Child Getting Cavities Despite Brushing? Here’s What to Know
Updated: Sep 30
It’s easy to think, “Maybe my child is not brushing properly.” But don’t be too quick to blame them. You’re not the only parent who follows a good brushing routine and is still dealing with childhood cavities.
The Canadian Dental Association (CDA) describes early childhood tooth decay as a complex, multifactorial condition influenced by factors including diet, oral bacteria, the child’s individual susceptibility, and social determinants of health.
So, if your child keeps getting cavities despite regular brushing, there may be more going on. Here are some common reasons and a few things you can try at home.
What Causes Cavities in Children?
Cavities happen when bacteria such as Streptococcus mutans and Streptococcus sobrinus use sugars and starches from food and drinks to produce acids, especially lactic acid. These acids can damage tooth enamel and, over time, can create a hole or cavity in the tooth. In children, several factors can increase this risk:
1. Brushing Alone May Not Be Enough
Your child may brush twice a day, but that doesn’t always mean every part of the mouth is being cleaned properly. This is especially common with young children. They may rush through brushing, skip between teeth or back teeth, focus mostly on front teeth or have difficulty reaching the back molars.
What parents can do
You can try to make brushing a shared routine:
Make bedtime brushing non-negotiable because during sleep saliva flow decreases
Help your child reach the back teeth by opening wide and gently brushing.
Brush gently along the gumline through gentle movements
Spend enough time, like 2 minutes, cleaning every tooth surface.
Replace the toothbrush when the bristles become worn because it may not clean teeth effectively.
Continue supervising brushing until your child can clean their teeth properly.
Important: Have children's toothbrushes that are small enough to reach the back of the mouth comfortably.
CDA notes that cavities can develop in deep tooth grooves and between teeth, where brushing may not reach well. So, even if your child brushes regularly, plaque can still hide in these hard-to-clean areas and cause cavities.
2. Your Child May Be Eating Sugar More Often Than You Realise
Do you know that it is not only the amount of sugar your child eats that matters? How often their teeth are exposed to sugar matters too.
Each sugary snack or drink can give cavity-causing bacteria another opportunity to produce acids that can weaken and remove minerals from the tooth enamel.
When these exposures happen repeatedly throughout the day, the Salvia and fluoride have less time to recover enamel between acid attacks.
Some common sources of sugar include:
Juice
Soft drinks
Flavoured milk
Sweetened cereals
Cookies
Gummies
Candy
Chocolate
Dried fruit
Sweetened yogurt
Sticky snacks
Even foods that seem healthy can contain natural sugars or carbohydrates that oral bacteria can use. The bigger concern is how frequently your child’s teeth are exposed to them.
Nutrients Your Child’s Teeth Need
Nutrient | Why It Matters | Food Sources |
Calcium | Strengthens teeth and bones. | Milk, yogurt, cheese, tofu, beans |
Phosphorus | Supports strong teeth and bones. | Dairy, lentils, nuts, seeds, fish |
Vitamin A | Supports healthy gums and oral tissues. | Carrots, sweet potatoes, leafy greens, eggs |
Vitamin C | Helps maintain healthy gums and tissues. | Citrus fruits, berries, peppers, broccoli |
Vitamin D | Helps the body absorb calcium for healthy teeth and bones. | Fortified milk, eggs, fatty fish, fortified cereals. |
Tip: Instead of allowing your child to sip juice throughout the day, offer water between meals. If your child wants something sweet, have it with a meal.
3. Your Child May Not Be Cleaning Between Their Teeth
A toothbrush cannot effectively clean the front, back, chewing surface or area between teeth. The bristles may not reach the tight contact points between neighbouring teeth where plaque and food particles can remain.
If two teeth touch each other closely, plaque and food particles can remain trapped between them. With continued neglect, this can contribute to plaque, cavities, and gum inflammation.
This is why flossing or another appropriate interdental cleaning method can be important for children whose teeth touch. If you are unsure when or how to floss your child's teeth, ask a pediatric dentist to demonstrate the technique.
4. Your Child May Need More Fluoride Protection
Fluoride is an important part of cavity prevention because when it is present in the mouth it helps replace minerals lost from enamel during acid attack. It also makes teeth more resistant to future acid attack and the development of early signs of decay.
However, the right amount of fluoride depends on your child's age, cavity risk and other sources of fluoride such as drinking water, Fluoride toothpaste, mouth rinses, etc.
For example, the CDA recommends different toothpaste amounts and supervision based on age.
Age | Fluoride Toothpaste Amount | Parent Guidance |
Under 3 | Rice-sized | Adult brushing; ask a health professional if fluoride toothpaste is needed. |
3–6 years | Pea-sized | Supervise brushing and encourage spitting. |
6+ years | Appropriate amount | Supervise until the child can brush independently. |
Important: Parents should not give children additional fluoride supplements, rinses, or other fluoride products without professional advice.
5. Bedtime Brushing Is Especially Important
If you only have enough energy to make one brushing session extra consistent, make bedtime brushing a priority. Because nighttime saliva production decreases, leaving plaque and food sugars on the teeth overnight gives bacteria more opportunity to produce acids.
A simple routine can look like:
Dinner → water → brush → spit → bedtime
Try to make brushing the final oral-care step before sleep.
6. Your Child's Teeth May Have Deep Grooves
Look at the chewing surfaces of your child's back teeth.
You may notice tiny grooves, pits and fissures. These form naturally as back teeth develop. The chewing surfaces of molars are not flat; they have raised areas separated by tiny grooves and pits. Toothbrush bristles may not reach all the way into them because of their narrow and deep structure. Plus, they can trap food debris and plaque.
This is one reason why a child can have good brushing habits but still develop decay.
A pediatric dentist can examine these areas and determine whether your child has a higher risk of cavities.
Note: Some parents think cavities in baby teeth do not matter because they eventually fall out. But baby teeth are important for chewing, clear speech, and holding space for permanent teeth.
Why cavities keep happening → What parents can change → When to see a dentist → What a dentist can check
What Parents Can Change
If cavities are becoming a repeated problem, don't simply tell your child to “brush better.” Brushing is important, but sometimes cavity risk can be influenced by diet and frequency of sugar exposure, oral bacteria, fluoride exposure, tooth anatomy, previous cavities, oral hygiene habits, dry mouth, certain health conditions or medications.
Instead, look at the entire routine to find what may be contributing.
Start with these steps:
1. Check brushing technique: Watch your child brush rather than assuming they are cleaning the back teeth, the gumline or other hard-to-reach areas. It will help you spot missed areas and guide them on proper technique.
Step | How |
Gumline | Hold the brush at a 45° angle. |
Movement | Use small, gentle circles. |
All surfaces | Clean outer, inner and chewing surfaces |
Back teeth | Spend extra time on molars and grooves |
Duration | Brush for 2 minutes, twice daily |
Supervision | Help or check brushing until your child can do it properly. |
2. Make bedtime brushing consistent: Brush every night using an age-appropriate amount of fluoride toothpaste based on your dentist's advice. Because every tooth, fluoride treatment, and product is different.
3. Look at snacks and drinks: Pay attention to how often your child has juice, sweet drinks, candy and sticky snacks to reduce repeated acid attacks and cavity risk.
4. Choose water between meals: Plain water does not contain sugar, so these cavity-causing bacteria do not get that same fuel from drinking water. It can also help wash away food particles and dilute acids in the mouth.
5. Clean between teeth: Ask your dentist if your child needs to floss every day or use another way to clean between their teeth. However, the interdental method can also vary depending on the child’s age, spacing between teeth, braces, and cavity risk.
6. Keep regular dental visits: Your dentist can check teeth closely, including back teeth, grooves, gumline and areas between teeth that are difficult to clean. They monitor early changes that may not be easy to notice at home.
7. Ask about fluoride: Ask the dentist, “How much fluoride protection does my child need based on their cavity risk?” This will help you get an idea of whether your child simply needs fluoride toothpaste or fluoride treatment based on cavity risk.
When To See a Dentist?
Make a dental appointment if you notice:
White, brown or dark spots on the teeth
A visible hole or rough area
Tooth sensitivity
Pain while eating or drinking
Swollen gums
Facial swelling
Bad breath that does not go away
Difficulty chewing
A child avoiding certain foods because of tooth discomfort.
A regular dental visit is very important to identify early signs of decay before cavities become visible or painful.
Protect Your Child’s Smile Beyond Brushing
Healthy smiles start early.
Good brushing, smart food and drink choices, fluoride protection, cleaning between teeth, and regular dental checkups all play a role. Together, these habits can help reduce cavity risk and keep your child’s teeth strong and healthy.
At Sullivan Dentistry, Dr Sepideh Maleki and her pediatric dental care team look beyond brushing habits and evaluate diet, enamel quality, bite development, and overall oral health.
Since 2019, we’ve focused on making children’s dental care in Scarborough simple and comfortable. With clear explanations, a calm approach, and practical guidance for home, we provide children’s dental exams, professional cleanings, fluoride treatments, and dental sealants to help protect young smiles.
Concerned about repeated cavities? Book your child’s dental checkup today.
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