Why we are an amalgam-free practice

What is amalgam?

The amalgam used in dental fillings (often called silver, or black, fillings) is a powdered metal alloy made up of copper, tin and silver which is amalgamated, and held together, by liquid mercury. Amalgam is approximately 50% elemental mercury by weight.

It is used in dental fillings because when mixed with the powdered alloy, it becomes a pliable material which is easily placed into a cavity. It is a relatively cheap material and is fairly quick to use.

Reports vary, but amalgam has been used routinely for almost 200 years in dentistry. However, there has been controversy surrounding amalgam and its uses for some time. Two main reasons for this are:

it contains mercury which is a heavy metal. This is important because it is classed as a neurotoxin, which means it affects the nervous system and can bioaccumulate in other organs such as the liver, kidneys and lungs. The World Health Organisation (WHO) have placed it in their list of Top 10 chemicals or groups of chemicals of major concern to public health
it is released into the air as mercury vapour which can be inhaled, or into the environment via waterline systems

Alternatives to amalgam

Gold
Porcelain
Composite

Historically, gold was used as an alternative, although a very expensive one. Occasionally, we use porcelain or porcelain bonded to metal when the tooth requires more support as a result of extensive loss of tooth structure.

At The Keith Dental Practice, we use composite material for most of our restorations. Composite is a resin-based material with filler particles. The composites we use now benefit from a bonding system during placement. This means that the material bonds to the remaining tooth structure whereas amalgam does not. As a result of this, we only need to remove tooth structure which is affected by tooth decay, and leave the healthy structure.

With amalgam, which does not bond to the tooth, we need to remove more tooth structure and create “undercuts” so that the filling has some retention. This can significantly weaken the remaining tooth structure, and when we take into account that over time amalgam corrodes and expands, it can fracture the remaining walls or cusps of the tooth.

Amalgam’s causing fractures

As mentioned above, amalgam expands over time as it corrodes. This can be a good thing in that as it corrodes, it seals the marginal gap between the tooth and the restoration, and as a result, can reduce microleakage. However, by the same corrosive action, it can also cause fractures in the tooth. These fractures, depending on the severity and where they are, can sometimes mean the tooth is irreparable. There are many types of fractures but the 3 main ones that we deal with in practice are:

Oblique cusp fractures – most common type of fracture which causes the cusps to fracture off.
Mesio-distal fractures – caused by vertical loads driving adjacent cusps apart. Fractures travel vertically into pulp rather than obliquely allowing bacteria to enter dentinal tubules and eventually the pulp chamber.
Poisson effect fractures – these fractures occur under older amalgam restorations causing micro-fracturing of the dentine covering the pulp chamber.

This is why it is important to determine where the fractures are, and also where the forces on the tooth are, as management and treatment varies. If fractures remain untreated, or are incorrectly treated, the tooth can continue to exhibit symptoms which could potentially be incorrectly diagnosed as irreversible pulpitis (for which the only treatments are root canal treatment or extraction).

Phasing-out amalgam

The Minamata Convention of 2017 gathered the EU parliament to implement a phase-down of amalgam use. Over 140 countries signed the treaty in January 2013.

“The Minamata Convention on mercury is a global treaty to protect human health and the environment from the negative effects of mercury”.

The treaty aims to reduce the release of mercury into the environment. The phase down regulations include: no amalgam to be used in deciduous teeth (baby teeth), children under 15 and in pregnant or breastfeeding women; mercury is to be sold in pre-dosed capsules – no bulk mercury can be purchased; amalgam separators are mandatory; and authorised waste management contracts must be in place.

A complete phase-out was not implemented as amalgam is sometimes the only restorative material available.

In order to phase-out completely, we believe a greater emphasis on prevention is necessary, as well as increased research into amalgam alternatives. If our prevention practices were better there would be less tooth decay and thus less need for fillings. It must be said that on the whole, oral hygiene and preventive practices have improved since the 1990’s in Britain. This could be because of the generational change at this time – our younger generation (the “millennials”) are more health conscious and more conscious of their appearance in general – or because of better education by our dentists and in-school programmes such as Childsmile, where qualified dental nurses go into schools and apply topical fluoride to the children’s teeth, as well as educating them about how to look after their teeth.

Therefore, we have opted to not use amalgam at all within our practice as we believe it carries with it unnecessary risks, some of which can cause irreparable damage to a tooth and could potentially be harmful to our health.

References:

BDA – https://bda.org/amalgam

FDI – https://www.fdiworlddental.org/news/amalgam

ADA – https://www.ada.org/en

Dentaly.org – https://www.dentaly.org/en/tooth-filling/amalgam-fillings

WHO – https://www.who.int/news-room/fact-sheets/detail/mercury-and-health

Dental Statistics (UK & Worldwide)

Written by Miss Faye Law

Senior Dental Nurse at The Keith Dental Practice

13/02/2020