Using an interdental brush is straightforward: hold it like a pencil, gently insert it into the gap between two teeth, and move it back and forth two to three times. That’s the core technique. But getting the size right, reaching your back teeth, and building a consistent habit are where most people need guidance.
Choosing the Right Size
Interdental brushes come in sizes ranging from about 0.6 mm to over 5 mm in diameter, and most people need more than one size because the gaps between your teeth vary. The brush should fit snugly, with the bristles lightly pressing against both teeth on either side. If it slides through without touching, it’s too small to clean effectively. If you have to force it or the wire catches, it’s too big.
A good starting point is the smallest size that doesn’t slide through loosely. According to ISO standards, the brush should actually be slightly larger than the gap itself to ensure the bristles make proper contact. In clinical testing, over 90% of people reported a snug fit once they were matched to the correct size. Most commercially available brushes fall at 2.0 mm or smaller, which covers the majority of interdental spaces. If you’re unsure, your dentist or hygienist can measure your gaps and recommend specific sizes for different areas of your mouth.
Step-by-Step Technique
Hold the brush between your thumb and index finger, the same way you’d hold a pencil. This gives you the control you need without gripping too tightly. For your front teeth, insert the brush straight through the gap from the outside. Don’t angle it up or down into the gum line. Push gently until the brush passes through to the other side, then pull it back. Repeat this back-and-forth motion two to three times per gap, and move on to the next space.
You don’t need to use toothpaste. In fact, laboratory research has shown that dipping interdental brushes in toothpaste causes measurable wear on the softer root surfaces of teeth over time. The abrasive particles in toothpaste, combined with the scrubbing action of the bristles, can damage tooth structure. A dry brush or one rinsed with water does the job without that risk.
Reaching Your Back Teeth
The spaces between your molars are the trickiest to access but also the most important to clean, since plaque tends to accumulate heavily there. For smaller brush sizes, you can gently curve the flexible neck with your finger to create a slight bend. This angle makes it much easier to slide the brush in from the cheek side. For larger sizes, you can carefully bend the wire portion itself into a slight curve.
Another option is buying brushes with angled heads, which are specifically designed for posterior access. These have a longer handle and a pre-angled brush head that reaches between back teeth from both the outside and inside. When cleaning molars, it helps to brush from both sides of the tooth row. Insert from the cheek side, clean, then go around and insert from the tongue side. This catches plaque that a single pass might miss.
Wire Brushes vs. Silicone Picks
Traditional interdental brushes have a thin metal wire core surrounded by nylon bristles. Silicone-coated interdental picks are a newer alternative with a flexible rubber core and soft fins instead of bristles. Clinical trials have found that both types are equally effective at removing plaque and reducing gum bleeding.
The difference is comfort. In one split-mouth trial where participants used both types, pain was significantly lower with silicone picks, and patients rated them as easier to use and more comfortable. Every participant in the study said they’d buy the silicone picks again, while several said they wouldn’t repurchase the wire brushes. Wire brushes can sometimes cause sensitivity or irritate gum tissue, particularly for beginners. If you’ve been avoiding interdental cleaning because traditional brushes feel uncomfortable, silicone picks are a solid alternative with the same cleaning benefit.
How Often to Use Them
Once a day is the standard recommendation from the American Dental Association for cleaning between your teeth, whether you use floss, interdental brushes, or another tool. The time of day doesn’t matter much. Some people prefer doing it before bed so their mouth is clean overnight, while others work it into a morning routine. The best time is whatever time you’ll actually do it consistently.
Interdental brushes outperform traditional floss for most people. In comparative studies, interdental brushes reduced plaque by roughly 40% and gum inflammation by about 43% more than floss. The likely reason is that the bristles conform to the curved surfaces between teeth better than a flat ribbon of floss can.
Bleeding Is Normal at First
If your gums bleed the first few times you use an interdental brush, that’s a sign of existing inflammation, not a sign you’re doing something wrong. The bleeding reflects gum tissue that’s been irritated by plaque buildup. Research tracking adults who started interdental brushing found that bleeding dropped by 46% after just one week and by 72% after three months of regular use. Don’t stop cleaning because of bleeding. If it persists beyond two weeks of daily use, that’s worth mentioning to your dentist, as it could indicate gum disease that needs professional treatment.
When to Replace Your Brush
With daily use, an interdental brush typically lasts about one to two weeks. The signs that it’s time for a new one are visible: bristles that are frayed, splayed outward, or bent, or a wire core that’s kinked or deformed. A worn brush won’t clean effectively and a damaged wire could scratch your gums. Rinse the brush under water after each use and let it air dry. Some people get more life out of their brushes depending on how tightly the bristles fit between their teeth, but once the brush looks misshapen, toss it.