2. Bonded Amalgam Restorations

Learning Outcomes

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

  • Describe the aims of amalgam bonding
  • Describe the stages in amalgam bonding
  • Adequately place a bonded amalgam in a plastic simulated tooth

Before completing this section you should view the Dental Amalgam Revision section.

Amalgam Bonding

Amalgam can be bonded to the tooth using an adhesive system. Potential benefits include:

  • Decreased microleakage
  • Decreased incidence of recurrent caries
  • Decreased pulpal inflamation
  • Decreased post-operative sensitivity
  • Increased fracture resistance of the tooth
  • Decreased cuspal deflection
  • Treatment of cracked cusp
  • Conservation of tooth substance
  • Increased retention

Amalgam bonding requires more clinical time and is therefore more costly and more technique-sensitive. It is of use when additional retention and resistance features are required but where there is insufficient or weakened tooth tissue, in which to build in these features.

To download the associated PowerPoint presentation for this section click here.

 

The first Video clip shows a natural, carious tooth with a large cavity present, accompanying the clinical scenario is a radiograph of the tooth, showing the caries present. During your practical class you shall be using plastic teeth.



Click on each of the links below to view the video and then attempt to answer the questions after viewing the video.


Tools and how to clean between the margins of a cavity



Question:
When removing caries, why should you clear the margin first?
Your Answer:
Correct Answer:
Always clear around the margins of the caries first so that as you approach the pulpal area you are not at risk of infecting the sensitive pulp tissue with bacteria, from an active carious site.


Carious Dentine



Carious Dentine Question

Q1 . Carious dentine is often stained (a dark colour). How does carious dentine feel?
  • Hard and Coarse
  • Soft and Leathery
  • Soft and Coarse



Ensure all caries is removed



Question:
Once all caries is removed, what should sound dentine look and feel like?
Your Answer:
Correct Answer:
It can be white or stained in colour but it should feel hard with the sharp probe.


Materials required for bonding



Question:
Wedges are used with the matrix ban interproximally. Define interproximal.
Your Answer:
Correct Answer:
Interproximal is the triangular area between teeth usually filled with the interdental papilla.


Method of Bonding Amalgam



Method of Bonding Amalgam Question

Q1 . What is the etch used likely to be?
  • 17% orthophosphoric acid
  • 27% orthophosphoric acid
  • 37% orthophosphoric acid



Restore with amalgam



Finishing Amalgam



Question:
Can you name the instruments used in carving this amalgam?
Your Answer:
Correct Answer:
Discoid cleoid and a Ward's carver


Carving Amalgam



Remove the wedges and carefully remove the matrix system, supporting the amalgam with cotton wool in tweezers as you do. Finish with a ball ended burnisher and damp cotton wool.

Summary

Do you understand the indications for a bonded amalgam restoration?

  • Heavily broken down coronal tooth structure
  • High load bearing, large restoration core build-up for posterior teeth
  • Difficult moisture control conditions for a posterior composite

 

Further Reading

A good review article from Dental Update: Staninec M; Setcos J C. Bonded amalgam restorations: current research and clinical procedure. Dental update 2003;30(8):430-4, 436.