CSA Biocompatibility Flashcards
What is a biomaterial ?
substance ) or combination of substances synthetic or natural in origin, used for any period of time, as whole or asa part of system which treats, augments, or replaces any tissue, organ, or function of body’.
What are examples of biomaterials?
- Artificial heart valves
- Hip joints
- Adhesive bridge
- Subperiostal implant
- Amalgam
What can happen sometimes when material placed into living tissues?
• Interactions may result in inflammation
What is biocompatibility ?
ability of material to elicit appropriate biological response in given application
What factors involved in biocompatibility?
- Patient (host)
- Material
- Function of material
Why does bodies response to biomaterials change over time?
Host related general factors • Disease • Ageing Changes to material • Corrosion • Fatigue Local factors • Changes to loading on material due to Occlusion/ Diet
What are biological effects of materials?
o Leaching, leading to toxic and allergic reactions
o Formation of degradation product
Why are toxic reactions unlikely with dental materials ?
- Materials largely insoluble
- Only one time exposure
- Slow dissolution rates
What are allergic responses mediated through ?
Immune system
What allergens are found in dental materials?
- Eugenol
- Mercury
- Nickel
- Chromium
- Cobalt
- Components of resin-based materials (TEGDMA, HEMA)
- Formaldehyde (allergic and direct toxic effects)
- Methyl methacrylate
What allergens cause hypersensitivity ?
Nickel
Methacrylates
Resin based materials
Latex
What causes allergic reactions with dental staff?
Amalgam Casting alloys Resin-based materials Latex -o Inhalation of particulates
what are intra oral adverse reactions to dental materials?
Lichen planus type reaction
Swelling, tenderness or reddening
Burning sensation or taste changes
Ulceration or blisters
what are Hands, wrists and finger adverse reactions to dental materials?
Dermatitis, eczema or urticaria
Itching, dry, cracked or burning skin
Swelling, tenderness or reddening
Ulceration, blisters or vesicles
what are face/lip adverse reactions to dental materials?
Swelling, tenderness or reddening
Ulceration or blisters
Dermatitis, eczema or urticaria
Burning sensation or tingling
what are general adverse reactions to dental materials?
Breathing problems wheezing and asthma
Runny, irritated eyes or nose
Coughing, sneezing or sore throat
Headache, nausea or dizziness
What are patients most at risk from?
metals
What are dental staff most at risk from?
rubber products/latex
What are technicians most at risk from ?
resin polymers
Why are risk assessments needed?
- Exposure potential is different among patients, dental workers and industrial workers
What are exposure factors ?
o Quantity o Route o Length of exposure o Accumulation in tissues o Excretion characteristics
What are human factors ?
o Age o Sex o Foetal exposure o Allergic potential o Diet o Pre-existing disease o Nutritional status
What are toxic in high concs?
o Zinc o Iodine o Selenium o Cobalt o Iron o Molybdenum o Copper o Chromium
What reactions must be considered between elements?
between elements in biological enviro and dental material
o E.g. proteins in saliva and bacteria in plaque
What do metals undergo?
chemical or electrochemical reactions with environment
o Results in dissolution or formation of chemical compounds
What can casting allow cause?
contain more than 25 elements which can corrode and leach into oral cavity
What is methyl mercury?
associated with biosynthesis and bio-accumulation
- very toxic and readily absorbed in tissues of fish and mammals
How can a dentist be exposed to mercury?
- Incorrect storage or spillage of mercury/waste amalgam
- Preparation of amalgam
- Placement of amalgam
- Removal of amalgam
- Polishing of amalgam
How is biological response of material measured?
o Location of placed material
o Duration of material
o Stress placed on the material
What tests are used to measure biocompatibility of dental materials
- In vitro tests
- Animal tests
- Usage tests
How do in vitro tests work?
• Material into contact with biological system: Mammalian cells Cellular organelles Tissues Bacteria Enzyme
What are in vitro cell culture used to investigate?
Toxicity of material
Influence of different setting conditions etc.
What are advantages of in vitro ?
- Controllable
- Can isolate and test specific function of cell
- Repeatable
- Fast
- Relatively inexpensive
- Relatively simple
What are disadvantages of in vitro
misleading results
What are usage tests?
• Places materials into intact organism in enviro clinically relevant to use of material
o Known as ‘clinical trials’ with humans
o Used as gold standard
What animals used for usage test?
mice rats hamsters ferrets guinea pigs
What are advantages of usage tests?
- Most relevant test
* Allows for complex interactions
What are disadvantages of usage tests?
- Expensive
- Time consuming
- Difficult to control
- Difficult to interpret
- Legal and ethical issues
What aspects to consider with a filling ?
- Systemic health
- Patient’s habits
- Our expectations
- Dynamic relationship between material, host and function
What systemic health aspect to consider?
o Is patient diabetic or a smoker?
- Response of gingiva to placement of subgingival restoration may be affected
What patient habits to consider?
o Does patient drink acidic drinks?
- Corrosion properties of amalgam and tissue response may be affected
What to expect ?
o Don’t assume material biologically acceptable in different role
- E.g. resin materials biologically acceptable as denture bases but may not be as resin-based cements
Why do we monitor patient over time?
A patient who is not allergic to nickel may become allergic in the future
