Biocompatibility 1

Question 1

Why do patients need to know about biocompatibility?

Answer 1

• lots of materials in dentistry that are put in the body, a harsh oral env
• body reacts with ‘foreign bodies
• new materials to deal with constantly

Question 2

Sources of potential biocompatibility harm

Answer 2

• patient
• dentist
• dental team
• environment

Question 3

Patients can encounter dental materials via …

Answer 3

• materials placed by a clinician
• over the counter
• online sites (often poorly regulated)

Question 4

Define ‘medical device’

Answer 4

• an instrument or similar that is used to
• diagnose, prevent or treat disease or other conditions
• and doesn’t achieve its purpose through chemical action within or on the body (not a drug)

Question 5

How are medical devices classified?

Answer 5

• in the EU
• Annex IX of the Council Directive

Question 6

How many classes of instruments?

Answer 6

4
Class I, IIa, IIb, III

Question 7

Explain Class I instruments

Answer 7

• low risk
• elastic bandage, dental floss, dental instruments

Question 8

Explain class IIa and b instruments

Answer 8

• medium risk
• direct filling material, contact lenses

Question 9

Explain class III instruments

Answer 9

• high risk
• implantable pacemaker etc

Question 10

Medical devices need to be … before use

Answer 10

regulatory approved

Question 11

Approval steps of devices

Answer 11

• depends on device category
• class 1 is by manufacturer
• all other classes - requires authorised body

Question 12

How is regulatory approval signposted?

Answer 12

• CE mark
• number identifies the authorising body
• enables sale in EU and worldwide

Question 13

Liability regarding medical devices

Answer 13

• dentist informs patient of indications for use
• specifications set by manufacturer
• always read product data sheets - list components
• regularly check science lit - adverse effects may have been reported

Question 14

Malpractice for medical devices

Answer 14

• material applied outside range of indication
• material not applied due to manufacturer’s specifications

Question 15

Define ‘biomaterial’

Answer 15

• a substance other than a drug
• used for any period
• to treat, augment or replace any tissue, organ or function of body

Question 16

Define ‘biocompatibility’

Answer 16

• the ability of a material, device or system
• to perform an appropriate host response in a specific application

Question 17

Difference between biocompatibility and biological safety

Answer 17

• biocomp weighs up potential risk and benefit
• safety is the complete absence of any reaction

Question 18

How is biocompatibility tested?

Answer 18

• performed by manufacturer to obtain CE mark
• stimulate in vivo as closely as possible
• many tests gone through

Question 19

Tests for evaluation of Biocompatibility

Answer 19

• three levels
• group 1 - primary tests. in vitro
• group II - secondary tests, animals
• group III - usage tests. clinical trials

Question 20

Explain cytotoxicity testing

Answer 20

• material in a fresh or cured state
• placed directly on tissue culture cells or on membranes overlying them

Question 20

What happens in primary tests?

Answer 20

• cytotoxicity tests
• genotoxicity tests

Question 21

What happens in genotoxicity tests?

Answer 21

• determines carcinogenic/mutagenic potential
• mammalian or non-mammalian cells (bacteria, yeasts, fungi)
• evaluates changes caused by dental materials (gene mutations, changes in chromosomal structure, DNA of genetic changes)

Question 22

Advantages of primary testing

Answer 22

• in vitro test, done in controlled experimental condition
• rapid, economical and easily standardized
• large scale screening

Question 23

Disads of primary testing

Answer 23

• lack of relevance to in vivo use of material
• lack of immune, inflammatory and circulatory system

Question 24

Ads of secondary testing

Answer 24

• intact biologic system to respond to a material
• provides important bridge between in vitro environment and clinical use of material

Question 25

Disads of secondary testing

Answer 25

• more expensive and hard to control
• time consuming
• ethical concerns for animals

Question 26

Ads of usage tests

Answer 26

• material in clinically relevant env

Question 27

Disads of usage testing

Answer 27

• complex and difficult to perform
• exceptionally expensive and very time consuming
• ethical concerns for humans

Question 28

Are clinical and usage trials the same?

Answer 28

no

Question 29

Why might you use usage trials over clinical ones?

Answer 29

• clinical trials give evidence basis but expensive and logistically complicated. Not mandatory and problems with materials may appear after years not in trials
• usage trials less complex
• smaller scale and practionerer based to collect data and raise product awareness
• not as rigorous as a randomized controlled trial - results interpreted with caution

Question 30

Usage trials compare what to what?

Answer 30

• compare a new material with one currently used

Question 31

Phases of clinical trials

Answer 31

• Phase I (early) - biomaterial tested on a small group of people (60-80)
• Phase II - larger group (100-300)
• Phase III - effectiveness of new treatment compared to management standard (1000-3000)