In June, the U.S. government released the latest dietary guidelines, which lacked a recommendation dating back to 1979 — they no longer include advice to floss every day.

But before you throw out the white thread and celebrate the extra time in your day, it’s important to understand why the government stopped giving advice on flossing, and why your dentist may still tell you it’s necessary.

Government recommendations require evidence-based research, and when a reporter pressed the government for research showing that flossing prevents gum disease, they couldn’t produce definitive studies. Some dentists say this lack of research is because it would not be ethical or practical to conduct randomized clinical trials involving people who floss and those who don’t. The possible benefits of flossing — and the potential drawbacks of not flossing — may not be evident for many years. Also, people sometimes fib about their flossing habits, leaving researchers in the dark about faithful flossing.

Even after the government dropped the recommendation, many dentists say they see evidence from the patients in their dental chairs that flossing works. And the American Dental Association emphasizes that a lack of scientific evidence is not the same as a lack of effectiveness when it comes to flossing. These flossing fans say it rids teeth of plaque that can lead to gum problems. More than 500 different species of bacteria live in plaque, and they can contribute to long-term dental disease if they remain in close contact with teeth and gums.

So don’t throw away that tiny piece of string quite yet. Instead, schedule time to talk to your dentist and determine what’s best for your teeth.