Scared my teeth are going to fall out and my gums are not well. What are my options if that happens?

What exactly are dental implants? I was in the middle of a $15k treatment plan before leaving for college. My dentist said I needed to go get cleanings every 3mo because I produce a lot of saliva. I had lost a little bone she said, but that was my first experience at the dentist. Almost ever, I had only gone 2x as a kid. I had a better job before leaving for college. I'm so scared they are going to fall out and my gums are not well. What are my options if that happens. I'm so scared.