Why would you let it worsen like that?
I know some dental care is expensive, depending on where you live. You can do a lot of good though with a toothpaste like Oral-B Deep Clean and for mouthwash I find tea tree oil in normal alcoholic mouthwash works very well.
Other than that... I'm in the UK so as needed I see the dentist for cleaning.
I've also got some fillings and I do have one crown also because one of my teeth was in a bit of a state. It needed a root canal and then a crown. I left it too long because I was younger and didn't really understand how it worked fully.
So yeah that's most of my dental story, lol