The short answer: The two habits with the strongest evidence are brushing twice a day with a fluoride toothpaste and cutting down how often you have sugary foods and drinks. Spit out the toothpaste rather than rinsing, clean between your teeth daily, and keep sweet snacks and drinks to mealtimes. Sealants and fluoride varnish give extra protection, especially for children, and sugar-free gum may help a little. See your dentist at the interval they recommend for your risk, so early decay can be caught while it can still be reversed.
Cavities form when bacteria in plaque feed on sugars and produce acids that draw minerals out of the enamel; fluoride works mainly by slowing that mineral loss and helping weakened enamel rebuild itself, a process called remineralization (Featherstone, 2000). Untreated tooth decay in permanent teeth is the most common health condition in the world (World Health Organization, 2025), yet much of it can be prevented with a few well-studied habits.
This guide sets out eight steps, explains the evidence behind each one, and covers what to do if you get cavities often, have a dry mouth or are looking after a child’s teeth.
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What are the best ways to prevent cavities?
These are the eight steps covered below:
- Brush twice a day with fluoride toothpaste
- Spit, don’t rinse, after brushing
- Clean between your teeth once a day
- Cut down how often you have sugar
- Ask about sealants and fluoride varnish
- Use fluoride mouthwash if you are at higher risk
- Chew sugar-free gum after meals
- Don’t smoke, and see your dentist regularly
How often should you brush to prevent cavities?
Twice a day, for two minutes, with a fluoride toothpaste and a soft-bristled brush (American Dental Association, 2024; American Dental Association, 2026b). A Cochrane review found that fluoride toothpaste prevents cavities better than non-fluoride toothpaste in children, teenagers and adults (Walsh et al., 2019). Frequency matters too: in a meta-analysis of 33 studies, people who brushed infrequently had 50% higher odds of developing new cavities than frequent brushers (odds ratio 1.50) (Kumar et al., 2016).
Spit, don’t rinse
For adults, the NHS recommends a toothpaste with at least 1,350 ppm fluoride. After brushing, spit out the excess but don’t rinse with water, so that the concentrated fluoride stays on your teeth (NHS, 2025a). Our guide to fluoride for teeth explains toothpaste strengths, and the daily dental hygiene routine walks through each step.
Does flossing prevent cavities?
The ADA recommends cleaning between your teeth once a day (American Dental Association, 2024), because plaque left there can harden into tartar that only a dental professional can remove (American Dental Association, 2026a). Most of the trial evidence concerns gum inflammation rather than cavities: a Cochrane review found that flossing plus brushing may reduce gingivitis compared with brushing alone, based on low-certainty evidence (Worthington et al., 2019). See how to floss for technique.
How does sugar cause cavities, and how much is too much?
Sugar is the fuel for the acid-producing bacteria in plaque (Featherstone, 2000). A systematic review carried out for the World Health Organization found moderate-quality evidence that tooth decay is lower when free sugars make up less than 10% of daily energy (Moynihan & Kelly, 2014), and the WHO recommends keeping free sugars below 10%, ideally below 5% (World Health Organization, 2015).
How often you have sugar matters as well as how much, so keep sugary foods and drinks to mealtimes rather than snacking or sipping through the day (Office for Health Improvement and Disparities, 2025). Acidic drinks such as soda and fruit juice can also wear away enamel; rinsing with water afterward helps, and the ADA suggests waiting before you brush (American Dental Association, n.d.). Our guide to foods for healthy teeth has practical swaps.
Do sealants and fluoride varnish prevent cavities?
Yes, especially in children. Sealants are thin coatings painted onto the grooves of the back teeth. A Cochrane review found that resin sealants on the permanent molars of children aged 5 to 10 prevented decay: if 40% of unsealed surfaces decayed over 2 years, sealing would cut that to about 6%, based on moderate-quality evidence (Ahovuo-Saloranta et al., 2017).
Fluoride varnish, painted on by a dentist or hygienist, was linked to 43% fewer decayed, missing or filled surfaces in permanent teeth and 37% fewer in baby teeth, also based on moderate-quality evidence (Marinho et al., 2013). For adults at high risk, particularly with exposed roots, an ADA guideline recommends a prescription 5,000 ppm fluoride toothpaste for early root cavities (Slayton et al., 2018).
Does fluoride mouthwash help prevent cavities?
It can, for people at higher risk. A Cochrane review found that children and teenagers who used a fluoride mouthrinse regularly under supervision had 27% fewer decayed, missing or filled surfaces in their permanent teeth (Marinho et al., 2016), and the ADA notes strong evidence for fluoride rinses in children at higher risk of cavities (American Dental Association, 2024). For most adults it is optional. If you use one, choose a different time from brushing, such as after lunch, because rinsing straight after brushing washes away the fluoride from your toothpaste (NHS, 2025a).
Does chewing gum prevent cavities?
Sugar-free gum may help a little. Chewing stimulates saliva, which washes away food and contains minerals that help protect teeth (National Institute of Dental and Craniofacial Research, 2024). A meta-analysis of 12 trials found that sugar-free gum reduced new decay by about 28%, but the authors described the evidence as tentative because of differences between the trials (Newton et al., 2020).
Xylitol gum is often promoted as the best choice, but a Cochrane review found little reliable evidence that xylitol products other than toothpaste prevent cavities (Riley et al., 2015), and an observational study has linked high blood xylitol levels to major cardiovascular events such as heart attack and stroke, which needs more research (Witkowski et al., 2024). Any sugar-free gum will do. Our article on chewing gum and your teeth covers the details.
Does smoking cause cavities?
Smokers tend to have more tooth decay than non-smokers, although the studies behind this finding are not very representative (Jiang et al., 2019). Smoking also doubles the risk of gum disease (Centers for Disease Control and Prevention, 2025), and avoiding tobacco helps if you have a dry mouth (National Institute of Dental and Craniofacial Research, 2024).
How often should you see a dentist to prevent cavities?
At the interval your dentist recommends for your risk. The ADA supports tailoring check-ups to each person (American Dental Association, 2024), and a Cochrane review found little to no difference in cavities or gum bleeding between 6-month and risk-based check-ups for adults who attend regularly (Fee et al., 2020). Check-ups matter because early decay can often be stopped without a filling; see can a cavity heal on its own? and how dentists find cavities early.
What it means for you
If you get cavities often
Ask your dentist whether you are at high risk and whether fluoride varnish, a fluoride mouthwash or a prescription-strength toothpaste would help (Marinho et al., 2013; Slayton et al., 2018). Look hard at how often you snack or sip sugary drinks (Office for Health Improvement and Disparities, 2025).
If you have a dry mouth
Saliva protects your teeth, so a dry mouth raises your risk. Sip water, chew sugar-free gum and avoid tobacco (National Institute of Dental and Craniofacial Research, 2024). Our guide to saliva and dry mouth covers causes and relief.
If you’re caring for a child
Sealants and fluoride varnish have their strongest evidence in children (Ahovuo-Saloranta et al., 2017; Marinho et al., 2013). Our parent’s guide to kids’ teeth covers toothpaste amounts by age and the first dental visit.
Questions to ask your dentist
- Am I at low, moderate or high risk of cavities?
- Would fluoride varnish or a higher-strength toothpaste help me?
- Should my children have sealants on their back teeth?
- Do I need a fluoride mouthwash, and when should I use it?
- How often should I come back for check-ups?
When to see a dentist
Book a dental visit if (NHS, 2025b):
- You have toothache or a sharp pain when eating or drinking hot, cold or sweet things
- You notice white, brown or black spots on a tooth
- Your gums are painful, swollen or bleed when you brush
For a knocked-out or broken tooth, facial swelling or other urgent problems, see what to do in a dental emergency.
The bottom line
Brushing twice a day with fluoride toothpaste, spitting rather than rinsing, and cutting down how often you have sugar are the foundations of preventing cavities. Sealants and fluoride varnish add strong protection for children, fluoride mouthwash helps people at higher risk, and sugar-free gum may help a little. Regular check-ups at a risk-based interval catch early decay while it can still be reversed (Walsh et al., 2019; Moynihan & Kelly, 2014; Fee et al., 2020).
References
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American Dental Association. (n.d.). Dietary acids and your teeth. MouthHealthy. https://www.mouthhealthy.org/all-topics-a-z/dietary-acids-and-your-teeth/
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References checked October 2026 · Editorial policy · Report a correction
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