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Few topics in everyday dental care generate as much debate as flossing. You may have seen headlines questioning its value, or perhaps you have quietly wondered whether the effort is genuinely worthwhile. It is a question that many adults ask — is flossing actually necessary, or is brushing alone enough to keep teeth and gums healthy?
The discussion was brought into sharper focus in 2016 when an Associated Press investigation highlighted the limited strength of the clinical evidence supporting flossing, prompting widespread media coverage and considerable public confusion. Since then, the question has remained one of the most commonly searched dental topics online.
Understanding what the evidence actually says — rather than relying on headlines — is important. The answer is more nuanced than a simple yes or no, and it has real implications for how you approach your daily oral care routine.
This article examines the clinical evidence for and against flossing, explains the dental science behind interdental cleaning, explores the alternatives, and offers balanced, practical guidance. As always, individual needs vary, and your dental professional is best placed to advise on the most effective cleaning routine for your specific oral health.
The clinical evidence for flossing is more limited than many people assume, but dental professionals continue to recommend interdental cleaning as part of a thorough oral care routine. Whilst large-scale, long-term randomised trials on flossing are lacking, the underlying principle is well-supported: a toothbrush cannot clean the tight contact points between teeth where plaque accumulates and gum disease often begins. Interdental cleaning — whether with floss, interdental brushes, or other tools — addresses these areas. The most suitable method depends on the size of your interdental spaces and individual dexterity.
To understand why cleaning between teeth is important, it helps to understand where dental disease most commonly starts.
Each tooth has five surfaces: the front (labial or buccal), the back (lingual or palatal), the biting surface (occlusal), and two interproximal surfaces — the sides of each tooth that face adjacent teeth. These interproximal surfaces account for a significant proportion of total tooth surface area, yet they are the areas a toothbrush — whether manual or electric — cannot effectively access.
Dental plaque — the soft bacterial biofilm that continuously forms on all tooth surfaces — accumulates between teeth just as readily as it does on accessible surfaces. When plaque remains undisturbed in these interproximal spaces, it triggers two key processes:
The biological rationale for interdental cleaning is therefore clear: removing plaque from between teeth reduces the risk of both decay and gum disease in areas that brushing alone cannot address.
The debate around flossing centres on the quality and strength of the clinical evidence, rather than the underlying biological principle.
The 2016 AP investigation highlighted that many studies on flossing had significant limitations — small sample sizes, short durations, and methodological weaknesses. A Cochrane systematic review of flossing studies found:
It is important to understand why this evidence is weak. Conducting rigorous, long-term studies on flossing is inherently challenging:
Limited evidence is not the same as evidence of no benefit. The absence of large-scale, long-term trials does not mean flossing is ineffective — it means the specific level of benefit has not been conclusively quantified. The biological plausibility of removing plaque from between teeth remains strong, and clinical experience consistently supports its value.
Despite the headlines questioning flossing, virtually all major dental professional bodies — including the British Dental Association, the British Society of Periodontology, and the American Dental Association — continue to recommend daily interdental cleaning. There are good reasons for this position.
Dental professionals observe the consequences of inadequate interdental cleaning on a daily basis. Patients who do not clean between their teeth consistently tend to present with more interproximal plaque accumulation, higher rates of gum disease, and more frequent interproximal decay compared with those who do. Whilst clinical observation is not the same as controlled trial evidence, it represents decades of professional experience across millions of patient interactions.
Given the strong biological rationale and the low risk associated with interdental cleaning, dental professionals generally take the view that recommending it is prudent. The potential benefits — reduced plaque between teeth, healthier gums, and lower decay risk — outweigh the minimal time and effort involved. Waiting for definitive trial data before recommending something that is biologically sound and carries virtually no risk would not serve patients' best interests.
Importantly, the evidence debate is not limited to traditional string floss. Interdental brushes — small, bottle-shaped brushes designed to fit between teeth — have a stronger evidence base than string floss for plaque removal and gingivitis reduction. This has led many dental professionals, particularly in the UK, to recommend interdental brushes as the primary interdental cleaning tool for most patients.
The question of whether to floss or use interdental brushes is an important one, as the evidence suggests they are not equally effective for all patients.
Research consistently shows that interdental brushes remove more plaque from between teeth than string floss, particularly where there is sufficient space for the brush to fit comfortably. A systematic review published in the Journal of Clinical Periodontology concluded that interdental brushes were superior to floss for plaque removal and at least as effective for reducing gingivitis.
Interdental brushes are particularly effective because:
String floss remains useful in situations where interdental spaces are very tight — typically between teeth that are closely aligned with minimal gaps. In these areas, an interdental brush may not fit, and floss is the most practical option for disrupting plaque at the contact point.
| Feature | String Floss | Interdental Brushes |
|---|---|---|
| Plaque removal evidence | Moderate | Strong |
| Best suited for | Very tight contacts | Most interdental spaces |
| Ease of correct use | More difficult | Easier |
| Size options | One size | Multiple sizes |
| Gum stimulation | Limited | Good |
| Access to back teeth | Can be challenging | Generally easier |
| Cost | Low | Low to moderate |
Many dental professionals now suggest using interdental brushes as the primary tool for cleaning between teeth, supplemented by floss for any areas where the brushes do not fit. Your dental hygienist can recommend the correct sizes and demonstrate the most effective technique during a hygiene appointment.
Beyond traditional floss and interdental brushes, several other tools can help clean between teeth.
Water flossers (oral irrigators) use a pressurised stream of water to dislodge food debris and plaque from between teeth and along the gum line. They can be particularly useful for:
The evidence for water flossers suggests they can reduce gingivitis and bleeding, though they may not remove established plaque biofilm as effectively as mechanical tools like interdental brushes. They are best considered as a supplement to, rather than a replacement for, mechanical interdental cleaning.
Pre-threaded floss picks can make flossing easier for those who find manipulating string floss difficult. However, they offer less control than standard floss and cannot curve around the tooth surface as effectively. They may be a useful option for occasional use or for patients who would otherwise not clean between their teeth at all.
Flexible rubber picks with soft bristles are a relatively recent addition to interdental cleaning options. Early evidence suggests they may be effective for plaque removal in wider interdental spaces, and many patients find them comfortable and convenient. However, the evidence base is less established than for interdental brushes.
If you are uncertain about the most effective interdental cleaning method for your teeth, or if you have noticed changes in your gum health, a professional assessment can provide personalised guidance.
Consider arranging a dental check-up if you experience:
Your dental hygienist can assess your interdental spaces, recommend the most appropriate tools and sizes, and demonstrate the correct technique. This personalised guidance is far more valuable than any general recommendation, as everyone's teeth and gums are different.
Whether you choose floss, interdental brushes, or a combination, the key is consistency. Here is a practical framework for an effective daily routine.
It is never too late to begin interdental cleaning. When you first start, you may experience some bleeding from the gums — this is a common sign of existing gum inflammation responding to the disturbance of plaque that has been sitting undisturbed. In most cases, bleeding reduces significantly within one to two weeks of consistent daily cleaning as the gums become healthier. If bleeding persists beyond two weeks, it is worth mentioning this to your dental professional, as it may indicate gum inflammation that requires further assessment. Start gently and gradually build the habit into your daily routine.
There is some evidence to suggest that cleaning between teeth before brushing may be slightly more beneficial. This sequence loosens plaque and debris from between teeth, allowing the subsequent brushing to remove it more effectively and enabling fluoride from toothpaste to reach the interproximal surfaces more readily. However, the most important factor is that you clean between your teeth consistently — whether you do so before or after brushing is less critical than doing it at all. Choose the sequence that feels most natural and sustainable for your daily routine.
Interdental brushes come in a range of sizes, typically colour-coded from very small (often pink or orange) to larger (often blue, purple, or grey). The correct size is one that fits snugly between your teeth with gentle insertion — you should feel slight resistance from the bristles but not need to force the brush through. Most people need two or three different sizes because the gaps between their teeth vary. Your dental hygienist can measure your interdental spaces and recommend the appropriate sizes during your next appointment. Using a brush that is too small will not clean effectively; one that is too large may cause discomfort.
When performed correctly with a gentle technique, flossing should not damage healthy gum tissue. However, aggressive flossing — snapping the floss down forcefully between teeth or sawing back and forth against the gums — can cause cuts, soreness, and gum recession over time. The recommended technique involves gently guiding the floss between teeth, curving it around the side of each tooth in a C-shape, and sliding it up and down along the tooth surface. If you find flossing consistently causes pain or bleeding despite a gentle technique, discuss this with your dental professional, as there may be an underlying issue requiring assessment.
Interdental cleaning becomes relevant for children once their teeth are in contact — meaning adjacent teeth are touching and a toothbrush cannot reach between them. This typically begins to occur from around the age of two to three years, though it varies. For younger children, parents or carers should assist with interdental cleaning, as children generally lack the dexterity for effective flossing until around the age of ten or older. Interdental cleaning helps prevent interproximal decay in primary (baby) teeth, which can affect the health and positioning of permanent teeth. Your child's dental professional can advise on when and how to begin.
Water flossers can be a useful addition to an oral care routine, particularly for patients with orthodontic appliances, dental bridges, implants, or dexterity limitations. They are effective at dislodging food debris and can help reduce gum inflammation. However, most dental professionals consider them a supplement to mechanical interdental cleaning rather than a direct replacement, as they may not remove established plaque biofilm as thoroughly as interdental brushes or floss. For patients who find traditional interdental cleaning difficult or unpleasant, a water flosser may be better than no interdental cleaning at all. Discuss with your dental professional whether a water flosser is appropriate for your needs.
Is flossing actually necessary? The honest answer is nuanced. The clinical trial evidence for traditional string flossing is weaker than many people assume — but this reflects the inherent difficulty of studying a daily hygiene habit over the long timescales needed to measure outcomes like decay and bone loss. It does not mean that cleaning between teeth has no value.
The biological rationale for interdental cleaning is robust: plaque accumulates between teeth just as it does on accessible surfaces, and a toothbrush cannot remove it. Leaving this plaque undisturbed increases the risk of interproximal decay and gum disease. Whether you use floss, interdental brushes, or a combination, the principle remains the same — disrupting plaque between teeth supports better oral health.
For most adults, interdental brushes are now considered the most effective tool for interproximal cleaning, with floss reserved for very tight contacts. Your dental hygienist is the best person to recommend the right tools and technique for your individual needs.
The most important takeaway is this: consistency matters more than perfection. Cleaning between your teeth daily — even imperfectly — is significantly better than not cleaning between them at all.
Dental symptoms and treatment options should always be assessed individually during a clinical examination.
Disclaimer:
This article is intended for general educational purposes only and does not constitute personalised dental advice. Individual diagnosis and treatment recommendations require a clinical examination by a qualified dental professional.
Next Review Due: 13 March 2027