Do old amalgam fillings need to be replaced?

Key points in brief

• Old amalgam fillings usually do not need to be replaced if they fit tightly, there is no decay next to them and the tooth has not cracked. Age and a dark colour on their own do not mean that a filling needs treatment.
• A filling usually needs to be replaced when there is extensive decay at its edge, or when the tooth or the filling itself has cracked. The dentist often repairs smaller defects without removing the whole filling.
• Every replacement makes the cavity bigger, because the dentist removes some healthy tooth together with the old filling. For fillings in good condition, it is therefore enough to have them looked at during routine check-ups.
• If a piece of the tooth or of the filling has broken off, or the tooth hurts when you bite, see a dentist within a few days. If you have swelling or a fever, see a dentist the same day.
• The EU ban on amalgam, in force since 2025, applies to placing new fillings and is meant to reduce the amount of mercury in the environment. According to current knowledge, old fillings in good condition are safe for most people.

What the dentist looks at when assessing an old amalgam filling

The dentist judges an old amalgam filling by whether it fits tightly against the tooth, whether there is decay at its edge, and whether the tooth or the filling itself has cracked. The dentist judges white fillings in the same way, including when it comes to secondary caries and replacing fillings. Secondary caries is decay at the edge of a filling. Amalgam differs from white fillings in three ways: it is dark in colour, it contains mercury, and in the European Union, apart from certain exceptions, new amalgam fillings are no longer placed.

Amalgam is an alloy of mercury with silver, tin and copper, commonly called a silver filling. For decades it was the main material for filling back teeth, which is why many people have fillings that are 20 or 30 years old. There is, however, no age after which a filling is replaced automatically.

Over the years the surface of amalgam turns dull, and small steps appear at its edge. If there is no decay, the dentist usually leaves such a step as it is or only smooths it. What is worrying is a gap into which a thin instrument clearly drops as it is run along the line between the filling and the tooth, or soft tooth tissue at the edge. This is a sign that bacteria may be getting in under the filling.

Decay between the teeth is easier to see on a bitewing X-ray than during an examination. A bitewing is a small X-ray of the back teeth, taken while you bite together. Neither the examination nor the X-ray is reliable on its own, so the dentist combines what the X-ray shows with what they see during the examination. When in doubt, the dentist usually suggests looking at the filling again sooner, rather than drilling straight away.

Old amalgam can be dark, and the tooth around it grey. Over time, metal from the filling stains the surrounding tooth tissue, and the filling itself shows through thin enamel. Such a colour usually does not mean decay if the edge is hard and smooth. If colour alone decided whether to replace a filling, most old amalgam fillings would have to be replaced.

Teeth with large fillings also often have fine lines in the enamel. These lines on their own usually do not need treatment. What is worrying is a short, sharp pain when you bite down, or at the moment you release the pressure, because it may mean a cracked tooth.

At your check-up, you can ask whether the examination and the X-ray show anything at your filling that needs treatment, and whether the tooth is cracked. Also ask what will happen if you leave the filling as it is for now.

When an amalgam filling needs to be replaced, and when a repair is enough

An amalgam filling usually needs to be replaced when there is extensive decay at its edge, when the filling has cracked or is loose, or when the tooth has cracked. With smaller defects, the filling is usually watched, smoothed or partly repaired. The dentist works through a few questions in turn:

1. Is there decay at the edge of the filling, confirmed by the examination and the X-ray? When the decay is in one easy-to-reach spot, the dentist often removes it and fills just that part. Decay around a large part of the filling usually means replacement.
2. Has the filling cracked, chipped or become loose in the tooth? A small chip at the edge can sometimes be repaired. Cracked amalgam across the whole width of the filling, or a filling that moves, usually needs to be replaced.
3. Has the tooth cracked, or has a cusp, that is one of the raised points on the chewing surface, broken off? In that case, instead of a new filling, the dentist often suggests an onlay, which is made in a dental laboratory and bonded to the tooth, or a crown. Both cover the weakened walls of the tooth.
4. Does the tooth hurt when you bite, on its own, or for a long time after something cold? The dentist then looks for decay, a crack or inflammation of the nerve in the tooth, and treats the cause of the pain.
5. Does the filling have a sharp edge or an overhang, that is excess material sticking out beyond the tooth, where food gets caught? Such an edge is usually smoothed and polished without removing the filling.
6. Do you have a confirmed allergy to the components of amalgam, or a change in the lining of your cheek or tongue at the spot that touches the filling? This is rare. If the dentist confirms that the change is linked to the filling, replacing it may help. An allergy is checked with patch tests, that is patches containing allergens that are stuck onto the skin.
7. Is the tooth due to have a crown or a bridge for another reason? In that case, the old filling is removed when the tooth is prepared.

If the answer to every one of these questions is “no”, an old filling usually stays. If the answer to any of questions 1–6 is “yes”, the dentist starts with the smallest procedure that will solve the problem, for example smoothing, repairing part of the filling or replacing just the filling. The dentist suggests an onlay or a crown only when the tooth is weakened.

Studies show that a lot depends on what counts as a reason for treatment. When the appearance of the edge was also taken into account, roughly one in three fillings in back teeth was repaired or replaced. When only decay counted, roughly one in twelve was treated. Over the following few years, the fillings in both cases needed treatment again at a similar rate.

With a large filling, no crack and no pain, it is not known whether an onlay placed in advance will protect the tooth from cracking. The dentist then assesses how many strong walls of the tooth remain and whether you clench or grind your teeth.

What the tooth loses when an amalgam filling is replaced

After every replacement of an amalgam filling, the cavity in the tooth is bigger than before. The dentist has to remove all the old material, and in doing so the drill also takes away a thin layer of healthy tissue around the filling. Tissue removed during a replacement does not grow back.

Each further replacement enlarges the cavity by another layer. Over time a filling becomes a larger filling, then an onlay or a crown. The less of your own tooth remains, the more easily a wall can crack. Drilling in a deep cavity may also irritate the nerve in the tooth. Such a series of replacements may eventually hasten the loss of the tooth, which is why replacing a filling without a clear reason is not without consequences.

A repair saves more of the tooth. The dentist then removes only the damaged part of the filling or the decay at its edge and fills that spot, leaving the rest of the tightly fitting filling in place. In an old amalgam filling, this is usually done today with a white material. A repaired filling - including an amalgam one - may last about as long as a replaced one.

If the colour of a filling in a visible place bothers you, you can ask for the silver filling to be replaced with a white one. Such a replacement also takes away some healthy tooth, and with a large filling it may end with an onlay or a crown instead of a white filling. Before you decide whether to replace amalgam fillings just because of their colour, ask the dentist how big the new cavity will be and what material will be enough to fill it.

How the dentist removes amalgam safely

When a replacement is needed, the dentist removes the amalgam in a way that limits the amount of mercury vapour and metal particles produced during drilling. In a filling, the mercury is bound to the other metals. When a filling is placed or removed, however, more mercury vapour is released for a short time. For this reason, removing a filling in good condition purely out of concern for your health may do more harm than good.

During removal, the dentist usually uses:

• plenty of cooling water, which limits heating of the metal,
• strong suction right next to the tooth, which draws away water, vapour and particles,
• a rubber dam, that is a thin rubber sheet placed over the tooth, which separates it from the rest of the mouth.

The amount of mercury released also depends on how many fillings the dentist removes at once. This is why the dentist may replace several fillings at separate appointments. They usually start with the teeth that have decay or a crack.

The replacement itself is much like having an ordinary filling placed. The dentist numbs the tooth, places the rubber dam and removes the old material. Then they examine the cavity, because only then can they see whether there is decay underneath and whether a crack runs through the tooth. What the dentist puts in place of the amalgam depends on this. A white filling is usually placed at the same appointment. An onlay or a crown usually needs 2 appointments, because it is made in a laboratory - until then, a temporary filling or crown protects the tooth.

What to replace an old amalgam filling with

What to fill the tooth with after the amalgam is removed depends above all on the size of the cavity and on how many strong walls of the tooth remain. For a small or medium-sized cavity, the most common choice is a composite filling, that is a white filling made of resin and hardened with light. When thin, weakened walls remain, an onlay or a crown can be a better solution. This applies especially to teeth that have had root canal treatment.

When the cavity covers only the chewing surface, a white filling usually lasts about as long as amalgam. How long a new filling lasts also depends on how easily you get decay and whether you clench or grind your teeth. If the replacement involves several teeth, the dentist sets the order as part of a treatment plan in restorative dentistry, that is, treating decay and filling cavities in the teeth.

What should you do if you have old amalgam fillings?

If nothing hurts and the dentist sees no decay or cracks at your fillings, leave them in place and show them to the dentist at regular check-ups - just like your other teeth. Replacing a filling in good condition removes healthy tooth tissue, and there is no evidence that it prevents disease. See a dentist within a few days if a filling or a piece of tooth chips off, or if the tooth starts to hurt when you bite. Until the appointment, do not bite hard foods on that side, and keep your tongue and toothbrush away from any sharp edge so as not to irritate the lining of your mouth.

Frequently asked questions

Is amalgam toxic?

According to current knowledge, amalgam fillings in good condition are not linked to chronic diseases in most people. New amalgam fillings are avoided in people with an allergy to its components or with severe kidney disease. In kidney disease, old fillings in good condition are usually left in place, but discuss the decision with your dentist and the doctor who treats your kidney disease. The EU ban from 2025 is meant to protect the environment from mercury.

Is a dark patch on the gum next to a filling dangerous?

A grey-blue patch on the gum or cheek next to an old filling is usually an amalgam tattoo, that is tiny particles of metal that got into the tissue when a filling was placed or removed. Such a patch does not need treatment, but show it to your dentist, because dark patches in the mouth need to be told apart from changes that do need treatment. If it has appeared recently, is growing or is changing shape, do not wait until your check-up.

Does removing amalgam hurt?

Removing an old filling usually does not hurt, because the dentist does it under local anaesthetic, just like placing a new one. During the procedure you mainly feel the vibration of the drill and the cooling water. If anything hurts, say so straight away, because more anaesthetic can be given.

Can amalgam fillings be replaced during pregnancy?

During pregnancy and breastfeeding, amalgam fillings in good condition are not removed in order to prevent disease. Removal briefly increases the amount of mercury vapour released, so the dentist usually postpones a replacement that can wait. Decay, a crack or pain are treated during pregnancy too. When you book the appointment, say that you are pregnant or breastfeeding.

How long can a tooth be sensitive after an old filling is replaced?

Sensitivity to cold and when biting is usually strongest in the first 24 hours after the replacement and eases over the following days. If the tooth starts to hurt on its own, wakes you at night, or the pain after something cold lasts a long time, see your dentist within a few days. Swelling or a fever is a reason to be seen the same day.

What happens in the first few days if decay is found under the amalgam?

The dentist removes the decay and usually places a new filling straight away. If the decay reached close to the nerve in the tooth, the dentist may first place a dressing (a temporary filling containing a medicine). For a few days after the procedure the tooth can be sensitive to cold and pressure. Tell your dentist within a few days about pain that comes on by itself, wakes you at night or gets worse. If you have swelling or a fever, see a dentist the same day.

Read more:

• Aesthetic and Restorative Dentistry in Warsaw
• Composite filling, ceramic inlay or crown: what decides is how much tooth is left
• Secondary caries: when an old filling really needs replacing, and when it can be left alone
• A cracked tooth — when it can be saved and when it must be removed
• Tooth decay stages: when can it be stopped without drilling

Content and liability disclaimer

This article is informational and educational in nature and does not constitute medical advice, a diagnosis or a therapeutic recommendation — it does not replace a consultation with a specialist. If you are experiencing symptoms, have doubts or are facing a decision about treatment, consult a dentist. The methods described and the data cited are general in nature. The results of scientific studies relate to populations, not to an individual patient. The course and outcome of therapy depend on the individual clinical situation and may vary between patients. No information contained in this article constitutes a guarantee of result. The content has been prepared with due care, based on publicly available medical knowledge and the scientific publications indicated in the Sources section. We do not advise taking or refraining from any health-related action solely on the basis of the content of this article, without prior consultation with a doctor.

Sources

Source 1

Links https://doi.org/10.1007/s00784-022-04814-1 │ https://pubmed.ncbi.nlm.nih.gov/36504246/

Description Hickel R, Mesinger S, Opdam N, Loomans B, Frankenberger R, Cadenaro M, Burgess J, Peschke A, Heintze SD, Kühnisch J. „Revised FDI criteria for evaluating direct and indirect dental restorations-recommendations for its clinical use, interpretation, and reporting.” Clinical Oral Investigations. 2023;27(6):2573-2592.

Source 2

Links https://doi.org/10.1007/s00784-020-03431-0 │ https://pubmed.ncbi.nlm.nih.gov/32643090/

Description Schwendicke F, Splieth CH, Bottenberg P, Breschi L, Campus G, Doméjean S, Ekstrand K, Giacaman RA, Haak R, Hannig M, Hickel R, Juric H, Lussi A, Machiulskiene V, Manton D, Jablonski-Momeni A, Opdam N, Paris S, Santamaria R, Tassery H, Zandona A, Zero D, Zimmer S, Banerjee A. „How to intervene in the caries process in adults: proximal and secondary caries? An EFCD-ORCA-DGZ expert Delphi consensus statement.” Clinical Oral Investigations. 2020;24(9):3315-3321.

Source 3

Links https://doi.org/10.1177/00220345241247773 │ https://pubmed.ncbi.nlm.nih.gov/38752325/

Description Digmayer Romero VH, Signori C, Uehara JLS, Montagner AF, van de Sande FH, Maydana GS, Chaves ET, Schwendicke F, CaCIA Collaborative Group, Braga MM, Huysmans MC, Mendes FM, Cenci MS. „Diagnostic Strategies for Restorations Management: A 70-Month RCT.” Journal of Dental Research. 2024;103(7):697-704.

Source 4

Links https://doi.org/10.1186/s12903-022-02112-6 │ https://pubmed.ncbi.nlm.nih.gov/35300657/

Description Signori C, CaCIA collaborative group, Uehara JLS, Romero VHD, Moro BLP, Braga MM, Mendes FM, Cenci MS. „Comparison of two clinical approaches based on visual criteria for secondary caries assessments and treatment decisions in permanent posterior teeth.” BMC Oral Health. 2022;22(1):77.

Source 5

Links https://doi.org/10.1111/idj.12552 │ https://pubmed.ncbi.nlm.nih.gov/31985815/

Description FDI World Dental Federation. „Repair of restorations: Adopted by the General Assembly: September 2019, San Francisco, United States of America.” International Dental Journal. 2020;70(1):7-8.

Source 6

Links https://doi.org/10.1007/s00784-022-04459-0 │ https://pubmed.ncbi.nlm.nih.gov/35362754/

Description Mendes LT, Pedrotti D, Casagrande L, Lenzi TL. „Risk of failure of repaired versus replaced defective direct restorations in permanent teeth: a systematic review and meta-analysis.” Clinical Oral Investigations. 2022;26(7):4917-4927.

Source 7

Links https://doi.org/10.1111/iej.14186 │ https://pubmed.ncbi.nlm.nih.gov/39840523/

Description Patel S, Teng PH, Liao WC, Davis MC, Fidler A, Haupt F, Fabiani C, Zapata RO, Bose R. „Position statement on longitudinal cracks and fractures of teeth.” International Endodontic Journal. 2025;58(3):379-390.

Source 8

Links https://doi.org/10.1016/j.identj.2021.11.007 │ https://pubmed.ncbi.nlm.nih.gov/35074199/

Description FDI World Dental Federation. „Amalgam (Part 2): Safe Use and Phase Down of Dental Amalgam: Adopted by the FDI General Assembly: 27-29 September 2021, Sydney, Australia.” International Dental Journal. 2022;72(1):12-13.

Source 9

Links https://doi.org/10.2341/19-295-C │ https://pubmed.ncbi.nlm.nih.gov/36098547/

Description Rodrigues NS, de Souza LC, Cunha DA, Souza NO, Silva PGB, Santiago SL, Loguercio AD, Silikas N, Saboia VPA. „Postoperative Sensitivity of Composite Replacement of Amalgam Restoration: A Randomized Clinical Trial.” Operative Dentistry. 2022;47(5):481-491.

Source 10

Links https://doi.org/10.1016/j.identj.2023.11.004 │ https://pubmed.ncbi.nlm.nih.gov/38071154/

Description Schmalz G, Schwendicke F, Hickel R, Platt JA. „Alternative Direct Restorative Materials for Dental Amalgam: A Concise Review Based on an FDI Policy Statement.” International Dental Journal. 2024;74(4):661-668.