Should You Floss First or Brush First?

If you've ever wondered whether the order of brushing and flossing matters, the answer is yes — and research actually points toward a clear winner. 

Flossing before brushing appears to be more effective than flossing after, for a specific and logical reason. That said, the most important thing by a wide margin is that both happen at all, every day. For kids and teens especially, building any consistent routine is more valuable than optimizing the order of a routine that isn't happening. 

Here's what the research says, why it matters, and how to build a routine for children that's simple enough to actually stick.

What the Research Says: Floss First, Then Brush

A 2018 study published in the Journal of Periodontology compared two groups — one that flossed before brushing and one that brushed before flossing — and found that flossing first produced better outcomes on two specific measures:

Interdental plaque (the plaque between teeth that only flossing can reach) was reduced more effectively when flossing came first. And fluoride concentration in the interdental spaces — the areas between teeth — was significantly higher when brushing followed flossing rather than preceded it.

The logic behind this makes sense: when you floss first, you loosen and dislodge plaque and food particles from between the teeth. Brushing afterward then sweeps those loosened particles away and deposits fluoride throughout the mouth — including into the now-cleared interdental spaces where it can do the most work. When brushing comes first, the fluoride that's applied tends to get rinsed out during subsequent flossing, and the dislodged interdental debris doesn't get as efficiently cleared.

Why This Matters More for Children Than Adults

Children and teens are at higher cavity risk than adults during certain developmental windows, particularly when permanent teeth are actively erupting and have more porous, less mature enamel. The interdental spaces — the areas between teeth — are consistently among the most common sites for cavities in children, because they're the hardest spots to clean and the easiest to miss entirely.

Getting fluoride into those spaces after flossing, rather than before, gives developing enamel an extra layer of protection at exactly the time it matters most.

Helping kids avoid cavities starts with getting both brushing and flossing right — and for children who do both, doing them in the right order adds a meaningful extra benefit with no extra effort.

The Best Oral Hygiene Order for Kids

The recommended sequence, based on current evidence:

1. Floss — remove plaque and food debris from between all teeth, including the back molars. For young children, parents should floss for them; kids typically don't have the manual dexterity to floss effectively on their own until around age 10.

2. Brush — two minutes, with a soft-bristle brush and fluoride toothpaste, angled at 45 degrees to the gumline. Brush all surfaces: front, back, and chewing surfaces of every tooth. This sweeps away the loosened debris from flossing and applies fluoride throughout the mouth, including the now-accessible interdental spaces.

3. Spit, don't rinse — after brushing, have your child spit out the toothpaste but avoid rinsing with water immediately afterward. Rinsing washes away the fluoride that's sitting on the teeth. Letting it sit for even a few minutes significantly increases how much fluoride is absorbed by the enamel.

4. Mouthwash (optional but helpful) — for children old enough to use mouthwash without swallowing it (typically age 6 and up), a fluoride rinse as a final step adds another layer of protection. Use it as the last step, after brushing.

What to Use for Flossing with Kids

The right tool makes a significant difference in whether flossing actually happens consistently. Traditional string floss is effective but challenging for children to manage, particularly for younger ones.

The best dental floss picks for kids offer a much easier alternative — a pre-loaded pick with a short piece of floss that requires only one hand and no wrapping around fingers. Many children who refused traditional flossing accept floss picks immediately, since the mechanics are so much simpler.

For children with braces, a floss threader or water flosser is needed to reach under the archwire — standard floss picks won't reach the interdental spaces effectively when brackets are in the way.

Building a Routine That Actually Sticks

The research-backed order is: floss first, then brush. But "floss first" is only better than "brush first" if flossing is happening. Getting both into a daily routine is the priority.

A few things that genuinely help with children:

Do it at the same time every day. Bedtime is the most important session — overnight is when bacterial activity peaks and when fluoride applied before sleep has the longest uninterrupted time to work. Morning brushing is valuable too, particularly before breakfast rather than after, so fluoride is on the teeth before food arrives.

Start early. Brushing infant teeth begins at the first tooth — usually around 6 months — and flossing begins as soon as two teeth are touching and a toothbrush can no longer clean between them. Starting young means the routine is established long before kids are old enough to argue about it.

Floss for young children, supervise older ones. Children under about 8 don't have the hand dexterity to floss effectively on their own. Parents should floss for them. Between ages 8 and 10, guided practice with supervision works well. By age 10-11, most children can floss independently — though checking in periodically ensures the habit hasn't quietly slipped.

Notice if gums bleed. Bleeding during flossing is usually a sign that gums are mildly inflamed from inconsistent flossing rather than a reason to stop — gums that hurt or bleed after flossing typically resolve within 1–2 weeks of consistent daily flossing as the tissue adapts.

Professional Cleanings Complete the Picture

Even a perfect home routine has its limits. Plaque that hardens into tartar — which happens within days in some areas — cannot be removed by brushing or flossing at home. Professional dental cleanings remove tartar, allow your dentist to check for any early cavities or gum issues, and apply professional fluoride varnish that significantly strengthens enamel between visits.

For most children, cleanings every 6 months is the standard recommendation — more frequently for children at higher cavity risk.

Learn more about preventive pediatric dentistry at Kidco Dental

Frequently Asked Questions

Should you floss before or after brushing?

Research suggests flossing before brushing is more effective. Flossing first loosens plaque and debris from between the teeth; brushing afterward sweeps it away and deposits fluoride into the now-cleared interdental spaces, where it can strengthen enamel most effectively. A 2018 study in the Journal of Periodontology found both interdental plaque reduction and fluoride retention were better with floss-first.

Does the order of brushing and flossing really matter for kids?

Yes, though what matters more is that both happen consistently every day. The floss-first order adds a meaningful benefit — particularly for children, who are at higher cavity risk in interdental spaces during the years when permanent teeth are erupting. Getting flossing into the routine at all is the first priority; optimizing the order is the next step.

Is it better to floss before or after brushing for cavity prevention?

Flossing before brushing is better for cavity prevention because it allows the fluoride from toothpaste to reach the interdental spaces right after they've been cleared of plaque. Fluoride applied to clean, plaque-free surfaces is more effective than fluoride applied before plaque has been disturbed.

When should kids start flossing?

Children should start flossing as soon as two teeth are touching and a toothbrush can no longer clean between them — typically around age 2-3 for most children. Parents should floss for young children, as children don't typically develop enough manual dexterity to do it effectively on their own until around age 8-10.

Should kids rinse after brushing?

No — spitting out toothpaste but not rinsing with water allows fluoride to remain on the teeth longer, where it continues strengthening enamel. Rinsing immediately after brushing washes away a significant portion of the fluoride benefit.

What's the easiest way to get kids to floss?

Floss picks are significantly easier for children than traditional string floss, requiring only one hand and no finger-wrapping. Letting children pick their own floss picks and building flossing into the bedtime routine alongside brushing — at the same time, every night — are the most effective ways to establish the habit.

Book your child's next preventive visit at Kidco Dental — 5 locations across Brooklyn and Queens