Thanks to the advent of new technologies, dentists and their patients now have access to a variety of materials used to fill cavities. The ones you’re probably most used to are amalgam fillings. They can be recognized by their metallic appearance, and have been around for quite some time. Composite fillings are newer, and you might not have noticed them because that’s the point: they’re made to match the color of the tooth.

So, is one better than the other? Not necessarily. Both filling types have advantages and disadvantages, and the appropriate material will depend upon the size and location of the filling, as well as your personal preferences. To learn which one is best for you, read on – then discuss your options with your dentist when developing your treatment plan.

Amalgam Fillings

Amalgam fillings have been used since the 1800s to fill cavities in hundreds of millions of patients worldwide. As mentioned above, they’re metallic in appearance, so they’re easily recognizable.

What is an amalgam filling made of and how is it placed?

Amalgam is a mixture of metals, including elemental (liquid) mercury, silver, tin, and copper. Amalgam is about 50% mercury, which allows it to react with and bind with silver, tin, and copper particles to form a solidified filling, or amalgam. Amalgam fillings are often referred to as “silver fillings” due to their silver color.

It is necessary to use mercury for an amalgam filling, as no other known material is able to bind the copper, tin, and silver particles together to create a solid filling. Mercury is unique in that it is both liquid at room temperature and bonds well with the particulate metals.

To place an amalgam, the dentist drills the tooth to remove the decay, and shapes the cavity to allow placement of the amalgam filling. The powdered metal silver, tin, and copper particles are then mixed with the mercury to form an amalgam putty, which is then placed in the cavity. Upon placement, amalgam rapidly hardens into a solid filling. Once it has hardened, the dentist shapes the filling to be even with the chewing surface of the tooth.

What are the advantages of amalgam fillings?

Amalgam fillings are cheaper than composite fillings, so may be preferred by patients for billing reasons. They are also significantly easier to work with than composite fillings, so some dentists prefer them for this reason.

Amalgam fillings are also stronger than composite fillings, so may be especially beneficial for back teeth, where higher-pressure chewing and grinding require a stronger filling. They may also be longer-lasting for this reason.

What are the disadvantages of amalgam fillings?

The primary disadvantage of amalgam fillings is cosmetic, as they have a conspicuous silver appearance. For this reason, they may be best-suited for back teeth, where they won’t be as visible.

Additionally, amalgam fillings contain mercury, and while it does not readily leach out, amalgam fillings do release a small amount of mercury vapor that can be inhaled and absorbed by the lungs.

Why does this matter? Because mercury is toxic, and high amounts of mercury vapor can damage the brain and kidneys. However, the relatively small amount of mercury contained in amalgam fillings is unlikely to do significant harm.

Composite Fillings

Composite, or ceramic, fillings are a relatively new option, but they’ve still been around for a number of years. They are also known as “white” fillings due to their coloration.

What is a composite filling made of and how is it placed?

Composite fillings are made of a mixture of glass and plastic, usually with silica as a binder.

To place a composite filling, the dentist drills to remove the decay and shapes the cavity to allow placement of the filling – similar to the process for an amalgam filling.

Once the cavity has been opened up, the dentist applies an acidic conditioner to etch the tooth’s exposed surfaces. This comes in gel form and is usually dispensed from a syringe, and is rinsed off in 15-30 seconds. The dentist then applies a liquid plastic adhesive (or bonding agent), and cures it with a curing light – this is the blue light that you see towards the end.

The dentist then adds the composite, which has a putty-like consistency, in layers to successively build a restoration. Once the composite is positioned, it is cured with the same blue curing light for another 10-40 seconds. The dentist may then apply additional layers of composite using the same process.

Once the composite restoration is complete, the dentist will use a drill to shape the restoration properly, checking your bite using carbon paper, and finally use polishing stones to create a smooth, shiny finish.

What are the advantages of composite fillings?

The primary advantage of a composite filling is that it cannot be distinguished from the surface of the tooth, so is a better cosmetic option than an amalgam filling. Composite fillings may also be a better bonding agent than amalgam, so may be preferable for some forms of restorative dentistry.

What are the disadvantages of composite fillings?

Composite fillings are more costly than amalgam fillings, and some insurance plans do not cover them. They are also softer than amalgam fillings, so may not be as long-lasting. For this reason, some dentists may opt to not use composite on molars that undergo a lot of pressure and grinding.

Regardless of what filling type you choose, if you have a cavity, it’s important to get it taken care of as soon as possible, as it will continue to grow. Discuss your options with your dentist prior to the procedure, and he or she can help develop the most appropriate treatment plan for your needs.