What are the stages of tooth decay?
Cavities are usually divided into four stages. Decay moves inward in this order: the outer enamel (the hardest outer layer), the dentin beneath it, the pulp that contains the nerve and blood vessels, and then the root tip. “It doesn't hurt — do I really need a filling?” is the question I hear most often in the treatment room, and the answer depends on which layer the decay has reached.
| Stage | Extent | Common symptoms | Treatment |
|---|---|---|---|
| Stage 1 | Enamel | Almost none | Monitor with fluoride and care, or a composite filling if the surface is soft |
| Stage 2 | Dentin | Brief sensitivity to cold or sweet things, or sometimes none | Composite filling, or an inlay if the area is large |
| Stage 3 | Pulp (nerve) | Lingering pain after a stimulus, spontaneous throbbing, pain at night | Root canal treatment followed by a crown |
| Stage 4 | Root tip | Pain when chewing, gum swelling or pus; the pain may also disappear | Root canal treatment or extraction |
Can I leave an early cavity untreated?
An early cavity that stays within the enamel can be monitored without drilling. When a cavity has stopped progressing, not drilling preserves more of the natural tooth. However, monitoring only makes sense together with fluoride toothpaste, floss and interdental brushes, and habits that cut down on sugar, and a fluoride application is added if needed.
If the surface is soft or the decay is progressing quickly, I treat it early even if it is at an early stage. The same goes for cavities on the surfaces where teeth touch each other. They are hard to clean and the enamel there is thin, so they progress quickly. I wrote more about this in Cavities between teeth.
If it doesn't hurt, does that mean it's not a cavity?
No. Enamel has no nerves, so early cavities don't hurt, and dentin cavities often have no symptoms either, depending on where they are. If you leave it because it isn't sensitive, it can lead to pulpitis.
Many people think only black spots are cavities. An opaque white spot on a dried tooth surface can also be an early cavity. On the other hand, when the nerve dies completely, a severe toothache can disappear — it hasn't healed; the sensation has simply been cut off. If a pimple-like bump with an opening appears on your gum, come in right away even if it doesn't hurt.
How does treatment differ by stage?
The earlier a cavity is found, the smaller and shorter the treatment. Stages 1–2 are often finished the same day with a composite filling that fills only the affected spot. From stage 3 on, root canal treatment is needed, and in most cases it continues to a crown, so the number of visits and the cost increase considerably.
Food does not fill a cavity. Cutting down on sugar only slows the progression; it cannot reverse a cavity that has already formed.
That is why I recommend regular checkups — to reduce those moments when I think, “If only you had come in a little earlier.” If something seems to hurt, coming in even one day sooner keeps the treatment smaller. Teeth are less sensitive than you might think, so by the time you feel pain, the decay has often already moved one stage deeper.
How we do it at Wonjin Dental
I decide when to treat by looking at which layer the decay has reached, whether the surface is soft, and whether it is between teeth. I don't treat “early” and “doesn't hurt” as meaning the same thing. When I suggest monitoring, we set the date of the next checkup together. Monitoring is not neglect.
Frequently asked questions
Do early cavities heal on their own?
A cavity that has formed a hole does not fill itself in. A very early lesion within the enamel can sometimes stop progressing with fluoride and care, but it needs to be confirmed with regular checkups.
Does fluoride toothpaste help prevent cavities?
Yes. Fluoride strengthens enamel and slows the progression of early cavities. To keep the effect, it's better not to rinse with water too many times after brushing.
How often should I get checked for cavities?
I usually recommend every 6 months to 1 year. For people who get cavities often or whose teeth are tightly packed, I set a shorter interval, including X-rays. People who often drink sweet beverages or whose mouths are often dry also tend to be at higher risk for cavities, so a shorter interval is better for them too.
Can a treated tooth get a cavity again?
Yes, it can. The border between the filling material and the tooth is a spot where bacteria easily remain, so a new cavity can form in that gap. Clean the border carefully and have it checked regularly.
