Single Tooth Indirect
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Transcript Single Tooth Indirect
March 11, 2009
STI
Go for the Gold!
Characteristics
Parallelism
○ No undercut areas like in direct restorations
Lost wax technique
Higher strength than direct restorations
Control of contours and good proximal contacts
Ability to create acute margins: use less metal,
take away less tooth structure
Gold casting alloy
Multiple appointments
Considerations
1. Biocompatibility
Most biocompatible
Best long lasting
Low reactivity in oral environment
○ No emission of electrons: no corrosion
2. High gold alloys best >75% (wt)
gold/platinum
Lower % gold performs well
Considerations
3. Proximal caries
Extensive involvement
○ Casting transmits energy throughout to hold tooth
together to prevent spread of fractures
Control of contours and contacts
Difficult subgingival margins are more properly
restored
4. Facial/lingual
Caries high? Caries rate?
Existing restorations: consider full coverage
crown
Considerations
5. Endodontic treatment
Consider an onlay
Design considerations
6. Fractured teeth
Presence of fracture lines
Cusp replacement
7. Elimination of electrical or corrosive
activity
Considerations
8. Diastema closure and occlusal plane
correction
Need to extend mesial/distal dimension
Correction of occlusal irregularities
9. Removable prosthodontic abutment
Control of rest seats and guide planes
Partial denture forces
Considerations
10. Economics
More chair time needed
Laboratory fees
11. Age of patient
Pulp size and anatomy
○ Example: In young patient, full gold crown requires
removal of a large amount of tooth structure. Wait until
the patient is older and pulp has receded a little bit.
Caries rate
Health vs. prognosis
12. Esthetics
Metal may be seen
Consider alternatives: e.g. porcelain
The Inlay
Defined
Posterior teeth
Intracoronal = between the cusps, NOT over
cusps
○ Within the cusps (intracoronal)
Class I or Class II (includes marginal ridge)
May involve a cusp
Indications
Patient desire
Form and function
Removable partial denture rest seat
The Inlay Preparation
Convenience form
Plane cut tapered fissure burs (No. 271, No.
169L)
Obtain uniformly tapered walls
Smooth walls, floor, and seat
“Draw”
Concept of Draw
All walls must diverge from gingival to occlusal
No undercuts
Path of the “draw” is usually along the long axis
10-20 degree divergence—near parallel
10 degrees if walls are necessary short
20 degrees if walls are long and deep
SO: as length of wall increases, the degree of
taper should increase
Path of Draw
The wax pattern (casting) must “draw”
from the tooth. There can be NO
undercuts or obstruction.
The Inlay: Outline form
Depth is 1.8 - 2.0 mm measured from pit
closest to the involved marginal ridge
Maintain the bur parallel to the long axis
of the tooth at all times.
Exception: Lower molars and
premolars with crowns tilted
lingually. Tilt bur 10 degrees to lingual.
Maintain dentin support of uninvolved
marginal ridge
The Dovetail: Retention Form
Dovetail Retention Form
Resists mesial/distal displacement of the
casting
Allows casting to placed only from an
occlusal direction
Placed even at the expense of noncarious grooves
Proximal Box
Maintain bur parallel to long axis
Drop bur as you would an amalgam, BUT
Buccal and lingual walls do NOT converge
toward the occlusal !!
Walls of box DIVERGE with angle of the
bur
Contacts are opened buccally and lingually
and 0.5 to 1.0 mm gingivally
NO "S" or reverse curve !
Bevels and Flares
Bevels and Flares
Better fit at margins
Lesser angle metal margins are easier to finish to
die and/or tooth
Proximal Flare - 40 degree metal margin
Placed when the restoration angle is greater that
40 degrees.
Allows a marginal enamel angle of 140 degrees
Buccal wall may be limited by esthetics
The Bevel Advantage
Gingival Bevel - 30 degree metal margin
Casting discrepancies at the margins
are minimized
Provide firm enamel support for margin
(no fragile)
Placed with a GF 11 or flame-shaped
finishing bur (#7901)
Bevels
The Bevel Advantage
=1/2 D
Bevels
Occlusal Bevel - 40 degree metal
margin
Provides a strong but burnishable
margin
Not indicated if the cusp inclines are
steep so that a 40 degree angle already
will occur
All bevels and flares should
"blend" together to allow a continuous
margin.
The Inlay Preparation
Other Types of Casting
Types of Finish Lines
The Onlay
Defined
Posterior teeth
Class II involvement
All cusps are "capped"
Indications
Large defective amalgam or resin
restorations
Weak buccal/lingual cusps that require
splinting
Heavy occlusal wear
Other Casting Types
Margin Requirements
All margins should be supragingival
○ Easy to evaluate and finish the margin
○ Easier for patient to keep clean
○ No gingival irritation
except due to:
○ Existing caries/restorations
○ Short crowns - retentive walls need 4 mm
○ Esthetics
Bottom Line
General Principles of Partial Veneer
Castings:
Necessity to see all surfaces
Weak tooth is splinted
Adequate metal - proper amount of
reduction
Esthetics
Smooth junctions between tooth surfaces