This is a question we get asked all the time.
"Are you sure I have a cavity. Because it doesn't hurt."
Well, saying that is like saying, "Why do I need to change my oil when my car is
running just fine?"
Your car may be running fine and you could save yourself $49.99 by not changing your oil.
However, when you engine seizes up your repair bill is now about $4,000 for a new motor.
You didn't end up saving a lot in the end.
Same is true with teeth and cavities.
you could save yourself the small cost of getting a cavity filled but then when it starts to hurt you will need to get a root canal and a crown. That means that your cost, and your discomfort, will be significantly more.
Save yourself the money and the discomfort.
Get your cavities filled when they are small.