Gingivitis is the inflammation of the gums caused by plaque, and is the earliest form of gum disease. The bacteria in the plaque irritate the gums making them bleed, and they become red and swollen. You may notice this sometimes when you brush or floss your teeth. Usually there is no discomfort from gingivitis, so you may not be aware you have it.
If the Gingivitis is not treated, the inflammation can work its way down under the gum towards the bone and tissues which are the main supporting structures of the tooth. This causes a deepened space down the side of the tooth called a periodontal pocket. As these pockets get deeper the supporting structures of the tooth are destroyed. Over time this will cause teeth to become loose, resulting in tooth loss. This is termed as Periodontal (gum) disease.