How to Use an Interdental Brush Correctly

If you've ever been told by your dentist that brushing alone isn't quite enough, you're certainly not alone. Many adults across London and the UK wonder how to properly clean the spaces between their teeth — areas where a regular toothbrush simply cannot reach. This is one of the most common questions dental professionals hear, and it's the reason so many people search for guidance on how to use an interdental brush correctly.

Interdental brushes are small, specially designed brushes that slide between the teeth to remove plaque and food debris from areas that account for a significant proportion of tooth surfaces. Despite their proven effectiveness, many patients are unsure about the correct technique, appropriate brush size, or how often they should be used.

This article provides a clear, step-by-step explanation of how to use interdental brushes effectively as part of your daily oral hygiene routine. Please note that this content is for general educational purposes only and does not constitute personalised clinical advice. Treatment suitability and oral hygiene recommendations depend on individual clinical assessment. We'll cover the science behind why interdental cleaning matters, how to choose the right brush size, common mistakes to avoid, and when it may be helpful to speak with a dental professional for personalised advice. Understanding these fundamentals can make a meaningful difference to your long-term oral health.

What Is an Interdental Brush and Why Does It Matter?

“How do you use an interdental brush correctly? To use an interdental brush correctly, gently insert the brush into the space between your teeth without forcing it. Use a slow back-and-forth motion to clean the surfaces on either side. Choose the correct brush size for each gap, use the brush once daily, and replace it when the bristles become worn. An interdental brush helps remove plaque from areas a regular toothbrush cannot reach, helping to support gum and tooth health.”

Why Interdental Cleaning Is Essential for Oral Health

Standard toothbrushing, even when performed thoroughly, typically cleans only around 60% of the total tooth surface. The remaining 40% consists largely of the interproximal surfaces — the sides of your teeth that face neighbouring teeth. These narrow spaces are where plaque readily accumulates and, if left undisturbed, can contribute to both tooth decay and gum disease.

Interdental brushes are widely regarded by dental professionals as one of the effective tools for cleaning these hard-to-reach areas. Research published in dental journals has consistently demonstrated that interdental brushes may be more effective at removing interproximal plaque than floss alone, particularly for patients with sufficient space between their teeth.

By incorporating interdental brushing into your daily routine, you are taking a proactive step towards reducing plaque build-up in the areas most vulnerable to disease. This is especially relevant for patients who have noticed early signs of gum inflammation, such as slight bleeding when brushing — a common indicator that plaque may be accumulating in areas that aren't being adequately cleaned. If you're experiencing persistent bleeding, it is always sensible to arrange a dental check-up so a clinician can assess your gum health properly.

Choosing the Right Interdental Brush Size

One of the most important aspects of using an interdental brush correctly is selecting the appropriate size. Interdental brushes are available in a range of diameters, typically colour-coded according to ISO standards, from very small (often pink or orange) to larger sizes (often green, blue, or purple).

The correct size should fit snugly into the interdental space with gentle resistance. If the brush slides through without touching the sides of the teeth, it is likely too small to clean effectively. Conversely, if you have to force the brush or it causes discomfort, it is too large and could potentially damage the gum tissue.

Most people require more than one size because the spaces between teeth naturally vary throughout the mouth. The gaps between front teeth are usually narrower than those between back teeth.

Practical tips for choosing the right size:

• Start with a smaller size if you are unsure
• The wire should not press against the teeth — only the bristles should make contact
• Your dental hygienist can measure your interdental spaces and recommend specific sizes during a routine appointment
• It is perfectly normal to use two or three different sizes across your mouth

Step-by-Step Guide: How to Use an Interdental Brush Correctly

Following the correct technique ensures you gain the full benefit of interdental cleaning while minimising any risk of tissue irritation.

Step 1: Select the Appropriate Brush

Choose the correct size for the space you are about to clean. Have your different sizes to hand if needed.

Step 2: Insert Gently

Hold the brush between your thumb and forefinger. For front teeth, insert the brush straight through the gap from the outside. For back teeth, you may find it helpful to angle the brush slightly or use a longer-handled version for easier access. A slight curve to the wire can help reach posterior teeth more comfortably.

Step 3: Use a Gentle Back-and-Forth Motion

Once the brush is positioned in the interdental space, move it gently back and forth two to three times. This action disturbs and removes the plaque clinging to both adjacent tooth surfaces. Avoid using excessive force or a sawing motion.

Step 4: Rinse and Repeat

Rinse the brush under running water after each space to remove debris, then move to the next gap. Work systematically around your mouth so you don't miss any areas.

Step 5: Clean and Replace

After use, rinse the brush thoroughly and allow it to dry. Replace the brush when the bristles become bent or worn — typically after around one week of daily use, though this can vary.

The Dental Science Behind Plaque and Gum Disease

Understanding why interdental cleaning matters requires a basic appreciation of how plaque affects oral health. Plaque is a soft, sticky biofilm composed of bacteria that naturally forms on tooth surfaces throughout the day. When plaque is not regularly removed, it can mineralise into calculus (tartar), which cannot be removed by brushing alone and requires professional deep cleaning.

In the interdental spaces, undisturbed plaque triggers an inflammatory response in the gum tissue. This early stage, known as gingivitis, typically presents as redness, slight swelling, and bleeding during brushing or interdental cleaning. Recognising the early signs of gum disease is important, as gingivitis is generally reversible with improved oral hygiene.

However, if plaque accumulation continues unchecked, the inflammation may progress to periodontitis — a more advanced form of gum disease that affects the supporting bone and structures around the teeth. Periodontitis can eventually lead to tooth mobility and tooth loss if not managed appropriately.

By effectively removing plaque from between the teeth on a daily basis, interdental brushing plays a critical role in preventing this progression. It is worth noting that some bleeding may occur when you first begin using interdental brushes, particularly if plaque has been present for some time. This typically subsides within one to two weeks of consistent use. If bleeding persists beyond this period, a professional assessment is advisable.

Common Mistakes to Avoid

Even with the best intentions, patients sometimes develop habits that reduce the effectiveness of interdental cleaning or cause unnecessary discomfort:

• Using only one size: As noted, most mouths require multiple brush sizes. Using a single size throughout means some spaces are cleaned inadequately while others may experience unnecessary pressure.
• Forcing the brush: If the brush does not slide in comfortably, try a smaller size. Forcing a brush that is too large can damage the delicate papilla (the triangular gum tissue between teeth).
• Neglecting the back teeth: Posterior teeth are often the most prone to plaque accumulation and decay yet are frequently missed during interdental cleaning. Angled or longer-handled brushes can make access easier.
• Inconsistent use: Interdental brushing is most effective when performed daily. Occasional use is unlikely to provide the same level of plaque control.
• Replacing brushes too infrequently: A worn brush with splayed bristles is far less effective. Regular replacement ensures consistent cleaning performance.

When Professional Dental Assessment May Be Needed

While interdental brushes are an excellent addition to any oral hygiene routine, certain situations warrant professional evaluation. Consider arranging a dental appointment if you experience:

• Persistent bleeding that does not improve after two weeks of regular interdental brushing
• Soreness, swelling, or tenderness in the gums that does not resolve
• Difficulty fitting any brush size into certain spaces, which may indicate crowding or other structural considerations
• An unpleasant taste or odour that persists despite thorough cleaning
• Loose teeth or receding gums, which may suggest an underlying periodontal condition

These symptoms do not necessarily indicate a serious problem, but they are best evaluated by a dental professional who can carry out a thorough clinical examination and provide tailored recommendations. Early assessment often leads to simpler and more conservative management.

If you are uncertain about the correct interdental brush technique or sizing for your teeth, a session with a dental hygienist can provide personalised instruction and ensure you are cleaning effectively.

Prevention and Oral Health Advice

Interdental brushing is one component of a comprehensive oral hygiene routine. To support the long-term health of your teeth and gums, consider the following practical guidance:

• Brush twice daily with a fluoride toothpaste for at least two minutes, using a systematic technique
• Use interdental brushes once daily, ideally in the evening before brushing so that fluoride from toothpaste can reach the cleaned interdental surfaces
• Attend regular dental check-ups and hygiene appointments as recommended by your dental team — frequency is best determined on an individual basis
• Limit sugary snacks and acidic drinks, particularly between meals, to reduce the risk of decay
• Avoid smoking, which is a significant risk factor for gum disease and can mask symptoms such as bleeding
• Stay hydrated to support natural saliva flow, which helps neutralise acids and wash away food particles

Consistency is key. Building interdental cleaning into your daily routine takes only a few minutes but can have a considerable positive impact on your oral health over time.

Key Points to Remember

• Interdental brushes clean the 40% of tooth surfaces that a regular toothbrush cannot reach
• Correct sizing is essential — most people need more than one brush size
• Gentle technique with a simple back-and-forth motion is all that is required
• Daily use provides the greatest benefit for plaque control and gum health
• Some initial bleeding is common and usually settles within two weeks
• Professional guidance from your dentist or hygienist can help you select the right sizes and refine your technique

Frequently Asked Questions

Can interdental brushes replace flossing?

For many patients, interdental brushes are considered more effective than traditional floss at removing plaque between teeth, particularly where there is sufficient space for the brush to fit. However, in very tight contact points — common between some front teeth — floss may still be the most practical option. Your dental hygienist can advise which tool is most appropriate for each area of your mouth. In some cases, a combination of both interdental brushes and floss may be recommended for optimal cleaning across all interdental spaces.

How often should I use an interdental brush?

Dental professionals generally recommend using interdental brushes once a day. Evening use is often suggested as it allows you to remove the plaque that has accumulated throughout the day. When followed by brushing with fluoride toothpaste, this routine allows fluoride to penetrate the freshly cleaned interdental spaces more effectively. Consistency is more important than frequency — using interdental brushes thoroughly once daily is considered more beneficial than occasional or rushed use multiple times a day.

Is it normal for my gums to bleed when I first start using interdental brushes?

Yes, some bleeding is quite common when you first begin using interdental brushes, particularly if plaque has been present in those areas for some time. The bleeding is typically a sign of mild gum inflammation (gingivitis) and usually improves within one to two weeks of consistent daily use as the gum tissue becomes healthier. It is important not to stop cleaning because of initial bleeding. However, if bleeding persists beyond two weeks or is accompanied by pain or swelling, it is advisable to seek a professional dental assessment.

What size interdental brush should I use?

The correct size varies between individuals and even between different spaces in the same mouth. The brush should fit into the gap with gentle resistance — the bristles should touch the tooth surfaces on either side without the wire pressing against the teeth. Starting with a smaller size and gradually trying larger sizes until you find the right fit is a sensible approach. Your dental hygienist can measure your interdental spaces precisely and provide specific size recommendations tailored to your mouth.

Can I reuse an interdental brush?

Yes, interdental brushes are designed to be reused for several days. After each use, rinse the brush thoroughly under running water and allow it to air dry. Replace the brush when the bristles appear worn, bent, or splayed — this typically occurs after approximately five to ten days of daily use, depending on the brand and how many spaces you are cleaning. Using a worn brush significantly reduces cleaning effectiveness, so regular replacement is important.

Are interdental brushes suitable for everyone?

Interdental brushes are suitable for the majority of adults. However, the spaces between teeth vary considerably from person to person. Some individuals with very tight contact points may find that even the smallest interdental brush cannot fit comfortably, in which case dental floss or tape may be more appropriate for those specific areas. Patients with orthodontic appliances, dental implants, or bridgework may also benefit from interdental brushes but should seek guidance from their dental team regarding the most appropriate sizes and techniques for their particular situation.

Learning how to use an interdental brush correctly is a straightforward yet highly valuable step towards better oral health. By selecting the right brush sizes, using a gentle and consistent technique, and making interdental cleaning part of your daily routine, you can significantly reduce plaque accumulation in the areas most vulnerable to decay and gum disease.

While this guide provides general educational information, it is important to remember that every mouth is different. What works well for one person may not be ideal for another. Your dental team is best placed to provide personalised advice based on a thorough assessment of your teeth, gums, and individual oral health needs.

If you are unsure about your interdental cleaning technique, experiencing persistent bleeding, or have any concerns about your gum health, seeking professional dental guidance is always a sensible step.

Dental symptoms and treatment options should always be assessed individually during a clinical examination.

This article is intended for general informational purposes only and does not constitute dental advice, diagnosis, or treatment recommendation. South Kensington Medical & Dental is regulated by the Care Quality Commission (CQC). All dentists are registered with the General Dental Council (GDC). Medical practitioners are registered with the General Medical Council (GMC).