Can Cavities Spread?

Cavities are possibly one of the least things you can think of as contagious. However, cavities can also spread like the way you catch a cold.

What Are Cavities?

Cavities are the result of tooth decay due to the acids released by the disease-causing bacteria. Once acids are successful in breaking down the enamel, the next target would be the dentin, where blood vessels are found. Bacteria only need sugar and acids for larger cavities to form and destroy the tooth structure.

How and when do cavities spread?

Cavities spread through saliva. The cavity-causing bacteria can be transferred to another person during an exchange of saliva. That means you can acquire a cavity through the following situations:

Sharing a toothbrush

Dentists always remind us that we can share anything in the world but toothbrushes. The disease-causing bacteria found in plaque and blood can accumulate in your toothbrush without you noticing it. So, when you use your loved one’s toothbrush, you’re welcoming a new set of disease-causing bacteria to enter your body.

Storing multiple toothbrushes next to each other

Our toothbrushes can still hold disease-causing bacteria even if we wash them several times a day. When toothbrush heads are placed close to each other, you are already transferring the bacteria and germs indirectly to your loved ones.

As advised by most dental professionals, toothbrushes should be stored apart, placed upright, and without cover to let them dry. It is also recommended to replace your toothbrush every 3 to 4 months to get rid of the accumulated bacteria in your toothbrush.


Anything can start with a kiss, even tooth decay. As unappealing as it may sound, kissing is a direct exchange of saliva wherein the bacteria can freely migrate to another person’s mouth. Not to mention your high probability of acquiring cavities if your partner has poor oral hygiene or has an early stage of tooth decay.

Sharing utensils like spoons, forks, and glasses

Sharing your drinks is once known as an act of indirect kiss. Since sharing of utensils has become a norm, so does the spread of cavity-causing bacteria. The saliva left on the utensils becomes the passport of the bacteria to transfer from one mouth to the other. Due to utensil sharing, researchers found that 80% of two-year-old kids were infected with the cavity-causing bacteria from their parents or guardians.