@lucybunyard I don't know how your body will react to metals in a dental crown. I had crowns with base metals including one that was titanium, and I only know that my body reacted because when they were removed and my body became metal free, my asthma improved immediately with less phlegm in my lungs, and when I fractured my ankle and had to accept titanium fixation hardware, my asthma became worse again immediately with increased phlegm and within 6 months I had other symptoms of chronic hives, pain and skin discoloration. Then when I had the titanium hardware removed, my health improved immediately when I became metal free again. In my case, getting dental crowns and implants made of Zirconia was a big improvement for my health, and my biological dentist said that they were bio-compatible because of not containing metals. Zirconia is a kind of ceramic. While I understand that your dental crown didn't fit correctly from your description, that may not be the cause of dry mouth and oral symptoms, and I am not a medical specialist so I have no expert opinion about your situation.

I reread your original post, and having Sjogren's Syndrome does affect the body causing dry mouth. Do you think that this may explain your symptoms? I don't have this, so I don't have relatable experience. Have you discussed this possibility with your physician? Prescription medications also may have side effects that cause dry mouth.

I didn't know what material your crown was made from, and since you didn't tell me it was Zirconia, I thought you were describing metal based crowns. I know decisions are difficult when you don't have a lot of exact information. My personal experience was that removing dental work with metal and replacing it with Zirconia was a big improvement. I know you expressed urgency in resolving the situation, but rushing into an anxious decision may be a mistake. You should take advice from your consulting medical and dental providers and seek other opinions if you are unsure of their recommendations. I have not found any reference to Zirconia reacting with acids in the mouth. Everything I read indicates it is stable.

Here is medical literature about Zirconia in dental restorations.

"The Zirconia Ceramic: Strengths and Weaknesses"
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4026739/
You may be interested in this literature about how metals in dental restorations react with the acids of the mouth. I found these quotes in the following literature:
"patients with autoimmune diseases often have hypersensitivity to metals. "

"the most common clinical manifestations of adverse effects associated with dental alloys include allergic reactions, mouth burning, and white oral lesions. Regarding hypersensitivity, it may be diagnosed by the use of skin or blood tests. Nevertheless, the diagnosis of oral galvanism remains a complicated issue since, to date, there is no standardized method for the determination of intra-oral electric currents."

If you look at section 3, there are detailed descriptions of issues caused by reactions to metals with photographs of oral lesions. This is worth your time.

"Minimization of Adverse Effects Associated with Dental Alloys"
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9658402/
Here is a link to Mayo information about Sjogren's.
https://www.mayoclinic.org/diseases-conditions/sjogrens-syndrome/symptoms-causes/syc-20353216
I hope this helps with your decision.

Jennifer