Biocompatibility 1 Flashcards
Why do patients need to know about biocompatibility?
- 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
Sources of potential biocompatibility harm
- patient
- dentist
- dental team
- environment
Patients can encounter dental materials via …
- materials placed by a clinician
- over the counter
- online sites (often poorly regulated)
Define ‘medical device’
- 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)
How are medical devices classified?
- in the EU
- Annex IX of the Council Directive
How many classes of instruments?
4
Class I, IIa, IIb, III
Explain Class I instruments
- low risk
- elastic bandage, dental floss, dental instruments
Explain class IIa and b instruments
- medium risk
- direct filling material, contact lenses
Explain class III instruments
- high risk
- implantable pacemaker etc
Medical devices need to be … before use
regulatory approved
Approval steps of devices
- depends on device category
- class 1 is by manufacturer
- all other classes - requires authorised body
How is regulatory approval signposted?
- CE mark
- number identifies the authorising body
- enables sale in EU and worldwide
Liability regarding medical devices
- 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
Malpractice for medical devices
- material applied outside range of indication
- material not applied due to manufacturer’s specifications
Define ‘biomaterial’
- a substance other than a drug
- used for any period
- to treat, augment or replace any tissue, organ or function of body
Define ‘biocompatibility’
- the ability of a material, device or system
- to perform an appropriate host response in a specific application
Difference between biocompatibility and biological safety
- biocomp weighs up potential risk and benefit
- safety is the complete absence of any reaction
How is biocompatibility tested?
- performed by manufacturer to obtain CE mark
- stimulate in vivo as closely as possible
- many tests gone through
Tests for evaluation of Biocompatibility
- three levels
- group 1 - primary tests. in vitro
- group II - secondary tests, animals
- group III - usage tests. clinical trials
Explain cytotoxicity testing
- material in a fresh or cured state
- placed directly on tissue culture cells or on membranes overlying them
What happens in primary tests?
- cytotoxicity tests
- genotoxicity tests
What happens in genotoxicity tests?
- 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)
Advantages of primary testing
- in vitro test, done in controlled experimental condition
- rapid, economical and easily standardized
- large scale screening
Disads of primary testing
- lack of relevance to in vivo use of material
- lack of immune, inflammatory and circulatory system
Ads of secondary testing
- intact biologic system to respond to a material
- provides important bridge between in vitro environment and clinical use of material
Disads of secondary testing
- more expensive and hard to control
- time consuming
- ethical concerns for animals
Ads of usage tests
- material in clinically relevant env
Disads of usage testing
- complex and difficult to perform
- exceptionally expensive and very time consuming
- ethical concerns for humans
Are clinical and usage trials the same?
no
Why might you use usage trials over clinical ones?
- 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
Usage trials compare what to what?
- compare a new material with one currently used
Phases of clinical trials
- 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)
