri-implantitis
  • Increased risk of failure
• Factors to consider with implants:

  • General health - pts getting implants are going to undergo a surgical procedure & will need to attend regularly for maintenance - if anything could jeopardise that then they might not be suitable)
  • Local health (health of oral tissues - don't want to put implants into an area which might not heal well afterwards - bisphosphonate treatment/radiotherapy could jeopardise it)
  • Bone condition/volume (can't put implants into weak bone/bone that isn't there)
  • Pt's expectations
  • Cost
• Implant supported dentures can still have the same problems as conventional dentures, and more!

  
• If the anatomy is unfavourable for implants, change it:

  • Pre-prosthetic surgery eg sulcoplasty (cut open sulcus to change the depth)
  • Ridge augmentation
  • Various types of "implant support"
  • Sub-periosteal implants - BLADES "improve" the denture bearing area (image below)
  • Osseointegrated implants

  
• Osseointegration = direct structural and functional connection between ordered, living bone and the surface of a load carrying implant.

  • PDL links natural tooth to bone - don't have that in implants
  • Implant is a more rigid structure in the bone - no capacity for viscoelastic movement
  • Gingival crevice around natural tooth
  • Have a healing pocket at the margin of an implant - result is long junctional epithelium
  • Therefore it's possible to have a healthy implant with pocketing but no bleeding

  
• Factors for implant integration:

  • Biocompatibility in the implant material
  • Implant design - shape and design to facilitate bone healing
  • Implant surface - morphology and how it had been treated
  • State of host bed - state of oral tissues
  • Surgical technique
  • Loading conditions

  Long-term osseointegration of an implant is dependent on control of the six factors. Poor control of only one of these factors may lead to soft tissue formation and a poor clinical outcome.
• Technique for implant placement:

  • Aseptic technique
  • Incision-sulcular/crestal
  • Paracrestal
  • Attached mucosa
  • Mucoperiosteal flap in-tact mucoperiosteum
  • Surgical stents
  • Make sure tools don't heat up during procedure - cause bone necrosis
• Implant placement:

  • Minimise physical and thermal trauma
  • Maintenance of osseous vitality
  • Close surface apposition to implant
  • Primary stability
• Implant alternatives:

  • No treatment
  • RPD (removable partial denture)/CCD (complete conventional denture)
  • Bridgework - full coronal vs RBB (resin bonded bridgework). Keep bridge designs simple.
  • Implant-retained (stuck on implant and can't be removed) vs implant supported (can be removed)
• Failure to plan is planning to fail - think about whole dentition and whole mouth rather than just one tooth:

  • Occlusion
  • Aesthetics
  • Function
  • Periodontal health
  • Maintenance
  • So not surgeons alone managing the planning
• Space and biological width:

  • Between implants and teeth
  • Between proposed implants
  • Soft tissue coverage. Peri-implant soft tissue quality.
  • Interocclusal space
• Kennedy Class 1 RPD (removable partial denture):

  • Retained anteriorly (keep anterior teeth, usually 4-4, for retention)
  • Design important
  • Tendency to rock
  • Food packing under saddles posteriorly
  • Not well-tolerated (because these pts had been able to get by with just their anterior teeth)
• ISMOD (implant supported mandibular overdenture):

  • Retained anteriorly - implants go anterior to the mental foramen; anatomy posterior is more likely to encroach on the inferior dental canal - therefore don't want to damage the nerve or the blood vessels in there)
  • Design important
  • Tendency to rock
  • Food packing under saddles posteriorly
  • Well-tolerated (because for these patients, this option is better than what they had before)
• Implant design:

  • Anterior tooth position - the further ahead of the axis of rotation the greater the rock
  • Number and location of implants
  • Don't put them in posterior mandible; don't want to risk damage to inferior dental canal
  • Ball attachment or locator vs bar retainer
  • Ball attachments and locators in symmetrical places fixes the axis of rotation
  • Bar retainer connects both implants and is shaped to extend further forward - helps to reduce rotational effects - more technique sensitive though and difficult to maintain - also more expensive
  • Cost
• Comparison of stages:

  • C/C Conventional
  • Primary impressions
  • Major impressions
  • Registration on permanent base
  • ISMOD
  • Primary impressions
  • Order components/identify system
  • COMPOUND
  • Major impressions using elastomer (helps to pick up implant attachments better)
  • Registration