March 11, 2009 STI
Feb 20, 2016
March 11, 2009 STI
Go for the Gold! Characteristics
Parallelism ○ No undercut areas like in direct restorations
Lost wax techniqueHigher strength than direct restorations Control of contours and good proximal contactsAbility to create acute margins: use less metal,
take away less tooth structure Gold casting alloyMultiple appointments
Considerations 1. Biocompatibility
Most biocompatibleBest long lastingLow reactivity in oral environment
○ No emission of electrons: no corrosion 2. High gold alloys best >75% (wt)
gold/platinumLower % gold performs well
Considerations 3. Proximal caries
Extensive involvement ○ Casting transmits energy throughout to hold tooth
together to prevent spread of fracturesControl of contours and contactsDifficult 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 onlayDesign considerations
6. Fractured teethPresence of fracture linesCusp replacement
7. Elimination of electrical or corrosive activity
Considerations 8. Diastema closure and occlusal plane
correctionNeed to extend mesial/distal dimensionCorrection of occlusal irregularities
9. Removable prosthodontic abutmentControl of rest seats and guide planesPartial denture forces
Considerations 10. Economics
More chair time neededLaboratory fees
11. Age of patientPulp 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 rateHealth vs. prognosis
12. EstheticsMetal may be seenConsider alternatives: e.g. porcelain
The Inlay Defined
Posterior teethIntracoronal = between the cusps, NOT over
cusps○ Within the cusps (intracoronal)
Class I or Class II (includes marginal ridge)May involve a cusp
IndicationsPatient desireForm and functionRemovable partial denture rest seat
The Inlay Preparation Convenience form
Plane cut tapered fissure burs (No. 271, No. 169L)
Obtain uniformly tapered wallsSmooth walls, floor, and seat
“Draw” Concept of Draw
All walls must diverge from gingival to occlusalNo undercutsPath of the “draw” is usually along the long axis10-20 degree divergence—near parallel10 degrees if walls are necessary short20 degrees if walls are long and deepSO: 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 non-
carious 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 marginsLesser angle metal margins are easier to finish to
die and/or toothProximal Flare - 40 degree metal margin Placed when the restoration angle is greater that
40 degrees. Allows a marginal enamel angle of 140 degreesBuccal 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 teethClass II involvementAll cusps are "capped"
IndicationsLarge defective amalgam or resin
restorationsWeak buccal/lingual cusps that require
splintingHeavy 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 surfacesWeak tooth is splintedAdequate metal - proper amount of
reductionEstheticsSmooth junctions between tooth surfaces