Hi: I have a lump in the back of my mouth around the next to last tooth. This is between the gum and cheek. The raised area is below the visible tooth area. When it first showed up I bought a better Water Pik and it went away and stayed away for months. It has now showed up again many months latter. It is only remotely sore, but the tooth isn't sore at all. I had a cavity in the tooth 2 years ago, and did not like the dentist. If you think there is a relation between the two and think it needs attention more than a newer Water Pik, then I will search for a new Dentist. Thank you