Some parts of this article are taken directly from our Tooth Decay Masterclass.
Dental fillings are used to fill a tooth after a cavity (tooth decay) has been removed. Every filling has its estimated lifespan, but you can affect this in many ways (mostly by shortening it), and this is why in this article we will comprehensively describe all the important aspects of fillings durability and lifespan.
1. Types of fillings
These days there are three most common types of dental fillings or restorations, each having a different estimated lifespan:
- Composite resins (so-called white fillings), longevity studies: ,  – they are made from mix of acrylic and ceramic resins and make your tooth look natural so it’s really hard to tell which part is a filling and which part is your natural tooth. On average these fillings last around 7 years. If correctly placed their lifespan (time before they fall out or are still in place but need replacement) should be between 5 and 20 years. In most cases, you will get exactly this type of filling.
- Amalgams (silver/mercury fillings), longevity studies: ,  – these fillings are less expensive than composites but are less and less popular as they are suitable only for posterior teeth due to their dark color. They are more durable than composites with average lifespan often above 15-20 years, but amalgams do not adhere to the tooth structure, which is why they need more aggressive drilling before they are placed. Mercury amalgam fillings also pose a risk of toxicity, which for some may be a concern. Still, due to their antibacterial properties, they don’t get recurrent decay on the margins as much as composite resins.
- Ceramic restoration restorations (crowns, inlays, onlays) – these are used for larger restorations, as they usually require more than one visit to be placed and are most expensive type of restoration. Ceramic fillings are milled in a dental lab to fit a patient’s tooth and then are cemented on it by a dentist. Thanks to the good mechanical properties of zirconium, which they are made of, they can last up to 20 years but are not suitable for any kind of filling.
2. Early detection
There is a simple rule of thumb when it comes to estimating how long will your filling last (given that we compare fillings made using the same material): the bigger it is, the shorter it will last (in other words filling’s size is inversely correlated with its longevity). This is why prevention and early detection of decay are crucial:
- if decay is caught really early you’ll be able to arrest it (stop it from progressing) with fluoride and simply improving your oral hygiene
- if decay is caught before penetrating dentine (inner layer of a tooth) it may be treated with ICON infiltration (still without drilling the tooth!)
- if decay has penetrated into the dentine and the tooth needs to be drilled smaller filling always has a better prognosis than a large one
So how do you detect decay early? It’s super simple: by visiting your dentist every 6 months and taking bitewing radiographs every 6 to 12 months (depending on how prone to cavities you are). This will let you detect both new and recurrent decay on the two most affected surfaces that is proximal caries (between teeth) and occlusal caries (on top of the crown, below the enamel). Please note that routine checkups without x-rays are not effective, as your dentist won’t be able to see secondary caries – decay that’s beneath a filling until it’s very, very large! This could give you a false feeling that your teeth are fine (because the dentist said so) when in fact decay is growing deeper and deeper, just can be seen with a naked eye yet.
3. Quality of dental work – find a good dentist
It is extremely important that your fillings are well made. While it’s hard to compare dentists’ skills there certainly are some important traits to look for!
First of all take a look if your dentist:
- is using rubber dam isolation when placing a filling (this is crucial for good adhesion) – if your dentist is using cotton rolls instead of rubber dam you should either change dentist or opt for an amalgam filling instead of composite resin, which requires perfectly dry conditions to settle properly (amalgam does not). We need to emphasize here, that other tips from this section may be beneficial, it is absolutely crucial to have your composites placed with rubber dam isolation.
- is using an operating microscope or at least wearing a dental loupe (magnifiers, binoculars) – this helps them see their operating field better – while this is not critical it’s helpful and in some cases can affect the quality of your fillings. There are multiple YouTube videos of dentists explaining why dental work done with magnification has better outcomes, let us simply quote part of one
- is working according to the minimally invasive principle, which means is not drilling any parts of the tooth more than absolutely necessary – some old school dentists drill more than they really have to make better conditions for a filling, with modern adhesives this is not necessary, nor recommended – why lose healthy dentine and enamel? (this is irreversible)
- is using modern techniques to clean well tooth before filling it (sandblasting and ultrasounds)
- dental filling is one of the most basic dental tasks – if you are being treated in a large clinic make sure that you are not being treated by an entry-level dentist (usually a young dentist straight after school that does only fillings
- is working with a dental assistant – this helps the dentist in some difficult situations, when it’s handy to hold a matrix by a third hand, but also helps the workflow and lets the dentist focus better on his job.
- after your filling is placed we recommend that you don’t eat anything hard or sticky that day, and do not eat anything at all for at least 2 hours
After having used the microscope for about 5 years I can think of so many examples of subtle mistakes that I wouldn’t have caught if it wasn’t for the enhanced visualization and magnification of the microscope. Little things, just like matrix bands not being properly sealed on the gingival floor of a proximal box, especially in those deeper proximal boxes, it’s amazing how it looks sealed at 2.5x magnification, but as soon as you turn it up to a little bit higher you can really see there is a gap there and that fluid is creeping in while you’re trying to fill that tooth.
– Michael the Dentist on YouTube
We need to explain here that all these kinds of mistakes can actually make a difference if your filling is going to fail prematurely or not (in other words: if it’s going to last 15 years with no problems or fall out after just 1 year or so).
Pictured below is classic dentistry that should be avoided: no rubber dam isolation, no microscope magnification, no dental assistant nearby.
4. Adequate types of restorations – direct vs indirect, composite vs ceramic
As you may already know the larger the filling the shorter it will last. Now it is important to understand that your restoration may be done in different ways and using different materials.
Firstly there are two types of restorations:
– direct restorations (in most cases made from composite resins)
– indirect restorations – inlays, onlays, overlays, and crowns (made from ceramics or composite resins)
Then there are two main types of materials:
– composite resins
– all forms of ceramic restorations
In some cases of large restorations, it is advised to have indirect restorations placed over your direct composite restorations. This is because of the problem with large chewing forces placed on large composite direct restorations – in order to distribute chewing forces more evenly it’s advised to cover whole chewing surface of the tooth. Yes, that involves removing even more healthy tooth structure, but it will prevent your tooth from breaking apart when you chew on something really hard! Be aware that some dentists do not place indirect restorations and do not inform patients it’s advised in their case!
Consult your dentist if your filling can stay the way it was built right after tooth decay was removed or if it should be upgraded with indirect composite or ceramics on top of it to extend its strength, durability, and lifespan. Often this can double or even triple your filling’s lifespan but dentists frequently omit to discuss this problem with their patients after a filling is placed.
To sum up: In case of large fillings on both sides of the tooth indirect composite will protect your tooth better from breaking than direct composite. Indirect ceramics will be even better as ceramics are more durable than composite resings.
5. Already have fillings? Have them checked and reviewed!
The most common reason for premature failure of a filling is when you get a recurrent decay under or at a margin of the filling. Remember that a filling is only a repair of damage to your tooth, and placing a filling does not stop or limit the decay processes in your mouth – this should be addressed by improving your oral hygiene, diet, and habits!
If you already have fillings it is necessary that you use X-rays to check if your fillings do not leak, meaning no new decay has appeared below them (on their margins). This is important because this kind of decay can’t be seen without x-rays, and once it actually appears and can be seen it will surely be too late to save this tooth.
Another important thing is to check if your fillings were made correctly and do not have any overhangs which may cause increased plaque accumulation.
During your routine checkups, your dentist can also check if your fillings are not leaking but probing them with a dental explorer. If you are interested in consulting the quality of your fillings on an x-ray use our contact form as we’d love to help!
If you have a panoramic radiograph of our teeth analyze it carefully, especially look at which teeth you have fillings and how big are they. Carefully notice which of them are big and may be touching the gums – these places are most prone to recurrent decay, which is why you need to pay extra attention and floss these spots perfectly (more than one time a day is recommended). Every time you clean your teeth give extra attention to your vulnerable spots! Also if you have large fillings on one side of your mouth and you have to chew something hard try to use the other side for this task.
7. Diet and habits
There are some dietary mistakes that can decrease the lifespan of your fillings. Avoid them and you will avoid their premature failure:
- limit your daily sugar intake, stay away from sticky snacks with starches – this obviously causes tooth decay, and recurrent decay is the main reason why fillings fail
- try not to bite down on hard foods or ice as this can cause mechanical damage to your fillings
- avoid acidic drinks like sodas and juices that can negatively affect margin of your fillings
- avoid very sticky foods that may pull the filling from a tooth
- you should not use your teeth for anything else than eating, biting on a pen or nails may also damage your fillings
- clenching or grinding your teeth is another reason why your fillings may fail prematurely – if you have such tendencies wear a nightguard when sleeping
- when flossing, if your floss is stuck between the teeth or under the overhang of a restoration try to remove it carefully, do not pull hard
This article is complete and was published on September 16, 2021, and last updated on June 7, 2023.