OPERATIVE Restoration of Teeth Flashcards
___ are effective disinfectants, provide cross-linking of any exposed dentin matrix and occlude dentinal tubules by cross-linking tubular proteins
sealers (aka desensitizers)
sealers provide occlusion of the dentinal tubules which limits the potential for ___
tubular fluid movement and resultant sensitivity
sealers are typically ___ solutions
aqueous
historically, ___ was used as a liner under amalgam restorations
copal varnish
what are some examples of desensitizers that some sealers contain?
gluteraldehyde, hydroxyethylmethacrylate (HEMA), benzalkonium chloride, or chlorhexidine
___ are thin layers of material used primarily to provide a barrier to protect the dentin from residual reactants diffusing out of a restoration, from oral fluids, or from both, which may penetrate leaky tooth-restoration interfaces
liners
what are some ways liners act as barriers?
- contribute initial electrical insulation
- generate some thermal protection
- some formulations provide pulpal treatment
___ are used to cover a direct or near pulpal exposure and to line very deep areas of a tooth preparation in vital teeth
liners
___ and ___ are examples of typical liners used with direct restorations
calcium hydroxide and RMGI
___ are used to provide thermal protection for the pulp and to supplement mechanical support for the restoration by distributing local stresses from the restoration across the underlying dentin surface
bases
how thick should bases be?
1-2mm typically
additional bulk from a base affords ___ and ___ protection to the pulp under metal restorations
mechanical and thermal
___ or ___ are recommended as a base to overlay any calcium hydroxide liner that has been placed
RMGI or conventional glass ionomer cement
RMGI or conventional glass ionomer cement base provides additional strength to resist ___ in amalgam restorations, as well as protection of the liner from dissolution during ___ procedures
- amalgam condensation pressure
- bonded
describe how to use bases and/or liners in amalgam restorations with shallow excavations
- shallow excavation = remaining dentin thickness >2mm
- use a dentin sealer/desensitizing agent such as gluma or G5
- sealers/desensitizers replace the traditional use of copal varnish
describe how to use bases and/or liners in amalgam restorations with moderately deep excavations
- remaining dentin thickness is 0.5-2mm
- use light cured RMGI base, followed by a dentin sealer/desensitizing agent
- objective is to provide 2mm of insulation between the restorative material and the pulp
- this replaces the traditional approach of using a zinc oxide eugenol base material followed by a copal varnish
describe how to use bases and/or liners in amalgam restorations with deep excavations
- noncarious (or mechanical) pulpal exposure less than 1mm in diameter or excataions where the remaining dentin thickness is <0.5mm
- use a thin (0.5-0.75mm) layer of calcium hydroxide liner on the suspected exposure site followed by RMGI base to seal immediate site of exposure
- objectives are to prohibit bacterial infiltration and protect the liner from dissolution
- a dentin sealer/desensiziting agent or an appropriate amalgam bonding agent is placed on the remaining dentin
describe how to use bases and/or liners in composite restorations with shallow to moderately deep excavations
- remaining dentin thickness is 0.5mm or more
- no liner or base material is indicated
- only a dentin bonding system along with the composite restorative material is needed
describe how to use bases and/or liners in composite restorations with deep excavations
- noncarious (or mechanical) pulpal exposure <0.1mm in diameter or excavations where the remaining dentin thickness is judged to be <0.5mm
- use a thin (0.5-0.75mm) layer of calcium hydroxide liner placed on the suspected exposure site followed by RMGI base and the proper application of a bonding agent along with the composite restorative material
- objective is to prevent bacterial infiltration while avoiding dissolution of the liner
describe how to use bases and/or liners in indirect restorations with shallow excavations
- remaining dentin thickness is 2mm or greater
- no sealer, liner, or base is needed
- RMGI cement or a resin-based cement may be used for cementation, providing excellent dentinal sealing
describe how to use bases and/or liners in indirect restorations with moderately deep excavations
- remaining dentin thickness 0.5-2mm
- RMGI or conventional glass ionomer cement may be used to restore axial or pulpal wall contour and to ensure an adequate thermal barrier
- objective is to provide 2mm of insulation between the restorative material and the pulp
- RMGI or resin based material is recommended for cementation
describe how to use bases and/or liners in indirect restorations with deep excavations
- noncarious (mechanical) pulpal exposure less than 1mm in diameter or excavations where remaining dentin thickness is <0.5mm
- use a thin (0.5-0.75mm) layer of calcium hydroxide liner placed on the suspected exposure site followed by RMGI base to restore axial or pulpal wall contour, ensure an adequate thermal barrier, and seal the exposure site
- objective is to prevent bacterial infiltration while avoiding dissolution of the base
in indirect restoration cases where pulp exposures occurred during preparation, where there is an increased risk of endodontic complications secondary to the pulp exposure, strong consideration should be given to performing ___ before completion of the indirect restoration
endodontic therapy
what are the two types of amalgams?
- low copper (generally inferior, seldom used)
- high copper (spherical and admix)
is spherical or admix amalgam better? why?
- admix
- less leakage and less postoperative sensitivity
the linear coefficient of thermal expansion of amalgam is ___ than that of tooth structure
greater
the compressive strength of high copper amalgam is ___ than tooth structure
similar
the tensile strength of high copper amalgam is ___ than tooth structure
lower
amalgams are brittle and have ___ edge strength
low
high copper amalgams exhibit ___ creep or flow
no clinically relevant creep or flow
is amalgam a high or low thermal conductor?
high
what are the clinical disadvantages of amalgam?
marginal fracture, bulk fracture, and secondary caries
what are the uses for amalgam restorations?
- nonesthetic cervical lesions
- large class I and II preparations where heavy occlusion would be on the material
- class I and II preparations where isolation problems exist for bonding
- temporary or caries-control restorations
- foundations
- patient sensitivity to other materials
- where cost is a factor
- inability to do a good composite
what are the advantages of amalgam?
strength, wear resistance, easy to use, less technique-sensitive, self-sealing margins over time, history of use, lower fee, long-term clinical longevity
what are the disadvantages of amalgam?
not esthetic, conductivity, tooth preparation more demanding and less conservative
is there scientific evidence that amalgam poses health risks to humans?
- no, with the exception of rare allergic reactions
- there is actually no evidence ensuring that alternative materials pose a lesser health hazard
true amalgam allergies are rare. how many have been reported since 1900?
50
what is the estimate of human uptake of mercury vapor from amalgams?
5 ug/m^3
which amalgam type is likely to produce a more successful restoration?
high copper
how thick does amalgam need to be to increase its success?
1-2mm
after the tooth preparation for most amalgam restorations, a ___ is placed on the prepared dentin before amalgam insertion to ___
- sealer
- occlude the dentinal tubules
- this step may occur before or after the matrix application
what are the 4 objectives of a matrix?
- provider proper contact
- provide proper contour
- confine the restorative material
- reduce the amount of excess material
what are the 4 characteristics a matrix needs to be effective?
- be easy to apply and remove
- extend below the gingival margin
- extend above the marginal ridge height
- resist deformation during material insertion
in terms of trituration, what two features affect the setting reaction of the material?
the speed and time of the mix
of spherical and admixed (lathe-cut) amalgam, which is easier to condense?
spherical
how is floss used to to check the proximal contact of an amalgam restoration?
- insert floss inter proximally first by wrapping the floss around the adjacent tooth and pulling it through
- wrap floss around restored tooth and move it occlusally and gingivally to determine if excess material exists and to smooth it
how do you repair an amalgam restoration?
-the defective area must be prepared again as if it were a small restoration, with appropriate depth and retention form
what are the causes of postoperative sensitivity from amalgam restorations?
- lack of adequate condensation, especially lateral condensation in the proximal boxes
- lack of proper dentinal sealer or pulp protection
what are the causes of marginal voids from amalgam restorations?
- inadequate condensation
- material pulling away or breaking from the marginal area when carving bonded amalgam
what are the causes of marginal ridge fracture of amalgam restorations?
- axiopulpal line angle not rounded in class II tooth preparations
- marginal ridge left too high
- occlusal embrasure form incorrect
- improper removal of matrix
- overzealous carving
are amalgam restorations safe?
- yes, as reported by the US Public Health Service
- proper handing of amalgam is of vital importance
which type of high-copper amalgam provides higher earlier strength and permits the use of less pressure? which one permits easier proximal contact development because of higher condensation forces?
- spherical
- admixed
are bonded amalgam restorations recommended?
- not any longer
- however, if bonding an amalgam, the use of typical secondary retention form preparation features are still required
- small to moderate amalgam restorations should not be bonded
what are the indication for proximal retention locks?
- may be beneficial for large amalgam restorations (not necessary for smaller restorations)
- correct placement of proximal retention locks is difficult
what are the advantages of bonding to tooth structure?
less micro leakage, less marginal staining, less recurrent caries, less pulpal sensitivity, more conservative tooth preparation, improved retention, reinforcement of remaining tooth structure, and more conservative treatment of root-surface carious lesions
what are the uses of adhesive techniques?
change shape and color of anterior teeth, restore class I-VI lesions, improve retention for metallic or PFM crowns, bond ceramic restorations, bond indirect composite restorations, seal pits and fissures, bond orthodontic brackets, bond periodontal splints, bond conservative tooth-replacement restorations, repair existing restorations, provide foundations for crowns or onlays, desensitize exposed root surfaces, impregnate dentin and enamel to make them less susceptible to caries, bond fragments of anterior teeth, bond prefabricated and cast posts, and reinforce remaining enamel and dentin after tooth preparation
what is sufficient to etch enamel?
10-15 second acid etch (30-40% phosphoric acid) is sufficient
is micro leakage common at etched enamel margins?
no, it is virtually nonexistent
enamel bonding resists ___ forces of composite
polymerization shrinkage
how is dentin bonding accomplished?
either etch and rinse (simultaneous with enamel etch) or self etch (with a self etching primer or all in one adhesive)
how does dentin bonding compare to enamel bonding?
- less reliable, less durable, and not as predictable as enamel bonding
- may have some micro leakage, especially after aging of the restoration
- may have similar or higher bond strengths than enamel
- may not resist polymerization shrinkage forces
what are the factors that affect the ability to bond to dentin vs enamel?
- microstructural features of enamel and dentin
- material factors
- preparation factors
describe the difference in composition of enamel vs dentin
- enamel is 90% mineral (hydroxyapatite)
- dentin is much less mineral and more organic (type I collagen) and water
are enamel prisms and inter prismatic areas etched and bondable?
yes
what are the 3 types of dentin tubules?
peritubular, intratubular, and intertubular channels
dentin tubules extend from the ___ to the ___
pulp to the DEJ
what do dentin tubules contain?
odontoblastic extensions and fluid
how do dentin tubules range in size/number as they near the pulp?
- much larger (2.4um) and numerous (45,000/mm^2) near the pulp
- near DEJ (0.6um, 20,000mm^2)
fluid movement inside dentin tubules is dictated by ___
pulpal pressure
dentin that is aging, below a caries lesion, or exposed to oral fluids exhibits increased mineral content (sclerosis) and is much more resistant to ___
- acid etching
- therefore, the penetration of dentin adhesive is limited
what is the smear layer?
- debris left on the surface after cutting
- consists of hydroxyapatite and altered denatured collagen and fills the orifices of the tubules (smear plugs), decreasing dentin permeability by 86%
how is the smear layer removed?
etching removes the smear layer, resulting in greater fluid flow onto the dentinal surface, which may interfere with adhesion
how is the linear coefficient of thermal expansion of dentin altered when subjected to thermal changes compared to composite?
dentin is 4x less than composite
composites shrink when they polymerize, creating stresses up to ___ megapascals
7 (1MPa = 150lb/in^2)
preparations with multiple walls or boxlike shapes (configuration) have limited ___ opportunity for the composite material (polymerization shrinkage), and the high configuration factor (C factor) may result in ___ and ___
- stress relief
- internal bond disruption and marginal gaps
C factor is determined by the ratio of ___ vs ___ within a tooth preparation
prepared (bonded) vs unprepared (unbounded) walls
high C factor may indicate increased chance for ___
postoperative sensitivity
what are the two current adhesive systems used for bonding?
etch and rinse, and self etch
etch and rinse is also called ___
total etch (etch enamel and dentin)
what are etch and rinse three step systems?
- aka multibottle or fourth gen systems
- etch, primer, and adhesive
what is the purpose of etch?
demineralizes enamel and dentin selectively, increases surface area, and cleans the surface of debris
T or F:
etched enamel and dentin appear chalky
- false
- enamel appears chalky, but dentin does not
etched dentin exposes a layer of ___
collagen
what is the purpose of etch, primer, and adhesive?
- etched dentin exposes a layer of collagen
- primer increases the collagen
- adhesive flows between the collagen and interlocks with it to form a sandwich (or hybrid or resin-reinforced) layer
most bond strength is from the formation of the ___ layer
- hybrid (aka sandwich or resin-reinforced)
- the surface layer is only a few microns thick, creating a demineralized layer of dentin intermingled with resin
etch and rinse three step (etch, primer, and adhesive) systems ___ the dentin, which decreases ___
seals, postoperative sensitivity
etch and rinse three step systems provide good dentin bonding strengths. how does it compare to enamel bonding?
same or better
there must be a bond strength of ___ MPa to resist polymerization contraction force of composite
17-21
how long should you etch enamel and dentin?
10-15 seconds
what does etching enamel and dentin do?
- etches enamel
- removes smear layer
- opens and widens dentin tubules
- demineralizes dentin surfaces
- etches out mineral (hydroxyapatite) but leaves collagen fibrils (these have low surface energy)
what are the 4 steps for etch and rinse three step systems (from application to composite placement)?
- etch enamel and dentin for 10-15 seconds
- rinse well and leave moist or rewet (aqua prep or gluma desensitizer)
- apply 2-3 layers of primer HEMA/biphenyl dimethacrylate
- apply adhesive (bonding agent) - bisphenol A-glycidyl methacrylate or other methacrylate
- place composite
what is HEMA/biphenyl dimethacrylate?
- resin monomer wetting agent
- dissolved in acetone, ethanol, and water
- bifunctional
- acts as a solvent
how is HEMA/biphenyl dimethacrylate bifunctional?
- wets dentin (increases surface tension)
- bonds to overlying resin
adhesives may also contain HEMA or other primer constituents to enhance ___
bonding
adhesives (bonding agents) penetrate ___, provide a ___ surface layer, and bond ___
- intertubular dentin and tubules
- polymerized surface layer
- primer and composite
what are etch and rinse two step systems?
- aka one bottle or fifth generation systems
- primer and adhesive are combined but still need etchant
in etch and rinse two step systems, primer and adhesive are ___
combined
etch and rinse two step systems require etchants in order to ___
remove the smear layer
most etch and rinse two step systems require ___ bonding
wet
the bond mechanism of etch and rinse two step systems is ___
the hybrid layer formation
how does the bond strength of etch and rinse two step systems compare to multibottle systems?
generally not as high, but this is likely not clinically significant
T or F:
etch and rinse two step systems are very technique sensitive, and manufacturer’s instructions must be followed exactly
- true
- must have dentin wettability just right
etch and rinse two step systems are used primarily for ___ procedures
direct
T or F:
etch and rinse two step systems are faster than multibottle materials
false
what are the steps in the etch and rinse two step systems?
- etch for 10 seconds
- rinse well and leave moist or rewet
- apply 2-3 layers of primer/adhesive, thin gently with air, and light cure
- reapply adhesive, thin, and light cure
- place composite
the objective or self etching systems is to remove ___
operator variables (rinsing and drying)
what do self etching systems include?
etchant and primer, or etchant, primer, and adhesive combined
what is the possible reason why self etching systems leave less postoperative sensitivity?
they do not completely remove the smear layer
why do self etching systems need to be refrigerated?
reactive components
why should you avoid using diamond burs when using self etching systems?
- because they have a much thicker smear layer, which makes bonding more difficult because self etching systems do not completely remove the smear layer
- use carbide burs
T or F:
self etching systems etch enamel comparatively to phosphoric acid
- false
- they do not etch enamel as well as phosphoric acid
- enamel etching with phosphoric acid may be beneficial, but do not etch dentin because it decreases the dentin bond
why should self etching systems be air dried?
- the material has water and needs to have a longer drying time to remove the water
- dry for at least 10 seconds
of the self etch categories, which is the most “risky”?
self etch one step systems (aka all in one)
do self etch one step systems remove the smear layer?
no
T or F:
self etch one step systems are very easy to use
true
self etch one step systems provide a bond to dentin of ___ MPa
25 (not great)
what is self etch two step?
self etch primer and then a bonding adhesive
self etch two step requires how many coats?
about 5
do self etch two step systems remove the smear layer?
no
are self etch two step systems easy to use?
yes, fast and easy
T or F:
self etch two step systems do not require rinsing
true, no worry about moisture
is postoperative sensitivity common with self etch two step systems?
no
self etch two step systems do not bond well to ___
- uncut enamel (12 MPa)
- must roughen enamel and consider etching
what are the advantages of self etch systems?
- easy to use
- eliminates variables with wet bonding
- depth of etch is self limiting
- sensitivity is reduced
what are the disadvantages of self etch systems?
- bond strengths to enamel and dentin generally lower
- some do not adequately etch uncut enamel
- bond strengths to autocuring composites are poor
- clinical performance is not proven
- bond durability questionable
what are some important technique suggestions for etch and bond systems?
- use microbrushes to apply primer/adhesive
- place bonding agent in a small well to minimize evaporation
- replace caps quickly and tightly
- dispense 1-2 drops for each tooth
what are important techniques for optimum bond?
- proper isolation
- roughen sclerotic dentin (increases surface area and removes some of the sclerotic dentin)
- may still need mechanical retention
- bevel or roughen and etch enamel
- must have dentin moist (or rewet) for etch and rinse systems
- dispense adhesives just before use
- apply and dry primer adequately
what happens if you dispense adhesive too long before use?
the solvent evaporates
what happens if you don’t apply and dry primer adequately?
- may have gross leakage and postoperative sensitivity (gently dry with air syringe)
- too much primer is better than too little
what happens if bonding agent (adhesive) is over-thinned?
may get an air-inhibited layer only, and it does not bond as well
laboratory results of resin-dentin bonds show a loss of bond strength over time. why?
- possibly from hydrolysis of the adhesive resin or the collagen fibers, or both
- all in one types show the worst results
bond durability is much greater when the peripheral margin is all in ___
enamel
dentin and enamel bonding strength are ___ for most etch and rinse systems
similar
most etch and rinse adhesive systems bond better to ___ dentin
moist (leave dentin moist or remoisten with water or a sealer/desensitizer)
one bottle systems may be simpler but are not better; ___ systems may still be best
three step
dentin variability, including ___, remains a problem in dentin bonding
sclerosis, tubule size, and tubule location
enamel bonding is ___, ___, and ___
- fast, strong, and long lasting
- dentin bonding may be strong, but may not be long lasting
what are the 7 types of composite material?
- macrofilled
- microfilled
- hybrid (midifill, minifill)
- microhybrid
- nanofilled/nanohybrid
- flowable
- packable
what is the average particle size of macrofilled composites?
10um
macrofilled composites are ___ generation restorative composites
first
how do macrofilled composites cure?
chemical cure
macrofilled composites have poor ___ and ___ properties
physical and mechanical
describe shade matching with macrofilled composites
- limited shade matching capabilities
- poor esthetics
what is the average particle size for microfilled composites?
0.04um (40 nm)
how are microfilled composites cured?
light cured
describe the fracture toughness of microfilled composites
- suboptimal
- not strong for occlusal bearing areas
describe the esthetics of microfilled composites
- excellent esthetics and polishability
- use primarily in anterior restorations
microfilled composites have a lower ___, so it is better in class V situations
elastic modulus
what is the average particle size of hybrid (midifill, minifill) composites?
1um (0.001mm)
how are hybrid composites cured?
light cured
hybrid composites have good properties and good esthetics, but are not as ___ as microfills
polishable
what are the best uses of hybrid composites?
universal - good in anterior and posterior restorations
what is the average particle size of microhybrid composites?
0.4-0.8um (400-800nm)
how are microhybrid composites cured?
light cured
microhybrids retains good properties of hybrids (___), with improved ___
- strength
- handling
the polishability of microhybrids is almost equal to ___
microfills
what are the best uses of microhybrid composites?
universal use - good in anterior and posterior restorations
what are the filler characteristics of nanofilled/nanohybrid composites?
vary with brand but typically 20nm nanomers and 0.6-1.5um nanoclusters
how are nanofilled/nanohybrid composites cured?
light cured
nanofilled/nanohybrid composites have excellent ___, are highly ___, and have low ___
- handling
- polishable
- shrinkage
what are the uses of nanofilled/nanohybrid composites?
anterior and posterior restorations
what is the ratio of content in flowable composites?
high matrix/filler ratio
flowable composites have higher ___
polymerization shrinkage
packable composites have increased ___
viscosity
what are the benefits of packable composites?
no documented benefits
what are the properties of composite materials (coefficient of thermal expansion, water absorption, polymerization shrinkage, wear resistance, surface texture)?
- high coefficient of thermal expansion
- high water absorption
- all composites undergo polymerization shrinkage
- wear resistance has improved substantially with research and development
- surface texture is a function of filler size (smaller = smoother) and type
what does the high coefficient of thermal expansion of composites result in?
percolation, recurrent caries, and stain
what does the high water absorption of composites result in?
deterioration of material
describe the clinical performance of composite materials
- marginal fracture (microfilled composites)
- bulk fracture is rare
- secondary caries
- wear when used in heavy occlusal load areas
- marginal leakage is heavily dependent on bonding
are chemical (auto) cured composites still used?
no
what are the advantages of light cured composites?
- controlled insertion time
- less finishing time required
- less porosity
what are the 2 types of curing lights?
- quartz/tungsten/halogen
- light-emitting diode lights are more promising light systems available today
what are the uses of composite materials?
class I-VI restorations, sealants, esthetic enhancements, hypocalcified areas, partial veneers, full veneers, anatomic additions, resin bonded bridges, luting agent, diastema closure, foundation
what are the advantages of composite materials?
esthetics, insulation, bonding to tooth structure, conservation of tooth structure, less mechanical retention form needed, strengthening of remaining tooth structure, minimal to no microleakage
how do composite materials strengthen remaining tooth structure?
reinforcement of remaining tooth structure by bonding (believed to be temporary)
what are the advantages of minimal to no microleakage provided by composite materials?
decreased interfacial staining, recurrent caries, or postoperative sensitivity
what are the disadvantages of composite materials?
- wear potential (only when all occlusal contact on composite)
- technique sensitive (dry field, difficult to do, takes more time)
- polymerization shrinkage (may cause contraction gaps on root surfaces between composite and root)
- sensitivity caused by C factor (especially in class I lesions)
what are the 4 requirements for a successful composite restoration?
- etched or primed enamel and dentin and adhesive placement
- all occlusion should not be on composite
- must not contaminate operating area
- adequate technical skill
all composite restorations are bonded with a ___. a liner or base (or both) may be needed depending on ___. when a matrix is used, typically the ___ is placed before matrix placement, and the ___ is placed after matrix placement.
- dental adhesive
- remaining dentin thickness
- liner/base
- dental adhesive
what are the objectives of a matrix?
- provide proper contact and contour
- confine restorative material
- reduce amount of excess material
what are the characteristics a matrix should have to be effective?
- easy to apply and remove
- extend below the gingival margin
- extend above the marginal ridge heigh in posterior restorations and the incisal edge in anterior restorations
proper incremental placement of composite is important to ensure what two things?
- adaptation to tooth preparation and margins
- avoid voids or gaps in between increments
what are two options for composite insertion instruments?
- composite hand instruments (metal or plastic)
- syringe
composite should be placed in incremental portions because light only cures to ___mm depth in most composite curing units
2-3mm
composite light cure time depends on the manufacturer and varies depending on what 3 things?
composite type, shade, and opacity
what should be used to remove gross excess composite after curing? what should be used to obtain proper contour?
- medium-coarse diamond instruments
- fine diamond finishing instruments, 12-bladed carbide finishing burs, and abrasive finishing discs
what is the difference between an inlay and an onlay?
- inlays are intracoronal indirect restorations
- onlays are intracoronal indirect restorations that cover all cusps
what are the advantages of gold inlay and onlay restorations?
- excellent track record
- good fit
- excellent method to restore occlusal relationship
- structurally sound material
what are the disadvantages of gold inlay and onlay restorations?
- nonesthetic
- complicated tooth preparation
- complicated marginal finishing
- need adequate laboratory support
- cost
what are the indications for a gold inlay/onlay?
large occlusal surface needs, tooth contour needs, fractures, splinting, bracing for teeth with RCT, bridge retainers, partial retainers
what are the requirements for a successful gold onlay?
- tooth preparation
- lab fabrication
- cementation
describe the tooth preparation for a gold onlay restoration
- removal of weakened tooth structure
- divergence of the external surface of 2-5 degrees per prepared wall
- beveled finish lines
- pulpal protection
- soft tissue management
in gold onlay preparations, what are some causes of inadequate soft tissue management?
- careless, traumatic preparation
- poor fitting temporary
- temporary cement irritation
- careless use of retraction cord
in gold onlay preparations, what are some problems resulting from bleeding or unhealthy tissues?
- access and vision impairment
- impression difficulty
- temporary fabrication difficulty
- cementation difficulty
what are important considerations for lab fabrication of gold inlays and onlays?
- accurate impression
- appropriate waxing
- adherence to lab protocol
what are the most important aspects of successful cementation of gold inlays and onlays?
- adequate marginal finishing
- proper manipulation of luting agent
what are the characteristics for incorporation of draw/draft in gold inlay/onlay tooth preparations?
- 2-5 degrees per wall
- the longer the wall, the greater the amount of draw/draft
- must draw for casting to seat on tooth
- more parallel = more retention
what is primary retention provided by in gold inlay/onlay preparations?
- draw/draft
- length of longitudinal (vertical) walls
what is secondary retention provided by in gold inlay/onlay preparations?
- retention grooves (proximally)
- skirts
- groove extensions
what are the objectives for beveled margins on gold inlay/onlay preparations?
- good fit of gold to tooth
- strong tooth margin (usually strongest enamel margin)
- burnishable gold margin
describe burnishable gold margins in gold inlay and onlay restorations
- can bend a 30-50 degree gold margin
- less than 30 degrees may be too thin and may break
- greater than 50 degrees may be too thick and will not bend
what are pulp protection options for gold inlay and onlay restorations?
- liners, bases, and build-ups
- must be retained in preparation for impression, temporary, try-in, and cementation
describe occlusal extensions in gold inlay/onlay preparations
- cap cusps as soon as possible (use depth cuts, removes weakened tooth structures, increases access and visibility)
- preserve noncapped cusps
- preserve noninvolved marginal ridges
- smooth outline form
describe wall design in gold inlay/onlay preparations
- use #271 bur
- 2-5 degree taper per wall
- increased wall height increases retention
- increased draw decreases retention
describe proximal box design in gold inlay/onlay preparations
- gingival extension to include all faults and obtain clearance with adjacent tooth
- draw (2-5 degrees)
- facial and lingual extensions to include all faults and obtain clearance with adjacent tooth
- cavosurface margin 30-40 degrees
- blend with other bevels
what are the general rules for margination and bevels in gold inlay/onlay preparations?
- use fine diamond
- cut dry for final marginating for better vision
describe the design of the occlusal bevel in gold inlay/onlay preparations
- 0.5mm width
- 40 degree gold margin
- on occlusal surface
- may not need bevel because angulation of the facial and lingual cusps may provide for the fabrication of a 40 degree gold margin without preparation
- lingual/facial groove extension bevel should also be 0.5mm width and 40 degree gold margin
describe the cusp counterbevel design in gold inlay and onlay preparations
- 0.5-1mm width
- 30 degree gold margin
- for nonesthetic capped cusps
describe the stubbed margin design in gold inlay and onlay preparations
- 0.25-0.5mm width
- perpendicular to long axis of the crown
- for esthetic capped cusps
describe the secondary flare design in gold inlay and onlay preparations
- extends facial and lingual proximal margin into facial and lingual embrasure
- 40 degree gold margin
- diamond held perpendicular to long axis of preparation
- occlusogingival width is not uniform
describe the collar design in gold inlay and onlay preparations
- beveled shoulder design around a capped cusp
- provides bracing
- shoulder prepared with #271 bur
- 0.5mm bevel prepared with diamond
describe the skirt design in gold inlay and onlay preparations
- extends casting around line angle
- increases retention form
- increases resistance form
- “minicrown prep”
- use diamonnd
- facial and lingual finish lines result in 40 degree gold margin
- gingival finish line is a chamfer with a minimum depth (not uniform) of 0.5mm and extended into the gingival 1/3 of the crown
describe the gingival bevel design in gold inlay and onlay preparations
- 0.5-1mm width
- 30 degree gold margin
- all bevels must blend with each other
