Noticing a tooth cavity yourself may be shocking to you. If you see it incidentally, most of the time it is not causing any pain. Otherwise, the pain will direct you to look for it intentionally. Then questions may pop up in the head: can I leave the cavity since it is not painful? How long can I leave it?
Any trained dental personal will tell you to fill the tooth cavity as soon as it is found and do not wait for anything wrong to happen. It is practically and ethically right to say that. However, there may be some circumstances where you could not make yourself to the doorstep of the dental clinic, due to either physical or emotional restraints.
But really, how long can you leave the cavity on the tooth untreated before it is non-salvageable? I am sure no one will answer this question because the progression of tooth decay is quite unpredictable. So, in giving a trustable answer, I looked across some scientific studies and wrote this article.
One of the best guides for providing the answer will be to find out how fast does tooth decay progress.
How Fast Does Tooth Decay Progress?
As I have mentioned, the progression of tooth decay is quite unpredictable. Fortunately, many scientific studies looked at a huge amount of teeth and showed us collectively how fast tooth decay spread through the tooth layer. I present how fast tooth decay progresses through the enamel and the dentin separately in the subtopics below.
Tooth Decay Through Enamel
- Combining the results of a few studies, for permanent teeth (adult teeth), it takes around 2 to 5 years for decay to start at the enamel surface to reach the dentin. [2,3,4]
- For the young adults’ teeth, it may take a shorter time for decay to progress through enamel because the minerals in young adult teeth are less than older adult teeth. [5]
- For primary teeth (first set of teeth) in children, the progression of decay through enamel is even faster, which is around one year. [2,3]
- If the cavity is already present, it is faster for decay to progress further. [6] It may be because the cavity serves as a reservoir for food to accumulate and bacteria to grow.
Tooth Decay Through Dentin
- When the decay has reached dentin, it seems to progress two times faster than it is in enamel. [6]
- However, to my best knowledge, there is no study I could find which tells us how long dental decay takes to reach the pulp (which contain nerves and blood vessel).
How Long Can You Leave A Tooth Cavity Untreated
Facts from the scientific evidence
From the results, we see that cavity does not develop in weeks, and it can take up to 5 years before decay reaches your pulp nerve from the outer tooth surface.
Furthermore, if a cavity is already present, it may be a lot faster for decay to reach the pulp and destroy the tooth. This may be because of the cavity serving as a reservoir for food accumulation and shelter for bacteria.
It may take days, weeks, or months depending on the activity of the decay. No trial study has been done on this, otherwise it will raise ethical issues.
How long before I should do something?
So, when you see a cavity on the tooth, it means that it has already worsened from just a surface decay. It would have started with only small initial decay on the enamel. You may not feel any discomfort when it is still in enamel.
However, most of the time, you may start to feel some sensitivity when it reaches the dentin. This is the warning sign given by your tooth to provoke you to do something about it before it progresses further.
It is impossible to know when the teeth will start hurting (discussed below). So even if the cavity does not hurt, you should get it filled by a dentist as soon as possible. This is because the food will accumulate in the cavity and become a good nutrient supply to the bacteria. Bacteria will start to grow more and produce acids that dissolve the tooth, causing more decay in the tooth.
How Long Before a Tooth Cavity Starts to Hurt?
Why the tooth hurt?
A tooth will start to hurt when the bacteria have breached through the enamel and reached the dentin. The toxins released by bacteria stimulate the tooth and cause inflammation in the tooth pulp. This results in a toothache. This is why sometimes you have a toothache even though the cavity is not visible, because the cavity may be too tiny to be noticed.
If you have a cavity and it is not causing any pain, it may be that your tooth has defended against the bacteria well enough. In this case, the tooth lays down more dentin inside the pulp, acting as a barrier for the bacteria and their toxins.
However, this defense mechanism can reach its limit. If the bacteria in the cavity bacteria continue to strive and dissolve more tooth structures with the acids, the cavity will become larger. Eventually, it will progress until it reaches the pulp. At this stage, there will be a lot of inflammation inside the pulp. The person will feel extreme pain because of the intense inflammation.
When will the cavity start to hurt?
Unfortunately, it can never be known when a cavity will start to cause discomfort. It depends on how fast the tooth decay progresses and how well the tooth responds with its defense mechanism. This explains why toothache is intermittent.
If the tooth decay progresses fast, and the tooth could not defend well, then the cavity may start to hurt at an early stage. If the tooth decay goes slowly, and the tooth could protect well by layering more dentin inside, the tooth may not hurt.
There may be a situation where a tooth has a cavity but it is not any pain. This may mean that the bacteria have spread into the pulp and cause the tooth to lose its vitality. The tooth is dead, and hence the person would not feel anything. You can refer to this article which talks about root canal infection by clicking here.
Summary
In a nutshell, for a permanent tooth, it may take up to 5 years for tooth decay to spread through the enamel to dentin. Cavity in the dentin may progress twice as fast to reach to pulp and cause the tooth to lose its vitality.
Even though this sounds like a long time, it is highly variable and unpredictable. For example, decay can progress rapidly if it has already caused a cavity.
Therefore, when you notice a cavity on the tooth, you should start scheduling a dental appointment. Even though it may not cause you pain, you cannot be sure at which stage the progression is. If it is left untreated, the cavity will progress into a larger size. The consequences are that more treatments will be needed to save the tooth, and the tooth will have to be removed if it is non-salvageable. It is advisable to have the decay removed and the cavity filled as soon as possible.
Reference
- Arrow P. Incidence and progression of approximal carious lesions among school children in Western Australia. Australian Dental Journal. 2007;52(3):216-226.
- Craig G, Powell K, Cooper M. Caries progression in primary molars: 24-month results from a minimal treatment programme. Community Dentistry and Oral Epidemiology. 1981;9(6):260-265.
- Peyron M, Matsson L, Birkhed D. Progression of approximal caries in primary molars and the effect of Duraphat treatment. European Journal of Oral Sciences. 1992;100(6):314-318.
- Shwartz M, Gröndahl H, Pliskin J, Boffa J. A longitudinal analysis from bite-wing radiographs of the rate of progression of approximal carious lesions through human dental enamel. Archives of Oral Biology. 1984;29(7):529-536.
- Zamir T, Fisher D, Fishel D, Sharav Y. A longitudinal radiographic study of the rate of spread of human approximal dental caries. Archives of Oral Biology. 1976;21(9):523-526.
- Meyer-Lueckel H, Paris S. When and How to Intervene in the Caries Process. Operative Dentistry. 2016;41(S7):S35-S47.
