How dental caries form: Dental assisting

Dental caries, or tooth decay, is a chronic, communicable disease that affects people throughout their lifespan. Dental caries don’t develop instantly. Instead, they develop over time through an ongoing, dynamic process. As a dental assistant, understanding how dental caries develop and how risk assessment guides prevention, treatment, and patient education is essential.

Alright, so, several factors contribute to the development of dental caries, including the presence of dental biofilm, a person’s diet, and a susceptible tooth. There are also protective factors like saliva and proper oral hygiene.

Dental biofilm, or dental plaque, is a key contributor to dental caries that adheres primarily to tooth surfaces and dental materials within the oral cavity. It even adheres to dental appliances like retainers and aligners, as well as dental restorations like fillings, crowns, and implants. It’s made up of communities of bacteria, especially mutans streptococci, or MS, and lactobacilli, or LB which are the two main groups of cariogenic bacteria, which simply means the bacteria are responsible for dental caries.

In terms of a person’s diet, the bacteria in dental plaque feed on fermentable carbohydrates like sugars and starches which are abundant in foods like bread, rice, pasta, and fruit, as well as processed foods, sugary drinks, and candy. In as little as five minutes after eating or drinking fermentable carbohydrates, the bacteria start to metabolize these carbohydrates, producing acids which disrupt tooth enamel by dissolving minerals like calcium and phosphate, a process known as demineralization.

When the plaque pH drops below about 5.5, enamel begins to lose minerals — this is known as the critical pH threshold. As the mineral loss continues, the enamel weakens, and the tooth becomes more susceptible to the formation of dental caries.

As far as protective factors go, the body uses saliva as a built-in mechanism to help prevent caries from forming using physical, chemical, and antibacterial mechanisms. Saliva washes away food particles, providing a cleansing effect; however, its effectiveness depends on adequate flow of saliva with normal water content, so patients with xerostomia, or dry mouth, are at increased risk of dental caries. Saliva also neutralizes acid produced by bacteria, and through the process of remineralization, saliva replaces the minerals stripped away from the teeth by bacterial acids. Lastly, saliva provides antibacterial protection with substances like immunoglobulins.