Evidence Based Dental Materials Selection

Question 1

What evidence may be looked at regarding materials?

Answer 1

Clinical longevity/durability
Aesthetics
Cost effectiveness
Pt acceptability
Ease of use
Safety

Question 2

What evidence to consider?

Answer 2

Peer reviewed papers:

• RCT
• Systematic reviews (Cochrane)
• Scientific papers

International/national databases
Clinical/senior peers judgement/opinion
Manufacturers marketing materials

Question 3

Pros of peer reviewed publications?

Answer 3

Peer reviewed
Methods of data must be accurate
Generally accessible to healthcare professionals
Generally include sufficient details as to be understandable/useful

Question 4

Cons of peer reviewed publications?

Answer 4

Quality of peer review may differ between journals
Other sections may contain more opinion than fact - risk of fraud
Public/GDPs may find key papers behind a paywall
May contain extensive technical jargon

Question 5

How is a peer reviewed paper produced?

Answer 5

Authors design and do a study
Submit findings to journal = reviewers make comment and recommendations
Manuscript published as a paper

Question 6

Layout of a scientific paper?

Answer 6

Most highly regarded scientific publications deal with experimental materials/systems and scientific papers based on commercial material data help in lower regard

1st page = title, authors, affiliations, abstract
Intro = describes background, context and rationale for research, conclude with aim/hypothesis
Methods/experiment = describe experimental design and steps, statistics
Results - date generated by the experiments
Discussion = authors considered interpretation of the data
Conclusions = summary of findings, acknowledgements

Question 7

Aims of peer-reviewed papers?

Answer 7

Raise quality of published research and reduce risk of fraud
Publications form an ever expanding and permanent record of non-clinical and clinical knowledge

Question 8

How to classify biomaterials?

Answer 8

By material
By application
By tissue interaction
By risk

Question 9

How to classify by material?

Answer 9

Metals (permucosal implants, amalgam)
Polymers (denture base)
Ceramics and glasses (ceramic crowns)
Composites (resin composite, GI cements)
Natural or biological materials

Question 10

How to classify by application?

Answer 10

CV system
Nervous system
Skin and integument
Skeletal systems - bone, teeth

Question 11

How to classify by tissue reaction?

Answer 11

Bioinert
Bioactive
Bioresorbable

Question 12

How to classify by risk?

Answer 12

Important in context of medical devices regulations and safety testing, classified as class I (low),II (intermediate) and III (high) risk based on:
Type of exposure
- Surface/skin contact
- Indwelling
- Blood contacting
Length of exposure
- <24hrs
- Days
- Permanent

Question 13

What risk are most dental materials?

Answer 13

Class IIb (intermediate) risk devices

Question 14

Define biocompatibility

Answer 14

The ability of a material to perform in a specific application with an appropriate host response

Non-toxicity is only part of biocompatibility
Biocompatibility is a site and application specific term

Question 15

How to test biocompatibility?

Answer 15

In vitro evaluation
- Cell free models 
- Cell culture
In vivo evaluation (animal testing)
Clinical testing and trail 
Post market surveillance 

Biocompatibility testing = CE mark

Question 16

Advantages of in vitro determination of biocompatibility?

Answer 16

Rapid
Cost effective
Reproducible
Ethically straightforward/non-controversial

Question 17

Disadvantages of in vitro determination of biocompatibility?

Answer 17

Poor model of complex situation

Question 18

Advantages of in vivo determination of biocompatibility?

Answer 18

Whole complex animal model

Question 19

Disadvantages of in vivo determination of biocompatibility?

Answer 19

Expensive
Intermediate reproducibility
Ethical debate/controversy
Not always a reliable model of human body, tissue or disease

Question 20

Advantages and disadvantages of clinical trial to determine biocompatibility?

Answer 20

Advantage
- Real human use/clinical model

Disadvantages

• Expensive
• Some ethical issues
• Not always a good representation of real clinical practice (often performed by skilled clinicians, pt’s selected)

Question 21

Features of post-market surveillance (PMS)?

Answer 21

May provide early warning of hazard or side effect of tx
Some adverse reactions are extremely rare - may only be detected by PMS
Strengthens evidence base for the use of a biomaterial as part of tx
Implementation may be expensive
PMS is required by law

Question 22

Why are dental materials safe?

Answer 22

Gone through packaging, pre-market testing, post-market surveillance, regulatory environment including CE marketing, clinical vigilance

Question 23

Pre-market testing features?

Answer 23

Required by law for new biomaterials
Tests based on ISO 10993 guidelines
Part 1 = guidelines on test selection, determined by evaluation of materials risks and clinical application
Tests include cytotoxicity, haemolysis, irrigation, systemic toxicity, genotoxicity
Additional studies not legally required but data may be submitted towards CE marking or FDA approval

Question 24

Testing and reporting associated with determination of biocompatibility?

Answer 24

In vitro evaluation
- Cell free models (stimulated body fluid)
- Cell culture
In vivo evaluation (animal testing)
Clinical testing and trial (pre-market)
Post market surveillance (e.g. adverse reaction reporting project)

Question 25

What is Branemark associated with?

Answer 25

Pioneering osseointegrating implant (TiO2 implants), careful surgery and pt selection

Question 26

What did in vitro biocompatibility of titanium discover?

Answer 26

TiO2 surface biocompatible
Readily colonised by cultured osteoblasts
Rough modified surfaces were superior in terms of cell response (e.g. collagen type 1 production)

Question 27

What have in vivo studies found regarding TiO2 implants?

Answer 27

Osseointegrating an established term in 1980s
Titanium implants still studied in animal models today
HaP was superior to a titanium alloy in terms of osseointegration

Question 28

Summary of in vitro and in vivo studies?

Answer 28

Titanium (TiO2 surface) exhibits excellent in vitro and in vivo compatibility
Published scientific reports must be read and interpreted very carefully, especially where it is suggested you change your clinical practice
In vitro and in vivo date alone is rarely/never sufficient to change clinical practice

Question 29

What did Pierre Simonis1,Thomas Dufour2and Henri Tenenbaum1. Clinical Oral Implants Research, 2010 find regarding implant survival?

Answer 29

Long term implant cumulative survival rate up to 16 yrs was 82.94%
Prevalence of biological complications 16.94%
Cumulative complication rate after an observation period of 10-16 yrs was 48.03%
Majority of implant losses and biological complications were concentrated in a small no of pts

= Long term survival rate but biological and technical complications were frequent
= Pts with a history of periodontitis may have lower implant survival rates than pts without a history of periodontitis (and prone to peri-implant mucositis and peri-implantitis)

Question 30

Key points in material testing?

Answer 30

No amount of testing guarantees absolute safety
No material is risk free
Intention of testing, clinical evaluation and monitoring = reduce risks as far as possible to acceptable levels
Clinical vigilance remains a critical element in ensuring pt safety
Published biocompatibility studies are of no real value in clinical decision making
Clinical trials have value but must be read carefully