Opinions on if I need a root canal or how to deal with dentist over the issue.
You don't need root canals, or dental implants. You need to educate yourself about both in relation to your health. Can I assume that the fillings you had done were amalgam? Another health hazard.
If you ask a dentist if you need a root canal you are asking for trouble in most cases because many of them will do whatever brings in the most money.
If you don't want teeth problems the best way is to take care of what you have. Flossing, brushing gums, and teeth at least twice a day. Using products that don't contain flouride, and other chemicals. Don't believe the crap on the commercials. Read the ingredients.