When Should Old Dental Fillings Be Replaced?

Dental fillings do not last forever. But that does not mean every old filling needs immediate replacement. The question is not how old the filling is. It is whether the filling is still doing its job.

Here is how to tell the difference between a filling that is fine to leave and one that needs attention.

How long fillings typically last

Different filling materials have different lifespans.

These are averages. A small composite filling on a low-stress tooth may last 15 years. A large amalgam filling on a grinding molar may crack after 8. Location, bite forces, oral hygiene, and habits all influence durability.

Signs a filling may need replacing

Your dentist checks the condition of existing fillings at every check-up. But between visits, watch for these indicators.

Sensitivity or pain. A tooth with an old filling that becomes sensitive to hot, cold, or pressure may indicate the filling has cracked or the seal has broken. Bacteria can seep underneath a compromised filling and cause new decay.

Visible cracks or chips. Look in the mirror. If you can see a crack in the filling material or a piece has broken off, the filling is no longer sealing the tooth properly.

A rough or sharp edge. Run your tongue over your fillings. If one feels rough, sharp, or different from how it used to feel, the surface may have worn or chipped.

Discolouration around the filling. A dark shadow around the edge of a white filling can indicate decay underneath. This is one of the most common reasons for replacement and is often only visible on an X-ray.

Food getting trapped. If food suddenly starts catching around a filled tooth that never had that problem before, the filling margin may have broken down, creating a gap between the filling and the tooth.

The filling feels loose. If you can feel movement or the filling shifts when you bite, it needs replacement before it falls out entirely.

What happens when a filling fails

A failing filling does not always cause pain immediately. The most common failure mode is a gap developing at the margin (the join between the filling and the tooth). Bacteria colonise this gap and decay progresses underneath the filling where you cannot see it.

This is why routine X-rays matter. Your dentist can spot decay under a filling on a bitewing X-ray before it causes symptoms. Catching it early means a simpler, less costly repair. Waiting until the tooth hurts often means the decay has reached the nerve, potentially requiring root canal treatment or a crown.

Should you replace amalgam fillings with composite?

This is a common question at our Brisbane clinics. The short answer: there is no clinical need to replace a sound amalgam filling for health reasons.

The Australian Dental Association's position is that dental amalgam is a safe and effective restorative material. Replacing a functioning amalgam filling removes more tooth structure and introduces risk (any time a tooth is drilled, there is a small risk of nerve irritation).

However, there are valid reasons patients choose to replace amalgam:

• Aesthetics. You want white fillings instead of silver, particularly on visible teeth.
• The filling is failing. If the amalgam is cracked, leaking, or has decay underneath, replacement is clinically necessary. Replacing with composite at that point is a reasonable choice.
• Tooth fracture risk. Large amalgam fillings do not bond to tooth structure. Over time, the remaining tooth walls around a large amalgam can flex and crack. Replacing the amalgam with a bonded composite or an onlay/crown can reduce fracture risk.

If you are considering amalgam replacement, discuss it with your dentist. They can assess each filling individually and advise which ones are worth replacing and which are better left alone.

What a filling replacement involves

The process is similar to having a new filling placed.

1. Anaesthesia. The area is numbed with local anaesthetic.
2. Removal. The old filling material is drilled out. If decay is present underneath, it is removed as well.
3. Assessment. Once the old filling and decay are cleared, the dentist assesses how much healthy tooth structure remains. This determines whether a new filling will suffice or whether a crown is needed.
4. Restoration. A new composite filling is placed, shaped, and cured with UV light. For larger cavities, an inlay, onlay, or crown may be recommended instead.
5. Bite check. The bite is tested and adjusted so the new restoration sits comfortably.

The appointment typically takes 30 to 60 minutes per tooth.

When a filling becomes a crown

If the old filling was large and the tooth has lost significant structure, a new filling may not be strong enough. The general rule: if more than 50% of the biting surface has been lost to decay or previous filling, a crown is typically the better option.

A crown covers and protects the entire visible portion of the tooth, distributing bite forces evenly. This reduces the risk of the tooth cracking under load. Crowns at Ivy Dental start from $1,600 per tooth.

Your dentist will explain if a crown is recommended and why. You will receive an itemised quote before any work begins.

Filling replacement costs in Brisbane

Indicative pricing. Your quote may differ based on clinical assessment.

Health fund rebates typically apply to filling replacements. We accept all major health funds with HICAPS on site at our Everton Park and Nundah clinics.

How to make fillings last longer

• Brush twice daily and floss daily. Decay at the filling margins is the most common reason for replacement.
• Reduce sugary and acidic foods. These accelerate enamel breakdown around filling edges.
• If you grind your teeth, a custom splint protects fillings from excessive force.
• Attend six-monthly check-ups. Your dentist monitors filling condition and catches problems early.
• Avoid using filled teeth to open packaging, crack nuts, or chew ice.

Book a check-up at Ivy Dental to have your fillings assessed. Book a consultation, or call (07) 3266 7120.