Do You Have Your Dogs' Teeth Cleaned?

We have a dog who had fish breath a few years ago . We got her teeth cleaned when she was getting spayed so she was already asleep. Her breath was great afterwards.
Now we have to decide if it’s time again; they put them to sleep and this concerns me. How do you know if or when it’s time and are you nervous about it? Or do you let their teeth just “go.” A bad tooth, not extracted, can lead to blood poisoning or heart attack, right?