When a tooth is damaged by decay, dental fillings are needed to replace tooth structure and restore it to its normal function and shape. Amalgam, “silver,” and composite, “tooth-colored,” fillings are long lasting, though they can fail with wear and tear or when the tooth is damaged by fractures or further decay.

In this article, we explore the signs and symptoms that indicate your filling may be failing and what types of fillings are best to replace them with.

When to replace a filling

A dental filing needs to have a tightly sealed fit with the tooth. If any space exists between the tooth and the filling, decay can form under the filling. Decay occurring underneath a failing filling can be difficult to notice, and if left too long, decay can spread deeply into the tooth.

How are fillings evaluated?

Regular dental exams and x-rays are used to evaluate dental fillings. It is important therefore, to visit your dentist regularly for check-ups and not to delay in replacing failing fillings. After all, dental crowns and root canals are significantly more time consuming and costly treatments.

Signs of a failing dental filling

Although there may not be obvious signs of a failing filling, teeth that are sensitive to temperature or chewing indicates a potential problem. It’s important to follow up on your observations. If indeed a filling is failing and requires replacement you’ll be rewarded for not waiting by having a simple filling replacement to correct the problem. 

About amalgam or “silver” fillings

Traditionally dental fillings were made from an amalgam of metals, including silver, tin, copper, zinc, and mercury. Amalgam fillings are known to be very strong and durable, however, they have significant shortcomings. 

Since amalgam expands and contracts with temperature changes, it is known to cause fracturing of the tooth.  Also, since amalgam fillings are packed into the cavity of the tooth rather than bonded to the tooth, as with composite fillings, there is more likelihood of a space opening up between the tooth and the filling.

Amalgam fillings are not as cosmetically pleasing.  Whereas composite fillings can be colored to match surrounding teeth, amalgam fillings are dark and stand in stark contrast to natural teeth.

There is also a debate about the danger of mercury being present in amalgam fillings.  The form and quantity of mercury in amalgam fillings is considered safe by health regulators.  However, the perception of danger can be a powerful influencer of people’s decisions. 

Given all of the other shortcomings of amalgam fillings, Millennium Dental uses only composite fillings without any amalgam.

Should I replace my amalgam fillings?

If you have amalgam fillings and are considering having them replaced, it’s best to consult with your dentist.  Your dentist will look at factors such as how old the fillings are and how well they are holding up.

What type of filling should I have?

Typically composite resin fillings are the preferred choice.  Composite fillings actually help preserve more of the natural tooth structure since a smaller hole can be filled.Since composite is bonded to the tooth, it provides better structural support and serves to strengthen the tooth.

 Since composite material can be shaded, your dentist can ensure that your new filling is virtually invisible to others.


If you have pain or sensitivity around a current filling, don’t hesitate to make an appointment with your dentist to find out if it’s a sign of a failing filling.  Acting quickly could help you preserve your tooth for years to come.