The restorative technique of gold hammer filling (synonyms: Gold plug filling; direct gold filling; filling with plastic gold) is a very time-consuming and cost-intensive way of restoring small cavities (dental defects) with very margin-tight, biocompatible (biologically well tolerated) and particularly durable fillings.
Despite excellent results, this comparatively old technique is hardly used today; however, there is fortunately an increasing trend again, triggered by minimally invasive filling therapy.
Indications (areas of application)
In principle, the technique should only be used in patients with optimal oral hygiene and very low caries activity because of the high effort involved. Under this restriction, there are four possible applications:
- Small Class V cavities (cervical fillings); these preferably in the posterior region; in this case, the cavity can be both enamel-bordered and surrounded by root dentin;
- Small Class I cavities (fillings in the occlusal surface area); in this case, preferably in the dimples of the fissures (valleys in the occlusal surfaces);
- Small cavities of Class II or approximal surfaces (tooth surfaces in the interdental space), provided that they are freely accessible, e.g. in mixed dentition, as long as the neighboring tooth is still missing;
- After endodontic (root canal) treatment of a tooth restored with a gold crown; in this way, the trepanation site (the access to the root canals) can be closed in the area of the gold crown.
Contraindications
- Inadequate oral hygiene;
- Major defects;
- Proximity of the cavity floor to the pulp (to the dental pulp);
- Location of the defect in the occlusion-bearing (masticatory force-bearing) area;
- Root growth not yet completed;
- Periodontally damaged teeth with a degree of looseness II or greater;
- Extensively trephined tooth with a gold crown;
- Aesthetically undesirable positioning of the filling;
- Teeth with particularly strong thermal sensitivity.
The procedure
The material used today is powder gold for the filling body and foil gold rolled into pellets for the surface. The combination creates some time savings compared to gold leaf condensation alone. The gold, before being placed in the cavity (hole), is annealed over an alcohol flame. The treatment steps on the patient are as follows:
- Excavation (caries removal);
- Preparation (shaping of the cavity by grinding): as gentle on the substance as possible, with sufficient water cooling. The preparation must be oriented to the alignment of the enamel prisms, so that there is no enamel breakage in the marginal area. This results in diverging, parallel-walled or converging cavity walls. In the first case, additional retentions (undercuts) must be created to ensure the retention of the filling in the tooth. In the rest, sharp angles and edges provide retention (the hold of the filling).
- Provided there is sufficient space for an underfill, this will protect the pulp (the tooth pulp) from the high thermal conductivity of gold;
- Absolute draining with rubber dam (tension rubber) is inevitable, because the gold must not come into contact with liquid during the insertion;
- Condensation in cohesive technique: gold layers layered on top of each other are preferably condensed with condenser tips placed on mechanical hammers within a defined force range and cold welded in the process.
- Elaboration of the mold with hand instruments;
- Polishing with fine-grained polishing pastes; not dry, because due to heat conduction could damage the pulp (the pulp).
The result of condensing cold forming is a filling that is significantly harder than pure, cast gold and approaches gold alloys in hardness.
