Try calcium carbonate instead of sodium bicarbonate. Calcium carbonate gets the pH of the mouth much higher than sodium bicarbonate can.

Calcium carbonate can bring your mouth to pH 9.8 which should work quite well.

Sodium bicarbonate can bring your mouth to only pH 8.3 which isn’t very good.

I saw a study that proved that oral lime use alone can cause mouth cancer, so stay away from using lime.