What oral disease causes your gums to be inflamed?

Gingivitis..: .. And the more advanced periodontitis. Xerostomia, although not a disease but rather a side effect of other medical problems or medications, can also cause gingival inflammation. Acid reflux and carious lesions are also contributors. Have yourself examined by your local dentist.

Infection, abscess..: All of the followings: 1) gum disease/infection of the gum, 2) dental or periodontal abscess, 3)faulty restoration/open contacts that cause food impaction, 3)malocclusion, 4)open mouth breather, 5)dry mouth syndrome or any oral condition causing dry mouth, 6)lichen planus and other autoimmune diseases, 7)allergic reaction.