Replacing Old Fillings — When It Is Needed
Fillings do a quiet, steady job for years. They are also one of the most over-replaced restorations in dentistry, so we take a measured view at Sandgate Family Dental: we replace a filling when there is a clinical reason, not simply because it looks old or because the material has changed over time. This page walks through when replacement is genuinely needed, when it is reasonable to leave a filling alone, and what to expect from the appointment.
If you have been told a filling needs replacing, or you have noticed a chip, a sharp edge, or sensitivity around an existing filling, you can book an appointment online for a careful look.
Lifespan
How long do fillings last
There is no universal lifespan. A small filling in a well-cared-for tooth can last decades; a very large filling in a heavily-loaded back tooth can need attention much sooner. What matters more than the date the filling was placed is whether it is still doing its job — sealing the tooth, holding shape, and protecting the underlying structure.
Replacement
When replacement is genuinely needed
Decay around the edges (recurrent caries)
Bacteria can find their way under the edge of a filling that has shrunk slightly, chipped, or developed a tiny gap. Once decay forms underneath, leaving the filling in place allows it to spread. We diagnose this with a careful exam, bitewing X-rays, and sometimes by removing the filling and inspecting underneath.
Leakage or staining at the margin
A dark line forming around the edge of a tooth-coloured filling can simply be surface staining, or it can be early leakage. The difference matters. We assess each one in context rather than replacing on appearance alone.
A cracked or chipped filling
If part of the filling has fractured, the seal is compromised. Small chips at the edge can sometimes be repaired with a small composite addition. Larger losses usually mean a full replacement.
A cracked tooth around the filling
Large fillings in back teeth weaken the remaining tooth walls. Cracks in the tooth itself are one of the more common reasons we recommend stepping up from a filling to an onlay or crown. See our information on cracked teeth for more.
Sensitivity that points to the filling
Persistent sensitivity localised to a tooth with an older filling — particularly to cold or pressure — can mean the seal is failing. We assess this in context with bite testing and imaging before recommending replacement.
Loss of contact with the next tooth
A filling that has worn flat at the side can let food pack between the teeth, leading to soreness and decay risk on the neighbour. Rebuilding the contact point is one reason to replace.
Aesthetic reasons
Patients with visible amalgam fillings on premolars or front teeth sometimes want a tooth-coloured replacement. That is a valid reason for replacement — provided we are clear that the underlying filling is otherwise functional. The new restoration should match the rest of the tooth and not weaken what is left.
On this page
When it is reasonable to leave a filling alone
A filling that:
…does not need to be replaced just because it has been there a long time, or just because the material is no longer the current default. This applies to both composite and amalgam fillings. For background on the materials themselves see composite vs amalgam.
Replacement
Why over-replacement matters
Each time a filling is replaced, the cavity tends to grow slightly. Removing the old material and any new decay underneath always takes a small amount of healthy tooth with it. Over decades, this is one of the reasons teeth eventually move from filling to onlay to crown. We aim to slow this cycle by replacing only when there is a clear reason — and by stepping up to an onlay or crown earlier when a tooth is reaching the limit of what a filling can reliably do.
On this page
When a filling is not the right answer anymore
Sometimes the right move is not a new filling but a different restoration:
Replacement
How we plan a replacement
Appointment
What to expect on the day
A filling replacement is similar to a new filling. The area is fully numbed with local anaesthetic, the old filling and any decay are removed, the tooth is shaped, and a new composite restoration is placed and bonded. Most replacements take 30 to 60 minutes. If we find a crack or extensive decay underneath, we will pause and discuss whether to continue with a filling or step up to an onlay or crown.
Appointment
After the appointment
On this page
Who this may suit
This page is useful if you have been told a filling needs replacing and want to understand why, if a filling has chipped or feels different, or if you simply want a measured view before agreeing to multiple replacements at once. We are happy to go through each filling individually and explain our reasoning.
Payment
Health funds and payment
Filling replacements sit under general dental items, with separate item numbers for one, two, three, or more surfaces. We are HICAPS providers and can claim your eligible rebate on the day. The amount you receive depends on your individual policy, your level of cover, and your annual limits — your fund can confirm before your appointment.
FAQs
Replacing old fillings FAQs
How do I know if an old filling needs replacing?
Signs include chips or sharp edges, lingering sensitivity, food packing into a particular spot, or a dark margin you can feel with the tip of your tongue. A clinical exam and X-rays confirm whether replacement is needed.
Should I replace all my amalgam fillings at once?
No. We only recommend replacing fillings that have a clinical reason for replacement. Removing intact, well-sealed fillings just because of their material is not generally beneficial.
Can a small chip in a filling be repaired without replacing the whole thing?
Sometimes. Small chips at the edge can be smoothed or repaired with a small composite addition. Larger losses, or a chip that exposes the underlying tooth, usually need full replacement.
Will my tooth be sensitive after a replacement?
Mild sensitivity for a few days is common, particularly with deeper fillings. It usually settles within one to two weeks. Persistent sensitivity should be reviewed.
What if you find decay or a crack underneath?
We pause and explain what we are seeing. Depending on what we find, the plan may change to an onlay, crown, or root canal. We always discuss the options and the change in cost before continuing.
How long will the new filling last?
There is no fixed lifespan. With good home care, regular check-ups, and avoiding very hard foods on that side, composite fillings typically last many years. We monitor at each check-up.
Can I have white fillings on back teeth that currently have amalgam?
Yes. We routinely place composite restorations on back teeth, including when replacing existing amalgam fillings.
Related pages
Related pages
Need a filling done?
Talk to our team about the right filling for the tooth.
Or phone Sandgate Family Dental on (07) 3269 6252.