DENTAL GUIDES
Dental floss or interdental brushes: which should you use?
Floss may be suitable where tooth contacts are too tight for a brush. An appropriately sized interdental brush can be useful where there is space, especially after periodontal changes. The same mouth may need different tools in different places. Choose by fit, gum condition and what you can use consistently; neither forcing a brush through a narrow gap nor passing floss without contacting the tooth cleans the area well.
SHORT ANSWER
Floss may be suitable where tooth contacts are too tight for a brush. An appropriately sized interdental brush can be useful where there is space, especially after periodontal changes. The same mouth may need different tools in different places. Choose by fit, gum condition and what you can use consistently; neither forcing a brush through a narrow gap nor passing floss without contacting the tooth cleans the area well.
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Look at the space below the contact
Two teeth can touch tightly near their biting surfaces while leaving an open space closer to the gum. Elsewhere, the gum tissue may fill most of that space. Tooth shape, recession, periodontal support and restorations affect the route available to a cleaning tool.
A toothbrush cannot reliably reach all of these facing surfaces. Interdental cleaning is intended to disrupt the film attached to them, including when there is no obvious trapped food. A tool that removes a piece of lunch but never contacts the tooth surface may leave plaque behind.
Ask a dental professional to show you the spaces that are difficult to clean. The answer may be floss at one contact and a small range of brush sizes elsewhere. A printed size chart alone cannot show whether a brush fits your particular contacts and restoration contours.
When floss is the practical choice
Floss or dental tape can pass through a close contact that does not permit an interdental brush. Guide it gently rather than snapping it into the gum. Once through the contact, curve it against one tooth so that it follows the side surface, then clean the adjacent tooth surface as well.
Moving the thread only in the middle of the gap may remove loose debris without adequately cleaning either tooth. Repeated sharp pressure into the soft tissue can cause soreness or a cut. Ask for a demonstration if you cannot see or feel how to contact the surface without injuring the gum.
Different forms, such as a holder or tape, may make handling easier. The useful choice is the one that can reach and clean the intended surfaces. A particular brand or flavour does not replace technique. If floss catches or shreds consistently at one site, mention that to the dentist rather than repeatedly pulling harder.
Choosing an interdental brush that fits
A suitable brush should pass through a space with controlled gentle movement while the bristles contact the surfaces. It should not need force. A very small brush that barely touches the teeth can be ineffective; an oversized one can bend, scrape or traumatise the gum.
Different spaces may need different sizes. The SDCEP periodontal guidance describes a snug fit without the wire rubbing against the tooth. That is more useful than assuming that the largest available brush provides the most cleaning.
Show the dental professional how you use it, including the direction and handle position. Some areas can be approached more comfortably from one side than the other. Do not copy a route used beside a bridge onto a tight natural-tooth contact without checking that it is appropriate.
Gum disease changes the recommendation
After periodontitis, open interdental spaces can make brushes particularly useful. Supportive periodontal care guidance recommends appropriately sized interdental brushes where anatomy permits, with other aids where a brush cannot reach. That recommendation is made in a periodontal-care context; it does not mean everyone should force a brush between every pair of healthy tightly contacting teeth.
A dentist also considers whether inflammation, recession or a restoration is making cleaning difficult. If pockets remain or disease is active, home cleaning is only part of the plan. The periodontal treatment page explains why professional assessment and follow-up are needed.
The best tool may change after swelling reduces or treatment alters access. Ask whether a size needs to be reassessed rather than treating the first selection as permanent. A new gap does not always mean that a brush has physically pushed the teeth apart; changes in swollen tissue can make existing anatomy more visible.
What the evidence can and cannot say
The ADA's evidence summary reports that floss or interdental brushes added to brushing may improve plaque or gingivitis measures, with some findings favouring brushes. Much of the underlying evidence is short-term and of low or very low certainty. Those results do not establish a single winner for every mouth or a guaranteed reduction in future cavities.
There are stronger context-specific clinical recommendations for periodontal patients whose spaces accommodate a brush. Even there, the method must be fitted and taught. Good evidence for a category does not make an incorrectly sized tool useful.
It is also misleading to interpret limited long-term trial evidence as proof that cleaning between teeth has no purpose. The clinical question includes whether a person can remove plaque from their own hard-to-reach surfaces. Anatomy, dexterity and consistent use influence the practical result.
Bridges and fixed retainers
An ordinary strand of floss may not pass down from the biting edge where teeth are joined by a bridge or a fixed retainer. A threader, suitable specialised floss or a brush may provide another route. The bridge underside and gum margin around its supports both need attention.
Ask to see the route around the actual restoration. Forcing floss against a joined surface or using a sharp object to create a path can damage tissue or the restoration. If access seems impossible, this is information the dentist needs when assessing cleanability.
Persistent food trapping is a separate reason for assessment. Changing tools may help, but it does not establish that a contact, margin or restoration shape is satisfactory. A new problem around an old bridge should not be dismissed because the bridge has been there for years.
Implants and orthodontic appliances
An implant crown, a short implant bridge and a full-arch restoration have different contours. An aid that reaches one design may not clean another. Some brushes have coated wires intended for use around implants, but product choice and fit should be checked rather than inferred from the word “implant” on a packet.
Implants cannot develop decay, but their surrounding tissues can become inflamed. Bleeding or a persistent change around an implant requires assessment as well as cleaning advice. The implant aftercare guide discusses maintenance as part of long-term care.
With fixed braces, a small brush may help around wires and brackets, while other spaces may need a different aid. Cleaning around the appliance does not replace reaching the tooth surfaces and gumline. Instructions from the treating team should account for the particular appliance and any recent procedure.
What if cleaning makes the gums bleed?
Inflamed gums can bleed when first cleaned properly, and a rough technique can also injure tissue. Bleeding alone does not show which explanation applies. Check whether the brush is being forced or floss is hitting the gum sharply, and ask for a technique review.
Do not abandon every bleeding area for weeks. Persistent plaque can maintain inflammation. Equally, do not keep forcing a painful tool because you have read that bleeding should be ignored until the gums become used to it. Repeated bleeding, swelling, discharge or a loose tooth needs assessment.
The bleeding-gums guide explains why the amount of blood is not a diagnosis. If an area is acutely painful or ulcerated, seek individual advice about how to care for it while the cause is assessed.
Water flossers and other aids
An irrigator can be helpful for some people, especially when access or hand control is difficult. It does not follow that every water device is an equivalent replacement for all contact cleaning in every clinical situation. Ask which surfaces need direct cleaning and what an irrigator is intended to add.
Rubber picks, holders and other devices may be easier for some users. Their shape and size still need to suit the spaces. Do not improvise with sharp household objects or assume that scraping until the gum feels sore is a sign of adequate cleaning.
Someone helping another person with care may need a different setup from a person cleaning their own teeth. Tell the dental team about limited movement, reduced vision, difficulty gripping a handle or a strong gag reflex. Practical instruction should accommodate those limitations rather than prescribe a method that cannot be carried out.
When a chosen tool still does not reach the surface
If an aid repeatedly fails at one site, describe the exact difficulty. It may stop at a tight contact, pass through without useful bristle contact, or fit in one direction but not another. Those are different problems. A recommendation to use a brush is incomplete unless the person can locate a suitable route and repeat it.
An area can become easier to reach as inflammation reduces, or a different size may be needed after treatment. Ask for reassessment if the original fit changes. Do not automatically choose a larger tool to chase a gap or return to a smaller one solely because a deposit makes passage difficult.
The aim is access to the tooth surfaces, not to force the gum into a new shape. If there is a new gap, a change in tooth position or a persistent inability to clean around dental work, the area needs examination. Product trial and error cannot establish whether the contact, periodontal support or restoration has changed.
If several sizes are advised, ask the professional to identify which spaces each size is intended for. A simple personalised explanation is easier to use than a general instruction to clean every tooth with the same motion.
Timing, frequency and an achievable routine
The ADA generally recommends cleaning between teeth daily alongside twice-daily fluoride brushing. The time of day can be chosen for consistency. NHS advice suggests flossing before brushing, while ADA guidance accepts either order if cleaning is thorough. These recommendations need not become a barrier to doing the cleaning at all.
If evening care is easier, keep the tools where they will be used. If tiredness makes the routine unreliable, another time may work better. A personal plan after surgery or for a particular restoration can differ, so follow the instructions relevant to that situation.
Use and care for devices according to their instructions. Worn or damaged bristles, a bent wire or frayed floss are reasons to change the item rather than push harder. Do not assume that all products are intended to be reused in the same way.
What to ask at a technique review
Ask which spaces need floss, which accommodate a brush and whether more than one size is required. Have the method demonstrated, then show how you would repeat it yourself. This can reveal a handling problem that a verbal description misses.
Bring the devices you already use. Tell the professional which sites hurt, catch food or remain difficult despite daily cleaning. If inflammation persists, ask whether the next step is a different technique, a restoration assessment or periodontal treatment. Repeatedly buying additional products is not a substitute for finding out why one area remains a problem.
References
- American Dental Association: Dental floss and interdental cleaners. Tool selection, daily use and limits of the comparative evidence.
- SDCEP: Oral hygiene aids. Individually fitted brushes and alternatives in periodontal care.
- EFP: Step 4, supportive periodontal care. Interdental care in the maintenance context rather than a universal product recommendation.
General dental information. An examination is needed for individual diagnosis and treatment planning.