Why Do I Keep Getting Cavities Even Though I Brush and Floss?

Article reviewed by:
Dr Tan Kian Meng• Prosthodontist

Quick Answers

You brush twice a day, floss every evening, and still end up needing another filling. If that sounds familiar, you are not alone.

While good oral hygiene is one of the best ways to protect your teeth, it isn’t the only factor that affects whether cavities develop. Your diet, how often you snack, your saliva, the shape of your teeth and even certain medications can all play a part and contribute to tooth decay.

Tooth decay remains a common oral health problem in Singapore, with the 2019 National Adult Oral Health Survey reporting that 34.8% of adults had untreated dental cavities.

Understanding what’s driving your risk is the first step towards preventing future decay.v

Key Takeaways

• Brushing and flossing alone may not prevent cavities.
• Diet and how often you eat can have a significant impact on tooth decay.
• Dry mouth increases the risk of cavities because saliva helps protect teeth.
• Regular dental check-ups can detect early signs of tooth decay before they worsen.
• A personalised prevention plan can help reduce recurring cavities.

What Causes Dental Cavities?

Cavities don’t appear overnight. They develop gradually when plaque bacteria feed on sugars and starches left behind after eating or drinking.

As these bacteria break down food, they produce acids that repeatedly attack the tooth surface. Normally, saliva helps repair this early damage by replacing lost minerals. But when these acid attacks happen too often, the enamel doesn’t have enough time to recover (a process called demineralisation). Eventually, a permanent hole forms in the tooth, which is what dentists call a cavity.

6 Reasons You Keep Getting Cavities Even Though You Brush and Floss

If you’re brushing and flossing consistently but still getting cavities, one or more of these factors may be responsible.

1. Too Much Sugar or Refined Carbohydrates

Brushing removes plaque, but it can’t stop every acid attack that happens throughout the day.

Each time you eat or drink something containing sugar or refined carbohydrates, bacteria in your mouth produce acids that can attack your teeth for up to 60 minutes. If this happens repeatedly, your enamel spends more time losing minerals than repairing itself.

Many people are surprised to learn that even foods considered “healthy,” such as fruits, can contribute to acid production in the mouth.

Foods that can contribute to tooth decay include:

• Sweets and chocolates
• Cakes and pastries
• Soft drinks
• Bubble tea and sweetened beverages
• Sports and energy drinks
• Fruit juices
• White bread
• Crackers
• Chips
• Dried fruits

2. Frequent Snacking and Sugary Drinks

It’s not only what you eat that matters, but how often you eat.

Frequent snacking or slowly sipping sweet drinks means your teeth rarely get a break from acid attacks. Even if the total amount of sugar isn’t especially high, frequent exposure throughout the day makes it harder for your enamel to recover naturally.

Instead of grazing continuously, try to:

• Eat balanced meals at regular times.
• Limit sugary snacks between meals.
• Drink plain water after eating.
• Avoid sipping sweet beverages slowly for long periods.

3. Dry Mouth

Saliva is one of your mouth’s natural defence systems. It helps rinse away food particles, neutralises acids produced by bacteria and supplies minerals that strengthen tooth enamel.

When your mouth feels dry, those protective effects are reduced. As a result, plaque builds up more easily and cavities can develop faster. the risk of cavities increases as well.

Medications, dehydration, mouth breathing or certain medical conditions may cause dry mouth. If you’re experiencing persistent dry mouth, it’s worth discussing with your dental specialist.

4. Plaque in Hard-to-Reach Areas

Although brushing and flossing are important, they may not always remove plaque effectively if:

• Your brushing technique is incorrect.
• You rush your brushing.
• You miss difficult areas, such as the back molars.
• Your teeth are crowded or overlapping.
• You have existing dental restorations that require extra care.

Your dentist can demonstrate proper brushing and flossing techniques and recommend tools such as interdental brushes or water flossers if appropriate.

5. Genetics

Some people appear to develop cavities more easily than others, even when their oral hygiene is similar.

Genetics may partly explain this. The strength of your enamel, the shape of your teeth, how much saliva you produce and even the types of bacteria that naturally live in your mouth can all vary from person to person.

Even so, these inherited factors usually have less influence than everyday habits. A balanced diet, good oral hygiene and regular dental care remain the most effective ways to reduce your risk.

6. Existing Fillings or Crowns May be Leaking

A tooth that has already been repaired isn’t immune to future decay.

Older fillings, crowns or dental restorations can develop tiny gaps over time. These spaces allow bacteria to collect beneath the restoration, leading to new decay that may not be visible until it becomes larger.

Regular dental examinations and X-rays can help detect these hidden cavities early before they cause pain or require more extensive treatment.

How Can You Prevent Cavities?

Preventing cavities usually requires looking beyond your toothbrush.

Daily brushing and flossing remain the foundation of good oral health, but they’re most effective when combined with healthy eating habits and regular professional care.

To help reduce your risk:

• Brush your teeth twice daily using fluoride toothpaste.
• Floss once a day to remove plaque between teeth
• Limit sugary foods and drinks between meals
• Drink plenty of water instead of sweetened beverages
• Avoid frequent snacking throughout the day
• Visit your dentist regularly for regular dental examinations and cleanings

When Should You See a Dentist?

Cavities are much easier to treat when they’re found early.

In many cases, tooth decay begins without causing any discomfort. Regular dental examinations allow your dentist to detect these early changes before they develop into larger cavities that require more extensive treatment.

Schedule a dental appointment if you notice:

• Tooth sensitivity
• Pain when eating sweets
• Food trapping between teeth
• Persistent bad breath
• Dark spots or visible holes in a tooth
• Repeated cavities despite good oral hygiene

Frequently Asked Questions