Podcast
Questions and Answers
What is the objective of finishing the internal margin of a cast metal restoration?
What is the objective of finishing the internal margin of a cast metal restoration?
What can prevent complete seating of a cast metal restoration?
What can prevent complete seating of a cast metal restoration?
What should be the minimum space between the internal surface of the restoration and the tooth?
What should be the minimum space between the internal surface of the restoration and the tooth?
What is the result of a small nodule on the internal surface of the restoration?
What is the result of a small nodule on the internal surface of the restoration?
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What tool can be used to remove nodules from the internal surface of the restoration?
What tool can be used to remove nodules from the internal surface of the restoration?
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What is the purpose of finishing the internal margin of a cast metal restoration?
What is the purpose of finishing the internal margin of a cast metal restoration?
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What happens if a defect occurs in the internal margin of a cast metal restoration?
What happens if a defect occurs in the internal margin of a cast metal restoration?
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What is the significance of careful examination under magnification in the internal margin of a cast metal restoration?
What is the significance of careful examination under magnification in the internal margin of a cast metal restoration?
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What can be removed in the next phase if they are away from the margin?
What can be removed in the next phase if they are away from the margin?
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Why is it necessary to remove any contact between the internal surface of the restoration and the tooth?
Why is it necessary to remove any contact between the internal surface of the restoration and the tooth?
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Study Notes
Finishing of Cast Restorations
- The finishing process involves 7 distinct zones, each requiring specific procedures for proper finishing.
Zone 1: Internal Margin
- Objective: achieve a 1 mm band of metal well-adapted to the tooth surface to prevent cement dissolution.
- Defects in the margin may require a restoration remake.
- Nodules in the fitting surface can prevent complete seating and must be carefully examined and removed.
Zone 2: Intaglio Surface
- No contact should exist between the internal surface of the restoration and the tooth; a space of 25-35 microns is necessary for cement.
- Contacts should be identified and removed to prevent an increase in marginal gap width.
- Nodules can be removed using a small round carbide bur.
Zone 3: The Sprue
- Once the fit is acceptable, the sprue can be removed using a carborundum separating disc.
- Cutting is done around the sprue, then the last part is removed manually by twisting.
- Any excess material is refined with stones.
Zone 4: Proximal Contacts
- Proximal contact areas are adjusted to be correct (or slightly too tight) when evaluated in the mouth.
- Proximal contacts on the stone cast can be minimally relieved by careful scraping with a scalpel.
- Thin Mylar articulating can be used to identify contact areas.
Zone 5: Occlusal Surface
- Occlusal contacts are reestablished in static and dynamic relationships to the opposing arch.
- Occlusal structure must ensure positional stability and satisfy all functional requirements.
- Occlusal contacts are checked with thin Mylar articulating film to ensure they match the design in the waxing stage.
- Occlusal adjustments can be performed with flame-shaped finishing burs or diamonds.
Zone 6: Axial Walls
- Axial walls should be smoothly contoured and highly polished to enable the patient to carry out optimal plaque control.
- The most efficient method of polishing involves a sequence of progressively finer abrasives, each removing the scratches made by the previous grade.
- Light pressure is applied when using abrasives, and the instrument must be kept rotating.
Zone 7: External Margin
- Margin finishing is crucial for a restoration's longevity.
- A highly polished metal surface without ledges or steps as the transition is made from restoration to unprepared tooth.
- Care must be taken not to remove more metal than is strictly necessary without compromising the fit and/or emergence profile of the restoration.
- Finishing should be performed by gently brushing a fine-grit stone over the surface to remove casting roughness, followed by a soft rubber wheel or point, and finally by rouge on a brush.
Checking Occlusal Interferences
- Several marking agents are available to help identify interferences with seating, including water-soluble dyes, solvent-based dyes, powdered sprays, and rouge suspension.
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Description
Learn about the finishing of cast restorations, including adjusting occlusal contacts, polishing, and axial wall finishing. Understand how to achieve optimal plaque control and efficient polishing techniques.
