Introduction to biomaterials and surgery in dental implantology Flashcards Preview

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Flashcards in Introduction to biomaterials and surgery in dental implantology Deck (42)
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1

What is unusual about the dental implant compared with other biomaterials used in skeletal tissue repair? (2)

Penetrates the mucosa, interfacing with both soft and mineralised tissues

2

What is a dental implant? (2)

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

3

How is implantology growing and evolving? (4)

Pre-1990, majority of implants were placed in a hospital or specialist centre - now in dental practices
Full clinical competency provided by postgrad training, but dental schools are increasing teaching on clinical dental implantology
Not part of GDC's specialist lists
Over 200 companies manufacture dental implants worldwide

4

How many implants placed in USA per annum? (1)

5 million
European figures similar

5

Types of early implants (3)

Sub-periosteal implants
Bade implants
Trans-osteal implants

6

"Brånemark" osseointegrating implant (3)

Orthopaedic surgeon, 1950s research in bone metabolism
Used viewing chamber made from titanium
Placed 1st set of titanium 2-stage dental implants in pt 1965
Commercial launch 1985
Careful surgery & pt selection

7

Titanium biocompatibility (7)

Tough, light, and durable
TiO2 surface
Low corrosion (due to TiO2)
-TiO2 more like a ceramic surface than a metal
Biocompatible
Bioinert or bioactive?
Osseointegrating
Biointeraction?:
-protein adsorption
-calcium phosphate deposition

8

Options in managing a missing tooth (4)

Accept gap
Denture
Bridge
Implant

9

Key components of an implant (3)

Crown
Abutment and component screw with cotton??? on top
Implant (or fixture)

10

Engagement of prosthesis into implant (2)

Tri-channel system with anti-rotation device
Conical connection (with anti-rotation hexagonal connection at base of crown)
-more even distribution of stress, better for thin implants

11

Biological events at the bone/ implant interface associated with osseointegration (8)

Be aware that a lot of these studies have been done in vitra (biology) so be cautious about believing everything
(a) Protein adsorption
(b) Protein desorption
(c) Surface changes
(d) Inflammatory/connective tissue cells approach implant
(e) Possible release of matrix proteins and selected adsorption of proteins (e.g. BSP and OPN)
(f) Formation of a lamina limitans/adhesion of osteogenic cells
(g) Bone deposition on bone and implant surfaces
(h) Remodeling of newly formed bone
**Despite extensive research, it is still not certain which of these is most important with respect to clinical success, and the specific biological events that are most important remain subject to ongoing debate.

12

Terminology: "bioinert" vs "bioactive" (4)

Two terms coined originally to describe bone-biomaterial interaction
They may be applied conceptually to many biomaterials including dental materials (e.g. dental amalgam v. glass-ionomer cement)
They remain slightly misleading terms, with no material being totally inert following placement into the biological environment
Titanium (and TiO2 surface) not usually considered “bioactive”, but this has been claimed by some authors

13

Bone tissue response to "bioactive" HA ceramic vs "bioinert" ceramic (canasite glass ceramic)

The classical response of bone tissue to so-called “bioactive” materials has been well-known for a long time, albeit most data is from animal studies with relatively little histological data from human studies.
HA and bone - bioactive
Bone and canasite - bioinert

14

Hydoxyapatite: A “bioactive” or osteoconductive bioceramic used in bone augmentation (4)

Hydroxyapatite is a calcium phosphate ceramic that encourages new bone tissue formation/healing following implantation into established bone tissue.
The bone-hydroxyapatite interface is direct, forms relatively quickly, and is capable of fixing a medical device in bone tissue (“osseointegrating”).
Calcium phosphates are widely used synthetic bone graft substitutes, but not as effective as a bone grafts (clinical material of choice in implant therapy).
Calcium phosphates are too brittle to use alone as load-bearing implants, so they are used as particulates or coatings on metallic devices

15

Osseointegration: a clinical perspective - healing period (5)

3 months
-avoid micro-movement (could lead to fibrosis --> failure)
-can wear prosthesis over top, but need to relieve to avoid pressure on implant
-due to dense bone in mandible, some clinicians have shorter healing protocols
-can check stability with radiofrequency analysis (RFA)

16

Different designs on crowns

Cement retained
Screw retained

17

Cement retained crown (3)

Cemented like an extra-coronal restoration except no cement on top of screw

+ Ideal aesthetics
+ No chipping of access hole

- risk of peri-implantitis / **??cementitis (due to cement leaking)

18

Screw retained crown (3)

Crown itself is small screw hole - one piece solution. Screw crown into implant, then composite restoration on top

+ reduced risk of peri-implantitis

- aesthetics slightly reduced (e.g. for anterior teeth)
-risk of chipping access hole for screw

19

Compensating for poor position (3)

Angled screw channel
Screwdriver at "elbow joint" engages screw at angle
Angulation allows to change by up to 25 degrees for screw retained crowns

20

Material selection and implant failure - what could go wrong (3)

Failure to osseointegrate (short term)
Failure due to peri-implantitis associated with bacterial colonisation
Failure due to "cementitis"

21

Cementitis - describe (3)

“Cementitis” is used to describe a peri-implantitis-like condition where residual luting cement is associated with local inflammation and bone loss.
Biomaterial issue
Mechanical failure a much smaller issue

22

Describe periimplantitis (2)

Microbial colonisation and infection are associated with peri-implantitis, Wilson claimed that residual dental cements were associated with a reversible “cementitis” that subsided after removal of the material.
***

23

Bridges - multi-unit abutments (2)

+ Allows engagement of internal channel
- expensive (£180 per abutment)
Abutments must be convergent for retention
Retained by a screw

24

Bridges - fixture-level screw retention (3)

+ avoids cost of multi-unit abutments
-does not fully engage internal connection
-stress on screws

25

Bridges - cement retained bridge (4)

+ similar to standard crown and bridgework in terms of fit
+ engages internal connection
-cannot be unscrewed (has to be cut off and binned and redone)
-risk of cementitis

26

Options for bridges (3)

Multi-unit abutments
Fixture-level screw retention
Cement retained bridge

27

Denture options

Locator abutments
Ball attachments
Milled bar
Magnets

28

Denture - locator abutments (5)

Go to
Simple, relatively cheap, very successful
Male unit fits over top - male in the sense that it fits into underside of denture is in two parts
-locator males
-externally and internally locator male
Standard males 17 degrees divergence
Extended range 30 degrees divergence

29

Dentures - ball attachments

Choose tension of which you want to retain the denture

30

Dentures - milled bar (3)

+ Much greater stability
- requires more implants
- requires minimum 15-17mm height (depending on attachment type) - may need to cut back bone to increase OVD