Gingivitis is a common and mild form of gum disease (periodontal disease) that causes irritation, redness and swelling (inflammation) of your gums. Because gingivitis can be mild, you may not be aware that you have the condition. But it's important to take gingivitis seriously and treat it promptly. Gingivitis can lead to much more serious gum disease (periodontitis) and eventual tooth loss. The most common cause of gingivitis is poor oral hygiene. Good oral health habits, such as brushing at least twice a day, flossing daily and getting regular dental checkups, can help prevent gingivitis.