Why flossing matters and how to do it

Reviewed by Dr. Samar Fadavi, DDS

Short answer: Flossing, or cleaning between your teeth in another way, removes plaque from the tight spaces your toothbrush cannot reach. Those spaces are where many cavities and most gum disease begin. Clean between your teeth once a day, using floss, interdental brushes or a water flosser. A little bleeding at first is common and usually settles within one to two weeks of daily cleaning.

Why cleaning between teeth matters

Each tooth has five surfaces. A toothbrush cleans the front, back and chewing surfaces well, but the two sides where teeth touch their neighbours are mostly out of reach. Plaque, the soft sticky film of bacteria, builds up in these spaces and along the gum line between teeth.

Left in place, plaque irritates the gums and causes gingivitis, with redness, swelling and bleeding. Over time it can harden into tartar and lead to periodontitis, where the bone that holds the teeth starts to break down. Plaque between teeth also makes acids that cause cavities on the sides of teeth, which are often found only on x-rays.

This guide explains how to floss well, which tools suit different mouths, what to expect when you start, and common mistakes to avoid. It is general information for patients in Scarborough, the Danforth and East Toronto.

What daily cleaning between teeth helps with

• Healthier gums that bleed less and look pink and firm.
• Fewer cavities on the sides of teeth.
• Fresher breath, since trapped food and bacteria cause odour. Our mouth odour guide explains more.
• Less tartar build-up, so cleanings are quicker and more comfortable.
• Protection for fillings, crowns, bridges and implants, which need clean edges to last.

How to floss, step by step

1. Use enough floss. Break off about 45 centimetres (about the length of your forearm). Wind most of it around one middle finger and a little around the other.
2. Hold it firmly. Grip a short section, about 2 to 3 centimetres, between your thumbs and index fingers.
3. Slide gently between teeth. Ease the floss down with a gentle back-and-forth motion. Do not snap it into the gums.
4. Curve it into a C shape. Wrap the floss around the side of one tooth and slide it just under the gum line until you feel gentle resistance.
5. Scrape up and down. Move the floss up and down along the side of the tooth several times. Then curve it around the neighbouring tooth and repeat.
6. Use a fresh section. Unwind clean floss from one finger and wind used floss onto the other as you move from space to space.
7. Do not forget the back teeth. Clean behind the last tooth on each side too.
8. Rinse. Rinse your mouth with water to clear loosened plaque and food.

The whole routine takes about two to three minutes once it becomes a habit.

Other ways to clean between teeth

String floss is not the only option. What matters most is that you clean between your teeth every day with a tool you will actually use.

Interdental brushes

These small brushes come in different sizes and fit into the spaces between teeth. They can clean as well as or better than floss for people with larger gaps, gum recession or bone loss. Choose the size that fits snugly without forcing. Your hygienist can help you pick the right sizes for different areas.

Water flossers

A water flosser shoots a thin stream of pulsing water between teeth and along the gum line. It is helpful for people with braces, bridges, implants, limited hand movement or sensitive gums. It is easy to use and many people find it more comfortable than string floss.

Floss picks and holders

Plastic picks with a short piece of floss are easier for some people to handle, especially for back teeth or when helping a child. Use a clean pick, or rinse it often, and still curve the floss around each tooth.

Soft picks

Rubbery picks with soft bristles are gentle and handy on the go. They work well for many people, but may not clean as thoroughly in very tight spaces.

Floss threaders and super floss

These help you guide floss under bridges, around permanent retainers and between braces wires.

When to floss: before or after brushing?

Either order works. Some people like to floss first, so loosened plaque is brushed away and fluoride from toothpaste reaches between the teeth. Others prefer to brush first. Choose the order you will stick to. Many people find bedtime is the easiest time to clean between their teeth thoroughly, since the mouth then stays clean overnight.

What to expect when you start

If you have not flossed regularly, your gums may bleed and feel tender for the first week or two. This is usually a sign of gum inflammation, not a reason to stop. As plaque is removed daily, the gums heal and bleeding usually stops within one to two weeks. If bleeding continues after two weeks of daily cleaning, or your gums are very sore, book a check-up. Our guide on gum bleeding explains common causes.

Common flossing mistakes

• Snapping floss into the gums. This can cut or bruise the gum. Ease it down gently.
• Only going straight down and up. Without the C shape, floss misses most of the tooth surface.
• Skipping areas that bleed. Bleeding areas are the ones that need cleaning most.
• Reusing the same section. This moves bacteria from one space to the next.
• Flossing too hard. Firm but gentle pressure works. Aggressive flossing can contribute to gum recession. See our gum recession guide.
• Only flossing before a dental visit. Daily cleaning is what keeps gums healthy. Your hygienist can usually tell.

What to avoid

• Do not use toothpicks, pins or other sharp objects to dig food out. They can injure gums and damage fillings.
• Do not force an interdental brush that is too big. Use a smaller size.
• Do not stop cleaning between teeth because of mild bleeding at first.
• Do not rely on mouthwash alone. Rinses cannot remove the sticky plaque that floss and brushes remove.
• Do not ignore floss that shreds or catches in the same spot. It can mean a rough filling edge or a cavity.

Flossing with braces, bridges and implants

• Braces: use a floss threader, orthodontic floss with a stiff end, interdental brushes or a water flosser to clean around brackets and under wires. Our guide to braces and aligners covers daily care during treatment.
• Bridges: thread floss or a special super floss under the false tooth to clean where it meets the gum.
• Implants: clean gently around the implant crown with floss, implant-safe brushes or a water flosser. Healthy gums around implants are essential for them to last. Our dental implants page explains implant care.
• Permanent retainers: use a threader to clean behind the wire on the inside of the front teeth.

Flossing for children

Start cleaning between your child’s teeth as soon as two teeth touch, often between ages two and six. Parents usually need to do it for young children, and floss picks make it easier. Most children can begin flossing on their own around age eight to ten, with checks from an adult. Make it part of the bedtime routine, and praise the effort. Our guide to your child’s first dental visit has more tips for building habits early.

Flossing for older adults

As people age, gums may recede and spaces between teeth can widen, so interdental brushes often work better than floss. Arthritis or reduced grip can make string floss hard to use. Floss holders, thick-handled interdental brushes and water flossers are good options. Our guide to aging and dental health has more ideas, and our ergonomics guide covers easier grips.

Making it a habit

• Keep floss or interdental brushes next to your toothbrush so you see them every time.
• Link it to something you already do every day, such as brushing before bed.
• Start small. Clean between a few teeth each night and build up to all of them.
• Keep picks in your bag, car or desk for after meals.
• Track it on a calendar or phone app for a few weeks until it becomes automatic.

Most people notice that their gums stop bleeding and their mouth feels cleaner after a few weeks, which makes the habit easier to keep.

Does flossing really make a difference?

You may have seen headlines questioning flossing. Much of that debate came from the fact that large, long studies of flossing are hard to run, not from evidence that it does not help. Studies that looked closely, especially with good technique and interdental brushes, show less gum inflammation and bleeding. Dental organizations in Canada continue to recommend daily cleaning between the teeth, and dentists see the difference in people’s gums every day.

Choosing the right tool for your mouth

• Tight contacts between teeth: thin waxed floss or dental tape slides through more easily.
• Larger gaps, recession or bone loss: interdental brushes in the sizes your hygiene team recommends.
• Braces, bridges or a permanent retainer: floss threaders, super floss or a water flosser.
• Implants: implant-safe interdental brushes, soft floss or a water flosser.
• Limited hand movement: floss holders, thick-handled interdental brushes or a water flosser.
• Children: kid-sized floss picks used by a parent.

Many people use more than one tool: floss for tight front teeth and interdental brushes for wider back spaces. Bring your tools to your next check-up and ask the team to watch your technique. Small changes in angle or pressure can make a big difference.

Flossing and your overall health

Healthy gums matter beyond the mouth. Gum disease has been linked with diabetes, heart disease and other health conditions, and people with diabetes often find their blood sugar easier to manage when gum inflammation is controlled. Daily cleaning between teeth is one of the simplest ways to keep gums healthy. Our guide to oral health and overall health explains the connection.

When to see a dentist

Book a visit if:

• Your gums still bleed after two weeks of daily cleaning between teeth.
• Floss catches, shreds or snaps in the same place.
• Food packs between two teeth often.
• Your gums look red, swollen or are pulling back.
• You have bad breath that does not improve with good cleaning.
• It has been more than six months to a year since your last cleaning.

Our family dentistry page explains check-ups, cleanings and gum care. Our team is happy to show you the right technique and tools for your mouth.

Questions about flossing

How often should I floss?

Once a day is enough for most people. Choose a time when you can do it carefully, such as before bed.

Is a water flosser as good as string floss?

For many people it is a helpful alternative, especially with braces, bridges, implants or limited hand movement. Interdental brushes also work very well for larger spaces.

Why do my gums bleed when I floss?

Usually because of inflammation from plaque. Bleeding often stops within one to two weeks of daily cleaning. If not, book a check-up.

Can flossing create gaps between my teeth?

No. Gentle flossing does not create gaps. Spaces that seem to appear are often from gum swelling going down as gums heal.

Should children floss?

Yes, once teeth touch. Parents usually help until about age eight to ten.

Which is better, waxed or unwaxed floss?

Both work. Waxed floss or tape slides more easily between tight teeth. Pick the one you find comfortable.

How long should flossing take?

About two to three minutes for the whole mouth once you are used to it. Take a little longer at first while you learn the C-shape motion.

Is it too late to start flossing as an adult?

Never. Gums respond quickly to daily cleaning at any age. Many adults see less bleeding and fresher breath within two weeks of starting.

What if floss hurts?

Mild tenderness at first is common. Sharp pain, or floss that always catches in one spot, can mean a cavity or a rough filling edge. Book a check.