If you’ve been going back and forth on amalgam and whether you should continue using it in your practice, the findings of a new study could provide some clarity.

For two full years, five undergraduate students at Loma Linda University examined the impact of extreme contaminations on amalgam fillings during condensation. The goal of these dedicated research design students was to determine the shear-strength degradation effects on dental amalgam.

The researchers assessed the reaction of amalgam to gross contamination during condensation under the following elements:

• Water
• Saliva
• Blood
• Handpiece lubrication oil

The results, published under the title, “Amalgam Strength Resistance to Various Contaminants,”  demonstrated that amalgam is capable of withstanding “worst-case-scenario” levels of contamination equally or better than its alternatives, including resin-modified glass ionomer.

Just How Well Does Amalgam Retain Its Strength?

To summarize, here’s a breakdown of the findings discovered in the research discussed above:

• Amalgam strength wasn’t reduced to a significantly statistical extent (p= 0.05) by water contamination.
• Compared to water and blood-contaminated water, saliva reduced in between both.
• In saliva, the final remaining strength was the same or more than the uncontaminated strengths recorded in the available literature for other restorable materials (e.g., composite resin, resin-modified glass ionomer, glass ionomer.)
• Amalgam strength degradation was at its most significant – at around 50% – when fully immersed in handpiece lubrication oil during condensation. However, contamination from handpiece lubrication oil was proven to be highly unlikely in practice.
• Still, the oil contamination resulted in amalgam strengths were the same or more than other available restorative materials while exceeding the minimum compressive strength of 35,000 pounds per square inch

How Do the Alternatives Compare to Dental Amalgam?

The results above already indicate the dental amalgam can withstand contaminative circumstances better than many alternatives.

Let’s look closer at the alternatives and see how they stack up.

1. Composite Resin Fillings

As the most regularly used alternative to dental amalgam, composite resin fillings are tooth-coloured and white. Acrylic resin is the primary material used in the making of these fillings—and they’re reinforced with powdered glass filler.

It’s common for composite resin colours to be customized to match surrounding teeth. They’re also often light-cured by blue light in layers to lead into the last restoration.

Yes, there’s no doubting the strength and blending capabilities of these fillings. Also, they don’t need much removal of healthy tooth structure for placement.

But they come up short in other aspects.

First and foremost, the composite resin is harder to place than amalgam—plus, they’re infinitely more expensive. Lastly, while they are strong, these fillings appear to be less durable than amalgam.

2. Glass Ionomer Cement Fillings

Organic acids (such as eugenol), bases (such as zinc oxide), and potentially acrylic resins can be found in glass ionomer cement.

Glass ionomer fillings are tooth-coloured like composite resin, and its properties seem most ideal for more meagre restorations.

These fillings cure on their own and don’t necessitate a blue light for the setting process.

While ease of use and quality of appearances are definite plusses with glass ionomer cement, they’re not particularly useful for more significant restorations.

Is Amalgam Usage Long for this World?

Of course, we can’t forget that these findings are only part of a bigger picture on the use of dental amalgam.

The material’s mercury content makes dental amalgam a public health and ecological risk, particularly after its removal. On July 14, 2017, the Environmental Protection Agency (EPA) finalized regulation specifically targeting the use and disposal of dental amalgam. In Canada, dentists must use amalgam traps and filters to collect amalgam waste and recycle it appropriately.

As such, many dentists – as a protective measure – are opting to use alternatives to amalgam for health, safety and ecological reasons.