Why do I always get cavities despite brushing and flossing?

David Lin -

Wondering why you always get cavities despite taking all your dentists’ recommendations about brushing and flossing? It might not be entirely your fault! Some people are at higher risk of cavities because of a few health factors that that we’ll discuss in this article. Here we’ll summarize why some people always get cavities and some people never get any, and what you can do to reduce your risk of cavities.

What is a cavity?

A cavity is tooth decay, which is when the surface of the tooth has become damaged to create a literal hole, also known as dental caries, or cavities. Tooth decay can progress from a small hole to a large one over time. Incipient caries, which are the earliest cavities, are where damage to the tooth enamel is minor, and it can still be repaired through the normal process of remineralization. Products containing fluoride and nano-hydroxyapatite have been shown to improve remineralization, and protect enamel from decay. Additinoally, remineralization is a natural process where the cells in your teeth bind to calcium ions, and repair the enamel at the surface of the tooth.

If an early cavity is left to grow, decay can continue to damage the internal layers of the teeth, including the dentin and pulp. Decay at these layers causes irreparable damage that requires a dental filling to repair. These later stage cavities can be extremely painful and typically do not resolve on their own. In these deep cavities, it’s common for bacteria to invade the cavity, and cause a painful infection that requires a root canal.

What causes cavities?

Cavities are caused by specific type of bacteria that can live in dental plaque on your teeth. These bacteria are acid-producers are cavity-causing bacteria referred to as cariogenic, meaning they can cause cavities. It’s important to note that not all dental plaque can cause cavities. Dental plaque that harbors these acid-producing bacteria cause acidic erosion of enamel, and eventually cavities. Two of the most common bacteria in the mouth that cause cavities are Streptococcus mutans and Streptococcus sobrinus.

These acid-producing harmful bacteria can rapidly ferment excess sugars in your saliva, and on your teeth. This is a primary reason why avoiding sugar is critical to reducing the risk of cavities. Acid is produced as a byproduct of a process called fermentation, where sugar is metabolized and turned into energy for the bacteria, and acid is secreted by the bacteria in return. This acid causes a reduction in pH at the surface of teeth. Low pH causes erosion and demineralization of enamel. Importantly, both S mutans and S sobrinus can survive at low pH when other bacteria cannot survive (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5498100/). This distinguishing feature allows the cariogenic bacteria to quickly grow where no other bacteria are able to.

Research shows that later stage cavities harbor different bacteria that can thrive in an environment where decay has already begun.  Lactobacillus species are known to colonize deep cavities,. These Lactobacilli are also able to ferment sugar and survive in the presence of acid (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4547204/), and have been used as a biomarker of cavities.

So why do I always get cavities?

A number of factors can contribute to your risk for cavities and chronic cavities.

  1. Your oral microbiome. Everybody’s oral microbiome is different, and this means they may harbor cariogenic or gum disease causing microbes. These bacteria can persist in a person’s mouth at low levels, and can quickly grow when the environment is right, such as during times of snacking. Unfortunately this also means that bacteri
  2. The pH of your saliva. The low pH of saliva can be a major risk factor for caries. Low pH environments halt the remineralization process and cause demineralization of enamel, which further enables acidogenic microbes to colonize and cause cavities.
  3. Your saliva production. Dry mouth can cause oral microbiome dysbiosis, and allow for cariogenic bacteria to grow and cause cavities. Saliva has protective properties that limit the bacterial levels in your mouth. Saliva contains antimicrobial peptides and antibodies that can target and kill bacteria in your mouth.
  4. Your dental hygiene routine. Brushing and flossing are critical to reducing levels of bacteria broadly on your teeth. While not all dental plaque is bad, brushing and flossing removes food particles that cariogenic bacteria can feed on and create acid.
  5. Diet. Frequent snacking or drinking acidic and sugary drinks can increase risk of cavities. Snacking, specially on sugary foods, introduces sugars that cariogenic microbes can rapidly ferment and turn into acid. Acidic drinks directly demineralize teeth, and can contribute to destruction of enamel.
  6. Reflux. Gastroesophageal reflux disease (GERD) is a major risk factor for cavities. Patients with GERD often have more acidic saliva, as stomach acid flows from their stomach to their mouth.
  7. Diabetes. Patients with diabetes have elevated levels of glucose in their saliva, which allows cariogenic microbes to grow, ferment, and create acid. This is especially true in people with uncontrolled diabetes.
  8. Mouth breathing. Breathing through the mouth, especially at night, is a known risk factor that contributes to the outgrowth of microbes involved in cavities. This is because mouth breathing prevents saliva from accumulating in the mouth and coating teeth.

How can I reduce my risk of cavities?

  • Maintain a healthy oral microbiome. Cavities-causing bacteria propagate more easily in people with oral microbiome dysbiosis. Commensal healthy bacteria in the mouth can prevent S mutans and other cariogenic species from growing.
  • Reduce intake of simple sugars and sugary drinks that feed cavities-causing microbes. These bacteria require simple sugars for fermentation, and without fermentation, no acid is produced.
  • Test your oral microbiome. You can identify the types and levels of cariogenic bacteria in your mouth, and find ways to specifically address them.
  • Take xylitol lozenges or chews. Xylitol can reduce accumulation of acid by preventing fermentation of sugar.
  • Eat more arginine-containing foods. Arginine bicarbonate increases the pH of your mouth,  prevents enamel from demineralizing, and improves remineralization.
  • Use a fluoride toothpaste. Fluoride is a naturally occurring mineral that aids in tooth remineralization
  • Use toothpaste with nano-hydroxyapatite
  • Get more frequent dental checkups. 

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