Bad knees? Blame your mouth.

In a new study in the Journal of Clinical Rheumatology, researchers found traces of gum bacteria in the knees and hips of patients suffering from rheumatoid arthritis. In two cases, the bacteria in the mouth and around the knee were nearly identical.

Didn’t know there was a connection? Turns out poor gum hygiene can cause bacteria in your mouth to break down the barriers to your blood stream and allow it to circulate to joints that are inflamed from arthritis, says study author Nabil Bissada, D.D.S, a chairman of periodontics at the Case Western School of Dental Medicine. The result: more pain and swelling around the joints, or a wearing-away of the bone. Ouch!

Healthy gums are typically salmon-pink or slightly darker, but if they’re red and swollen or bleed after you brush them, it may signal early gum disease, says Kenneth Young, D.D.S., the Men’s Health dentistry advisor.

Dr. Young advises seeing your dentist at least twice a year, especially if you have bleeding gums. But there’s good news: Gum disease is reversible—and preventable. Here’s how to keep your mouth clean and pain-free. (Want the latest, greatest medical advice delivered straight to your inbox? Sign up for our free Daily Dose newsletter.)

Floss First
Sure, it's kind of like rinsing off a plate before putting it in the dishwasher, but before you brush your teeth, tear off a string off floss and get to work. Here's why: “You’re getting a lot of debris away from the teeth, so that leaves a cleaner area where fluoride can reach,” Dr. Young says. As for which floss to use, go with whatever type you find easiest to slip between your teeth. A recent study in the Journal of Periodontology compared different kinds of flosses, including unwaxed, woven, and shred-resistant, and found almost no difference in their ease of use or overall effectiveness. Once you can’t see remnants of your last meal, start brushing.

Choose Electric
Time is money, but these are minutes you can’t afford to waste. Dr. Young recommends using an electric toothbrush and, twice a day, setting a timer for two minutes. (Most brushes have built-in timers.) Divide your mouth into sections (upper left, front, upper right; same with the lowers), and hold your brush at a 45-degree angle as you move in a circular motion. Even better, the vibrations from the brush will automatically hit your gums. (For more tips on how to impress your dentist, learn The Better Way to Brush Your Teeth.)

Brush Your Gums
Bacteria can get trapped under the gum line where you can’t see, and just brushing your teeth won’t reach it. So Dr. Young suggests brushing onto the gum about a quarter of an inch from the top of the tooth. “It toughens the gum up a little bit so you’re not as tender and likely to bleed,” he says.

If you liked this story, you'll love: