Why Some People Get More Cavities Than Others — Even When They Brush

Have you ever felt frustrated after hearing your dentist say you have a new cavity — even though you brush and floss every day? You’re not alone. Some people seem to be more prone to tooth decay no matter how careful they are, while others breeze through check-ups with barely a filling in sight.

It might not seem fair, but there’s more to cavity prevention than just brushing your teeth. From genetics to diet, saliva and even how your teeth are shaped, many factors can influence your risk.

Let’s unpack why some people get more cavities than others — and what you can do to stay ahead of decay.

1. Not All Teeth Are Created Equal

The shape and alignment of your teeth can play a big role in how well you’re able to clean them. Deep grooves and pits in the chewing surfaces of molars, or crowded and overlapping teeth, can make it harder to remove plaque and food debris.

Even if you’re brushing thoroughly, some areas may be consistently missed. That’s why people with certain tooth shapes or bite issues may be more prone to decay, especially in hard-to-reach spots.

What you can do:

• Ask us if fissure sealants are right for you — they can help protect deep grooves.
• Use floss or interdental brushes daily to clean between crowded teeth.

2. Your Saliva Matters More Than You Think

Saliva does more than just keep your mouth moist — it neutralises acids, washes away food particles, and helps repair early signs of enamel erosion. If you have a dry mouth (called xerostomia), your risk of cavities increases significantly.

Dry mouth can be caused by certain medications, mouth breathing, dehydration, or medical conditions like Sjogren’s syndrome.

What you can do:

• Stay hydrated throughout the day.
• Chew sugar-free gum to stimulate saliva.
• Let us know if your mouth often feels dry — we can recommend saliva substitutes or other treatments.

3. Diet Plays a Big Role (Even Healthy Ones)

It’s not just lollies and soft drinks that cause decay. Frequent snacking on carbs — even things like crackers, fruit, or muesli bars — feeds the bacteria in your mouth and keeps acid levels high. The more often you eat, the less time your mouth has to recover.

Sticky foods, in particular, tend to linger on teeth and are harder to rinse away with saliva alone.

What you can do:

• Limit snacking between meals.
• Rinse your mouth with water after eating.
• Be mindful of dried fruit and other “healthy” snacks that cling to teeth.

4. Your Bacteria Are Unique to You

Just like your gut, your mouth has a microbiome — a mix of good and bad bacteria. Some strains are more aggressive when it comes to breaking down sugar and producing acid.

These bacteria can be influenced by childhood habits, the environment you grew up in, and even how your parents cared for your teeth when you were little.

What you can do:

• Keep up your oral hygiene routine consistently.
• Consider using a probiotic toothpaste or oral rinse (ask us for advice first).

5. Fluoride Exposure Varies

Fluoride strengthens enamel and helps prevent decay, but not everyone gets the same amount. Some areas don’t have fluoridated tap water, and people who avoid fluoride toothpaste (or rinse their mouth out right after brushing) may not be getting the full benefit.

What you can do:

• Use a fluoride toothpaste twice a day.
• Avoid rinsing with water immediately after brushing to let the fluoride sit on your teeth longer.
• Ask us if additional fluoride treatments are right for you.

6. Medical Conditions and Medications Can Influence Risk

Certain conditions — like diabetes, acid reflux, or autoimmune diseases — can increase cavity risk, either by changing saliva flow, increasing acidity, or altering your immune response.

Similarly, many medications list dry mouth as a side effect.

What you can do:

• Let us know your full medical history and any medications you’re taking.
• Manage chronic conditions with support from your GP.

The Bottom Line: Brushing Is Essential — But It’s Not Everything

Brushing and flossing are your first line of defence, but they’re only part of the picture. Understanding your unique risk factors — and working with us to stay ahead of them — is the best way to prevent cavities long term.

If you feel like you’re doing everything right but still getting decay, don’t get discouraged. There’s often an explanation, and there’s always something we can do to help.

Come and see us for a personalised approach to prevention. We’ll help you protect your smile — and keep those frustrating surprise fillings to a minimum.