Test 1 Flashcards
What is operative dentistry?
diagnosis, treatment, and prognosis of defects in teeth that do not require full coverage restoration for correction.
name some common causes for operative dentistry
caries, malformed, discolored, fractured, abrasioon, attrition, erosion
what is attrition?
wear of teeth by other natural teeth
what is abrasion
wear of teeth by foreign objects like tooth brush
what causes erosion?
chemicals like drugs, lemon juice acid reflux…..etc.
define abraction
theory that is used to explain the loss of enamel and dentin from flexural occlusal forces, particularly at the cemento–enamel junction (CEJ).
what are abfractions?
non carious cervical lesions on facial and lingual sides of cervical part of tooth.
what are direct restorations?
amalgam, composite resin, GIC. These are used to mold and shape proper contours of natural teeth.
what are indirect restorations?
inlay, onlay, crowns
what are advantages to direct restorations?
easy to place, fast, cost effective
what are disadvantages to direct restorations?
with large preps, mechanical proerties become compromised.
what are advantages to indiret restorations?
provide better mechanical propeties and stress distriution.
what are disadvantages to indirect?
time consuming and expensive
define a tooth preparation?
removing the defective, injured or diseased tooth to recieve a restorative material that will restore the healthy state of the tooth.
Why prepare teeth?
Prevent progression and recurrence
what kind of burs do we use?
diamond and carbide
high speed hand rotates at…. and slow speed at …..
high 2000,0000 rpm
slow 15,000 rpm
whats a major benefit to electrical hand pieces?
its torque doesnt change
slow speed is generally used for what?
polishing, removing caries, other tactile stuff
who is the faterh of operative dentistry?
G.V. Black, he classified caries according to their locations
class 1 lesions
occur in pits and fissures on the facial, lingual, and occlusal surfaces of molars and premolars and, less often, the lingual surfaces of maxillary anterior teeth (most frequently lateral incisors, less frequently central incisors, rarely canines).
** above height of contour***
in a direct restoration of amalgam the facial and lingual walls should converge/diverge for retention?
converge
walls of a preparation for bonded resin should converge/diverge for retentions?
diverge
class 2 lesions
occur in the proximal surfaces of the posterior teeth (molars and premolars).
if a proximal surface is involed, its a class 2.
It can have more than one proximal box as well ex MOD.
Class 3 (III) lesions occur
in the proximal surfaces of anterior teeth (central and lateral incisors and canines).
Class 3 cavities do not involve an incisal angle.
Class 4 (IV) lesions
occur in the proximal surfaces of anterior teeth when the incisal angle requires restoration.
Class 5 (V) lesions
occur in smooth facial and lingual surfaces in the gingival third of teeth. (Gingival to the height of contour)
class 6 lesions
preparations in the incisal edge of a canine and the cusp tip of a premolar/molar.
usually not a carious lesion.
starting what year was PPE required for treating patients?
1991
3 ways exposure occurs in the dental laboratory?
Air-borne contamination
Direct contamination
Indirect contamination
aerosols consist of invisible particles of what size?
5-50 micrometers
airborne contaminants exist as what 3 things?
spatter, mists, aerosols
which infection is transmitted hugely in aerosols thats a problem for dentists?
active pulmonary or pharyngeal tuberculosis
how far does spatter travel?
3 ft.
name some things used to reduce microbial exposure
rubber dam, mouthrinse, high vac suction, adequate air circulation….
what is the best way we protect ourselves?
barrier protection
what is direct contamination?
when we come in direct contact with bodily fluids. ( needle sticks, direct exposure to mucus membranes, direct skin exposure)
Whats indirect contamination?
Contaminated saliva is passed to surfaces that aren’t protected and someone picks it up.
how many clusters of HBV and HIV cases has there been in the USA from dental offices?
9, 1
when was OSHA passed in the USA?
1970, ( the act made employers protect employees)
what does OSHA;s communications program deal with?
risks from environmental and chemical hazards in the workplace
what does OSHA’s bloodborne pathogens program deal with?
occupational exposure to blood and other potentially infectious materials
All aspects of COSHA’s bloodborne pathogens program were required in dental offices starting what year?
1992
where are the non metals, metals, and metalloids on the periodic table?
metals- middle and left
non-metals- right
metalloids- between metals and non metals
What 2 elements are liquids at room temperature?
Br, Hg
ancient dental materials commonly included….
wax, bone, ivory, gold, porcelain
What are the criteria you need to remember for restorative materials?
not harmful, application, insertion in cavity, recreate anatomy, durable, color
whats an alloy?
combination of metals
What are other alloys used in dentistry
Dental amalgam, implants, crowns
what kind of alloy is amalgam?
its an alloy of an alloy because it is a silver-tin alloy. ( it was discovered the 4 element alloy was best)
how is amalgam made?
liquid mercury mixes with metal powder which reduces the toxicity and hardens
What is the amalgam metal powder made of?
Ag3Sn
who is Paracelsus?
Made groundbreaking advances in the field of medicine he said “ poison is in everything and nothing is without poison. The dosage makes it either a poison or a remedy”
who brough amalgam to the USA?
the crawcour brothers
What 5 metals are in amalgam?
Cu, Zn, Ag, Hg, Sn
when did the ADA adopt amalgam as their standard #1?
1929
what are the requirements of the ADA for element percentages?
> 65% Ag
<2% Zn
what are the two different amalgams and what do we use at lecom?
high coppuer and lower copper. Lecom uses high copper
what is the major and minor phases present in alloy powder?
Major: Ag3Sn
γ phase
Minor: Cu3Sn
ε phase
some amalgams contain more metals than others. A metal that is not in hight content is __ due to its high toxicity.
Cadmium
after amalgamation occurs how much free Hg is left over?
zero
is mercury hydrophilic?
no its hydrophobic
what kind of contact angle will mercury have?
high.
what is the usual particle size of amalgam?
15-35 micrometers
what happens if your amalgam contains smaller particles?
theirs more surface area so youneed more mercury to dissolve it. This also causes more rapid hardening and strengthening
describe lathe-cut powders of amalgam
an ingot of alloy is first annealed then fragmented by a cutting tool or bit.
describe atamized powder in amalgam
: Molten alloy is atomized (sprayed) in an inert gas to form fine spherical droplets
combination of the 2 alloy powder shapes is called…
admixtures
what is the technique called that utilizes the little capsules for amalgam tituration?
eames technique
what influences the setting speed?
alloys particle size, shape, and composition, trituration speed and time.
the coefficient of thermal expansion is higher/lower than dentin?
higher
whats a benefit of corrosion of amalgam
can seal the margins of the restoration
whats the galvanic reaction?
sense of a “current” or shock between dissimilar metallic restorations
amalgam is stronger than dentin and enamel. Its strength is determined by….
composition, microstructure, trituration, porosity
amalgams tensile strength goes up after about 24 hours T/F?
True
amalgam is banned in ….
norway, sweden, denmark and being phased out in asia
which lasts longer amalgam or composite?
amalgam
when alloyed with indium and tin, what element is in a liquid state and can be mixed with copper to form an amalgam?
Gallium, but its still not as good.
Once mercury is in the amalgam form its vapor pressure is how many times less than free mercury?
over 1 million times less.
is mercury the same in dental amalgam as fish?
no , in amalgam it is elemental mercury and in fish it is methylmercury wich is worse.
What are composites a cross between?
polymers and ceramics
the composites we work with include what 2 types of polymers or ceramic?
glass and resins
Define resins
monomers of sticky substance that comes from trees ( used in plastics alot)
Define plastics
polymers, capable of being deforemed continuously and permanently in any direction without rupture.
what were the composites made out of in the early 20th centurty and why were the problematic?
Silicate glass with alumina (Al2O3) & H3PO4,
marginal discoloration & they were soluble.
Acryllic resins in the 1940’s
were pretty good but they would wear easily( this is why glass was later added to prevent ware)
What kind of resins do we use?
methacrylate resins, ( they have a methacrylic acid)
how are methacrylate resins combined to make polymers?
free radical vinyl polymerization
After polymerization, what are the 3 methacrylate products usually seen in dentistry?
Bisphenol A glycidylmethacrylate
Triethylene glycol dimethacrylate
Urethane dimethacrylate
who recieved the lifetime achievment award for bettering composites?
Dr. Ray L. Bowen
What are the components of light cured composites?
Resin-
fillers ( covered in silane)- resist wear and add pigment
initiators-start the polymerization
inhibitors- prevent from polymerizing under ambient light
what are the light curers?
camphorquinone (CQ), phenylpropanedione (PPD)
lucirin (TPO)
Purpose of fillers
Reinforce resin, reduce shrinkage, improve esthetics, increase radiopacity.
silicon dioxide is a filler. what else is silicon dioxide known as?
silica, SiO2, ( it is not silicone) it adds resistance and radiopacity
what fillers are used for pigments?
Titania, tin oxide, iron oxide
TiO2, SnO2, Fe2O3
what do prepolymerized polymers do as fillers?
reduce shrinkage
what makes materials radiopaque?
high atomic weight ( you want it to be heavier than Ca)
what are coupling agents used for?
it sticks the resin to the glass, (organosilanes are major ones)
W/o these composites wear fast.
what are the steps for composites?
etch, prime, adhesive, composite placement, curing, polishing
factors of etching include…(mechanical adhesion)
time, % of acid in etch (35-37%), Fluoride content in tooth.
principles of adhesion include
wetting surface, rough surface for mechanical interlocking, chemichal bonding
What ways do composites cure?
chemical, light, dual cure
does the curing light emite uv rays?
no its blue light.
what disks do we use to polish composite?
alumina disk
what are disadvantages of composites?
needs bonding, shrinkage, lower strength, discoloration ar margins over time, expensive, shades vary among manufactures
why should degree of cureing be high? (DC)
higher strength, higher wear resistance, and less cytotoxicity
what is the DC/degree of conversion of monomers to polymers of composite?
50-60%
what does DC depend on?
Resin composition, access of curing light to composite, layer thickness, duration of cure, lamp used,
why are secondary caries an issue with composites?
due to the shrinkage around the margins. Bacteria like to attack here
BPA issues in composites
alot of composites have them to some degree, once composite sets up the chance of BPA to enter blood stream decreases aton.
how could composites be better?
shrink less, wear better, seal margins better
