biocompatibility e lec Flashcards
to introduce the concept of biocompatibility and the relevance to dentistry
what is the definition of biocompatibility
it is any substance other than drugs, natural or manmade that can be used for any period of time as a whole or part of a system which can treat, augments or replaces any tissue organ or function of the body
give common examples of biocompatible materials in medicine
heart artificial valves or hip joints
examples in dentistry
amalgams or casting alloy or implants
biocompatibility
the ability pf a material to elicit an appropriate biological response in a given application
is there absolute biocompatibility
no
what are the three important factors in biocompatibility
interaction with host, material and function of the material
biocompatibility is…
dynamic, ongoing
what host related factors can affect biocompatibility
aging and disease or the material might change due to corrosion or fatigue
what local factors can affect biocompatibility
loads places, occlusion/diet
how is biocompatibility affecting dentists
safety of the patient
legal liability
safety of dental staff
which potential biological effects can occur
toxic reactions
allergic reactions
what toxic reactions can occur
cancer or allergies
what causes a toxic reaction
direct contact with the material
what also causes a toxic reaction
leaching or degradation products
what is the definition of a toxic material
a toxic material is one that releases a chemical in sufficient quantities to kill cells either through direct or indirect inhibition of metabolic pathways
eg of toxic reactions
carcinogenic reactions are dose dependant
how do we get toxic effects
one large dose or small doses over the threshold
in dentistry toxic reactions occurs not as
a one time dose dependant reactions
toxic reactions are
dose dependant
allergic reactions are
dose independent
name some materials that can cause allergic reactions
mercury eugenol nickel chromium cobalt resin based materails formaldehyde(allergic and direct toxic effects) methylmethacrylate
name some known allergens
nickel
methylcrylacytes
resin based material
latex
why can these materials be more dangerous to dentists
due to exposure for a long time which can cause cumulative irritation allergic response
risks are greater for dental technicians from
gypsum
resin
mentals
how can these materials affect technicians
due to inhalation
intra oral reactions
lichen planus
swelling tenderness redness
burning sensation and ulceration
blisters
hands wrists for finger reactions
dermatitis urticaria eczema itching dry flaky skin swelling redness or blisters ulceration
face or lip reactions
swelling redness and tenderness
ulceration or blisters
dermatitis eczema and urticaria
burnign or tingling
general reactions
breathing issues runny irritated eyes coughing sneezing closed throat headache nausea dizziness
what needs to be carried out for safety
risk assessments
what is LOAEL
lowest observed adverse effect levels
NOAEL
no observed adverse effect levels
what is the numerical value for LOAEL
50 micrograms/m3 nephrotoxicity levels
what is the general public threshold for NOAEL
5 micrograms/m3
what is the factory threshold for NOAEL
25micrograms/m3
what is the threshold for children, sick , pregnant people
1 micrograms/m3
which factors should be considered
sex, age , allergic potential foetal exposure diet pre existing conditions and nutritional status
what exposure factors do we need to consider
quantity route length of exposure accumulation in tissues and excretion
what are the essential elements by WHO
zinc iodine selenium cobalt iron chromium copper molybdenum
why might a material not biocompatible
just because it is in the body doesnt men it will be biocompatible
what must also be considered
that reactions between the elements in the body already occur and the implant material must also be considered
what do metals undergo
electrochemical reactions with the environment which results in dissolution= corrosion
what can happen to casting alloys
they can result in leaching into the oral environment
is amalgam safe to use
yes
when was amalgam first used
mid 19th century
what did the hatters suffer from
neulogical poisoning of the Hg resulting in poor walking unable to speak clearly suffered from palsy
what type of mercury is associated with biosynthesis and bioaccumulation in fish
methylmercury
how many people have been estimated to have minamata disease in minamata, japan
over 3000
how are dentists exposed to mercury
due to spillage
waste mercury
incorrect storage
where does the amalgam come from
from prep
removal
polishing
placement of amalgam
when was the highest merucry level recorded
1980
what was the level of mercury in 1980
19.5 micrograms/ litre
what was the level of mercury in 1986
6.7micrograms/litre
what factors are looked at when measuring the biological response of the material
the location
the duration the stress thats placed on the material
what tests are used to measure biocompatibility
the in vitro test
the animal test
and the usage test
where are intro tests carried out
outside an organism in a test tube or dish
what is the material placed in contact with
biological systems- mammalian cells or tissues
advantages of in vinto test
controllable isolation repeatable fast cheap simple
disadvantages of in vitro test
provide misleading results
how do you carry out a usage test
place into intact organsims
which organisms is used
rats mice hamsters ferrets guinea pigs
advantage of usage tests
most relevant test
what is it called when a usage test is carried out on a human
clinical trials
disadvantages of usage tests
expensive time consuming hard to control hard to interpret results legal and ethical issues
FDA
food drug administration
ANSI
american national standard institute
ISO
international standards organisation
things to consider when we need a filling
systemic health
patients habits
expectations
dynamic relationship between the host function and material
