Periodontal Abscesses almost always happen in people who have existing periodontal disease that is advanced enough to have resulted in some loss of bone around the root of the tooth.  An area in which bone is missing around a tooth root is called a periodontal pocket,  and a periodontal pocket can be very hard to clean.  The bacteria living in the pocket change over time and more destructive species move in.  Byproducts of the bacteria cause more bone to dissolve.

Periodontal infection can be present without pain, but, if there is pus forming, and is it trapped under the gum,  the pain can be quite bad.  The infection can spread and seem like it is radiating into your ear or under your lower jaw and down into your neck.  It may be hard to open your mouth because of the inflammation and swelling.

An oral exam will reveal any swelling, whether any teeth hurt when tapped, whether suspect teeth are loose.   An X-ray will possibly show the presence of periodontal pocketing.  The depth of pockets  (in millimeters) will be checked with a periodontal probe.  Sometimes, an obvious bubble-type swelling is seen around the tooth.  When this area is probed,  pus and blood can drain out.  This is common in periodontal abscesses.  A patient may notice that if he or she pushes on the gum around the tooth, it hurts.

If your problem seems to be a periodontal abscess,  the dentist will probably place you on an antibiotic (amoxicillin 500 mg 4 times a day for 10 days.  Erythromycin will be used if you are allergic to the penicillin family). The gum area will be cleaned out a bit, debris removed and the pus allowed to drain.  You should start to feel better relatively quickly but it is important to realize that there was an underlying periodontal problem that needs to be addressed.

Left: A Periodontal (Gum) Abscess:   Here, you can see the periodontal pocket, or missing bone around the root.  Debris and bacteria collect in the pocket which is beneath the gum line and hard to clean.  Eventually, the infection spreads and the tooth becomes sore to the touch. There may be facial swelling and throbbing pain as the pus becomes trapped and pressure builds.  The area is red and inflamed and bleeds easily.