Re: why people usually go to the dentist when it is too late to do anything?

An interesting question.

I don't think that "going to the dentist too late" is a universal phenomenon - for example, I happen to be very pro-active when taking care of my teeth - but the frequent campaigns by dental associations would indicate that not all of the population shares this attitude!

One of the biggets reasons people seem to defer care is lack of access to a dentist, either because there are none nearby or because of cost. Public health services have been slow to take up dentistry as a medical expense, so there are large gaps in availability.

Sometimes people are afraid of going to the dentist, especially older folks who have had experience with older techniques and procedures that were, quite frankly, less sophisticated and more painful than current methods. And even now, a visit to te dentist can be uncomfortable.

And finally, it's not uncommon for people to ignore discomfort for quite a long time before they do something about it - a problem that is seen with all areas of medicine, not just dentistry.