Cavities, AKA dental caries or tooth decay, are caused by an acidic environment in the mouth. Acid dissolves tooth structure when the oral environment’s pH is lower than 5.5.

So how does the mouth’s pH get thrown off and become more acidic? Good question.

What you put in your mouth has a lot to do with it.

You’ve been told not to eat too much sugar, or you’ll get cavities. It’s not bad advice, but there’s’ more to it. The truth is, sugar by itself does not cause dental decay. Having naturally “soft teeth” is a myth.

NoBull Dental: Cavities are caused by acid, not sugar, which dissolves tooth structure.

Cavities are usually caused by:

  1. Bacteria in your mouth that metabolize sugar (and other starches) into acid 
  2. Foods and drinks that are acidic (like citrus juice, tomato juice, and sodas)
  3. Gastric reflux (GERD or heartburn), a condition that allows digestive acid to enter the mouth 
  4. Systemic or medication changes that increase acid in the oral environment

The Science

An acidic environment, most commonly caused by the foods we eat or from the byproduct created when bacteria metabolize sugars, dissolves the calcium and phosphorus that make tooth enamel hard.

A pH of less than 5.5 will demineralize tooth enamel. However, tooth enamel can be remineralized in an environment with a pH above 5.5. Calcium, phosphorus, or fluoride remineralize enamel. Fluoride also makes tooth enamel more resistant to low pHs. The speed of demineralization is dependent on how low the pH is and for how long a pH under 5.5 is maintained.


Fluoride treatment is the most common way to prevent cavities. Once cavities start, they can worsen and spread. Most dental decay is painless, which is why most people do not know it is there.

Advanced decay, not treated by a dentist, can result in tooth pain, as bacteria eventually make their way into the core of a tooth. Once the inner chamber of a tooth is penetrated by bacteria, the pulp becomes infected and the tooth may need root canal therapy or extraction. The good news is, tooth loss is preventable.

The best scenario is avoiding decay, but if a cavity develops, you’ll need a filling or crown.

NoBull Dental Tips

If you seem to regularly develop tooth decay, you should first rule out acid reflux and/or changes in systemic conditions or medications. Talk with your doctor about these issues.

Good advice for everyone to prevent tooth decay, from the time your baby teeth develop and for as long as you live, is to practice good oral health care at home. Brush your teeth well, for 2-3 minutes twice a day. Use only light force and a soft or medium bristle brush. Purchase a new toothbrush every three months. Opt for fluoride toothpaste and use antibacterial mouthwash if you like.

Also, floss at least once every other day, but preferably once a day before bed.

Fluoride is a mineral that strengthens enamel. Your dentist may suggest a fluoride treatment, especially if you’re prone to decay.

Children whose permanent teeth are still developing benefit from drinking fluoridated water. The fluoride in the water helps strengthen developing teeth. Too much fluoride ingested in this young population can result in fluorosis, white horizontal lines in tooth enamel that cannot be whitened.

Adults and children can benefit from topical fluoride, that’s why the ADA recommends you use fluoridated toothpaste. Adults should also use fluoridated water to rinse their mouths and have fluoride treatments at the dentist’s office.

See our section on dental sealants and why they may or may not be beneficial. These clear, plastic coverings painted on molars can create a barrier against bacteria and acids. Sealants can reduce the potential for cavities on molars,

Be mindful of the acidity and total contact time of foods you eat and drink. Drink as much water as possible throughout the day to neutralize acids in the mouth.

Rinse your mouth with water after snacks and meals. Water will wash away food particles and help re-stabilize the proper pH of saliva.

Still Have Questions?

Did you know?

  • Sugar by itself does NOT cause dental decay (cavities, caries)
  • Bottled water rarely contains fluoride
  • Flossing is thought to reduce the bacteria load in the mouth and therefore limit dental decay, but this has yet to be proven
  • A pH of 5.5 or lower will cause teeth to dissolve so cavities can form
  • There is no such thing as soft teeth
  • The concept of soft teeth is a myth
  • Absent very rare genetic conditions, everyone’s teeth, like our skin, start out at pretty much the same density
  • It is the oral environment and our habits that differ
  • A family history of decay (cavities) does not make someone more likely to develop or get cavities because of genetics
  • Tooth decay often does not hurt
  • Tooth decay is better characterized along a continuum rather than as present or not
  • Tooth decay is caused by acid, not sugar!
  • Dental decay takes a long time to develop, often months or more commonly years
  • Healthy patients who have a low-pH diet and brush twice a day for 3 minutes are very unlikely to develop decay between 6-month dental appointments
  • Decay between teeth often cannot be seen, except by x-ray

Similar Questions

  • What are cavities, caries, decay? 
  • Are cavities, dental caries, and tooth decay the same thing?
  • Are my teeth soft?
  • Is my dentist being aggressive?
  • Am I being ripped off?
  • What causes dental decay?
  • How does fluoride work?
  • Does fluoride work?
  • Is fluoride safe?
  • Are my teeth just soft?
  • I have a family history of soft teeth?
  • Have my genetics caused my teeth to be soft and made me cavity-prone?

Leave a Reply