Hello, The location you mention would have been the site of injection of the local anesthetic, this is the area that a dental nerve block would have been given. It is possible that a localized infection did occur at the site, particularly if you are describing a salty taste in your mouth. The description does not sound like a usual allergic reaction since you had prior dental work on the opposite side and did not notice the similar occurrence. I would recommend that you return to that dentist for an evaluation. My suspicion is that you do indeed have an infection at that site and may need a course of antibiotics. I have seen numerous patients with similar infections after dental procedures and typically they all resolve quite well but do require a course of antibiotics. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. David Girardi, Internal Medicine Specialist