Brighter Smiles: Floss First or Brush First?

Tuesday June 04, 2024

I have had a few patients ask recently about the order of oral hygiene activities. Does it matter if you brush or floss first, and should this be done before or after breakfast? Based on available research, it seems opinion matters as much as scientific facts.
A spokesman for the American Dental Association and a professor of restorative dentistry at the University of California, Los Angeles, recommends flossing first. His rationale? Get the unpleasant task out of the way to avoid the temptation to not do it. “Let’s face human nature, if you’re going to skip one, which one will you skip?”
By contrast, a professor of oral health sciences at the University of Washington in Seattle, advises her patients to brush with a fluoride toothpaste, then floss. She says that way your mouth will be awash with fluoride as you are maneuvering the floss.
So, what’s my opinion? I was taught and have always maintained that flossing before brushing is better. The rationale behind this is that plaque and other debris is dislodged during the act of flossing allowing toothpaste and the mechanical action of brushing to better penetrate the different surfaces of the tooth. Does it really matter? I don’t think so.
Have you heard your dental hygienist or dentist tell you to floss to prevent cavities between your teeth? Based on research, the main reason for flossing is not for prevention of cavities. Rather, flossing’s main benefit is stimulation of tissue to reduce gum inflammation known as gingivitis. Gingivitis can lead to more advanced gum disease and things like bad breath. That is why I believe that regular use of a water pik and an electric toothbrush is most ideal.
A review of 12 randomized controlled trials found that people who brushed and flossed regularly had less gum bleeding than the brush-only camp. No surprises there. There have been no studies, that I am aware of, reporting a reduction in cavities from flossing. Of course, these are difficult studies to conduct. There are many factors that contribute to decay occurring between the teeth.
There are also different schools of thought whether to brush and floss before or after breakfast. I don’t know about you, but I cannot eat or drink anything (especially orange juice) after I brush my teeth. So, although you might expect the solution to be brushing after breakfast, there is some risk with that.
If you eat or drink something sugary or acidic—like the fruits, juices, and other breakfast foods many of us eat in the morning— the mouth is in an acidic environment for at least 30 minutes after consumption. These acids weaken tooth enamel, and brushing too soon can cause damage to the enamel. If you know you’re going to eat or drink something very acidic ahead of time, you may want to brush your teeth first.
Alternatively, you can wait 30 minutes after you eat for your saliva to neutralize the pH of your mouth. Or, re-balance your oral pH right away with an alkaline mouth rinse and then brush. In the end, it depends a little on what you eat. Take stock of what you’re eating for breakfast and judge when you should brush based on its sugar or acid content.
Everyone, well… almost everyone, can stand some improvement with their oral hygiene. Many dental problems are completely avoidable with excellent home care, which is in your control. Ask your dentist or hygienist how to improve your home care. Strive for constant improvement.
Dr. St. Clair maintains a private dental practice in Rowley dedicated to health-centered family dentistry. He has a special interest in treating snoring, sleep apnea and TMJ problems. If there are certain topics you would like to see written about or questions you have please email them to him at

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