How Long Do Dental Fillings Last? Composite vs Amalgam Explained

Most people will need at least one dental filling during their lifetime. Whether placed to treat decay, repair minor damage, or restore a worn tooth, fillings are one of the most common dental restorations. Yet many patients are unsure how long their fillings should last, what signs of wear to look for, or when a filling may need replacing.

The lifespan of a filling depends on several factors, including the material used, the size and location of the restoration, and the patient’s individual habits. This article explores the key differences between composite (tooth-coloured) and amalgam (metal) fillings, the factors that influence durability, and what to be aware of as fillings age.

How Long Do Dental Fillings Usually Last?

There is no single answer to how long a dental filling will last, as longevity varies considerably from one patient to another. However, general estimates based on clinical research and professional experience can offer useful guidance.

Amalgam fillings have been used in dentistry for over 150 years and are known for their durability. On average, amalgam restorations may last between 10 and 15 years, with some lasting significantly longer when placed in favourable conditions and well maintained.

Composite fillings are a more modern alternative and are widely used today, particularly for visible teeth. These tooth-coloured restorations typically last between 5 and 10 years, although improvements in composite materials mean that many now perform well beyond this range.

It is important to note that these are general estimates. Some fillings may last considerably longer, while others may require attention sooner, depending on the circumstances.

What Is the Difference Between Composite and Amalgam Fillings?

The two most commonly discussed filling materials are composite resin and dental amalgam. Each has distinct properties that may make it more suitable for certain situations.

Amalgam Fillings

Amalgam is a mixture of metals, including silver, tin, copper, and mercury. Despite concerns sometimes raised about the mercury content, amalgam fillings have been extensively studied and are considered safe for use by regulatory bodies including the NHS and the British Dental Association. Amalgam is particularly hard-wearing and is often used for larger restorations in back teeth, where biting forces are greatest.

However, amalgam fillings are silver-grey in colour, which makes them visible when placed in areas of the mouth that can be seen during speaking or smiling. For this reason, some patients prefer alternative materials for aesthetic reasons.

Composite Fillings

Composite fillings are made from a blend of resin and fine glass particles. They can be closely matched to the natural shade of the surrounding teeth, making them a popular choice for visible areas. Composite is bonded directly to the tooth surface, which can help preserve more of the natural tooth structure during preparation.

While composite materials have improved significantly in recent years, they may still be more susceptible to wear and staining over time compared with amalgam, particularly in areas subject to heavy chewing forces.

Do Composite Fillings Wear Out Faster Than Amalgam?

In general terms, composite fillings may have a shorter average lifespan than amalgam, particularly when used in large restorations on molar teeth. The softer nature of composite resin means it can wear down more quickly under sustained biting pressure.

That said, the gap in durability has narrowed considerably. Modern composite materials are stronger and more wear-resistant than earlier generations, and when used appropriately—for example, in small to medium restorations or in areas with moderate biting forces—they can perform very well for many years.

The choice between composite and amalgam is not solely about longevity. Factors such as aesthetics, the amount of healthy tooth structure remaining, the location of the filling, and patient preference all play a role. A dentist can help determine which material may be most appropriate for each individual case.

What Factors Affect How Long a Filling Lasts?

Several variables influence the longevity of any dental filling, regardless of the material used.

• Size and location of the filling: Larger fillings and those on biting surfaces may experience greater stress and wear
• Oral hygiene: Good brushing and flossing habits help protect the margins of a filling from secondary decay
• Diet: Frequent consumption of sugary or acidic foods and drinks can increase the risk of decay around a filling
• Teeth grinding (bruxism): Habitual clenching or grinding places excessive force on fillings and can cause them to crack or wear prematurely
• Bite alignment: An uneven bite may concentrate force on certain teeth and their restorations
• Quality of the original placement: A well-placed filling with good technique and moisture control tends to last longer

Regular dental examinations allow a dentist to monitor existing fillings and identify early signs of wear, marginal breakdown, or recurrent decay before they become more significant problems.

When Should an Old Filling Be Replaced?

Not all old fillings need to be replaced. A filling that remains intact, well-sealed, and free from surrounding decay may continue to function effectively for many years, even if it shows cosmetic signs of ageing such as slight discolouration.

However, there are circumstances where replacement may be advisable. Signs that a filling may be failing include:

• Sensitivity to hot, cold, or sweet foods and drinks around the filled tooth
• Visible cracks, chips, or pieces missing from the filling
• A rough or sharp edge that can be felt with the tongue
• Darkening or discolouration around the margins of the filling
• Pain or discomfort when biting down on the affected tooth
• A gap developing between the filling and the surrounding tooth

A deteriorating filling can allow bacteria to enter beneath the restoration, potentially leading to decay underneath the filling that may not be visible or detectable without professional examination. If left unaddressed, this can progress to more extensive damage.

Can Fillings Be Repaired Instead of Replaced?

In some cases, a filling that has suffered minor damage—such as a small chip or slight marginal wear—may be repairable rather than requiring full replacement. A dentist can sometimes smooth, reshape, or add material to an existing restoration to extend its functional life.

However, repair is not always appropriate. If the filling has significant cracks, if there is decay beneath the restoration, or if the seal between the filling and the tooth has been compromised, full replacement is generally the more predictable option. The decision between repair and replacement depends on the clinical findings and will be discussed with the patient so they can make an informed choice.

When replacing old fillings, a dentist will remove the existing restoration and any decay, then place a new filling. This also provides an opportunity to reassess the tooth and consider whether a different material or type of restoration—such as an inlay or crown—may be more suitable.

Modern Alternatives to Older Metal Fillings

While amalgam remains a clinically effective material, many patients choose to have older metal fillings replaced with tooth-coloured alternatives for cosmetic reasons. Modern composite resins and ceramic materials can provide a natural-looking result that blends with the surrounding tooth structure.

For larger restorations where a standard filling may not provide sufficient strength, a dentist may recommend an inlay or onlay. These are custom-made restorations, typically crafted from ceramic or composite, that fit precisely within or over the damaged area of the tooth. In cases where a tooth is extensively damaged, a crown may be a more appropriate long-term solution.

It is generally not recommended to replace a well-functioning amalgam filling purely for aesthetic reasons unless the patient has a specific preference. Unnecessary removal of sound restorations involves drilling away healthy tooth structure, which is best avoided where possible. A dental assessment can help determine whether replacement is clinically justified or whether monitoring remains the most appropriate approach.

How to Help Your Fillings Last Longer

While no filling lasts indefinitely, there are steps patients can take to support the longevity of their dental restorations:

• Brush twice daily with a fluoride toothpaste and clean between teeth with floss or interdental brushes
• Limit sugary and acidic foods and drinks, which can weaken tooth enamel and filling margins
• Avoid chewing hard objects such as ice, pen caps, or boiled sweets
• Wear a protective mouthguard if you grind your teeth at night
• Attend regular dental examinations so fillings can be monitored over time

Preventive care and good oral hygiene remain the most effective ways to extend the life of any dental restoration.

Conclusion

Dental fillings are durable restorations, but they do not last forever. The lifespan of a filling depends on the material used, the size and location of the restoration, and individual factors such as oral hygiene, diet, and habits like teeth grinding. Amalgam fillings tend to be longer-lasting in high-pressure areas, while composite fillings offer a natural appearance and have improved significantly in durability.

Regular dental examinations are the most reliable way to monitor the condition of existing fillings and to identify early signs of wear or failure. Not every old filling needs replacing—many continue to function well for years beyond their expected lifespan—but when signs of deterioration are present, timely assessment can help prevent more extensive treatment.

Understanding what to expect from your fillings, recognising the signs of a failing restoration, and maintaining good oral care habits can all contribute to better long-term dental health.

If you have questions about your existing fillings or would like a routine review of your dental restorations, our dental team is available to provide a thorough assessment and discuss any options that may be relevant to your individual circumstances.