If you were to continue using the fluoride rinsefor a long period of time (measured in years, not weeks or months) the pain would eventually go away completely. Because by then the natural tooth will probably have been replaced by a very expensive post and crown.
But then if your drinking water is fluoridated the result will likely be the same whether or not you continue using the rinse.
Why would long-term use of fluoride lead to a post and crown?
I will not use the fluoride rinse for more than 10 days.
I do not know what effect the fluoride in drinking water
is, and I am not sure when I started drinking that water,
but most of my root canals took place 15 to 20 years ago,
and nothing much has given me problem since then.