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1. Amalgam Failure and Repair

Learning Outcomes

By the end of this interactive session you should be able to:

  • Understand why amalgam restorations may fail
  • Discuss repair of amalgam restoration

To view the accompanying lecture for this section please click here. (Establish PP file to link to)

Recommended Reading

  • Pickard's Manual of Operative Dentistry 9th edition, CH 8, "Recall, maintenance and repair"
  • Dent. Update 2006; 33: 094-098


Why do amalgam restorations fail?

It is important to realize that the causes for restoration failure are intrinsically linked with tooth failure and both are multifactorial.

Using the above resources, complete the table in your study guide on "Restoration and Tooth Failure".


How to Repair Amalgam Restorations

Click on the link below and watch the video and then in your study guide note down when an amalgam repair is possible.

View Video 2 below, imagine the mesial box needs to be repaired, perhaps there is caries present, on the amalgam is defective.

View video 3 and note how a tear drop shaped cavity is prepared and any caries is removed.

View Video 4 below and watch carefully how the occlusal key prep is carried out.

View Video 5 and observe how you use a slow speed handpiece and a round bur to smooth the cavity, hand instruments could also be used.

Video 6 will demonstrate how you should insert a wedge.

Watch Video 7 to see how the amalgam is placed and preliminary shaping takes place.

View video 8 and notice how the process is finished with the wedges removed first, followed by the matrix.


When using the slow speed handpiece and round bur you use a circular movement.

An occlusal key is used to provide a resistance form.

Wedge systems are used as they prevent overhangs after restorations are placed.


Before you move on to the next section you should ensure that you are confident on the following:

  • Understand when a repair is appropriate compared with a replacement.
  • Understand the need to create resistance and retention form in repair cavities
  • Know how to finish an amalgam restoration:
  1. Check marginal ridge height
  2. Finish with damp cotton wool pledget
  3. Check patient's occlusion, by getting them to gently bite together 
Amalgam - Failures, Repairs and Bonded Amalgam Restorations
Amalgam - Failures, Repairs and Bonded Amalgam Restorations