1. March 11, 2009 STI

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. The Inlay Preparation  Convenience form Plane cut tapered fissure burs (No. 271, No. 169L) Obtain uniformly tapered walls Smooth walls, floor, and seat

10. “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

11. Path of Draw  The wax pattern (casting) must “draw” from the tooth. There can be NO undercuts or obstruction.

12. 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

13. 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

14. 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 !

15. 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

16. 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

17. The Bevel Advantage =1/2 D

18. 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.

19. The Inlay Preparation

20. Other Types of Casting

21. Types of Finish Lines

22. 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

23. 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

24. 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