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Biomaterials
Biomaterials
31
Other
Graduate
09/24/2011

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Term
Federal Food, Drug, and Cosmetic Act of 1938 — 
Definition

Drug premarket approval, removal of fraudulent devices, proper labeling.

set up situation where you neededpre-market approval to market a particular drug
if you were to market a drug, had to go to govt and get pre-market approval to market it
made sure that they had the power to remove fradulent devices

proper labeling of drugs required 

Term
Medical Device Amendments of 1976 — 
Definition
Class I (least regulated) to Class III (most regulated).
Term
Safe Medical Devices Act of 1990 — 
Definition

expanded FDA authority in premarketing and postmarketing stages. Established tracking for some devices.

response to breast implant controversy

Term
a lot of law suits involved with breast implant issue
that a lot of companies got completely out of the medical device field
including manufacturers who supplied RAW materials

resulted in Biomaterials Access Assurance Act of 1998

 

Definition
limits the liability of biomaterials suppliers that are used to make medical devices
Term
class 1 devices 
if you sell a tongue depressor, and it leaves splinters in peoples tongues
no1 will buy it
you wont be able to sell it
general market control –
if you screw it up, no1 will buy it
not necessarily stuff that will significantly hurt some1
premarket approval is not required for this
in general
materials that are put ontissue
in contact with skin/gingiva = class 1 devices
crowns are included (although placed on prepared tooth)
dentures are included
Definition
A device for which market controls are sufficient to ensure safety and effectiveness.
Standards and premarket approval are not necessary.
Examples — Most short-term devices
dental floss
tongue depressor
surgeon’s glove
dentures, crowns 
Term
class 2
Definition
General market controls are insufficient but there is sufficient information for establishment of a performance standard.
Premarket notification is necessary.
Examples —
Oxygen mask
blood pressure cuff
ultrasound imager
dental restorative materials (amalgams and composites)
root form dental implants (classification change as of 4/04).
Term
root form dental implants
Definition
placed in live bone – come thru bone and soft tissue
only device that is placed in living bone THAT IS NOT A CLASS 3 DEVICE
a lot of implants are sold with abutments (which is the part that goes thru the skin)
abutment - is a class 2 device
class 2 and 3 device in the same package – did not work with the FDA
so root form dental implants were reclassified in 04’
only implantable device that is a class 2
Term
class 3
when fda first established this class – general idea was
if you had a new device, you would have to do an
IDE(investigational device exemption) and a
PMA – pre market approval documentation
and get this thru the FDA
could take several years bc it involves human clinical studies
Definition
Premarket Approval (PMA). Insufficient information for reasonable safety and effectiveness, required to have PMA.
These require some level of testing. See 510k rule.
Examples
Intraocular lenses
replacement heart valves,
orthopaedicimplants
blade form dental implants
root form dental implants.
Term
LOOPHOLE – 510k rule
substantial equivalence rule
Definition
everything you run across in the clinic has been 510ked into existence
means – if the device is substantially equivalent to something that was on the market/already on the market prior to 1976
do not have to completely test it
as soon as this law came out – people started to make incremental changes in their materials
saying this is the same as what we were making before 1976 – essentially 510k application

99.9% of everything that is on the market today has been 510 k approved

Term
FAT 510k
Definition
510 k that has data with it (you can actually make some claims)
allows you to make claims for ur device
FDA regulates CLAIMS you can make for your device
you cannot make outrageous claims unless you have DATA to support what ur making claims for
Term
Biocompatibility 
Definition
  • The ability of a material (biomaterial) to perform with an appropriate host response in a specific application.
  • Determined by the biomaterial and the host response
Term

Biomaterial 


For each biomaterial or device the definition of biocompatibility is different.

Definition

A biomaterial is a nonviable material used in a medical device intended to interact with biological systems

 



some of these now that are coming out on market fit in biologics category that are viable

artificial skin now
live artificial skin with live cells in it
sold for diabetic ulcer tx for burn victims

 

 

 

 

 

 

Term
BIOMATERIAL
Definition
surface characteristics
what your body, cells, tissue sees when you implant something
they see whats on the surface

bulk stability –
you do not want bulk Instability
èyou do not want a material that will release things –

mechanical properties
cannot use silicone rubber for joint replacement
not stiff enough
will not use stainless steal for breast implants
Term
HOST RESPONSE – we have the least control over
Definition
cellular level
toxicity
mutagenicity
carcinogicity
^these 3 terms make up tripartitie testing
new biomaterial – you can send to biomaterials lab some place
they can do these testing invitro with cell lines
to determine whether cells have toxigenic, mutagenic response, etc.
systemic/host level
can have 
inflammatory response
allergic response to the medical device
Term
interface is mediated by the environment
Definition
Saliva
Blood
heart valve
Extracellular matrix proteins
device planted in tissue
Cells (macrophages, fibroblasts, osteoblasts)
device planted in tissue
Mineral
implants that are put in bone
HAP most cases
Term

COMPROMISED BIOCOMPATIBILITY can be based on

- changes in biomaterials

Definition
Corrosion/degradation of a material
Release of component materials
Mechanical breakdown
total hip replacements undergo fatigue
they breakdown
Term

COMPROMISED BIOCOMPATIBILITY can be based on

- changes in HOST RESPONSE

Definition
Systemic problems (diabetes) leading to changes in host response
Hypersensitivity
Immediate type I
Delayed type IV
Term
allergic rxns in dentistry - most common ..
Definition

type I hyp

type IV hyp

Term
type I rxns
Definition
allergic asthma and rhinitis
food and drug reactions
reactions to insect stings.
Term
type IV
Definition
Immune response mediated by T cells, usually CD4
Cytokines are released
macrophage activation and local damage

  

Term
most common allergens
Definition
ŸLatex gloves
ŸMethacrylates
ŸDisinfectants
ŸAnesthetics
Term
most common allergens continued..
Definition
ŸMetals
mostly was women who were allergic to Ni
a lot of men now have piercings
they now too have Ni allergies, evened out a bit
ŸEugenol
ŸImpression materials
Polyethers
Term

Common allergens


most common is Ni (10-15% of population)

-most of this has been eliminated from use

Definition

Nickel

  Rubber compounds

  Mercuric chloride

  Cobalt salts

  Thimerasol

  Benzoyl peroxide

  Fragrance mix

Term

Hg and Biocompatibility

 

elemental mercury is not toxic
UNLESS made into vapor
carpets not in dental operatories anymore
if you drop small piece of amal and you grind it into carpet – you increase the surface area of it tremendously
mercury can VAPORIZE and you can inhale this
once in your body à becomes organic mercury compound/salt
èsalts are more toxic than organic
èmethyl mercury (organic mercury compound) is 7 x as toxic vs. elemental mercury
Definition
ŸHg forms
Elemental – vapor or liquid
Amalgam vapor
Organic (methyl Hg)
Highly toxic (~7x as toxic as elemental mercury)
ŸExposure (daily)
Atmosphere (vapor, 0.12 µg)
Drinking water (inorganic, 0.05 µg)
Food (non fish – inorganic, 20 µg)

FISH ( methyl Hg, 3.76 µg

Term
·Workplace vapor levels, OSHA Threshold Limit Value (TLV)
Definition

how much mercury your allowed to be exposed to

· 50 µg/m3 for 8 hr day, 5 days per week

reported levels are way less than threshold values
when you place amal
theres the most risk for vapor
bc as the amalsets
it becomes a more stable material
less likely to give off mercury
Term
·9 occlusal amalgams = 1% of work place safety levels that your allwoed to be exposed to in a manufacturing plant(TLV)
Definition
·One saltwater seafood meal per week
· Urine levels of 5-20 µg/L (WHO)
· 2 – 8 times exposure from dental amalgam vapor 
Term
whenever you take any material and you grind it up into particles – your BOUND to get an inflamm response to it
when drilling it out
get rid of all the materials
Definition
-foreign body giant cells
-capable of producing lots of cytokines and inflamm mediators
Term
Total hip replacement (Class III) articulating joint surface
Definition
one of the problems with these implants is THEY WEAR
solid metal ball on a polyethylene liner
polyethylene liner – can release wear particles over time (implants that are in for 15-20 yrs)
grind this up into small particles
can get a very nasty inflamm response to these particles
taking a material that is perfectly biocompatible in bulk form
but when grinded up into small particles causes a TREMENDOUS inflamm response

tissue response is more related to the surface area of the material than the material itself
when you grind up into particles è tremendously increase the surface area that the body responds to
Term
good example of what can happen with a class 3 device over long periods of time bc of wear and breakdown of materials into particles

polyethylene particles from hip joint replacement/implant
Definition

particles are generated int he synovial joint

- activation of osteoclasts and FBGC

 

the most biocompatible materials
if you grind them up into little particles – they cause a nasty response
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