Almost half of U.S. adults 30 and older have gum disease, according to the Centers for Disease Control and Prevention (CDC), and about 8 percent have what's considered to be severe gum disease, per July 2018 research in ​The Journal of the American Dental Association​, a phase associated with tooth loss that may be linked with other health conditions like diabetes.

Early gum disease — also called periodontal disease — can be easily treated and even reversed. Once it reaches a certain point, though, the disease can only be managed, not cured, per the American Dental Association (ADA).

Here, learn what causes gum disease, how it's treated and how to prevent it.

Gum disease, aka periodontal disease or periodontitis, is a bacterial infection that starts in the soft tissue of your gums. If it's not properly treated, it can destroy your gum tissue over time and lead to a host of oral health problems.

Some 700 species of bacteria and other microbes reside naturally in our mouths, according to the National Institutes of Health (NIH). They thrive on sugar from the foods we eat and form plaque, a sticky, invisible film that builds up on your teeth, explains Deborah Foyle, DDS, clinical associate professor in the department of periodontics at Texas A&M School of Dentistry in Dallas.

If not removed — with brushing, flossing and regular dental check-ups — that plaque hardens into tartar, which can trigger a wave of tooth and gum decay.

There are two main types of periodontal disease:

Some experts also refer to four gum disease stages: "initial," "early," "established" and "advanced." This is based on a seminal March 1976 scientific review in ​Laboratory Investigation​.

While research is still ongoing, chronic periodontitis has been linked to a higher risk of diabetes, lung disease, heart disease, rheumatoid arthritis and stroke.

Several factors can contribute to the buildup of plaque and tartar that leads to gum disease. Chief among them is smoking or using other forms of tobacco.

According to the CDC, smokers are twice as likely to develop gum disease as nonsmokers. Not only do smokers produce more plaque, the habit also reduces the amount of oxygen available in the bloodstream to help damaged gums heal, per the Oral Health Foundation. The lack of bloodflow may also mask early symptoms of bleeding, according to UIC.

Early stage gum disease (gingivitis) may have no warning signs at all, according to the American Academy of Periodontology.

When gum disease symptoms do appear, they can include:

Gum disease is usually diagnosed by a dentist. They will take your medical history, ask about symptoms and find out if you have any risk factors such as diabetes, smoking or a family history of the condition.

The dentist may also measure the space between your gums and teeth with a small ruler called a probe. This will indicate if you have any pockets where bacteria may be breeding. A normal pocket is usually 1 to 3 millimeters deep. Anything deeper than 4 millimeters may signal periodontitis, according to the Mayo Clinic.

X-rays to check for bone loss may also be taken. If you have periodontitis, your dentist may stage and grade the severity. They may also refer you to a periodontist, a specialist who treats gum disease, says Alice G. Boghosian, DDS, a dentist in Glenview, Illinois and consumer advisor for the ADA.

Only your dentist can tell for sure if you have gum disease, which is why it's so important to get regular check-ups (even if you have dental anxiety). Gum disease treatment depends on how far the disease has progressed. Early stage gum disease (gingivitis) is easily cured with regular brushing and flossing combined with check-ups.

Nonsurgical treatments to treat more advanced periodontitis include:

Surgical treatments for periodontitis may include:

No matter which treatment you receive, you will still need to take care of your teeth at home and take steps to reduce your risk factors, like quitting smoking, reducing alcohol and stress and limiting high-sugar foods and drinks.

"The best prevention for gum disease is to visit the dentist regularly, brush twice a day and floss once a day," Dr. Boghosian says.

The ADA recommends brushing twice a day for two minutes each time. Why two minutes? "A quick brush is not going to remove the plaque," notes Dr. Foyle.

Find a toothbrush with rounded bristles that is relatively soft so it doesn't cause your gums to further recede, she adds. Remember to replace it every three to four months.

The best toothpaste for gum disease (and cavities) is one that contains fluoride.

A toothbrush can only reach the top, front and back of the teeth. It can't go between teeth.

"In order to effectively remove plaque from between teeth, you have to use dental floss or an interdental cleaner [like a pick or "water flosser"] of some sort," says Dr. Boghosian. "That's critical."

Do this once a day.

For best results, floss before you brush. This loosens up the food particles and other gunk between your teeth so they can be swept away by your toothbrush.

Check-ups should take place every six to 12 months, recommends the Mayo Clinic. Not only will this detect cavities and gum disease, it can also provide a window into other aspects of your health.

"Oral health is connected to overall systemic health," says Dr. Boghosian.

In one case, a patient's abnormally bright, magenta gums led to a diagnosis of and treatment for liver disease. Another of Dr. Boghosian's patients was unable to control his blood sugar levels until his periodontitis was treated.

There's no clear role for either mouthwash or hydrogen peroxide in maintaining oral health. Hydrogen peroxide may help gingivitis by oxygenating (destroying) bacteria and plaque, according to one May-June 2016 study in the ​Journal of International Society of Preventive & Community Dentistry​. "It works a bit, but it's not a cure," says Dr. Foyle.

Mouthwash may rinse away some bacteria and make your mouth feel cleaner, she adds.

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Gum disease is caused when plaque composed of bacteria builds up on your teeth. If it's not removed, it can destroy both your gums and bones.

Early gum disease is called gingivitis and can be cured with good oral hygiene. More advanced gum disease or periodontitis can be treated but not cured.

The best way to prevent gum disease is to brush and floss regularly and make sure you keep appointments with your dentist.

See a dentist if you have bleeding, swollen or painful gums. Seek emergency help if your teeth start falling out or if you notice sores or lumps in or around your mouth.