final Flashcards
what does an MCC crown combine elements of
CVC and ACC
where to reduce more or less for an MCC crown
more reduction where ceramic will be placed
less where metal only will be placed
how do you ensure good esthetics on a MCC
substantial tooth reduction
minimal metal thickness on a MCC anterior corwn
.5mm at edge
.3mm at facial
1mm at lingual
Minimal metal thickness on a MCC posterior crown
.3mm at buccal
.8-1.2 mm at central groove
1.3-1.7mm at functional tip
.6 mm at the lingual
what are the consequences of under prepping an MCC
Opaque looking crown
Over contoured gingival margin
Minimal porcelain thickness for an anterior crown
- 2mm facial
1. 5 mm incisally
Minimal porcelain thickness for a posterior crown
- 2mm facial
1. 3-1.7 at facial cusp tip
what happens if you don’t correctly shape the second facial plane
opaque looking crown
over contoured gingival margin
Bulls-eye opaque area on incisal 1/3
how thick overal should an MCC crown be
1.5mm for porcelain/metal areas
1.2mm for porcelain
.3mm for` metal
how should the cavosurface margin look on the facial for a MCC
Porcelain Labial margin (90 degrees) Slopped shoulder (120 degrees)
what should the cavosurface margin look on the lingual side of the cavosurface margin
Chamfer (.5mm)
why is the sloped shoulder important
Allows for metal to come right to the cavosurface margin
what finish line is used for metal crown
Knife (feather edge)
Chamfer
what finish line is used for MCC (PFM)
Sloped shoulder
Shoulder
Beveled shoulder
when is a knife (feather) edge useful
Very subgingival margins
what is a porcelain butt margin
A porcelain labial margin of 90 degrees
what is a conventional margin
Sloped shoulder (120 degrees)
what to use to achieve uniform tooth reduction
Guide groves
Depth grooves
Precision reduction indicators
how should the labia be reduced
two plane redction (1.3-1.5mm)
how should the lingual be reduced
1mm
chamfer on the lingual
.5mm
why does lipping occur
when the chamfer diamond is used at more than 1/2 depth
how to identify lipping
Visual and tactile
lingual concavities
Incisors: uniform slight concave
Canines: biconcave
layers at the margin for an MCC
metal framework
Opaque porcelain
Translucent porcelain
what is needed for determine margin location
Evaluation of the smile line
pros and cons of 90 degree butt joint
brittle
looks good
pros and cons of 120 degree sloped shoulder
gives more strength
supports margin
looks bad (Creates a shadow)
when are margins visible for a smile
With a high lip line (margins not visible if lip line is low
what happens if the margin is not placed deep enough under the tissue for a crown
risk for recession and potential exposure of the crown margin (esthetically unacceptable)
what happens if the margin is placed too deep
risk for possible biological width impingement
what is a greatetr problem too deep or not deep enough
Too deep due to biologic width impingement
what is the best biological response
Supra gingival
what is the best esthetic response
sub gingival
what to pay attention to for the best of both worlds when restoring a crown
Attention to details of the biologic width
why does a porcelin labial margin of 90 degrees look nicer
allows light to transmit down the root
why does a sloped shoulder cast a shadow
does not allow light to transmit to rooot (creating a shadow in the root)
what causes the darkline at the margin of an MCC
metal collar or conventional sloped shoulder designs
Dark underlying root structure from trauma or previous endo treatment
what determines where the restorative margin is placed relative to the tissue and the response of that tissue
Biology itself
what are biologic consideration
Prevention of damage during tooth preparation
what must be important for biologic considerations
Adjacent teeth
Pulpal response
Soft tissue (biologic width)
the empty space between gingiva and enamel
Sulcus
where the epithelium of the gums attaches to the tooth
Epithelail tissue
what is the biologic width
the amount of stuff between the deptth of gingival sulcus and the tip of the alveolar bone
what is the biological width made of
the PDL connective tissue and epithilium above the alveolar bone
what is the correct biologic width necessary for
for the existence of healthy bone and tissue from the most apical extent of a dental restoration
mean biological width
2.15-2.30mm (usually about 50:50 with maybe a bit more connective tissue)
range of biologic width
.2-6.73mm
average sulcus depth
1mm
what is the significance of biologic width
Its importance relative to the position of retorative margins and its impact on poastsurgical tissue position
what is the goal concerning biologic width
Bone is 3mm below the gingival margin of the prep
what types of gingiva exist
Flat
Scalloped (more rounded)
how common is the thin gingival biotype
1/3 of the population
more prominent in women
how common is the thick gingival biotype
2/3 of the population
more prominent in men
what size of crown is at the greatest risk of recession
Narrow crown is at greater risk than square wide incisors
Periodontum thickness of scalloped and flat periodontum
Scalloped: Delicate thin perio
Flat: thick heavy perio
location of gingiva in the scalloped and flat gingiva
Slight gingival receion in scalloped
coronal gingiva in flat gingiva
how much keratine is there in scalloped and flat gingiva
Scalloped has minimum zones of keratinized gingiva
Flat has wide zones of keratinized
contact are of scalloped and flat gingival area
small incisal contact area of scalloped gingiva
Broad apical contact area of flat gingiva
anatomic crowns of scalloped and flat gingiva
Triangular anatomic crowns: scalloped
Square anatomic crowns: Flat
what does insult do to scalloped and flat gingiva
Insult leads to recession in scalloped gingiva
insult leads to pocket depth or rebundnat tissue in flat gingiva
convexities in the cervical 1/3 of the facial surface of scalloped and flat gingiva
Scalloped: subtle diminutive convexities
Flat: bulbous convexities
bone thickness of flat and scalloped gingiva
Thick in flat gingiva
thin in scalloped gingiva
what gingiva is easier to work on
Flat (less inflammation and change)
why is having dark gingiva important
needed for esthetics to cover underlying materials (implant and restorative dentin)
How to detemine the biotype of gingiva
Placement of a probe within the gingival sulcus and looking at prob visicibility
- seen: thin
- not seen: thick
do deep or shallow sulcuses have more risk of recession
deep has more risk
does thick or thin gingiva have deeper sulcuses
No relation sadly
cord sizes for subgingival margins
#00: thin tissue #1: most tisuee
where is cord placed for shallow sulcus patients
.5mm to .7mm apical to the prep margin
what do you dampen the cord with for shallow sulcus patients
damp with aluminum chloride solution
what does the first cord do when placed for shallow sulcus patients
retracts the tissue
represents the correct position for the final prep margin (.5 to .7mm subgingival
how far should you prep subgingivally when using cord for shallow sulcus patients
prep to the top of the cord using a bur that provides adequate depth and shape for your finish line
hw should a second cord be place for shallow sulcus patients
placed and pushed down apically so it sits at the level of the prepped margin
should be able to be visuallized around the tooth
what is done after the impression istaken with the cord for shallow sulcus patients
Complete the restoration
how far should probing be allowed to go (max) for subgingival crowns
max of 1.5mm
how far deep should the prep be done with no cord for deep sulcus patients
prep to the existing gingival margin (leave only the subgingival margin to be done)
how should the first round of cords be placed for deep sulcus
2 layers (ultrapack 1# first, followed by Ultrapack 2#)
how high should the 1st round of cord be from the prepped margin for preps with deep sulcuses
top of cord is 1.5mm below the previously prepped margin (1.5mm below the gingival margin)
roll of cord in subgingival preps
moves gingival out of the way
using cord if margin is supra-gingival
No need
how are cords easiest to put in
Dry
what should happen if you do a good impression with cords
Come out with the impression
what should be done in deep sulcus preps after the cords have been placed
prep the margin to the top of the cord 1,5mm below starting gingival margin
what should be be done after you preped to the top of the second cord in a deep sulcular prep
place a 3rd cord (ultrapak 1) so it sits between the prep margin and gingiva (no deeper) and is easily seen around the tooth
why would you want to keep cord dry
allows for the impression material can go in and around it so impression looks good
how should the last cord always look
should be able to be seen from the top
what is done before taking an impression witha deep sulcus
remove the 3rd cord, but should be able to see the 2 cords around the margin
Good esthetics starts with what
Good gingival health
what instrument is good to retract gingiva
8A(also good for cord)
what is need to control final tissue level
need to start with healthy tissue
how to control saliva in the max anterior
easy, usually cotton role isolation
tissue displacement is done how for impressions
Cords and the 8A
how to control hemorrhages
Chemicals
Lasers
Electrosurgery
Types of trays
Custom
Disosable stock
Triple tray (Closed mouth
when are tripple trays good to use
Good posterior
Anterior less good
What are elastomeric materials
Polyvinylsiloxanes (OSU clinic)
Polyethers (OSU clinic)
Polysulfides
when to use light and heavy body polyvinylsiloxanes
Light: injection type
Heavy: tray material
benifit of polyvinyl siloxanes
dimensionally stable
pros and cons of polyethers
Easier to use than polyvyniles but taste like shit
what do we need to send to the lab for crown fabriaction
Final Impression
Interocclusal Record
Opposing Arch impression or cast
are most preps supra-gingival
No, most are subgingival
how are impressions poured for the lab
Poured in type 4 stone
why is the cast marked in the working model in die
For location of pins
what is sent to the lab exactly
Plaster model or impressions depending on the material used
characteristics of type 4 stone
hardest and most accurate stone
what keeps the working model and die from connecting to the type 3 stone poured under it
stone separator
Roll of the pins
allow for the working die to be removed and reput back into the cast as to allow easier working
what do you do once you remove the dies from the cast
Trim margins of the die so they can be clearly identified
How is the final die shape determined
Done using a wax up
when do you do a full contnour wax design
For all memtal or all cermaic crowns
when do you do a facial cutback wax design
Facial porcelain coverage
when do you do a cull cutback wax design
Full porcelain coverage
when are crowns cast
Metal
when are crowns pressed
Glass ceramics
Analysis of dimensional changes for crown casting does what
goal to get the overal dimension change as close to zero as possible
roll of the opaque later in a crown
Masks metal color
Bonds porcelain to metal
steps of porcelain latering
Body porcelain
Incisal porcelain
Post-sinter contouring
what is the most common digital path
Traditional Impression
Tradition working model
lab scanner
Most modern digital path
Direct intraoral scan
Digital crown design via virtual waxup
Digital Manufacturing
What are the types of Digital Manufacturing
Subtractive manufacturing (CNC milling) Additive Manufacturing (3D printing
what is currently the most common manufacturing method for permanent restoration and prosthesis
CNC milling
when is 3d printing used
Some items, mostly temporary items
development of 3D printing
Many new devices under develofopment
what are most anterior teeth made out
80% all ceramic
what areposterior tooth made of
60% all ceramic
are metal ceramic or all ceramic more expensive
MEtal ceramic are more expensive due to extra metal
what bur should be used to establish uniform should width
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