restorative and aesthetic material ch 43 Flashcards
amalgam =
name given to “silver things”
consists of many different metals with silver being the predominant metal. Mixed with approx, equal parts of mercury
dental amalgam
contraindications to dental amalgam
asthetics are important
pt has a history of allergy to mercury
cost
alloy powder mixed with mercury
forms a soft pliable mixture
when placed in a tooth, condensed, carved, and allowed to harden, the mixture become a permanent
dental amalgam
silver
65% gives amalgam its strength and silver color
tin
29% for its workability and strength
copper
6% for its strength and corrosion resistance ability
zinc
2%, to suppress oxidation
—-+—– = amalgam
alloy + mercury
physical characteristics of mercury
liquid at room temp
vaporizes with increased heat
highly poisonous
where to store scrap amalgam
in a wide mouth airtight container marked
non-contact amalgam
amalgam handling
do not contact skin
protect against spillage during mixing
do not throw away in general waste
advantages of amalgam
best restorative material for posterior teeth
user friendly can be mixed, placed, and carved in a short time
can last very long
disadvantages of amalgam
non-esthetic in color
contains mercury so its dangerous
takes 24 hrs to completely set
capsules (600 mg of alloy)
for small or single surface restorations
capsules (800 mg of alloy)
for larger restorations
trituration
process by which the mercury and alloy powders are mixed together to form the mass of amalgam
what is mixing done by
an amalgamator
Etch can be supplied as
liquid/gel
malice acid
phosphoric acid
what removes the smear layer
acid etching
when you apply etch to enamel how long do you leave it for
ranges from 15-30 secs
T/F; avoid contact with soft tissue, rinse thoroughly if contaminated with acid etch .. Protect pulp
True
Bonding agents function
reduce microleakage, reduce sensitivity , help living tissue inside tooth recover from stress
when to place bonding agents
placed in tooth after cavity prep and just before placement or restorative material
reducing the microscopic gap can
improve retention by creating micro mechanical retention
enamel bonding is placed
directly onto the intact enamel surface
examples of enamel bonding
sealants, bonded veneers, resin bonded bridges, bonded ortho brackets
dentin bonded is placed
on prepared dentin in order to bond .
t/f; before you put dentin bond, smear layer must be removed first for successful bonding (use of etchant)
True, smear layer acts as a semi impermeable layer which prevents the bonding from contacting actual surface of dentin
what are the 3 different cures
light cured
self cured
dual cured
how long should you light cure for
20-30 secs, following manufactures instructions
composite resins uses and characteristics
good for anterior teeth
can be placed in poster teeth but not as strong as amalgam
matches teeth color
advantages of composite resin
helps prevent breakage and damage
last 6-12 yrs
very little sensitivity to hot/cold
dentist will not drill as much of the tooth
disadvantages of composite resin
require more time to apply
higher cost
Conventional composites contain the largest filler particles, therefore provide the greatest strength, but duller and rougher on the surface
macrofilled (posterior teeth)
contain inorganic filler that is much smaller and is capable of producing a highly polished finished restoration, used primarily in anterior restoration
microfilled
composites contain both macrofill and microfill particles. Can be polished smooth and has good strength
hybrid
process in which the resin material is changed from a pliable state into a hardened restoration
polymerization
glass ionomer cement
most versatile
binds chemically to tooth
releases fluoride
low solubility
when and where you use glass ionomer cement
primary teeth
sealants
final restorations for non-bearing areas class V AND root surfaces
supply of glass ionomer type I (power/liquid)
Mixed on a paper pad or on a cool dry glass slab
supply of glass ionomer type I (premeasured capsules)
triturated and expressed through a dispenser
tooth whitening products
peroxide based gel
gel comes in 10, 16, 22 % concentration
precautions to follow when using light cure
use protective sheild
dispense materials
THE DARKER THE SHADE, THE LONGER THE CURING TIME
Contradications for using composite resins
when aesthetics not important
pt who do not have daily oral hygiene
cost
