Fillings are among the most common dental restorations in the world — and most people who have had any tooth decay will have at least one. But fillings are not permanent. Like any dental restoration, they have a lifespan, and at some point they will need to be replaced. Knowing when a filling has reached the end of its useful life — and why replacement matters — is an important part of maintaining your oral health through general dentistry appointments.
Many patients are surprised to learn that an old filling can itself become a source of dental problems. A filling that has cracked, broken down, or begun to pull away from the surrounding tooth creates exactly the conditions that led to decay in the first place — a space where bacteria can become trapped and multiply. Understanding the signs of a failing filling, and acting before problems develop, can save considerably more complex treatment down the line.
How Long Do Fillings Last?
The lifespan of a filling depends on several factors: the material used, the location of the filling (whether it is on a front or back tooth, and on a chewing surface), the size of the filling, and the patient’s oral hygiene and habits (including whether they grind their teeth). As a rough guide:
- Amalgam (silver) fillings: Typically 10–15 years or more, though some last considerably longer
- Composite (white) fillings: Typically 5–10 years, though again this varies considerably
- Gold fillings and inlays: Often 15–25+ years — among the most durable restorations available
- Ceramic inlays and onlays: Similar durability to gold, often 10–20+ years
These are averages, not guarantees. A composite filling in a front tooth used only for aesthetics may outlast one placed in a heavy back molar that endures significant biting forces. Your dentist monitors the condition of all existing restorations at each check-up.
Signs That a Filling May Need Replacing
In many cases, your dentist will identify a failing filling before you are aware of any symptoms. This is one of the important reasons why regular check-ups are so valuable — problems with restorations can often be caught before they cause discomfort or secondary decay. However, there are also signs that patients themselves may notice:
Pain or Sensitivity
Sensitivity to hot or cold foods and drinks, or pain when biting down, can indicate that a filling has cracked or that decay has developed at the margin of the filling (where it meets the tooth). Persistent toothache should always be investigated — do not assume it will resolve on its own.
A Visible Crack or Chip
If you can see or feel with your tongue that a filling has chipped or cracked, it is important to have it assessed promptly. A cracked filling is vulnerable to further fracture and allows bacteria access to the underlying tooth.
The Filling Feels Rough or Different
Fillings should feel smooth to the tongue. A surface that feels rough, sharp, or uneven may indicate wear or surface breakdown. If your bite feels different — as if the tooth is meeting the opposing tooth in a new way — this may also indicate a change in the filling’s shape or position.
Discolouration Around the Filling Margin
Dark discolouration at or around the edge of a white filling may indicate secondary decay — new decay forming underneath or around the filling. This requires prompt assessment.
The Filling Falls Out
Fillings can occasionally fall out — particularly if they were small or if the surrounding tooth has been weakened. A lost filling leaves the tooth exposed and vulnerable; contact your dentist promptly to have it replaced.
Why Replacing a Failing Filling Matters
A filling that is still in place but has begun to break down at its margins creates a micro-gap between the filling and the tooth. Saliva and bacteria can enter this gap, but saliva cannot flush it out effectively, and a toothbrush cannot reach it. Decay forms in this protected environment and progresses — often without causing any symptoms — until it has penetrated significantly into the tooth structure.
When this secondary decay is caught early, the old filling can be removed and a new one placed with minimal additional tooth preparation. When it is caught late — after it has reached the pulp — root canal treatment or even extraction may be necessary. Timely replacement of a failing filling is almost always significantly simpler and cheaper than the treatment required after secondary decay has progressed.
Amalgam Fillings: To Replace or Not?
Many patients have old amalgam (silver-grey) fillings placed in previous decades and wonder whether they should replace them — either because of concerns about the appearance or because of questions about mercury content. This is worth understanding carefully.
Dental amalgam has been used safely for over 150 years and, according to NHS information on dental fillings, the evidence on amalgam safety is reassuring. The mercury in amalgam is bound to other metals in a stable compound, and the small amounts released during normal use are at levels far below those considered harmful.
That said, if an amalgam filling is showing signs of wear, cracking, or secondary decay, replacement is clinically indicated regardless of the material choice. In this case, many patients choose to replace with a white composite or ceramic filling, which can be aesthetically superior. Removing a serviceable amalgam filling purely for cosmetic reasons is not generally recommended, as the process of removal releases more mercury vapour than ongoing use and requires additional healthy tooth structure to be removed.
Filling Replacement: What the Procedure Involves
Replacing a filling is straightforward in most cases. The area is numbed with local anaesthetic, the old filling is removed using a dental drill, the tooth is examined for any secondary decay (which is removed if present), and a new filling is placed. With composite (tooth-coloured) fillings, the material is layered and cured using a special light, then shaped and polished. The whole procedure typically takes 30–60 minutes per tooth.
In cases where significant tooth structure has been lost — either due to secondary decay, an enlarged old filling, or a cracked tooth — a crown, inlay, or onlay may be recommended rather than a simple filling. These restorations offer greater strength and longevity where a tooth has been substantially weakened.
Filling Material Comparison
| Material | Appearance | Typical Lifespan | Best For |
|---|---|---|---|
| Amalgam | Silver-grey | 10–15+ years | Large back tooth restorations (NHS) |
| Composite resin | Tooth-coloured | 5–10 years | Front teeth and visible areas |
| Ceramic inlay/onlay | Tooth-coloured | 10–20+ years | Large back teeth, high durability |
| Gold inlay/onlay | Gold | 15–25+ years | Longevity-focused cases |
Aftercare for New Fillings
After a filling is placed, you may experience some sensitivity to temperature and pressure for a few days. This usually settles without any treatment. If sensitivity persists beyond two weeks, or if the bite feels uneven, contact your dentist. Composite fillings can also stain over time with heavy consumption of tea, coffee, red wine, or tobacco — good home hygiene and regular professional cleaning help maintain their appearance.
Monitoring Your Existing Fillings
The most effective way to ensure your fillings are in good condition is through regular dental check-ups. Your dentist will examine all existing restorations at each visit, take X-rays where appropriate to check for secondary decay, and advise you if any filling is approaching the point where replacement is advisable — ideally before it causes symptoms or requires more extensive treatment.
At Tarbert Dental Surgery, we take a proactive approach to monitoring existing dental work and will always discuss the options available to you clearly and without pressure. If you have concerns about an old filling, or if it has been a while since your last check-up, we would love to see you. Give our team a call on 01880 820387 and we will arrange a convenient appointment.