Healthy gums are firm and pale pink and fit snuggly around teeth. Signs and symptoms of periodontitis can include:

• Swollen or puffy gums
• Bright red, dusky red or purplish gums
• Gums that feel tender when touched
• Gums that bleed easily
• Gums that pull away from your teeth (recede), making your teeth look longer than normal
• New spaces developing between your teeth
• Pus between your teeth and gums
• Bad breath
• Loose teeth
• Painful chewing
• A change in the way your teeth fit together when you bite

There are several different types of periodontitis. The more common types include those below.

• Chronic periodontitis is the most common type, affecting mostly adults, though children can be affected, too. This type is caused by plaque buildup and involves slow deterioration that may improve and get worse over time but causes destruction in the gums and bone and loss of teeth if not treated.
• Aggressive periodontitis usually begins in childhood or early adulthood and affects only a small number of people. It tends to affect families and causes rapid progression of bone and tooth loss if untreated.

Necrotizing periodontal disease is characterized by the death of gum tissue, tooth ligaments and supporting bone caused by lack of blood supply (necrosis), resulting in severe infection. This type generally occurs in people with a suppressed immune system — such as from HIV infection, cancer treatment or other causes — and malnutrition.

In most cases, periodontitis begins with plaque — a sticky film composed mainly of bacteria. If left untreated, here's how plaque can eventually advance to periodontitis:

• Plaque forms on your teeth when starches and sugars in food interact with bacteria normally found in your mouth. Brushing your teeth twice a day and flossing once a day removes plaque, but plaque re-forms quickly.
• Plaque can harden under your gumline into tartar (calculus) if it stays on your teeth. Tartar is more difficult to remove and it's filled with bacteria. The longer plaque and tartar remain on your teeth, the more damage they can do. You can't get rid of tartar by brushing and flossing — you need a professional dental cleaning to remove it.
• Plaque can cause gingivitis, the mildest form of periodontal disease. Gingivitis is irritation and inflammation of the part of your gum around the base of your teeth (gingiva). Gingivitis can be reversed with professional treatment and good home oral care.
• Ongoing gum inflammation can cause periodontitis, eventually causing pockets to develop between your gums and teeth that fill with plaque, tartar and bacteria. In time, these pockets become deeper, filling with more bacteria. If not treated, these deep infections cause a loss of tissue and bone, and ultimately you may lose one or more teeth. Also, ongoing chronic inflammation can put a strain on your immune system.

Factors that can increase your risk of periodontitis include:

• Gingivitis
• Poor oral health habits
• Smoking or chewing tobacco
• Older age
• Hormonal changes, such as those related to pregnancy or menopause
• Substance abuse
• Obesity
• Inadequate nutrition, including vitamin C deficiency
• Genetics
• Certain medications that cause dry mouth or gum changes
• Conditions that cause decreased immunity, such as leukemia, HIV/AIDS and cancer treatment
• Certain diseases, such as diabetes, rheumatoid arthritis and Crohn's disease

Periodontitis can cause tooth loss. And some research suggests that the bacteria responsible for periodontitis can enter your bloodstream through gum tissue, possibly affecting your heart, lungs and other parts of your body. For example, periodontitis may be linked with respiratory disease, rheumatoid arthritis, coronary artery disease or stroke. But more studies are needed to confirm a link.