Would having a root canal done make Parkinson's symptoms worse?

It seems logical to me. It's possible that there's not a scientific explanation, but this procedure is a trauma for your husband (and you, I might add). Trauma of any kind can kick in latent symptoms or make symptoms worse. You may want to talk with his neurologist and see if there's anything to make this easier.
Take care,
Carol

I have suggested coconut oil for Alzheimers, but it seems that it is supposed to work on Parkinsons too. 3 tablespoons daily mixed in yogurt or pudding. I've heard from one friend that it works wonders on her mother.

I'm not sure, but I would certainly ask his physician about the changes you are seeing in him.

I do know that anesthesia or injuries cause permanent decline in my husband with Lewy Body Dementia..Lewy Body is somehow linked to parkinsons, I believe

Perhaps the most famous case of severe complications from dental surgery is the one on actor Peter Falk (of the "Colombo" detective series). He went from an intellectually sharp man, to a man with severe Alzheimer's within weeks of the surgery.
Root canals involve mercury. Mercury poisoning is known to damage the nervous system.

Just to be safe, I would ask the dentist if he or she uses mercury. And either ask him or her not to use it, or find another dentist who doesn't.

Root canals do not involve mercury. I'm a dental hygienist so I wanted to correct that statement. Mercury is found in a small amount in the alloy of metals used in amalgam (metal) fillings. If mercury caused Parkinson's there would be scads more people with it..

My husband has had PD for 18 years. Anytime he is under stress for an reason his symptoms worsen for a week or so.

I have Parkinson's, i do not feel pain, i do not feel temperature, i do not know i am getting hot in the summer, i do not feel cold in the winter. I am an electrical engineer.
I have to be very careful about touching wires. I could be touching a live wire and getting electrocuted and not feel it. The only way i know something is wrong is my ears start ringing.
My advice to you is to get the fecal metal test. look for mercury and other heavy metal in you poop. it is a non-invasive test, they don't enter your body.

May you have Peace and Long life

I don't think any dentists use mercury anymore. But They couldn't get into the nerve last week so we have to go back next week so they can try again.