Ask a Dentist, Gums, gums & teeth, Health

Cavities and Decay Explained

Cavities, Explained

Q&A With Dr. Chrystle Cu


What's a cavity?

A cavity is an area of the tooth that is permanently weaker and decayed, i.e. "demineralized".  Cavities can be literal holes (cavitation), or soft spots.


What causes a cavity?

Acid.  Oral bacteria uses carbs in your diet to make acid. These acids can eat away at your teeth, forming weak spots and holes.


How do I know if I'm at high risk for tooth decay?

All of these can increase your risk for new tooth decay:  

  • not brushing/flossing
  • frequent snacking (especially carbs and candies)
  • soda, energy drinks and juices
  • history of recent cavities
  • exposed roots of teeth (caused by receded gums)
  • dry mouth
  • antidepressants
  • alcohol and/or drug use
  • digestive problems like acid reflux
  • eating disorders like bulimia


How do I know if I have a cavity? 

You may have one or some of the following:

  • Toothache
  • Sensitivity
  • Pain when eating or drinking sweets
  • Pain to hot or cold
  • Visible holes or pits
  • Dark areas (black, brown) on your tooth
  • No symptoms


How are cavities diagnosed?

Your dentist can diagnose cavities with a clinical examination and/or dental x-rays.  The clinical diagnosis involves both visual and tactile examination, using special instruments meant for finding cavities.  X-rays can show cavities in between teeth, which otherwise might not be found in the clinical examination.  X-rays can also be used to determine the extent of the decay.


Where do cavities most commonly form?

  • In between our teeth — at the points where teeth are in contact with each other.
  • In the naturally deep pits and fissures of our teeth.
  • Wisdom teeth.
  • Exposed root surfaces of teeth.

Can I catch cavities from someone else?

Not really.  However, cavities-causing bacteria can be passed from one person to another.  Mouths with active decay have an increased quantity of cavities-causing bacteria.  


Should I change my diet?

Generally, sugary foods and drinks can increase your risk for tooth decay (and diabetes!) but you should still be able to enjoy these things in moderation if you thoroughly brush and floss after consumption.


How can I prevent cavities?

  • Brush at least twice a day, floss at least once a day.  
  • Brush and floss after eating processed, sugary foods and candies.
  • Drink more water.
  • See your dentist for regular check-ups.  Cavities don't happen overnight.  It helps to see early if you have any areas of demineralization on your teeth.  
  • Ask your dentist for sealants.  Sealants are minimally invasive and preventive; they block off natural grooves and pits of teeth from sugar and bacteria.

    Are there any natural remedies?

    Maintaining a clean mouth and eating a healthy, balanced diet can reduce risk and possibly even slow down tooth decay.  Once a tooth already has a brown, soft, or cavitated spot, the only way to definitively and esthetically restore the tooth would be with a filling placed by your dentist.  


    How do genetics affect my risk for cavities?

    Certain caries risk factors can be inherited:

    • Teeth anatomy — teeth with naturally deep pits and fissures can be more prone to decay.
    • Crowding — very crowded areas of teeth can be harder to keep clean
    • Saliva flow — lower saliva flow can reduce your ability to buffer your oral pH and increase your risk of cavities.
    • Bacterial flora — caries-causing bacteria can be acquired from our parents and caregivers.  (Not genetically.)


    How does the PH of my mouth increase cavity risk?

    Acidic (low) pH increases ones risk for cavities. Our mouths contain both healthy bacteria and cavity-causing (acidogenic or acid-producing) bacteria. Many of the healthy bacteria are inhibited or killed by frequent or prolonged exposure to acidic conditions, enabling the bad bacteria to thrive.  

    Furthermore, when pH is low, minerals get pulled away from the tooth structure.  After a while, the weaker demineralized spot becomes a hole.  Remember high school chemistry class?  Spilling acid = hole in your jeans.  The same thing happens to teeth when they're exposed to very acidic conditions. 

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