Another treatment using salt requires 2 tbsp. of salt dissolved in 6 oz. of warm water. Rinse the mouth with this solution three to four times a day to draw fluid out of the sore, helping it heal.A third suggestion from Health 911 requires 1/4 tsp. salt, 1/2 tsp. goldenseal powder and 1 cup warm water.Rinse the mouth several times a day. A pinch of powdered goldenseal applied to the sore may help as well.nother treatment using salt requires 2 tbsp. of salt dissolved in 6 oz. of warm water. Rinse the mouth with this solution three to four times a day to draw fluid out of the sore, helping it heal.