What is gingivitis . Gingivitis is a common gum disease that is caused by inflammation of the gums. It is usually caused by poor oral hygiene, which leads to the buildup of plaque on the teeth and gums. If left untreated, gingivitis can progress to more serious forms of gum disease, such as periodontitis, which can lead to tooth loss and other complications. Gingivitis is caused by the buildup of plaque on teeth and gums. Plaque is a sticky film of bacteria that forms on teeth and gums. If not removed, it can harden into tartar, which can only be removed by a dentist or dental hygienist. Poor Oral Hygiene Poor oral hygiene is the primary cause of gingivitis. Failure to brush and floss regularly, as well as neglecting regular dental check-ups, can lead to the buildup of plaque and tartar.