Should you get a metal amalgam filling or a plastic composite filling?

Amalgam vs Composite!!

Amalgam vs composite is an ongoing controversy and depending on your desires, which one is best for you will depend.

Researching amalgam vs composite?

Read all about amalgams and dental composites here!  Amalgam is, as name implies, an amalgamation or mixture of different metals.  A composite is a plastic based material that we bond to the tooth.  If you want a filling that looks like a tooth then composite is your answer; as there is little argument about which one looks more natural.

However, this post will deal strictly with the longevity of the materials as a consideration for which to use.  There are people that believe the mercury in the amalgam is detrimental to your health, but many also believe the BPA or some other chemical in composite is too (BPA resin).  In my mind, the issue is a wash.  If either or both concern you, then use gold or porcelain.  I don’t think either is of  concern, since environmental doses of both far outweigh what you could get from fillings.  Amalgam use is more of an environmental threat than composite.  What happens to the mercury after you die is much more of an environmental issue than composite, especially if you are cremated.  Source noharm

Amalgam vs composite conclusion of research

Reviewing the research shows that amalgam lasts the same or slightly longer than composite in the 5-12 year period.  The increased survival rate of amalgam over composite is at most fairly small.  The research says no higher than about 5% over a 10 year time period.  My opinion is that this may not be true over very long time periods.  My thought is that amalgams will cause more teeth to fracture.  There is evidence that amalgam holds up better in those that are high caries risk individuals.

I base my opinions on the assumption that a well trained dentist is placing the composites and that the dentist’s compensation is fair.  Composites are much more technique sensitive so when corners are cut, the results suffer significantly.  I feel that when dealing with lower SEC in a public clinic type of office that amalgams will be FAR more superior in terms of efficiency and effectiveness; studies conducted in such environments confirm this.  I also think there are many PPO style practices and even some FFS style practices where the patient base would be better served if their dentist either placed more amalgams OR improved their materials and/or techniques.  More on composite techniques and materials can be found here.

I personally place nearly all composites except in some high caries individuals or along some gumlines.  For my demographics, I feel this is an acceptable way to treat the people in my practice.  I think composites are more likely to succumb to recurrent decay in the short term, but that amalgam is more likely to fracture a tooth in the long term (longer than many of these studies go).  Recurrent decay can be fixed with a new filling while a fractured tooth is either lost or needs a crown and/or root canal.  Even though, composite may cause more problems in the short term their solution to that problem is easier and cheaper than a fractured tooth. (Since I wrote this paragraph Opadam 2012 was published showing this to be true)

Meta and reviews amalgam vs composite research links

Composite performs best of all materials in primary teeth. EBD Gao 2018

Review of some research I have most included all below. 1

Meta-analysis 90% at 10 year for class II composite=about same as amalgam Heintze Rousson 2012

Both last about the same – Meta-analysis Hickel R, Manhart J. 2001

Resins higher failure rate than amalgam – Cochrane review Rasines Alcaraz 2014

Resins have higher failure rate than amalgam in vital teeth – Systemic review Afrashtehfar JPD 2017

Amalgam vs composite research links 2010 and newer

12 year study dental student placed amalgam and composites 2 surface only. Naghipur JPD 2016

• Nearly identical failure rates.  The failure rate is identical if you look at years 2-12.  This is interesting because it likely excludes many of the very poorly placed composite fillings.
• Amalgams did not fracture the teeth at significantly higher rates as I have claimed may be an issue.  However, I believe this is an issue farther out than 12 years, thinking more like 15+.

Amalgam is more decay resistant than composite or glass ionomer in vitro Guang-Yun 2013

British studies 2013      For the record I feel British dentistry, especially when the government is paying for the work, is quite possibly the worst dentistry performed on the planet.  This study is based on government work.  It’s difficult to screw up an amalgam, so I imagine the survival rates would be comparable to American ones.  Composites are much more technique sensitive and I would imagine a BIG difference in survival rates of American composites.

Opdam 2012 using same data set as above for amalgam vs composite

• Annual failure rate including those repaired of composite = .7%
• Annual failure rate including those repaired of amalgam = 2.5%
• Repairs of composite much more successful because of mechanism of failure (amalgam break tooth and composite recurrent decay)

Kopperud 2012 mean follow up of 4.6 years in Norwegian public health offices with 93% placed on children.  Composites are more technique sensitive and I am willing to bet that Norwegian public health does not draw the best and most ambitious dentists thus lower quality so I would expect the composite to be significantly lower.

• average of 3% failure rate a year composite
• average of 2% failure rate a year amalgam
• That means there is a 50% increase in failure rate when going from amalgam to composite!

A 12 year study of 3 surface Class II or higher finds composite fillings survive as well or better than amalgam in every situation other than “high caries risk 3 surface filling”.  Tested 3 surface and low and high caries risk Opdam Bronkhorst  Loomans  Huysmans 2010

• Did not look at class II 2 surface fillings but can infer at the very least amalgam would do better in the high caries risk people.
• 69 of 1202 teeth that received amalgam got crowns “not related to restoration failure”.  However, 0 of the 747 composite teeth did = Amalgam cracks teeth more?
• 93% composites were total etch 4th generation

Amalgam vs composite research links 2005 -2010

10 year survival of amalgam and composite – note composite are Class III-V ONLY  (F. J. T. Burke & P. S. K. Lucarotti 2008)

Both have same failure rates at 10 years Opdam NJ, Bronkhorst EM, Roeters JM, Loomans BA. 2007.

5 year 6-10 year olds amalgam better 11% failure and 15% failure composite.  Compomer/composite restorations on posterior tooth surfaces in children may require replacement or repair at higher rates than amalgam restorations, even within five years of placement. Soncini 2007

7 year study Amalgam (94%) performed better in 8-12 year olds than did composite (86%) restorations with 4th generation bonding. The difference in performance was accentuated in large restorations and in those with more than three surfaces involved.  Bernardo 2007 JADA June

Higher failure rates were observed in resin-based composite for amalgam vs composite 2007  Levin L, Coval M, Geiger SB.

Amalgam vs composite research links pre-2005

Survival times were 12.8 years for amalgam restorations, 7.8 years for resin restorations, and more than 14.6 years for crowns, considering all retreatment as failures  2003 Van Nieuwenhuysen JP, D’Hoore W, Carvalho J, Qvist V.

At 8 years, composite restorations in posterior teeth had failed at a rate two to three times that of amalgam restorations 1998 Collins CJ, Bryant RW, Hodge KL.

Both have same failure rates at 10 years Mair LH 1998.

5 year study both same Norman RD, Wright JS, Rydberg RJ, Felkner LL.1990

• One of few American studies and done in my state so I am bias in liking this study