Updated: Oct 14
While some cavities require immediate treatment, there are some that can be delayed for at least a year before evaluating it again. Therefore, how long you can wait to fill a cavity would depend on the stage of tooth decay that it is presently at.
How long you can leave a cavity untreated at each stage of tooth decay:
How long can you delay treatment on a cavity that is still in the enamel?
Tooth decay that is contained within the enamel only can be left untreated for up to a year before require re-evaluation. The re-evaluation requires a clinical exam by a dentist and also x-rays to compare whether or not the cavity has grown bigger or not.
The two reasons why enamel decay can be left untreated for up to a year is because cavities grow very slowly in the enamel and they can also be reversed.
Slow growth in enamel. Decay progresses very slowly while they're in the enamel because your tooth enamel is the hardest substance in the body. In fact, the enamel is actually harder than bone because it contains a high percentage of hydroxyapatite. Due to the hardness, it takes a very long time for bacteria make a hole through your tooth to reach the next layer which is the dentin.
Reversible. You may be surprised but cavities in the enamel can not only be stopped but also reversed. There are two ingredients within toothpaste which have the capability to reverse cavities and they are fluoride and hydroxyapatite. Since the cavity can possibly be reversed, it doesn't hurt to wait before you treat it with a cavity filling.
It is due to these two factors which allow cavities in the enamel to grow slowly, thus allowing you to delay treatment for so long. Nonetheless, just because you can delay it, it doesn't mean that you should permit it.
What does enamel decay look like?
It basically looks like a brown or black spot on your tooth and it may or may not be cavitated. Here is what a cavity that is contained within the enamel looks like on an x-ray:
The enamel decay shows up as a dark spot within the enamel on the x-ray. The enamel is very radiopaque or white on the x-ray while the cavity is radiolucent or dark.
Since tooth decay that is contained solely in the enamel grows slowly and can be reversed, it does not necessarily require treatment. However, you should try your best to maintain good oral hygiene and use a cavity reversing toothpaste so that you can possibly stop it.
Good oral hygiene. Brush for at least twice a day for 2 minutes each. Floss before you go to bed and try to use a mouthwash.
Cavity reversing toothpaste. Use either a fluoride toothpaste or a hydroxyapatite one because those are the only two that have cavity reversing potential. All other types of toothpastes do not have the same effect such as Xylitol and charcoal.
Minimize sugar intake. Make sure you try to decrease the amount of sugars and carbohydrates you eat. The reason is because bacteria require sugar in order to form cavities!
Nonetheless, there are times where your dentist may recommend that you do have the cavities treated such as if you're at a high risk for cavities. For instance, if you've been getting a new cavity every time you come in for your 6 month check up, you may want to have it treated. Based on your dental history, it shows that you're more cavity prone and that the chances for you to reverse them could be pretty low.
Alternatively, if you were going to move out of the country and won't be back for a few years, you may want to get all of your treatment completed before you leave. Medical tourism isn't exactly endorsed by all healthcare professionals!
How long can you delay treatment on a cavity that is in the dentin?
Tooth decay that has reached the dentin but has yet to reach the pulp should be treated as promptly as possible such as within a few weeks at most. The reason for the shortened time line as compared to enamel decay is because cavities grow faster in dentin and they're also irreversible.
Grow faster in dentin. Unfortunately the dentin isn't as hard as the enamel because it contains significantly less hydroxyapatite, which is a mineral that gives teeth its hardness. This means that cavities that are located in the dentin will grow exponentially faster. Due to this faster rate of growth, it is not advisable to let the decay grow.
Irreversible. Cavities that are located solely in the enamel can be reversed but once it reaches the dentin, it becomes irreversible. This means even if you brush your teeth twenty times a day with a fluoride toothpaste, you will not be able to stop nor reverse the decay. Therefore, it makes very little sense to delay treatment on a condition that is past the point of no return.
What does dentin decay look like?
It looks like a brown or black spot but it tends to be larger in size than decay that is simply in the enamel. The decay may or may not be cavitated.
Here is what it a cavity in the dentin looks like on an x-ray:
Cavities in the dentin look similar to those in the enamel except for the fact that it just looks bigger. This x-ray shows a medium sized cavity in the dentin of the premolar. You can see a big dark circle on the left hand side of the tooth. The darkness has extended beyond the enamel layer.
Cavities in the dentin should be treated as promptly as possible since they're irreversible and the treatment of choice is a cavity filling.
What to expect for a cavity filling:
Apply numbing gel. This is also referred to as the pre-numbing gel, which is used to prepare the area for the injection.
Administered local anesthetic injection. This is the actual tooth numbing step and the medication of choice is usually Lidocaine.
Remove decay by drilling. The decayed parts of your tooth must be drilled out because that is the only way to clean out a cavity. Your dentist does this with his drill that spins very quickly and squirts out water. This means that you're unable treat a cavity at home since you do not have access to a drill.
Restore tooth with filling. Once the cavity is cleaned out, your dentist will apply the conditioner, primer, and bonding. After that he'll fill it in with a tooth colored composite filling.
Adjust the bite. Next your dentist needs to check your bite by adjusting it until it feels even. Make sure your bite feels normal before you leave the office because an uneven bite or high filling can be very painful to chew on! That would require you to return and have the bite adjusted again so you might as well do it correctly the first time.
Polish the filling. The last step is to polish everything so that it looks good and it feels smooth. Rough or sharp edges on a filling can injure your tongue.
You're all done! Now that you're done, make sure you stay on top of your oral hygiene and minimize the sugar intake so you don't get another cavity.
How long can you delay treatment on a cavity that is in the pulp?
Tooth decay which has progressed beyond the dentin will arrive at the pulp. Cavities in the pulp need to be treated immediately or as soon as possible. The reason is because the pulp contains a lot of nerves which have the potential to cause you extreme tooth pain. The toothache can be so bad that it'll prevent you from sleeping.
Here are some symptoms of a cavity that is in the pulp:
Throbbing pain that comes and goes
Unbearable or extreme tooth pain
Constant dull ache
Can feel like it is pulsing
Can cause you a headache
Prevents you from sleeping
Chewing on it makes it hurt
You definitely do not want to wait on treating pulp decay because when it is left untreated, it can continue to progress. In fact, after the cavity reaches the pulp, it will start to progress through the stages of a tooth abscess.
You'll notice a pimple start to form on your gums first and then it'll eventually lead to facial swelling. If you still choose to ignore the facial swelling, it could spread to your throat and close off your ability to breath. That is what we would consider a life threatening situation so don't wait for treatment.
What does pulp decay look like?
Cavities that are in the pulp tend to be very large in size and they may or may not cause a big hole in your tooth. If it does cause a big hole, it'll look very black inside almost as if it is a black hole. Food will also get lodged inside of the hole, which only exacerbates the pain.
Here is what the decay looks like on an x-ray:
That upper molar in the middle where is the cavity into the pulp looks like. It is literally a big black mass inside of the tooth. You can actually tell that large piece of the tooth is missing.
A cavity filling is insufficient as treatment for decay that has reached the pulp of the tooth. The reason is because tooth fillings only treat cavities. If the nerve of the tooth becomes infected with decay, the nerve will need to be treated as well as the decayed parts of the tooth. The only way to treat an infected nerve is by performing a root canal.
A root canal procedure removes the infected nerve from the tooth. The only person who can do that is your dentist and what that means is that if you're having tooth nerve pain, there isn't a single home remedy in the world that will cure you.
Here is what to expect for a root canal procedure:
Apply numbing gel. Once again the pre-numbing gel is used to prepare the area for the injection.
Administered local anesthetic injection. This is the actual tooth numbing step and the medication of choice is usually Lidocaine. If the tooth is difficult to numb, it may re quire Articaine, which is a more powerful anesthetic.
Remove decay by drilling. The decayed parts of your tooth must be drilled out because that is the only way to clean out a cavity.
Remove the nerve. Your dentist will separate the nerve from your tooth with rotary instruments. The concept of taking out the nerve is similar to unclogging a drain.
Fill in the canal. After the nerve is cleaned out, your dentist will need to fill in the canal with a root canal filling material. Then a temporary goes on top to protect the tooth.
After the root canal is finished, treatment for the tooth is still not complete because you also need a core buildup and a dental crown. Once the nerve is removed, the blood supply also gets removed along with it. This means that over time the tooth will start to get very brittle since it is no longer receiving nutrients via the blood supply. If you happen to bite into something very hard the wrong way, you can fracture the tooth.
In order to prevent your tooth from racking, it is advisable to put a dental crown over it to protect it. In case you were wondering, this is a lot of additional procedures and it will cost you a lot more than a simple filling. This means that if you delay treating a cavity, it could end up costing you a lot more money!
To summarize, how long you can leave a cavity untreated would depend on the stage of tooth decay that it is in. If the cavity is only in the enamel, you can delay it for up to a year before needing it to be re-evaluated again. However, if the decay is in the dentin or the pulp it would require treatment as soon as possible since they've reached the point of no return.
Decay that is in the dentin and pulp cannot be reversed and that explains the difference between why enamel decay can be left untreated longer. This is why it is important to go in for your 6 month dental check ups because you can catch cavities early while they're still in the enamel. If you get lucky and happen to do that, you have a chance at reversing them with a fluoride or hydroxyapatite toothpaste.
So, what are you waiting for? Go schedule your dental check up!
Author: Written by Dr David Chen, a long island city dentist in NY.