Is It a Cavity? Why Your Tooth Is Decaying & What to Do Next

If you're wondering whether that tooth sensitivity, dark spot, or sudden pain is a cavity, you're not alone. Cavities are one of the most common health conditions worldwide — and the good news is that they're treatable, especially when caught early.

Let's walk through what a cavity is, why tooth decay happens, what signs to look for, and what medical steps you should consider next.

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What Is a Cavity?

A cavity (also called dental caries or tooth decay) is a permanently damaged area in the hard surface of your tooth that develops into a tiny hole or opening.

Your teeth are covered by a protective outer layer called enamel. When that enamel breaks down, bacteria and acid can erode deeper layers of the tooth. Over time, this damage creates a cavity.

Cavities do not heal on their own once a hole has formed. However, early tooth decay can sometimes be reversed before it turns into a true cavity.

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Why Is Your Tooth Decaying?

Tooth decay happens because of a combination of bacteria, food, and time.

Here's how it works:

1. Bacteria live in your mouth naturally.
2. When you eat sugary or starchy foods, bacteria feed on those sugars.
3. The bacteria produce acid as waste.
4. That acid attacks your enamel.
5. Repeated acid attacks weaken enamel and eventually form a cavity.

Common Causes of a Cavity

Several factors increase your risk of developing a cavity:

• Frequent snacking or sipping sugary drinks
• Poor brushing or flossing habits
• Dry mouth (low saliva production)
• Receding gums
• Not getting enough fluoride
• Previous cavities
• Cracked or damaged teeth
• Braces or dental appliances that trap food

Saliva normally helps wash away food particles and neutralize acids. When saliva production drops — due to medications, dehydration, or medical conditions — your risk of a cavity increases.

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Signs You Might Have a Cavity

Not all cavities cause pain right away. In fact, early decay can be completely painless.

Watch for these symptoms:

• Tooth sensitivity to hot, cold, or sweets
• Mild to sharp tooth pain
• A visible hole in the tooth
• Brown, black, or white staining
• Pain when biting down
• Bad breath that doesn't go away
• A rough or chipped area you can feel with your tongue

If decay reaches deeper layers of the tooth (the dentin or pulp), the pain can become more intense and persistent.

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When Is a Cavity Serious?

A cavity becomes serious when it spreads deeper into the tooth and affects the pulp — the inner part that contains nerves and blood vessels.

If untreated, a cavity can lead to:

• Severe toothache
• Infection
• Dental abscess (a pocket of pus)
• Swelling in the face or jaw
• Fever
• Tooth loss

In rare cases, untreated dental infections can spread to other areas of the body and become life-threatening. This is uncommon, but it's important not to ignore worsening symptoms.

Seek urgent care if you experience:

• Facial swelling
• Trouble swallowing or breathing
• High fever
• Severe, throbbing pain

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Can a Cavity Heal on Its Own?

Once a true cavity (a hole in the tooth) has formed, it cannot repair itself.

However, early-stage tooth decay — before a hole forms — may be reversed with:

• Fluoride treatments
• Improved brushing and flossing
• Reducing sugar intake
• Professional dental cleanings

The earlier you catch decay, the easier and less invasive treatment will be.

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Medical Next Steps: What Should You Do?

If you suspect you have a cavity, here's what to do:

1. Evaluate Your Symptoms

If you're experiencing tooth pain, sensitivity, or visible changes to your teeth, it's helpful to understand what might be causing them. You can use Ubie's free AI-powered Dental Caries symptom checker to get personalized insights about your symptoms in just a few minutes — no appointment needed.

2. Schedule a Dental Exam

A dentist can confirm whether you have a cavity using:

• Visual examination
• Dental probes
• X-rays to detect hidden decay

Even if symptoms are mild, a dental visit is important. Early treatment is simpler, faster, and less expensive.

3. Treatment Options

Treatment depends on how advanced the cavity is.

For early decay:

• Fluoride varnish or gel
• Prescription-strength fluoride toothpaste

For small to moderate cavities:

• A dental filling (the decayed part is removed and replaced with material such as composite resin)

For larger cavities:

• A crown (a cap placed over the damaged tooth)

If the pulp is infected:

• Root canal treatment (removal of infected pulp tissue)

If damage is too severe:

• Tooth extraction

Most cavity treatments are routine and very manageable with modern dentistry.

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How to Prevent a Cavity

Prevention is highly effective and often simple.

Daily Habits That Protect Your Teeth

• Brush twice daily with fluoride toothpaste
• Floss once daily
• Limit sugary snacks and drinks
• Drink water after meals
• Chew sugar-free gum to stimulate saliva
• Avoid frequent sipping of acidic beverages

Professional Prevention

• Get dental cleanings every 6 months (or as recommended)
• Ask about fluoride treatments
• Consider dental sealants for molars (especially for children)

Consistency matters more than perfection. Small daily habits make a big difference over time.

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Who Is at Higher Risk?

Certain groups are more likely to develop a cavity:

• Children and teenagers
• Older adults (especially with receding gums)
• People with diabetes
• Individuals taking medications that cause dry mouth
• People with a history of multiple cavities

If you fall into one of these groups, regular dental checkups are especially important.

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Should You Be Worried?

A cavity is common and treatable. It's not something to panic about — but it is something to take seriously.

Ignoring tooth decay doesn't make it go away. It almost always gets worse over time. Early action prevents more invasive procedures later.

Think of a cavity like a small leak in a roof: it's easier to patch early than to repair major water damage later.

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When to Speak to a Doctor or Dentist

You should speak to a dentist if you have:

• Persistent tooth pain
• Sensitivity that doesn't improve
• Visible holes or dark spots
• Swelling or gum tenderness

Seek urgent medical care if you develop:

• Fever
• Facial swelling
• Difficulty swallowing
• Difficulty breathing

While most cavities are straightforward to treat, untreated dental infections can become serious. If anything feels severe, worsening, or unusual, speak to a doctor immediately.

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The Bottom Line

A cavity is a common but progressive condition caused by acid damage to your tooth enamel. It often starts silently and becomes more noticeable as it worsens.

Tooth decay happens due to:

• Bacteria
• Sugar exposure
• Acid production
• Inadequate oral hygiene

The earlier you act, the simpler the solution.

If you're unsure whether your symptoms indicate a cavity or another dental issue, try using a free Dental Caries symptom checker to help guide your next steps, then follow up with a dental professional for proper diagnosis and treatment.

Most importantly, don't ignore persistent pain or swelling. Speak to a dentist or doctor about any symptoms that could be serious or life-threatening.

Taking action now can protect not just your smile — but your overall health.