Week 3 Class I and V Restorations Flashcards
what are the type of liners in placing an occlusal restoration
-calcium hydroxide
- glass ionomer
which liner releases fluoride over time
glass ionomer
how do you use calcium hydroxide liners
-mix with spatula end of dycal instrument
- use dycal instrument to place over area of nearest pulp
- often cover with RMGI
how do you use resin modified glass ionomer liner/ base
-mix with spatula end of dycal instrument
- use dycal instrument to place over area nearest pulp
- often used to cover calcium hydroxide
-light cured
what is the difference between a liner and a base
a liner is placed in a thin layer over dentin
a base is placed in thicker layer on floor of prepared cavity
what are the steps in placing an occlusal restoration
- place liner and/or base if needed
- seal dentinal tubules
when would you need to use a base
deep caries
when would you seal dentinal tubules
preps that would be especially prone to sensitivity
what are the types of desensitizers
- copal resin
- bonding agents
- gluteraldehyde (gluma)
what are the advantages and disadvantages of copal resin
advatages: inexpensive, quick to use
disadvantages: leaves a film thickness
what are the advantages and disadvantages to unfilled dentin bond agent
advantage: intermediate in cost
disadvantage: some required more than one step; involves some form of etching with an acid which may leave teeth more vulnerable to recurrent caries, leaves a film thickness
what are advantages and disadvantages to gluma
advantages: no film thickness, one step to apply
disadvantages: expensive, somewhat caustic to soft tissues and possibly to the pulp in deep preparations
how do you apply each desensitizer
-copal resin: wipe cavity walls with cotton pellet soaked in resin, then gently air dry
-dentin bonded resins: press resin into dentin using brush, gently air dry, light cure
- gluma: apply to walls for 30 seconds, dry, rinse, dry again. material is caustic; minimize contact with gingivae and protect pulp with liner/base in deep preps prior to application
why do we not use dentin desensitizers under amalgam
it makes negligible difference in tooth sensitivity because smear layer will seal most dentinal tubules and amalgam will seal itself with an oxide layer
what are the steps in placing an occlusal amalgam restoration
-place amalgam
-condense amalgam
- pre carve burnish
-carve anatomy
- refine restoration
what technique and instruments do yo uuse in condensing amalgam
- small condenser to pack firmly into all line angles at a 45 degree angle, using a pressing, wiggling motion in a step wise fashion
how much should you overfill the amalgam prep
1 mm
how do you do pre carve burnishing
-using side of the nib of the condensor or ball burnisher.
-burnish towards the margins to eliminate voids and to bring excess mercry to the surface where it can be carved away
- begin to define grooves
what tools do you use to carve anatomy into amalgam
-hollenback carver perpendicular to margins
-tip of the carver to recreate groove anatomy
how do you check and refine occlusion in amalgam restoration
-use articulating paper
-use discoid carver to remove high occlusion marks and inclined plane contacts
what should you try to preserve in amalgam restoration
- preserve cusp seats in the bottoms of fossae
what tools do you use to smooth the surfacr
-beavertail burnisher
- cotton pellet to leave matte finish
does carved amalgam gain longevity from the finishing process
no
how long do you have to wait to finish/polish amalgam restoration
24 hours after placement for amalgam to be set up
what is the instrument sequence for finishing amalgam
-green stone (coarse)
- white stone (medium)
- 12 bladed polishing bur (medium-fine)
what is the instrument sequence for polishing amalgam
-brown (pre-polish)
- green (polish)
- green with yellow collar (superpolish)
what are the finishing burs
-flame 7902
- round 7006
- bullet 7404
-small round 7002
- bullet pointed 7104
how do you place the finishing burs
-put the tip of the bur in the central groove and lay the bur across the enamel margin
what is the general sequence of finishing burs
most abrasive to the finest polishing instrument
what are the criteria for finished amalgam
-scratches and major surface irregularities should be gone
- high polish not necessary
-grooves should be definite but not deep
-no occlusal prematurities
what is the most important area in finished amalgam
-cavosurface margin
what circumstances would you finish an older amalgam resoration
-amalgam margins that have expanded beyond the caavosurface
- margins that were originally undercarved
- 1/3 of enamel thickness in localized area can be removed to extend the life of a restoration without replacing it
-margins with minimal ditching may be refined
- rough surfaces can be smoothed
why do we polish amalgam on slow speed
-rubber points may fall apart at high speeds
- tooth may overheat at high temp
-amalgam may overheat
what does it mean if you cant obtain a smooth surface on an amalgam restoration
surface was too rough to begin with, restart finishing procedure from beginning
what is the procedure for composite
-etch 2 sec, rinse
-place bond, gently air dry, light cur
- place composite increment, condense, light cure, repeat until prep is finished
-create anatomy, finish occlusal surface, light cure
-assess occlusion, refine restoration
-polish
what is the procedure for amalgam restoration
-titurate amalgam
-place amalgam
-condense amalgam
- pre-carve burinsh
-carve anatomy
-assess occlusion, refine restoration
what tools should use use to carve anatomy in composite restoration
-hollenback
- optasculpt
which type of restoration does the operator have more control over set up time
composite
can you polish a composite restoration in the same day
Yes
when should you finish during a composite restoration? when should you polish
finishing should be completed prior to light curing, polishing should be done after the restoration is finished
what are the advantages and disadvantages to composite
advantages: preparation can be more forgiving, esthetic, operator control over set up time, preserve tooth structure ( dont need to remove as much for retention)
disadvantages: restoration more technique senstivie, additional steps, may not last as long, not as strong, no moisture tolerance
what would be more traumatic to gingiva in a class 5 restoration: overcontouring or under contouring
overcontouring
what are the steps in placing a class v amalgam restoration
- follow same guidelines as occlusal
-use hollenback carver to remove excess amalgam
what are the 4 major classes of dental materials
-metals and alloys
- porcelains and ceramics
-polymers
-composites
what organizations regulate dental materials
american dental association and FDA
what does the FDA do in regulation of dental materials
-protect the public from hazardous or ineffective medical materials and devices
what happened in the 2009 FDA reclassification
reclassified amalgam from class 1 to class 2 where class 1: lowest risk -> class 3 highest risk
how does the ADA regulate dental materials
-specifications for dental materials, instruments, and equiptment
- restorative material specifications
what does performance of all dental materials depend on
their atomic structure
what are the types of interatomic bonds
-primary: ionic, covalent, metallic
- secondary: hydrogen bonds, van der waals forces
what does electrostatic attraction of positive and negative charges involve
electron transfer between ions
what are the properties of ionic bonds
-non directional, strong bonds
- no free electrons, good thermal and electrical insulators
what are ionic bonds
electrostatic attraction of positive and negative charges
what are examples of materials with ionic bonding
ceramics, gypsum
what is a covalent bond
2 atoms share an electron
what are the properties of a covalent bond
-directional bonds
- low electrical and thermal conductivity
- water insoluble
what are examples of materials with covalent bonding
water, glass, polymers, composite
what are metallic bonds
cluster of positive metal ions surrounded by a gas of electrons
what are the properties of metallic bonds
-non-directoinal bonds
-high electrical and thermal conductivity
what are examples of materials with metallic bonds
amalgam and gold alloys
what are the classes of material properties
-biological
-surface
-physical
- mechanical
what is the biological class of material properties and example
the biological response to a material when in contact with the human body
- ex: gingivitis
what is the surface class of material properties and example
the unique properties of a material associated with its surface
-denture retention, adhesive bonding
what is the physical class of material properties and example
depend on the type of atoms and the bonding present in material; size or shape have no affect
- optic (color, glass), thermal (conductive)
-structure insensitive
what is the mechanical class of material properties
reaction of a material to the application of an external force, size, and shape of specimen affect properties
- structure sensitive
-applied force referred to as load
what develops in response to load
stress
what is the relationship between stress and load
stress = load per unit area
strength of material =
stress at fracture
type of strength measured is dependent on type of ___
force applied
what are the types of force/stress
-compressive (pushing)
- tensile (pulling)
- shear (sliding)
- torsion (twisting)
- flexure (bending)
what is compressive strength
measure of the stress necessary to fracture a material by 2 opposing forces directed toward each other
what does compression push together
atoms and structure
what is the highest strength measure for most materials
compressive strength
what is the lowest strength for most materials
tensile strength
what is tensile strength
-pulling force
- measure of the stress necessary to fracture a material by 2 opposing forced directed away from each other
what loads cause failure in compression
higher loads
what loads cause failure in tensile strength
lower loads
what is shear strength
sliding force
- stress necessary to rupture a material by 2 opposing parallel forces directed towards each other but not in the same plane
what is a clinical situation with shear force/ strength
implant bone interface
what is the intermediate strength between compression and tensile
shear strength
what is torsion strength
-twisting force
what are examples of torsion strength in dentistry
-torque wrench w dental implants
- torsion test of implant bone interface stability/strength of osseointegration
- torsional fatigue of endodontic rotary files
-not relevant to direct or indirect dental restorations
what is flexural strength
-bending force
-measure of stress to cause failure in bending
what is the 3 point bend test
-compressive load
-combination of compressive and tensile stress
where is flexural strength vital in dentistry
-on direct restorations (amalgam and composite)
- indirect/removable restorations
what are examples of dental stress
-protrusive movement
-posterior occlusion
what is involved in protrusive movement
anterior teeth
-flexure load on incisors
where is the compressive load from chewing distributed
at marginal ridge contact areas, at fossa areas
what is the formula for occlusal stress
occlusal load/ occlusal contact area
what are tripodized occlusal contacts
allows distribution of occlusal load across maximum area for minimized stress
what does premature contact result in
decreased area
-patients occlusal force stays same but occlusal stress is increased
what is strain
the deformation that occurs in a material when force is applied to the material
what is the formula for strain
change in length (deformation)/ unit original length
what is the relationship between stress and strain
if you have one you will have the other
what is elastic strain
temporary distortion of material by applied force
-strain is below the elastic limit
when force is removed in elastic strain what happens to material
reverts to original form
what is plastic strain
permanent distortion of a material
-strain is beyond the elastic limit
-elastic portion of strain recovered
- plastic portion of strain not recovered
what happens when force is removed in plastic strain
shape remains changed
what are the benefits to amalgam
-easy to manipulate
- can be placed in plastic state and carved before it hardens
- excellent physical properties (strong, predictable, self sealing, good barrier against recurrent caries)
-cost effecting
what is the basic amalgam composition
-70% Ag
-16% Sn
- 13% Cu
-Zn 1%
-silver, copper, tin zinc
what is conventional amalgam
low copper
what is high copper amalgam and benefits over conventional amalgam
higher copper amount, results in stronger restoration
what are the phases of amalgam setting and what happens in each
-gamma: tin and silver react with mercury, forms silver- mercury and tin- mercury. strong, corrosion resistant
-gamma-1: silver-mercury. weaker, suscpetible to corrosion
-gamma-2: tin-mercury. weakest, most susceptible to corrosion
what happens when you add copper to amalgam
creates a copper-tin phase, eliminates tin-mercury gamma-2 phase
what are the phases of low copper amalgam? high copper?
-low: gamma + mercury -> gamma + gamma-1 + gamma-2
-high: gamma + copper + mercury -> gamma + gamma-1 + CuSn
what are the shapes of amalgam particles:
-lathe
-admixed
-spherical
what is lathe
outdated-particles formed by cutting block of alloy with a lathe
-results in large irregular particles
w
what is admixed
-lathe type particles mixed with small spheres
-reqiures more condensation force
- most commonly used type of amalgam
-low early strength (1 hr)
what is spherical
-spherical shape
-higher early strength (1 hr) and higher 24 house strength than admixed
-more difficult to achieve interproximal contact
-require less condensation force
what are the variables in amalgam manipulatoin
-mercury to alloy ratio
- trituration
- condensation
-carving and finishing
what is the ideal mercury to alloy ratio
-less mercury in final restoration better strength and corrosion resistance
-admixed alloys ~50% mercury
longer and faster trituration = ___
sets faster
what is the most critical variable in amalgam manipulation
condensation
is undercondensation or overcondensation the most common error made by dentists
undercondensation
why not remove amalgam due to mercury concerns
-unwarranted loss of tooth structure
-unnecessary expense
-limited longevity when replaced with inappropriate tooth colored restoration
what are the properties of amalgam
- high compressive strength and low tensile strength
- sensitive to moisture contamination during placement
- amalgam corrodes
how does water react with amalgam
reacts with the zinc in the amalgam and causes an eventual expansion of the alloy out of the preparation
how does amalgam create and regenerate a seal between itself and the tooth
the oxides expand and fill tiny voids and prevent microleakage
what are the disadvantages of amalgam
-poor esthetics
-need for good mercury hygiene
-remove more tooth structure for adequate bulk of material
-doesnt bond to tooth structure
-thermal conductor, need liner or base to prevent post op sensitivity on deeper restorations
-eventually may ditch at the margins, collecting plaque in that area
what are the advantages to amalgam
-more forgiving in areas where moisture control is hard
- high wear resistance and compressive strength
-can be placed in less time than other options
-relatively long-lasting
- regenerates its seal
-is less prone to recurrent decay than bonded composite resin restorations
what are the indications for amalgam
- moderate to large class 1 and 2 restorations
-heavy occlusal wear
-high caries rate
-difficult isolation
-gingival margins on root - class 5 restorations in non-esthetic zones
-temporary restorations on teeth with questionable prognosis - buildup under crowns for extensively damaged teeth
what are the indications for amalgam
- moderate to large class 1 and 2 restorations
-heavy occlusal wear
-high caries rate
-difficult isolation
-gingival margins on root - class 5 restorations in non-esthetic zones
-temporary restorations on teeth with questionable prognosis - buildup under crowns for extensively damaged teeth
what are the indications for amalgam
- moderate to large class 1 and 2 restorations
-heavy occlusal wear
-high caries rate
-difficult isolation
-gingival margins on root - class 5 restorations in non-esthetic zones
-temporary restorations on teeth with questionable prognosis - buildup under crowns for extensively damaged teeth
