Are there differences between direct composite resin fillings and amalgam fillings for permanent or adult posterior teeth ?
This summary is based on the Cochrane systematic review: Direct composite resin fillings versus amalgam fillings for permanent or adult posterior teeth (Review)
Rasines Alcaraz MG, Veitz-Keenan A, Sahrmann P, Schmidlin PR, Davis D, Iheozor-Ejiofor Z
Access the full review for the next 3 months (PDF)
Context
Amalgam has been the traditional material for filling cavities in posterior teeth for the last 150 years and, due to its effectiveness and cost, amalgam is still the restorative material of choice in certain parts of the world. In recent times, however, there have been concerns over the use of amalgam restorations (fillings), relating to the mercury release in the body and the environmental impact following its disposal. Resin composites have become an esthetic alternative to amalgam restorations and there has been a remarkable improvement of its mechanical properties to restore posterior teeth.
There is need to review new evidence comparing the effectiveness of both restorations.
Purpose of the Review
To examine the effects of direct composite resin fillings versus amalgam fillings for permanent posterior teeth, primarily on restoration failure.
Conclusions and Implications for Practice
- There is low-quality evidence to suggest that resin composites lead to higher failure rates and risk of secondary caries than amalgam restorations.
- This review reinforces the benefit of amalgam restorations and the results are particularly useful in parts of the world where amalgam is still the material of choice to restore posterior teeth with proximal caries.
- Though the review found insufficient evidence to support or refute any adverse effects amalgam may have on participants, new research is unlikely to change opinion on its safety since its proposed phase-down is due to safety concerns.
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So another long and exhaustive review and they have no opinion, one way or another! How frustrating! On a personal level, my office stopped placing any silver-mercury amalgam fillings in patients teeth since 2005, and I personally see no difference in longevity or wear resistance of direct nanofilled composites, when placed properly using the correct technique, which includes accurate moisture control.
We do however, remove a lot of old and rusted silver amalgams from patients’ mouths, and use the amalgam separator machines to prevent it going into our lakes and rivers, but the separation process is expensive and we bear an added cost due to it. It has to be disposed using a special company who are authorized by the government.
Let us follow Sweden, Switzerland, Finland and other EU countries and ban the product altogether. More than 55% dentists do not use it anyway in Ontario, we seriously do not need this toxic menace in the office or in patient’s mouths.
The evidence may be described as low quality, but if I had a dollar for every posterior composite that had failed and needed endo, core and crown then I could retire tomorrow. Purely anecdotal and thus a low-quality observation. No doubt, there are some fine posterior composites being done, but there are very many bad ones. There is, to my knowledge, no scientific evidence of systemic problems arising from mercury in amalgam restorations and yet this is brought up as a concern. The concerns regarding bias might be applied to this study.
Several thoughts:
1)Given ‘toxic menace’ concerns about amalgam, how about some discussion about estrogenicity,formaldehyde and bisGMA content of composite breakdown components. Admittedly trace amounts, but do we want to increase the amount of plastic/hormone mimicking byproducts we consume? Are patients advised of these environmental concerns when amalgam is being replaced by composites? Are they being offered biologically inert alternatives?
2)Durability of dentin bonding, especially in subgingival areas where there is no enamel to bond to is weak at best, and degrades rapidly. Even if rubber dam,retraction cord is used, it doesn’t come close to amalgam. In the practice there are many 20 year old amalgams, with deep interproximal extensions that are still functioning fine, but I’m always glad if a composite makes it to 10 years.
3)and finally…a little off topic
The gold inlays and onlays in my mouth are between 30-40 years old. These biologically inert, very durable restorations are a regular part of my practice. Why does the dental profession (and our university teaching programs)get persuaded by media/commerce created ‘needs’ of ‘popular, esthetic’ rather than teaching our patients and students the solid science of preserving healthy tooth structure in a predictably durable manner?
The placement of amalgams has been well documented to release significant amounts of mercury into the system which is bound in the system for months if not for as long as the amalgam fillings are present. This is a substance that should not be in our system, and unfortunately the studies required to truely prove its negative effects are unethical to perform. Not to mention the environmental impact this product has.
I agree that resins may be more prone to recurrent decay, but I believe they are less prone to contribute to tooth fracture from multiple aspects.
Pros and cons to both, and ultimately technique and skill of the dentist are the biggest factors for success of a resin (outside of patient home care and diet).
Re: Comparing amalgam and composite in molars. The worst thing about both of them is the WAY they are used.
Excessively large occlusal restorations filled with amalgam expand and eventually crack the molar. If the decay is deep, the dentist should place a thick base. Catastrophic fractures due to crude technique have given amalgam a bad name.
The worst things about composite is the difficulty in reliably obtaining anatomical contours / contacts and the inability to reliably bond in the absence of enamel.
I work in a “white” community where many people present with chronic tooth decay and all the problems that go along with it. I still do a few class two amalgams as well as replace lots of old amalgam with composite. Both materials often get a vitre-bond liner.
BOTH MATERIALS ARE GOOD. Neither is perfect. The problem with BOTH materials is the person holding the handpiece.
This year I’ve seen three new patients with moderate to severe post-operative sensitivity on multiple teeth from posterior composites all from the same dentist.
If you’re doing good dentistry, cleaning up after yourself and your patients are happy, I don’t care what material you use.
Amalgam has saved a lot of teeth that composite could not…large restorations with extensive cuspal coverage cannot reliably be restored with current composites. I use both materials, where suited in my practice, as do most dentists in my area. The science clearly doesn’t support eliminating the use of Amalgam. It’s interesting that the first poster notes that 55% of Ontario dentists don’t use amalgam…that still leaves 45% who do, and that’s a lot of dentists in Ontario alone. Until there’s a proven problem with Amalgam I’ll keep using it as will lots of my peers.