If the problem is from childhood, there is a chance that the permanent teeth were decayed due to milk teeth.
Next Steps
you can-
1. consult your dentist. Get the active cavities filled ASAP so that they dont turn into RCTs, the ones that can not be restored should be Root Canal Treated. Missing ones if any should be replaced
2. get a full mouth deep cleaning done
3. Ask your dentist to demonstrate to you, the correct brushing technique and flossing technique for you.
4. Cut down on Sweet, Sticky foods like candies.
5. Use a Tongue Scraper and Mouthwash.
warm salt water rinses done atleast twice a day are the best natural mouthwash there can be.
6. Make sure you brush every night before going to bed.
7. Ask your dentist to do preventive procedures like "Sealing Deep Pits" and "Flouride Application"
8. Check for signs of dryness of mouth, if any, increase your water intake, and make sure you dont breathe through your mouth
Health Tips
Tips - You can
1. Ask your dentist to prescribe an Anti-Cavity Toothpaste rich in Fluoride
2. You can include
Calcium-Rich foods to your Diet, and if required ask your physician to prescribe dietary supplements