Interdental brushes and floss: sizes, materials and cost per use

Please ask your dentist or hygienist

How to clean between your teeth, and which tool to use, depends on the spaces between your teeth and on your gums. A dentist or hygienist can show you, and can help you choose a size. This page does not say how well any product works. It explains labels, sizes and prices.

Interdental brush sizes

• Sizes are usually numbered, and many brands follow an ISO scale with color coding. Brands differ in how they label and color sizes, so a size from one brand may not match the same label from another.
• A brush should fit the space without force. Do not push a brush that is too big into a gap, and do not bend or reuse a brush that is worn out.
• Some brushes come in packs of several sizes, which can help you find what fits. Ask your dentist or hygienist for the sizes to start with.
• Check whether the wire is coated, and whether the handle is made for a firm grip.
• If using a brush causes pain or bleeding, stop and see a dentist.

Floss types

• Waxed and unwaxed: waxed floss has a coating that some people find slides more easily. Unwaxed floss is thinner and uncoated. Neither is right for everyone.
• Nylon and other synthetic materials: common and inexpensive. Some floss uses other materials as well, so read the label.
• Silk and plant-based: silk is an animal-derived fiber, and some floss uses plant-derived waxes such as candelilla. A vegan label means no animal-derived ingredients. Read the ingredients and what the maker states.
• Biodegradable claims: the FTC's Green Guides ask that these be clear about where and how the product breaks down. Check what the floss, the wax and the container are made of.
• Refillable containers: a reusable glass or metal container with refill spools can reduce packaging. Compare the refill price.

Floss picks

Floss picks are small handles with a piece of floss, meant for single use, and some have reusable handles with replaceable floss. They are easy to hold, which some people prefer. They cost more per use than a spool, and most are plastic, so compare them with reusable-handle options if packaging matters to you.

Our angle: price per use, not price per package

Floss is sold by length, usually in yards or meters, and interdental brushes and picks are sold by count, so the sticker numbers do not match. Convert all of them to a cost per use. For floss, divide the price by the length on the package to get the price per meter or yard, then decide how much you use per session and multiply. For brushes, note how long each brush lasts, since the wire wears. For picks, divide the price by the count. Add up the cost per day for your routine and compare options on that.

1. Find the length of floss, or the count of brushes or picks.
2. Divide the price to get the cost per meter or per piece.
3. Multiply by how much you use per session, then by sessions per month.

Buying tips

• Buy a small pack before a big one, since size and feel matter.
• Check how long a brush lasts and when to replace it, and ask your dentist.
• Compare refill packs with new containers.
• Keep brushes and picks out of reach of young children.