Mike - You're going in the right direction looking for natural healing techniques to get your mouth back in shape - but you may be overdoing it.
I wouldn't use anything as strong as Dr Bronners in my mouth for toothpaste - it can't be good for your gums. Ditto on the tea trea oil for any extended use.
And I don't know much about the benefits of grapeseed oil. But regular oil pulling with coconut oil WILL help disinfect your mouth and also absorb in your root canal cavitations. Adding a few drops of oregano oil from time to time greatly helps with infections also (though you don't want to do that constantly either(.
There's just nothing better you can do to maintain your oral health than oil pulling. And with all your root canals and other issues, steady oil pulling will make a huge difference in the long term.
With your broken teeth and other problems you'll probably need a dentist but don't be talked into any more root canals.
Don't declare war on your mouth and gums by using lots of harsh substances (like bronners tea tree oil etc). Start out oil pulling twice a day with coconut, flax seed, sesame oil etc. And after a few days add a few drops of oregano oil for a week or two and then stop it for another week or two.
It may not be the total solution, but it will help immensely over time. Good luck!