Amalgam is placed incrementally into a restorative preparation. It needs to be spread and pressed into place with hand instruments. The process, called condensation, removes air between particles and forces excess mercury to the surface where it can be removed. Inadequate condensation allows voids in the materials to compromise strength and marginal seal. When the preparation is well filled with amalgam, the surface can be burnished with a rounded instrument, such as an Acorn burnisher and T-ball burnisher, to seal the margins and expel the mercury-rich top layer of the amalgam.
An amalgam restoration should recreate the original contour of the tooth, with some simplification allowed. Cusp inclines, marginal ridges, pits and primary grooves should be reproduced. The amalgam is carved using instruments such as the Half-Hollenback, the Disco-cleoid, and Tanner carver. The Suter explorer can be used to smooth gingival margins of Class II restorations.
The consistency of amalgam undergoes continual change as it sets. Anticipating these changes and tailoring instrumentation and effort to these changes is a crucial part of learning to carve amalgam well.
Amalgam is placed incrementally as is done for Class I restorations. Increments placed into proximal box forms must be carefully and completely condensed vertically and laterally to ensure a complete fill to the proximal margins. Extra amalgam should be condensed in the marginal ridge area. All margins should be burnished and excess amalgam cleared away.
he Tofflemire retainer and band need to be removed after the amalgam has been condensed. How soon they are removed is a matter of personal preference. Some operators remove the band immediately to allow for gingival margins to be more easily carved, while others prefer to complete most of the occlusal carving before disassembly.
Amalgam pressed up against the matrix band (flash) can be removed with the tip of an explorer. The outer knob of the retainer is then turned CCW to release the band. The band should be stabilized by an available thumb or finger while the wedge is removed. A loose end of the band is grasped with a forcep or hemostat and slid out of the proximal contact in a diagonal direction. To prevent breakage, a large condenser can be placed on the marginal ridge while band is being removed.
As with occlusal amalgam restorations, the goal of Class II restorations is to reproduce a properly contoured tooth. This includes a tight proximal contact with anatomically shaped facial-lingual contours and anatomically shaped gingival--occlusal contour. There should not be an enlarged triangular space below the contact.
The contact should not be visibly open. It should be tight enough to provide a good snap to floss. It should be located vertically at the transition of middle and occlusal thirds and horizontally at the transition of middle and buccal thirds. It should not allow food impaction.
The occlusal portion of the restoration is carved in the same way that a Class I would be carved. The marginal ridge presents some difficulties because of its convexity and its distance from adjacent structures. A light hand and practice are required.
An important thing to remember when working with amalgam is that you want to verify that you have a good gingival seal in the box, and that you have good contact with the adjacent tooth after you have placed the matrix band and wedge. Select the largest wood wedge and sculpt the area of the wedge below contact point to create a contoured filling. Avoid the most occlusal area of the wedge impinging on the matrix band as it can open the contact or "flatten" the interproximal contour. The wedge should seal the proximal box at the gingival floor only and allow a full contour toward the occlusal as well as provide a tight contact. When you place the matrix band you will notice that you are unable to get the matrix band to touch the adjacent tooth. In that case, you may need to loosen the Tofflemeier holder ¼ turn after you have placed the first increment of amalgam and continue to do this until you have reached the contact point. Make an effort to condense amalgam against the adjacent tooth in a horizontal direction.
find the margins of the prep unless you have a good idea of the outline form of the prep.
When removing the matrix band from a Class II prep, remember to stabilize the amalgam and remove the matrix band at an oblique angle. Check the interproximal contact by flossing and then pulling the floss out the side. If necessary cut one side of matrix band next to tooth and pull band laterally from opposite side. Utilize a sharp expolorer to separate the matrix from the fresh amalgam at the marginal ridge area.
When condensing, make sure to condense the amalgam into the retention grooves. Retention groove placement should be 0.5mm into dentin. The 21B Acorn Burnisher works well with freshly packed amalgam to create anatomy in planes. Once the planes are formed and have created the basic occlusal morphology, the planes can be lowered if necessary to create harmonious occlusion with no "high spots".
1. Triturate capsule of amalgam for 8 seconds.
3. Load amalgam carrier with amalgam.
4. Condense first into retentive grooves.
5. Incrementally load and condense amalgam into preparation until it is slightly over-filled.
6. Start by using a Half Hollenback carver to remove excess from the occlusal and gingival margins.
7. Keep instrument resting on tooth structure to avoid ditching.
8. Gently round the occlusal plane with the gingival plane.
9. Smooth amalgam with a small ball of cotton.
10. Final surface should be slightly convex.
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