In an article published by Natural News, this is how Tony Isaacs recommends using black seed oil to fight a toothache.
Sunday, March 18, 2012 by: Tony Isaacs
Take one teaspoon of blackseed oil (Nigella sativa) and 1/2 cup of vinegar and boil. Cool and then use as a mouth rinse to reduce inflammation and infection. Rinse every couple of hours until the pain and/or swelling is gone.
Learn more: http://www.naturalnews.com/035284_toothaches_tooth_infections_natural_remedie...
Additionally, I will apply black seed oil directly to the tooth or gum. You can also gargle black seed with warm water, or swish it around the mouth for several minutes like a mouthwash.