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Bonded vs. non-bonded amalgam restorations?

This summary is based on the article published in the British Dental Journal: A comparative study of bonded and non-bonded amalgam restorations in general dental practice (April 2013)

Amalgam filling


Amalgam has been used to restore teeth since before G. V. Black described the classification of cavities over 100 years ago and is still a first choice material used by most clinicians to restore carious teeth, where aesthetics is not an overriding concern (Berry, Summit, Chung, and Osborne).

A relatively recent development in amalgam restorations has been the introduction of bonded amalgam restorations. The theoretical advantages of bonding amalgam restorations are that (Setcos, Staninec and Wilson):

  • Bonding creates an adhesion between amalgam and the tooth surface, reducing or eliminating reliance on macro-mechanical retention and allowing a more conservative cavity preparation without the need for pins.
  • Bonding improves natural tooth strength and fracture resistance.
  • Bonding creates a better marginal seal, reducing the risk of dentine and pulpal contamination and reduced incidence of secondary caries.
  • Bonding reduces postoperative sensitivity.

 Purpose of the Study

Compare the performance of non-bonded and bonded amalgam restorations in a general dental practice.

Key Messages

  • A retrospective cohort clinical study, including 231 non-bonded amalgam restorations which were compared with 231 bonded amalgam restorations and compared for survival rates and clinical performance.
  • Within the limitations of the study, the following conclusions can be drawn:
    • Bonded amalgam restorations provided significantly greater longevity than non-bonded amalgam restorations over a five-year period.
    • The comparison of postoperative sensitivity rates between the two methods of restoration was inconclusive.
    • Bonded amalgam restorations may offer a significant benefit compared to non-bonded amalgam restorations in terms of survival and re-intervention, but this is at the expense of additional clinical time and increased cost.


Berry TG, Summitt JB, Chung AK, Osborne JW. Amalgam at the new millennium. J Am Dent Assoc. 1998;129(11):1547-56.

Setcos JC, Staninec M, Wilson NH. The development of resin-bonding for amalgam restorations. Br Dent J. 1999;186(7):328-32.


Do you have any particular question on this topic? Do you have any comments or suggestions? Email us at oasisdiscussions@cda-adc.ca

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  1. Robert murray September 5, 2013

    The results of bonded amalgams are greatly improved by using caries detect to check the preparation. The use of miniature burs like #329 or # 1/4 to create micro mechanical retention helps a great deal. I disinfected all preparations before bonding as it turns out all preparations contain viable organisms. I used resin cement on the bonded preparation, air thining it and immediate placement of amalgam to restore huge preparations with good long term results.

  2. Dr. Hardy Limeback BSc PhD DDS September 5, 2013

    This study might encourage dentists to ‘experiment’ with bonded amalgams with little evidence that they are better than conventional amalgams. Besides, the Minamata Treaty suggessts that amalgams will soon be phased out altogether anyway. See

  3. George Cadigan September 5, 2013

    Amalgam is king. I had another new patient today with a carious exposure unde a failed composite four surface restoration in a mandibular first molar. When will we learn that an amalgam would have lasted 20 years and then could have been replaced. An average composite will last five years and often fail catastrophically; requiring endo core and crown. A cynic might think that posterior composites are a source of endless and increasing revenue. The amalgam bashers are doing a grave disservice to their patients and to the profession.

    1. terry shaw September 5, 2013

      If your composite are only lasting 5 years you better get some new instruction!!

      1. Name September 6, 2013

        I don’t do posterior composites, and 5 years is pretty good for some of the rubbish that I see on new patients!

  4. Terry Shaw September 5, 2013

    I was told years ago the percent increase in retention strength was only 10 % over non bonded — hardly seems worth the effort or time or expense. Have not used amalgam for over 25 years anyway – just wondering about strength numbers.

    1. JCDA Oasis September 11, 2013

      On Behalf of Dr. Terence Shaw:

      Wondering what the increase in retention is in bonded versus non-bonded amalgams. What is the percent increase ???

  5. Howard September 6, 2013

    Thank you for posting this amazing and informative study!

  6. dr.fawzia September 6, 2013

    i like this articles and overall discussion .i ‘d like to see product or photo please bec. in my country yemen this kind of restoration is not avaible .i mean the conventional is availiable ,but other type is not.thx again .it’s interwsting.

  7. Caes September 10, 2013

    I believe amalgam has its place. Any dentist who only uses composite in all situations is not a well rounded clinician in my opinion. There is no one restoration that will work in every situation

  8. Dr. P. B. September 11, 2013

    A poorly placed posterior composite restoration may only last 5 years but a meticulously placed posterior composite restoration has the ability to last just as long as any amalgam restoration. Composite restoration are very technique sensitive. They require proper isolation, complete caries removal, proper preparation design, good bonding protocol, proper composite placement technique, adequate light curing, and proper finishing.

  9. Kevin Mark September 11, 2013

    I do a great deal of bonded amalgam restorations and I have been able to avoid pins in almost all of them, allowing very large restorations with minimal trauma to the pulp. I can attest to the fact that they do appear to last longer than non-bonded amalgams (and certainly much longer than composite restorations).

  10. Chattar Gill September 18, 2013

    Interesting and useful information, would anyone like to share their bonding protocol for Amalgams? Thanks.

  11. Terry Shaw September 19, 2013

    Maybe all the dentists who frown on composites in the posterior should see some that have lasted 20-25 years. Properly placed posterior composites succeed quite nicely when done well. Granted I have seen some crappy composites in my 37 years, but I have seen a lot of crappy amalgams in that time as well. A lot depends on the operator and the meticulous attention to detail that all dentistry deserves to be practiced with.


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