CAST GOLD RESTORATIONS
A unique material with properties that are hard to beat.

WHY GOLD — AND WHY NOW?

Contemporary restorative dentistry is dominated by composite and ceramics. Understandably so—they are tooth-colored and allow us to create restorations that can be almost invisible. But who decided that an esthetic restoration has to be white?

A properly indicated gold inlay or onlay can be virtually invisible in the posterior region during a normal smile. And even when it is visible, it does not have to look like a compromise. Precisely finished and highly polished gold can look more like jewelry than a filling.
The main reason for returning to gold, however, is not its appearance. It is its exceptional combination of properties: biocompatibility, conservative tooth preparation, high casting precision, excellent marginal polishability, and above all, long-term mechanical durability.

This becomes particularly important in teeth exposed to high occlusal loads and parafunction. In situations where ceramic or composite restorations may be susceptible to wear, chipping, or fracture, gold represents a very interesting alternative.
And the longevity of gold is more than historical experience. One of the largest retrospective studies followed 1,314 cast gold restorations for up to 52 years and reported an overall survival rate above 95%.
Gold itself, of course, does not guarantee longevity. The final result depends on proper case selection, conservative preparation, an accurate impression, high-quality laboratory work, complete seating, cementation, and meticulous finishing.

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1. A conservative philosophy

The fundamental question when preparing a tooth for a cast gold restoration is not:
How much tooth structure do I need to remove?
But rather:
How much sound tooth structure can I preserve while still creating the geometry required for accurate fabrication, complete seating, and long-term stability of the casting?

A gold inlay or onlay does not automatically require extensive reduction of sound cusps. The design should follow the actual extent of the defect.
This also means that we do not always need to make the final decision about the type of restoration before opening the tooth. The definitive design often becomes clear only after removing the existing restoration and caries, when we can assess the quantity and quality of the remaining tooth structure.
This is a form of dynamic diagnosis.

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2. Removal of the existing restoration

The first clinical step is complete removal of the existing restoration and caries. At this stage, we are not yet trying to create the definitive preparation. First, we need to see what actually remains underneath the old restoration.

Amalgam can be sectioned with an appropriate diamond or carbide bur and then removed in pieces. Composite can be more challenging because the interface between the restorative material and sound tooth structure may be less visually distinct.

In the proximal area, whenever possible, we work from within the preparation, undermining and removing the existing material rather than unnecessarily extending the preparation toward the adjacent tooth.

Particular attention should be paid to the dentinoenamel junction (DEJ). Residual restorative material must be removed so that we can determine where the remaining enamel is truly supported by sound dentin.

Only after complete clean-out do we have a realistic understanding of the definitive design of the restoration. 

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3. Block-out: rebuild instead of drilling away

Block-out is one of the key concepts of the entire technique.

After removal of a large restoration, we are often left with an irregular defect containing undercuts, deep areas, and missing dentin. If we eliminated every undercut by further tooth reduction, we would sacrifice additional sound tooth structure.

Block-out reverses this logic. Instead of removing more sound tooth structure, we replace the missing volume.

This creates a new substrate from which we can prepare the desired geometry.

In deeper areas close to the pulp, an appropriate liner may be indicated depending on the clinical situation, such as Vitrebond Plus or Fuji Lining LC. In very deep carious lesions close to the pulp, pulpal status should also be considered and, when indicated, vital pulp therapy may include indirect or direct pulp treatment or pulpotomy. The goal is to preserve pulp vitality whenever possible and reduce the likelihood of future endodontic treatment that could significantly alter the prognosis and restorative plan.

The adhesive block-out itself can be created, for example, with opaque white ParaCore. The white color has a practical advantage: during subsequent preparation, the transition between the build-up and natural tooth structure remains clearly visible.

The block-out should not be overbuilt or unnecessarily extended onto sound enamel. It is preferable to keep it slightly below the future definitive surface. If the patient leaves after this stage, the build-up must also be adjusted appropriately for occlusion.

Alternatively, preparation can begin immediately after completion of the block-out.

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4. Block-out and enamel support

Some evidence supports preserving enamel that is supported by an adhesive build-up. The final decision therefore also depends on the operator’s treatment philosophy.

We prefer a conservative mechanical approach:

The definitive marginal enamel should be supported by dentin, not by the block-out material.

The preparation outline is therefore extended until the remaining enamel has reliable dentin support.

The block-out remains primarily where it truly replaces missing dentin—typically on the pulpal floor or in deeper areas of the preparation.

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5. Depth cut: geometry begins with depth

One of the most important steps is establishing a controlled depth cut.
Using a #330 bur, we create an initial cut approximately 1.5 mm deep, establishing the minimum space required for the cast gold restoration while providing a spatial reference for the rest of the preparation.

Once this reference depth has been established, we can maintain it as the preparation is extended, significantly reducing the risk of creating areas that are too shallow.

At the same time, we respect the anatomy of the occlusal surface. Because the cusps slope toward the central fissure, preparation depth cannot be evaluated at a single point. In onlay preparations, the known diameter of the bur can also serve as a useful guide for reduction.

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6. Divergence: the bur doesn’t create it—the operator does

After establishing the depth cut, we switch to a straight fissure carbide bur #57.

We actively change the angulation of the bur according to the wall being prepared. This allows us to create the desired divergence and establish a common path of insertion.

A cast restoration requires a clear, unobstructed path of insertion without undercuts. Walls that are too parallel may complicate both laboratory fabrication and clinical seating.
A simple analogy is a paper cup: the preparation should open slightly toward the occlusal surface. Total occlusal divergence may be approximately 10–12°, although there is no need to measure this angle clinically.

A much more practical check is simple: when viewed along the path of insertion, all relevant preparation walls should be visible simultaneously.

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7. Occlusal outline first, proximal box second

First, we complete the occlusal portion of the preparation, establish its outline, and define the basic path of insertion. Only once this geometry is clear do we proceed into the proximal area.

The occlusal portion then serves as a spatial reference for the proximal box.

If the proximal box is prepared too early, it is easy to lose control over its angulation, width, and relationship to the common path of insertion of the entire restoration.

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8. Exit angles

In the proximal area, we establish exit angles, ideally around 135°. A #169L carbide bur is particularly useful for this step.

As we pass the contact area, we proceed carefully, initially using only the tip of the bur to minimize the risk of damaging the adjacent tooth. The area is then gradually and carefully widened.

The exit angle is important not only for seating the casting.
We also need sufficient access for finishing discs during final marginal finishing.

We prepare not only for the casting, but also for its final finishing.
If the proximal area remains too closed, the casting may still be fabricated and seated, but precise intraoral finishing becomes considerably more difficult.

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9. Proximal box

Once the exit angles and common path of insertion have been established, we can create the proximal box itself.
Ideally, we begin with a narrow box in the buccolingual dimension, extend it to the desired gingival level, and only then carefully widen it buccally and lingually.
This allows us to preserve as much sound tooth structure as possible.

The axial wall should follow the anatomy of the tooth while respecting the common path of insertion. The gingival floor should be clearly defined, with smooth walls and no undercuts.

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10. Hand instruments

Rotary instruments establish the basic geometry of the preparation, but hand instruments allow very precise final refinement.

Fine chisels and gingival margin trimmers are particularly useful. They allow us to smooth proximal walls, remove minor irregularities and unsupported enamel rods, and precisely refine the line angles and gingival margin.

The final result should be a clean, smooth, and clearly defined preparation margin.
 

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11. Beveling the margin

Beveling is an essential part of cast gold preparation.
It creates favorable enamel-margin geometry while allowing the formation of a thin, precise gold margin that can be finished extremely well.

Not every part of the preparation requires the same degree of beveling. The gingival bevel is generally more pronounced, while in other areas the geometry depends on the specific preparation design.
In an onlay, the geometry naturally changes according to the cusp reduction and the location of the definitive metal margin.

The goal is not to create as many bevels as possible. The goal is a continuous, smooth, and mechanically sound preparation margin.

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12. Tissue management and impression

A perfect preparation is of little value if we cannot obtain a perfect impression.

An accurate impression is a critical step toward an accurate casting.
The impression material must reproduce the entire preparation, including all margins, proximal boxes, and exit angles.

Careful soft-tissue management is therefore essential. The rubber dam may remain in place while PTFE tape or retraction cords are positioned; if necessary, the interdental portions of the dam can be cut. The rubber dam is then removed before the definitive impression.

The light-body silicone must reach every detail. The syringe tip should therefore be guided deliberately along the preparation margins and into the internal angles. Simply “flooding” the preparation with impression material is not enough.

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13. Provisional restoration

The provisional restoration must simultaneously protect dentin and enamel, seal the preparation, stabilize the situation, and remain easy to remove without damaging the delicate preparation margins.

One option is a bis-acryl provisional restoration fabricated directly on the preparation. A very thin layer of separating medium, such as petroleum jelly, can facilitate its subsequent removal.
Before definitive cementation, however, the preparation must be thoroughly mechanically cleaned again.