Intro to implantology symposium: clinical concepts and materials bioscience Flashcards
When are synthetic materials (biomaterials) used in skeletal tissue repair?
Used in skeletal tissue repair Implants Bone grafts Membranes Sutures
What is an implant?
A metal device that is surgically placed in the jawbone. Acts as an anchor for an artificial tooth or teeth
What were the types of implants in the 1940s-1980s?
Sub-periosteal implants
- Placing implants on/around bone
- Required direct bone impression
- Co-Cr-molybdenum casting
Blade implants
- Linkow blade implant - in narrow ridge
- Roberts and roberts - ramus blade implant (titanium)
Trans-osteal implants
- Small introduced trans-osteal mandibular staple bone plate
- Limited to mandible only
Who made implants safer and better?
Brånemark” osseointegrating implant
Titanium
Careful surgery and pt selection
Titanium biocompatibility?
Tough, light, durable TiO2 surface Low corrosion (Due to TiO2) Biocompatible Bioinert or bioactive? Osseointegrating Biointeration? - Protein adsorption - Ca phosphate deposition
Options to manage a missing tooth?
Accept gap
Denture
Bridge
Implant
What makes up an implant?
Crown, abutment, implant/fixture
How to engage the abutment with the implant?
Tri-channel
Conical connection
What biological events happen at the bone/implant interface
Protein adsorption Protein desorption Surface changes Inflammatory/CT cells approach implant Release of matrix proteins Formation of a lamina limitans/adhesion of osteogenic cells Bone deposition on bone and implant surfaces Remodelling of newly formed bone
What is hydroxyapatite? What does it do?
= Associated with osseointegration
Hydroxyapatite = a calcium phosphate ceramic
Encourages new bone tissue formation/healing following implantation into bone tissue
Bone-hydroxyapatitie interface is direct, forms quickly and is capable of fixing a medical device in bone tissue (osseointegrating)
What are calcium phosphates used as?
Ca phosphates are used as synthetic bone graft substitutes
What are calcium phosphates not effective to be? Why?
but NOT effective as a bone graft
Too brittle to use alone as load bearing implants, so they are used as coatings on metallic devices
Osseointegration features?
3m healing period
- Avoid micro-movement
- Can wear prosthesis over top, but need to relive to avoid pressure on implant
- Due to dense bone in mandible, some clinicians have shorter healing protocols
- Can check stability with radiofrequency analysis
Types of crowns for implants?
Cement retained
- Ideal aesthetics
- No chipping of access hold
- Risk of peri-implantitis
Screw retained
- Reduced risk of peri-implantitis
- Aesthetics slightly reduced
- Risk of chipping access hole for screw
Why may implants fail?
May fail to osseointegrate (short tem)
Peri-implantitis associated with bacterial colonisation
Cementitis = residual luting cement is associated with local inflammation and bone loss - subsides after removal of material
Mechanical failure
No dental material responsible for failure so failure due to an inflammatory response to debris or contamination
Types of bridges with implants?
Multi-unit abutments
- Allows engagement of internal channel
- Expensive
Fixture level screw retention
- Avoids cost of multi-unit abutments
- Does not fully engage internal connection
- Stress on screws
Cemented retained bridge
- Similar to standard crown and bridgework in terms of fit
- Engages internal connection
- Cannot be unscrewed
- Risk of cementitis
Roles of abutments in stress relief?
Distribute stress at the suprastructure as they can be replaced
Denture types with implants?
Locator abutments
- Denture supported with implants to improve retention and stability
- Cheap
- Successful
- Male units in the ridge which slot into the denture
Ball attachments
- Ball will fit into the receiver no matter the angle
Milled bar
- Much greater stability
- Requires more implants
- Requires minimum 15-17mm height (depending on attachment type)
Magnets
- Generally a solution for poor implant position
- Able to compensate for significant angulation
- Able to provide low profile solution if limited vertical space
- Dome type and flat type
What happens to bone in 50% of cases where implants are inserted?
In 50% of places where implants are inserted there will be some exposure of the threads of the implants
SO add bone over the surface to replace bone where it should be = guided bone regeneration
Why are membranes used in implant surgery?
Employed to exclude soft/scar tissues from site where bone healing or regeneration is needed = Guided tissue regeneration or guided bone regeneration
What materials are used as membranes in implant surgery?
What are the problems with the membranes?
Non resorbable (GoreTex) Resorbable synthetic (PGA) Resorbable natural (collagen)
None have intrinsic regenerative properties beyond the barrier function
May be used with bone graft or synthetic bone graft substitute
What is the most popular membrane material?
Collagen membranes
Features of collagen membranes for guided tissue regeneration?
Derived from bovine or porcine sources
Small risk of adverse reaction or theoretical risk of disease transmission with possibility of religious or ethical objection
Flap designs for implant surgery?
Papilla spacing/sclar:
- Avoids papilla recession
- Scarring - hidden at point of mucogingival junction
Sulcal incision
- Avoids scarring
- Risk of papilla recession
