Are Dental Cavities Contagious? The Hidden Risk in Your Daily Habits

What Are Dental Cavities?

A dental cavity is a small hole that forms in the natural tooth structure due to tooth decay (also called dental caries). In the past, dental caries were a widespread issue affecting a larger portion of the population. However, oral hygiene awareness and preventive care reduced the prevalence of cavities. Poor dietary habits like adding too many sugars to the meal plate and improper oral hygiene can cause cavity formation. 

Ideally, hundreds of bacterial species inhabit the human mouth. Few among them are good, while others are bad. The ratio of good versus bad oral bacteria varies with the candidate's oral hygiene status.^[1] Maintaining a healthy balance between both is crucial for overall oral health. A rise in bad bacteria due to lifestyle or diet can cause gum diseases, tooth decay, and plaque formation. 

Why Are Cavities Bad?

Dental cavities are bad as they cause immense pain and discomfort and are most often associated with tooth sensitivity. An untreated infection is serious enough to spread to other teeth and even other body parts by entering the bloodstream. Besides disrupting the quality of life, dental cavities have the potential to end up in life-threatening situations in rare cases.     

Where Are Cavities Located?

Dental cavities can occur anywhere on your teeth, whether on the smooth sides or chewing surfaces, pits between the chewing cusps, portions near the roots, edges between the teeth, along the gum line, or tooth portions that have had previous dental treatment. 

The oral bacteria inside the mouth produce acids by breaking down the food we consume. These acids attack the mineral portion of the teeth, breaking it down to reach the dentin surface (which lies below the enamel). They reach the tooth interior, forming small holes called cavities. 

The food we eat adheres to the tooth surface and combines with saliva and bacteria, forming a sticky, colorless film called plaques. Plaque formation initially begins along the gum line and in the hard-to-reach areas that lie in between teeth. With time, it hardens, forming tartar. Dental plaques are a breeding ground for harmful bacteria-producing acids. These acids erode tooth enamel and lead to cavities and gum inflammation. Including lots of sugars and starchy foods behaves as a fuel for this process. The bacterial plaques gain an ideal environment for growth and multiply their number. Poor oral hygiene, unattended plaques for prolonged periods, and skipping regular dental check-ups contribute to cavity formation.

Where Are Cavities Most Common?

Dental cavities are most common in areas where food particles are usually trapped and are hard to access for cleaning. Usually, the molars and premolars with grooves and pits are hot spots for cavities. Plus, the areas around the gumline and portions between the teeth are also more prone to plaque buildup and cavity formation.

Are Cavities Common?

Dental cavities are one of the most common oral health problems that people suffer from during their lifetime. According to the WHO statistics, nearly 2 billion adults and 514 million children suffer from caries in their permanent and primary teeth worldwide.^[2] Further, over 90% of Americans aged between 20-64 years suffer from tooth decay.^[3] 

Dental Cavity Types

Dental caries or cavities are categorized based on location or the history of cavity formation. The common dental cavity types based on the location of the tooth are:

• Smooth surface cavity: These occur on the teeth's smoother edges and can be slowed down with proper oral hygiene.
• Pit cavities: These occur at the portions between the cusps on the tooth’s chewing surface.
• Root decay: These occur at the gum portion of the tooth and are most common in candidates with receding gums. 

Depending on the history of the dental cavity, they are either primary or secondary.^[4] 

• Primary cavities: These incipient cavities occur on teeth with no history of previous dental cavities.
• Secondary cavities: These recurrent cavities occur at the margins of tooth fillings, other dental restorations, or teeth that previously had dental cavities. 

How Do I Know If I Had Dental Cavities?

Dental caries or cavities cause mild, sharp pain when you bite on hot, cold, or sweet foods. It is often associated with tooth sensitivity and pain or aches in severe tooth infections. Some deeply progressing infections show up as dark-colored stains in between the tooth pockets or cusps on the chewing surface. 

Your dentist can detect the symptoms of tooth infection during your regular check-ups. However, do not neglect to see your dentist in case you notice any of the dental cavity symptoms. Some tooth infections spread to the brain and other body parts, worsening the condition. 

Does Tooth Cavity Spread?

Unfortunately yes, dental cavities spread when left untreated. However, cavity spread is unlike any other infection spread across the body. A tooth infection typically progresses deep inside the tooth, attacking the deeper layers and tooth pulp. The incidence of dental cavity spread relates to other factors like oral hygiene and diet. With prompt action and adherence to effective oral hygiene, dental cavities have a lesser incidence of spreading. 

Can Cavities Spread to Other Teeth?

Yes, cavities can spread to other teeth, though not in the way biological infections typically do. An untreated cavity continues to demineralize the enamel of the affected tooth. While this happens, the bacteria spread through saliva, settling on plaque-covered surfaces of nearby teeth. Once there, they begin attacking the enamel, increasing the risk of new cavities. 

The bad bacteria responsible for tooth decay live inside the oral cavity along with other harmless bacterial species. However, their population is higher than good bacteria when oral hygiene is poor and sugar intake is high. Neglecting regular oral care further creates a positive environment for bacterial growth. This, in turn, behaves as fuel, making multiple teeth prone to decay.

Are Cavities Contagious From Person to Person?

While dental cavities are not directly contagious from person to person, the causative bacteria can actively spread. The most common bacterial species causing dental cavities are the highly acidic and acid-tolerant species like Streptococcus mutans, Lactobacillus, Actinomyces, Bifidobacterium, and Scardovia.^[5] These spread to other persons through saliva while you kiss or share spoons and utensils with a person with poor oral hygiene. It's important to note that while bacterial spread seems simple, the recipient’s tendency to develop a cavity depends on their oral hygiene. 

How Contagious Are Cavities?

Dental cavities themselves aren’t contagious, but the causative bacteria responsible for cavity formation are. It is important to note that contagious bacteria spread through utensils, food, saliva, and actions like kissing or feeding. However, the person's ability to develop cavities from the transmitted infectious bacteria is largely related to their genes, oral hygiene, and dietary habits. 

How Do Dental Cavities Spread?

Bacteria break down the sugar in foods to generate acids that damage the tooth enamel and cause dental cavities. Certain activities boost cavity formation, deteriorating the tooth condition. While these do not directly harm the teeth, they provide a positive environment for bacteria to flourish and grow well. 

• Eating a diet rich in sugars and carbohydrates provides bacteria with a steady energy source. The bacteria utilize the food particles stuck to the plaques and multiply their numbers. The acids formed by the bacterial action dissolve tooth minerals that appear as the cavity spreads to the nearby teeth.   
• Failing to follow proper oral hygiene causes plaque buildup and tartar formation. Regular brushing and flossing physically remove plaque and sticky bacterial film. This reduces bacterial acid generation, which is a leading cause of cavity formation. Missing regular brushing and flossing leaves plaque on the teeth, enhancing cavity formation.
• Dry mouth conditions with reduced saliva production boost plaque and cavity formation. Saliva naturally cleanses the oral cavity and lowers the negative impact of bacterial action. It washes away the trapped food particles and neutralizes the acidic components produced by bacteria action. 
• Consuming sugary snacks and sipping carbonated beverages between meals prolongs the nutrient supply for cavity-causing bacteria. The persistent production of acid products damages the enamel continuously, progressing cavity formation.   
• Relying on a water supply devoid of fluoride can make your teeth' enamel weak and more prone to acid attacks. Fluoride in drinking water strengthens enamel and makes it resistant to acid attacks. Further, it inhibits the ability of bacteria to produce acids.^[6]

Does Dental Cavities Spread Without Physical Touch?

While dental cavities do not spread by themselves, the bacteria responsible for them spread through saliva. Contact mediums like feeding utensils, toothbrushes, and activities like kissing are common ways for bacterial spread. However, saliva droplets from coughing or sneezing can also carry bacteria, making transmission possible without direct physical touch.

That said, whether someone develops cavities depends on factors like bacterial load and oral hygiene. A strong oral care routine can prevent bacterial buildup, lowering the risk of tooth decay, even if exposure occurs.

Are Cavities Reversible?

Tooth decay is reversible during its initial stage. The minerals in saliva and fluoride in toothpaste aid in tooth enamel repair when the decay is in its early phase. However, the damage is irreversible when the decay has progressed over time and the enamel has started deteriorating. It is because the enamel is the strongest portion covering the tooth, and protecting the sensitive interior. A weakened and demineralized enamel cannot serve as a barrier for the progressive action of bacteria, making cavity formation irreversible at this stage.^[7]  

Who’s at Most Risk for Dental Cavity Spread?

While oral bacterial spread is common, the chances of an individual growing a dental cavity depend on individual factors. Here, we listed a few categories of candidates more prone to develop cavities spread from a person.

• Children and teenagers are more prone to develop cavities due to their contagious nature. Their still-developing enamel, habits like snacking, and sugar-rich diets generate an uplifting environment for cavity-causing bacteria. And if you ask us, “Are cavities contagious to babies?” the answer is yes, it is. Babies are at risk of acquiring cavities from their caregivers through activities such as kissing on lips, cleaning pacifiers with their mouths, sharing utensils, and tasting their food. 
• People with poor oral hygiene and brushing habits are at a greater risk of acquiring cavities. And if you ask us, “Are cavities contagious in adults?” The straight answer is that it depends on their oral hygiene. Unhygienic oral cavities and dental plaques serve as a breeding ground for cavity-causing bacteria. On the other hand, adults, even if they acquire cavity-causing bacteria through routine activities, may not develop cavities. Brushing and flossing regularly prevents plaque formation and can help to some extent in these cases. 
• Conditions like xerostomia, with prevailing dry mouth symptoms, boost cavity formation. Naturally, saliva washes away bacteria from the tooth surface, maintaining a hygienic environment.
• Aged seniors and those suffering from receding gums or gum diseases are at a higher risk of catching cavities. Aging is often associated with receding gums, which expose softer roots that are more prone to decay. Habits of sharing food and utensils can worsen their chances of catching dental decay.

Do Cavities Spread Fast?

The speed at which dental cavities spread varies with person. Some develop cavities within 6 months, while a few others take around 5 years. The speed at which a candidate develops dental cavities depends on the candidate's genetics, oral hygiene, diet, and location of the tooth. Genetic makeup determines tooth enamel strength, saliva, and the body’s immune response to the growing bacteria.^[8] These have a profound impact on dental cavity formation. Candidates consuming a high-sugar diet, with receding gums and poor oral hygiene, develop cavities quickly. 

It is always recommended that you see your dentist immediately after noticing symptoms of dental cavities. Remember that early intervention is the key. Signs of pain or discomfort around an infected tooth should not be ignored. They are a clear indication of the deeper spread of bacterial infection that requires immediate attention.

Myths Versus Facts Around Dental Cavity Spread

Misinformation spreads as fast as tooth decay. Bust away the myths with the following science-backed facts.

• Myth: Dental cavities occur only in children.

Fact: No. Cavities spread regardless of age. Anyone with compromised oral hygiene and a higher reliance on sugary foods is prone to cavities.  

• Myth: Only dietary sugars cause dental cavities.

Fact: No. A high-sugar diet, compromised oral health, and failure to follow routine dental care steps such as brushing and flossing are combined causes of dental cavity formation. 

• Myth: Painless cavities are not serious.

Fact: No. A cavity often starts silently and might have reached the deeper layers by the time you start noticing pain. Attending regular dental check-ups helps early identification of risk.

• Myth: Regular brushing cleans off cavities.

Fact: No. Brushing your teeth clears the plaques and bacterial film and reduces the intensity of cavity spread. It prolongs the duration of the cavity spread while the bacterial infection still spreads deep inside. Dental procedures like root canal treatment, filling, or tooth extraction are necessary to clear off the cavity. 

• Myth: Candidates with softer enamel are destined to catch cavities. 

Fact: Partial, yes. While genetics decide the strength of enamel and increase cavity risk, the incidence of a candidate developing dental cavities is largely an output of multiple factors. Lifestyle and dietary habits have a profound influence on genetics. Persons with soft enamel can reduce cavity incidence by following strict oral hygiene and cutting down on sugary snacks. Beyond everything, attending routine dental check-ups and cleanings makes a noticeable difference.  

Effective Ways To Deal With Dental Cavity Spread

You should adopt strict oral hygiene measures and make necessary dietary changes to limit cavity spread. Saltwater rinsing or oil pulling alleviates pain. Home remedies offer relief from pain and discomfort. While they slow down the bacterial progression, they cannot clear off the infection. 

Remember that an early intervention can potentially dilute the negative impact. Schedule a dental appointment as and when you see the symptoms of toothache, sensitivity, or discoloration. The dentist will discuss the effective oral hygiene measures you can implement along with the appropriate treatment options. Few cavities require cleaning and filling, while few others need root canal therapy. Your dentist will help you decide the best one based on your case. Further, they also recommend fluoride treatment options. This not only strengthens your enamel but also reduces further acidic attacks. 

It's always better to prevent cavity spread than to get yourself on management and mitigation strategies. Maintaining proper oral hygiene, along with a well-balanced diet, prevents plaque buildup and protects overall dental health.

Cavities don’t spread like the flu, but the bacteria that cause them can put your smile at risk. The good news? Prevention is in your hands. Get expert tips on protecting your teeth and keeping your oral health in top shape. Sign up with Envoy Health and take control of your smile! Schedule a free consultation and take the first step toward a healthier, cavity-free smile!

References 

1. Mouth Microbes: The Helpful and the Harmful
2. Oral Health
3. Dental Caries (Tooth Decay) in Adults (Ages 20 to 64 Years)
4. Dental Caries: A Review
5. The Evolving Microbiome of Dental Caries
6. Achievements in Public Health, 1900-1999: Fluoridation of Drinking Water to Prevent Dental Caries
7. The Tooth Decay Process: How to Reverse It and Avoid a Cavity
8. Evidence Of A Contribution Of Genetic Factors To Dental Caries Risk