| Gum Disease Information The American Academy of Periodontology's description of periodontal (gum) diseases, including gingivitis and periodontitis. http://www.perio.org/ |
| Gum Disease Information Bureau Advice on diagnosis and treatment of gum disease, gingivitis, periodontitis and mouth ulcers. http://www.gumdiseaseinfo.co.uk/ |
| MayoClinic.com: Gingivitis Symptoms, causes, treatment, and prevention. http://www.mayoclinic.com/ |
| Periodontal Health - OHSU Overview, symptom and treatment information from Oregon Health and Sciences University. http://www.ohsuhealth.com/ |