The Australian Dental Association's patient site, teeth.org.au, advises replacing your toothbrush every three months, and the American Dental Association gives a similar figure of every three to four months, or as soon as the bristles look frayed. Electric toothbrush makers give a similar guide for brush heads, about every three months with twice-daily use. The bristles themselves are often a better guide than the calendar.
What happens to bristles over time
Bristles are made to be slightly flexible, so they can bend into the grooves of the teeth and sweep plaque from along the gum line. With twice-daily brushing they gradually lose that spring and start to splay outwards. Splayed bristles tend to slide over the surfaces they are meant to clean, especially the narrow areas between teeth and at the gum margin.
The research on how much this matters is mixed. In two studies reported in the Journal of Clinical Dentistry (Conforti and colleagues, 2003), a new manual brush removed more plaque between the teeth than a three-month-old one, although whole-mouth scores were similar. With a powered brush, only the most heavily worn heads were clearly less effective. A study of 93 children aged 7 to 9 in the Eastern Mediterranean Health Journal (Malekafzali and colleagues, 2011) found no significant difference between new and three-month-old brushes. Taken together, a brush in reasonable shape may still clean well at three months, while one that is badly splayed is likely to leave more plaque behind.
Check the bristles, not just the date
How fast a brush wears depends on how you brush. People who press hard can flatten a brush in a month or two, while a light technique may keep it in shape for longer. Look at the head from the side: once the bristles bend away from the centre or lose their shape, it is time for a new one, even if three months have not passed. Many electric brush heads have coloured indicator bristles that fade as the head wears, which can help you judge.
If your brush wears out very quickly, it may be a sign you are brushing too hard. Firm scrubbing wears the bristles, and although research on whether hard brushing causes gum recession is inconclusive, a soft brush and a gentle technique are the safer combination.
After an illness
Some guidance suggests a new brush after a cold or flu, although there is little evidence that reusing a brush causes reinfection. The American Dental Association notes that continuing to use the same brush after an illness does not typically lead to reinfection, because your body has built up antibodies. It does suggest replacing all the brushes in a shared holder if someone using it has been sick, and replacing your brush after a cold sore or if you are severely immunocompromised. Replacing a brush after being unwell is reasonable if it reassures you, but it is not essential for most people.
Situations that call for a new brush
| Situation | Suggested step |
|---|---|
| Normal daily use | Replace about every three months |
| Bristles splayed, flattened or out of shape | Replace now, whatever the date |
| A sick person has shared the toothbrush holder | Replace all the brushes in that holder |
| After a cold sore, or if severely immunocompromised | Replace the brush |
| Children who chew their brushes | Check often, as they wear faster |
| Electric toothbrush | Replace the head on the same schedule |
Keeping a brush clean between replacements
Rinse the brush well under running water after use, stand it upright and leave it uncovered so it can dry. The ADA notes that storing a brush upright and uncovered can help limit bacterial growth. Keep brushes apart in the holder so the heads do not touch, and avoid closed covers or cases for everyday storage, as they hold in moisture. Never share toothbrushes.
Manual and electric brushes both need regular replacement. If you are deciding between them, our comparison of electric versus manual toothbrushes sets out the evidence. If your gums bleed when you brush, our guide to bleeding gums explains what it can mean, and if your teeth are sensitive, see our advice on toothpaste for sensitive teeth.
Common questions
Is it harmful to keep using an old toothbrush?
A worn brush is unlikely to harm you directly, but a badly splayed one may not clean as well, particularly between the teeth.
Do electric brush heads last longer than manual brushes?
Not usually. Manufacturers generally advise replacing a head about every three months with twice-daily use, or sooner if the bristles are frayed or the indicator bristles have faded.
Should I soak my toothbrush in mouthwash or a sanitiser?
The ADA notes that the benefit of sanitising toothbrushes has not been well studied. Rinsing it well and letting it air dry upright is usually enough.
Help with your home care
Replacing your brush every few months, and sooner when the bristles fray, is one of the cheapest ways to keep your cleaning effective. At a check-up and clean at our Melrose Park practice, a dentist or OHT can look at how you brush and suggest changes. You can book a visit or see our current offers.
Sources
- Australian Dental Association (teeth.org.au): Brushing teeth
- American Dental Association (ADA News): When should patients replace their toothbrushes?
- Philips Australia: How often should I replace my Philips Sonicare brush head?
- Conforti NJ et al. An investigation into the effect of three months' clinical wear on toothbrush efficacy. Journal of Clinical Dentistry, 2003
- Malekafzali B et al. Comparison of plaque removal efficacy of new and 3-month-old toothbrushes in children. Eastern Mediterranean Health Journal, 2011
- Rajapakse PS et al. Does tooth brushing influence the development and progression of non-inflammatory gingival recession? A systematic review. Journal of Clinical Periodontology, 2007
This article is general information and not a substitute for personal dental advice. Please see a dentist for care tailored to your situation.
