Intro to implantology symposium: clinical concepts and materials bioscience

Question 1

When are synthetic materials (biomaterials) used in skeletal tissue repair?

Answer 1

Used in skeletal tissue repair
Implants
Bone grafts
Membranes 
Sutures

Question 2

What is an implant?

Answer 2

A metal device that is surgically placed in the jawbone. Acts as an anchor for an artificial tooth or teeth

Question 3

What were the types of implants in the 1940s-1980s?

Answer 3

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

Question 4

Who made implants safer and better?

Answer 4

Brånemark” osseointegrating implant
Titanium
Careful surgery and pt selection

Question 5

Titanium biocompatibility?

Answer 5

Tough, light, durable 
TiO2 surface
Low corrosion (Due to TiO2)
Biocompatible
Bioinert or bioactive?
Osseointegrating
Biointeration?
- Protein adsorption
- Ca phosphate deposition

Question 6

Options to manage a missing tooth?

Answer 6

Accept gap
Denture
Bridge
Implant

Question 7

What makes up an implant?

Answer 7

Crown, abutment, implant/fixture

Question 8

How to engage the abutment with the implant?

Answer 8

Tri-channel

Conical connection

Question 9

What biological events happen at the bone/implant interface

Answer 9

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

Question 10

What is hydroxyapatite? What does it do?

= Associated with osseointegration

Answer 10

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)

Question 11

What are calcium phosphates used as?

Answer 11

Ca phosphates are used as synthetic bone graft substitutes

Question 12

What are calcium phosphates not effective to be? Why?

Answer 12

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

Question 13

Osseointegration features?

Answer 13

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

Question 14

Types of crowns for implants?

Answer 14

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

Question 15

Why may implants fail?

Answer 15

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

Question 16

Types of bridges with implants?

Answer 16

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

Question 17

Roles of abutments in stress relief?

Answer 17

Distribute stress at the suprastructure as they can be replaced

Question 18

Denture types with implants?

Answer 18

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

Question 19

What happens to bone in 50% of cases where implants are inserted?

Answer 19

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

Question 20

Why are membranes used in implant surgery?

Answer 20

Employed to exclude soft/scar tissues from site where bone healing or regeneration is needed = Guided tissue regeneration or guided bone regeneration

Question 21

What materials are used as membranes in implant surgery?

What are the problems with the membranes?

Answer 21

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

Question 22

What is the most popular membrane material?

Answer 22

Collagen membranes

Question 23

Features of collagen membranes for guided tissue regeneration?

Answer 23

Derived from bovine or porcine sources
Small risk of adverse reaction or theoretical risk of disease transmission with possibility of religious or ethical objection

Question 24

Flap designs for implant surgery?

Answer 24

Papilla spacing/sclar:

• Avoids papilla recession
• Scarring - hidden at point of mucogingival junction

Sulcal incision

• Avoids scarring
• Risk of papilla recession

Question 25

Implant diameters?

Answer 25

Narrow platform - 3.5mmD e.g. lateral incisor
Regular platform - 4.3mmD
e.g central, canines, premolars
Wide platform - 5mmD e.g. molar

Question 26

Why are healing abutments preferred over cover screws?

Answer 26

Healing abutment - placed on top of an implant and gum is stitched around it
Good for immunocompromised pts to help prevent bac entry
??

Question 27

What factors determine the clinical success of implants?

Answer 27

Biomaterials, biocompatibility, biomechanics, design
Extrinsic and clinical factors:
- Health and age of pt
- Careful surgery to avoid bone necrosis
- Clinical skills, training and experience
- Care of implants including hygiene, diet and smoking cessation

Question 28

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

Answer 28

The surface is TiO2 (formed instantly in air), a metal oxide.

Question 29

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

Answer 29

Low corrosion, passivating surface, non-toxic/ biocompatible.

Question 30

Name a synthetic bone graft substitute?

Answer 30

Hydroxyapatite (or calcium phosphate)

Question 31

Which material is currently most widely used as a membrane for GTR / GBR?

Answer 31

Collagen

Question 32

Which surgeon scientist is credited with the birth of modern dental implantology?

Answer 32

Per Ingvar Brånemark