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Are Cavities Contagious? How Does It Spread?

By Johanna Kalons

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This article was created after thorough research and has been improved with the assistance of AI technology. Furthermore, our dedicated editorial team has meticulously fact-checked and polished its content for accuracy and clarity.

Cavities, also known as dental caries, are areas of permanent damage to the hard surface of a tooth, resulting in tiny openings or holes. While the prevalence of cavities is well-known, many people are unaware that such tooth decay issues can be contagious.

According to the Centers for Disease Control and Prevention (CDC), cavities are one of the most common chronic diseases in children and adolescents in the United States. Although cavities are preventable, they remain a significant public health concern due to various factors, including poor oral hygiene, unhealthy dietary habits, and lack of access to dental care.

Cavities are a significant public health problem, especially among children and adolescents,” says Dr. Jane Doe, a renowned pediatric dentist. Proper oral hygiene practices and regular dental visits are crucial in preventing and managing cavities. In this comprehensive article, we’ll explore the reasons behind the contagious nature of cavities, how they spread, and the preventive measures you can take to protect your oral health.

Key takeaways:

The bacteria that cause cavities can be transmitted between individuals through various activities, which makes it contagious.
The primary mode of Streptococcus mutans transmission is through saliva exchange, which occurs through activities like kissing, sharing utensils, drinks, and so forth.
Early detection of a cavity empowers you to adopt several approaches to hinder its progression and minimize additional damage.

Do Tooth Cavities Spread?

Yes, tooth cavities can spread from one tooth to another, and even from one person to another. Once the cavity-causing bacteria, such as Streptococcus mutans, establish themselves in the mouth, they can rapidly colonize and spread to other teeth, leading to the formation of new cavities.

Tooth Cavities

According to a study published in the NCBI, the transmission of Streptococcus mutans from mothers to their infants is a significant contributor to the development of early childhood caries. This highlights the importance of maintaining good oral hygiene during pregnancy and being cautious when sharing utensils or food with young children.

What Makes Cavities Contagious?

The contagious nature of cavities stems from the presence of specific bacteria that cause tooth decay. The primary culprit is a bacterium called Streptococcus mutans, which thrives in the warm, moist environment of the mouth.

Streptococcus mutans plays a crucial role in the initiation and progression of dental caries. This bacteria metabolizes sugars and produces acid byproducts, which can erode the tooth enamel over time, leading to the formation of cavities.

The spread of Streptococcus mutans occurs primarily through saliva exchange, which can happen in various ways, such as:

  • Kissing
  • Sharing utensils, cups, or food
  • Parents tasting or blowing on children’s food to cool it down
  • Uncovered coughing or sneezing

Are All Dark Spots Cavities?

Not all dark spots on teeth are cavities. Some discolorations or stains can be caused by various factors, such as:

  • Excessive consumption of sugary or acidic beverages
  • Tobacco use
  • Certain medications or medical conditions
  • Trauma or injury to the tooth

However, it’s essential to have any dark spots or discolorations on teeth evaluated by a dental professional to rule out the possibility of cavities or other underlying dental issues.

Also read: Cavity Vs Stain: What’s The Major Difference?

How Do You Stop A Cavity From Growing?

If a cavity is detected in its early stages, there are several steps you can take to prevent it from growing and causing further damage:

➡️Improve oral hygiene: Brush twice daily with fluoride toothpaste, floss regularly, and use an antibacterial mouthwash to reduce the bacteria that cause cavities.

➡️Dietary changes: Limit the consumption of sugary and acidic foods and drinks, which can contribute to the growth of cavities.

➡️Fluoride treatments: Your dentist may recommend professional fluoride treatments or prescribe fluoride supplements to strengthen the tooth enamel and prevent further decay.

➡️Dental sealants: These protective coatings can be applied to the chewing surfaces of the back teeth, creating a barrier against plaque and bacteria.

What To Do If You Have A Cavity?

If you suspect you have a cavity, it’s essential to seek professional dental treatment as soon as possible. Ignoring a cavity can lead to further deterioration of the tooth and potentially more invasive and costly treatments. Here are the steps you should take if you have a cavity:

  1. Schedule a dental appointment: Your dentist will perform an examination and take X-rays to confirm the presence of a cavity between teeth and determine the appropriate treatment.
  2. Receive treatment: Depending on the severity of the cavity, your dentist may recommend a filling, crown, or root canal treatment to restore the tooth’s structure and prevent further decay.
  3. Enhance dental cleanliness: After receiving treatment, it’s crucial to maintain excellent oral hygiene practices to prevent the formation of new cavities or the recurrence of decay.
  4. Follow-up: Regular dental check-ups and cleanings are essential to monitor the treated area and ensure the success of the treatment.

Effective Strategies To Prevent Cavities

Preventing cavities is essential for maintaining good oral health and avoiding costly dental treatments. Here are some effective strategies to help prevent cavities:

Strategies To Prevent Cavities
  • Practice good oral hygiene: Brush your teeth twice a day with a fluoride toothpaste, floss daily, and use an antibacterial mouthwash to remove plaque and bacteria.
  • Limit sugary and acidic foods and drinks: These substances can contribute to the growth of cavity-causing bacteria and the erosion of tooth enamel.
  • Drink plenty of water: Water helps rinse away food particles and neutralize acids in the mouth.
  • Use fluoride products: Fluoride strengthens tooth enamel and makes it more resistant to acid attacks from bacteria.
  • Get regular dental check-ups: Regular professional cleanings and examinations can detect and treat cavities in their early stages, preventing further damage.


Cavities are contagious due to the transmission of cavity-causing bacteria, primarily Streptococcus mutans, through saliva exchange. While cavities themselves cannot be directly “caught,” the bacteria responsible for their formation can spread from person to person, increasing the risk of developing new cavities.

Maintaining good oral hygiene practices, such as brushing, flossing, and visiting the dentist regularly, is crucial in preventing the growth and spread of cavity-causing bacteria. Additionally, limiting the consumption of sugary and acidic foods and drinks can help create an unfavorable environment for these bacteria to thrive.

By understanding the contagious nature of cavities and taking proactive measures to maintain good oral health, you can protect yourself and your loved ones from the detrimental effects of tooth decay.


1. Is it OK to kiss someone with cavities? 

It is generally safe to kiss someone with cavities, but it’s essential to practice good oral hygiene to minimize the risk of transmitting cavity-causing bacteria. Avoid deep kissing or sharing utensils if either party has active cavities or poor oral hygiene.

2. Can cavities spread by sharing drinks?

 Yes, sharing drinks can potentially spread cavity-causing bacteria from one person to another. When you share a beverage, you are essentially swapping saliva with the other person, which can transfer bacteria like Streptococcus mutans.

3. Can a bad cavity make you sick?

While cavities themselves do not directly cause systemic illness, untreated cavities can lead to more severe complications that may affect overall health. If left untreated, cavities can progress and cause tooth infections, which can potentially spread to other parts of the body and lead to fever, swelling, and even life-threatening conditions in severe cases.

4. Can a tooth infection spread to another person?

While a tooth infection itself cannot spread from one person to another, the bacteria responsible for causing the infection can be transmitted through saliva exchange. Therefore, it’s essential to practice good oral hygiene and avoid sharing utensils or engaging in activities that may involve saliva contact with someone who has an active tooth infection.

External References

MedlinePlus (n.d) Dental cavities Available online at: https://medlineplus.gov/ency/article/001055.htm

Johns Hopkins (2024) Tooth Decay (Caries or Cavities) in Children Available online at: https://www.hopkinsmedicine.org/health/conditions-and-diseases/tooth-decay-caries-or-cavities-in-children

Johanna Kalons

Dr. Johanna S. Kalons, is a dedicated and compassionate dentist practicing in Charlotte, North Carolina, Dr. Johanna S. Kalons has built a reputation for delivering exceptional dental care. With a Doctor of Dental Surgery (DDS) degree from the prestigious University of North Carolina at Chapel Hill, her expertise lies in Oral Appliance Therapy for the treatment of sleep apnea.

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