There are more than 500 different species of bacteria living in our mouths, and while most are considered friendly, there are a few types known to increase your risk of developing gingivitis and other forms of periodontal disease, including A. actinomycetemcomitans and P. gingivalis [source: Ciancio]. This injurious bacteria lives on our teeth, in the pockets of our gums and on our tongue. And as it turns out, we're not very good at keeping our bacteria to ourselves, at least when it comes to those closest to us.
While research is still preliminary, studies have found links suggesting that people with periodontal disease pass along the disease-causing bacteria through saliva. Children under the age of 3 years are 26 times more likely to test positive for A. actinomycetemcomitans in their mouths if their mothers test positive for that bacteria. And spouses are no safer from transmission than kids. Multiple studies have found oral bacteria transmission through person-to-person, mouth-to-mouth contact, and one study specifically showed that if one spouse is colonized with A. actinomycetemcomitans and P. gingivalis, that spouse has a 20-to-30 percent likelihood of passing that bacteria on to his or her partner [source: Asikainen].
It's no wonder that periodontal disease, not cavities, is the No. 1 cause of tooth loss among adults in the U.S. [source: American Academy of Periodontology]. The good news, though, is that if you have gingivitis-causing bacteria in your mouth, it doesn't guarantee that you'll develop gum disease. Other factors such as oral hygiene habits, personal habits, health and heredity -- not just bacteria alone -- determine whether or not your gums will become infected.
And if your mouth does become home to P. gingivalis? More good news: Gingivitis is reversible. Because periodontal disease is caused by bacteria, you might want to reach for antibiotics to kill the disease, but treatment most frequently consists of a process called scaling and root planing, two therapies that help control the bacteria and infection and deep clean the gums. Prescription medications such as mouthwashes and gels that contain antibiotics and antimicrobial ingredients may help with long-term disease control, and there are also surgical treatments available for treating persistent or severe disease, including flap surgery (the deepest gum-cleaning therapy) and bone and tissue grafting.