Replacing old fillings: when it is needed and when it is not

Many fillings last for years, and every replacement removes a little more healthy tooth. That is why decisions about replacing old fillings are made after an examination, based on each filling’s condition rather than its age or colour.

Replacing old fillings: signs it is time

Fillings most often fail in one of two ways: the material breaks, or new decay develops at the edges (ADA). Your dentist will usually suggest a replacement if they find:

• a broken or cracked filling, or one with a piece missing
• a gap between the filling and the tooth that traps food
• new decay under the filling or at its edge, sometimes visible only on an X-ray
• a worn filling that has lost its shape or no longer touches the neighbouring tooth
• a cracked tooth around a large old filling

When changing an old filling is your choice

If a filling is sound but you do not like how it looks (for example, a white filling on a front tooth that has darkened), replacing it is a cosmetic choice rather than a medical need. Ask your dentist about the options and how much healthy tooth would be lost (Oral Health Foundation). For bigger cosmetic changes, see our guide to veneers, composite bonding and crowns.

When an old filling is better left alone

If an old filling is intact, has no gaps at the edges and the tooth does not hurt, it can usually just be monitored at your regular check-ups.

Each replacement means drilling out the old filling, usually along with a little healthy tooth tissue. The cavity gets bigger and the tooth weaker. Unnecessary drilling can also irritate the nerve inside the tooth (Oral Health Foundation).

This reflects ‘Save the tooth’, the motto of the Dr. Milanovski practice: keeping your natural teeth comes first.

Repairing a filling instead of replacing it

When only a small part of a filling is damaged, such as a chipped edge, that part can sometimes be repaired with new composite, without removing the whole filling.

The FDI World Dental Federation says the evidence supports repairing defective fillings rather than replacing them, where clinically appropriate (FDI). A repair keeps more of your tooth but is not always possible: if the decay under the filling is more widespread, or the filling is loose, it needs replacing in full.

Amalgam (silver) fillings: should you have them removed?

Amalgam is a silver-coloured material made of mercury combined with silver, tin and copper. Amalgam fillings are often called silver or metal fillings, and sometimes mercury fillings.

The US Food and Drug Administration (FDA) and the UK’s Oral Health Foundation agree: an intact amalgam filling in good condition should not be removed just because it contains mercury. Removal temporarily increases exposure to mercury vapour and takes away healthy tooth tissue (FDA).

The FDA says low levels of mercury vapour are generally not harmful to most people, but it advises some groups to avoid new amalgam fillings where possible:

• women who are pregnant, planning a pregnancy or breastfeeding
• children, especially those under 6
• people with neurological conditions (such as multiple sclerosis) or impaired kidney function
• people allergic to mercury or other components of amalgam

For these groups, the FDA recommends materials without mercury, such as composite or glass ionomer cement. The Oral Health Foundation does not consider amalgam a significant risk to the general population, and advises replacing an existing filling only if there is a confirmed allergy or a clear clinical need (Oral Health Foundation).

Since 1 January 2025, amalgam may not be used for dental treatment in the European Union unless the dentist considers it strictly necessary for the patient (European Parliament). The rule covers new fillings and does not require existing ones to be removed. North Macedonia is not an EU member state.

What can an old filling be replaced with?

The choice depends on how much of the tooth is left, where the tooth is and how hard you bite. You and your dentist choose the material together.

A white (composite) filling, also called a tooth-coloured filling, is bonded to the tooth in a shade close to your natural teeth. White fillings once did not last as long as amalgam, but modern materials are much stronger and in many cases last about as long (Oral Health Foundation). Large white fillings in back teeth, and those in people at high risk of decay, still fail more often (ADA). Read more about white fillings and composite bonding.

Inlays and onlays are fillings made outside the mouth, usually over two visits. They are used when a cavity is too large for an ordinary filling but a crown (cap) is not yet needed. If decay has reached the nerve, root canal treatment is needed first, and sometimes the tooth cannot be saved.

How a filling is replaced, step by step

1. Examination and X-ray. The filling and its edges are checked, with an X-ray if needed.
2. Local anaesthetic, if needed. The area is numbed and you stay awake.
3. Removing the old filling and decay. Only what is necessary is removed. Where decay is deep, it is removed selectively to protect the nerve.
4. Preparing the tooth. The tooth is kept dry and an adhesive (bonding agent) is applied to hold the new filling.
5. Building up the new filling. Composite is applied in thin layers, each hardened with a blue light.
6. Checking your bite and polishing. Your dentist checks how your teeth meet, then polishes the filling.

One filling is usually replaced in a single visit; several may take a few appointments. For white fillings, the Dr. Milanovski practice uses 3M ESPE Filtek Z550, a nano-hybrid composite.

What to expect afterwards

Avoid eating until the numbness wears off, so you do not bite your cheek or tongue. Mild sensitivity to hot and cold is common and usually settles within one to two weeks. Paracetamol or ibuprofen may help; follow the instructions on the packet.

If your bite feels high, call us for a small adjustment. After a deep filling, the nerve sometimes becomes inflamed; the tooth may then need root canal treatment or, in some cases, extraction (Cleveland Clinic).

How much does it cost to replace a filling?

The cost depends on the size of the filling and how many surfaces of the tooth it covers, which tooth it is, the material, whether an X-ray and anaesthetic are needed, and how many teeth are treated. After the examination, and before any treatment starts, you receive a written plan with your options and the cost. See our prices page for more.

If you are insured, you can register with Dr Kiril Milanovski as your chosen dentist (izbran stomatolog) under the Health Insurance Fund (FZO), because the practice has a contract with the Fund.

How long does a new filling last, and how can you protect it?

No filling lasts for ever. In a study cited by the American Dental Association (ADA), about eight in ten white fillings in back teeth were still functioning after 10 years (ADA). How long yours lasts depends on its size and position, your bite and chewing habits, your risk of decay and how well you look after your teeth (Oral Health Foundation).

• Brush twice a day with fluoride toothpaste and clean between your teeth.
• Keep sweet foods and sugary drinks to mealtimes rather than throughout the day.
• Do not bite your nails or pens, or open packets with your teeth.
• If you clench or grind your teeth, tell your dentist.
• Go for regular check-ups, where small problems can be picked up early.

When to see a dentist

Book an appointment if you notice:

• a filling that has broken, come loose or fallen out
• a sharp edge or hole you can feel with your tongue
• pain when biting, or sensitivity to hot or cold that does not go away
• a dark line or discolouration around a filling

If you have lost a filling, avoid chewing on that side and book an appointment soon. For toothache or a broken filling, you can ask for a same-day appointment during opening hours, when one is available. While you wait, read what to do about toothache.

Replacing old fillings: your questions answered

Not sure whether your old filling needs replacing? Book an appointment and we will go through the options together.