Decoding Dental Caries

Researcher: Dishita Ghai

Research Editor: Sahij Sidhu Late-night snacks and energy drinks during exams. Sound familiar? For many university students, these habits are a part of daily life.

Between lectures, assignments, part-time jobs, and social commitments, oral health can often slip down the list of priorities. Dental caries, also known as tooth decay or cavities, do not develop overnight. Instead, they result from small, everyday habits that slowly disrupt the balance of the oral environment. But before we talk more about dental caries, let’s take a look at the tooth’s structure and the oral microbiota that live in our mouth.

Structure of the Tooth and the Oral Microbiota

A tooth consists of two main parts: the crown, which is the visible portion above the gumline, and the root, which is anchored beneath the gums (Wilson & Wilson, 2021). Each tooth is composed of three primary layers: enamel, dentine, and pulp. The pulp is the innermost layer and contains nerves and blood vessels. Surrounding the pulp is dentine, a mineralized tissue made of collagen and hydroxyapatite, the same mineral found in bones. The outermost layer is enamel, the hardest substance in the human body, which is also primarily made of hydroxyapatite. Enamel serves as the tooth’s protective barrier against physical and chemical damage.

While this is the tooth’s structure, our mouths also host the oral microbiota, which consists of diverse types of microorganisms, including bacteria (Pitts et al., 2017). Many of these bacteria live on our teeth within a sticky, jelly-like layer (Wilson & Wilson, 2021; Pitts et al., 2017). This natural layer, or biofilm, is called "dental plaque." The plaque forms when bacteria attach to the pellicle, a protein-based layer that develops on clean enamel (Pitts et al., 2017; Hara & Zero, 2010).

Figure 1. Structure of the Tooth and the Dental Plaque.

This diagram of the tooth highlights the enamel, dentine, pulp, and other parts of the tooth’s structure. The biofilm, or dental plaque, is zoomed in, showing the pellicle layer and bacteria residing on it. Image from Pitts et al. (2017).

The Process Behind Dental Caries

Dental caries is a dynamic and progressive disease that occurs when changes in the oral environment disturb the balance of the biofilm (Wilson & Wilson, 2021). The most significant contributing factor is frequent consumption of dietary sugars. Reduced saliva flow and poor oral hygiene also increase risk (Wilson & Wilson, 2021; Pitts et al., 2017).

When we eat foods rich in carbohydrates or sugars, some bacteria in the biofilm break them down, producing acid (Wilson & Wilson, 2021). As dental plaque or biofilm becomes more acidic, or more cariogenic, sugar-metabolizing bacteria that can survive in acidic environments grow in number. This leads to even more sugar breakdown and acid production. 

The next step is demineralization (Wilson & Wilson, 2021). The main building block of enamel and dentine, hydroxyapatite, can be easily dissolved by acid (Featherstone, 2008). When acid comes into contact with the tooth surface, the enamel begins to break down, forming tiny gaps. Over time, the acid can get beneath the surface, creating lesions or white spots (Pitts et al., 2017).

Fortunately, the body has a natural way to fight this through remineralization (Featherstone, 2008). During this process, saliva helps wash away sugars and then neutralizes the acid (Pitts et al., 2021). Minerals such as calcium and phosphate, either from saliva or external sources, deposit on the tooth’s surface (Featherstone, 2008). However, if demineralization occurs more frequently than remineralization due to an increasing acid environment, sugar intake, or low saliva flow, cavities will eventually form (Pitts et al., 2017; Featherstone, 2008).

Figure 2. Demineralization and Remineralization of Teeth

The demineralization process gradually dissolves tooth enamel, leading to lesions and, if it continues, the formation of cavities or dental caries. However, remineralization can restore important minerals, such as calcium and phosphate, back to the enamel and reverse early damage if it's not too late. Image from Malcangi et al. (2023).

Why does this matter? And What Can You Do? 

Untreated dental caries can lead to several health complications, such as infections or abscesses, tooth loss, severe pain, and other oral health problems (Wilson & Wilson, 2021; Rathee & Sapra, 2023). The good news is that dental caries can be largely prevented with simple daily habits.

Here are some ways to prevent caries:

• Practice Good Oral Hygiene

Removing dental plaque daily by proper brushing and flossing can keep the acid-producing bacteria under control (Wilson & Wilson, 2021; Rathee & Sapra, 2023). It is recommended to brush twice a day and to wait at least 30 minutes after eating to avoid enamel damage (Ontario Dental Association, 2025).

• Use Fluoride Products

Fluoride not only stops demineralization, but it also deposits on the teeth and forms fluorapatite, which is resistant to demineralization by acid (Rathee & Sapra, 2023). Toothpaste and mouthwash are easy ways to include fluoride in your oral care routine.

• Limit Sugary Foods and Drinks

If you do consume sugary foods or drinks, rinse your mouth immediately (Ontario Dental Association, 2025).  

• Get Regular Dental Check-ups

Visiting the dentist for regular check-ups and cleaning can help catch early lesions and small cavities before they become bigger problems (Ontario Dental Association, 2025).

References 

Featherstone, J. D. B. (2008). Dental caries: A dynamic disease process. Australian Dental Journal, 53(3), 286–291. https://doi.org/10.1111/j.1834-7819.2008.00064.x

Hara, A. T., & Zero, D. T. (2010). The caries environment: Saliva, pellicle, diet, and hard tissue ultrastructure. Dental Clinics of North America, 54(3), 455–467. https://doi.org/10.1016/j.cden.2010.03.008

Malcangi, G., Patano, A., Morolla, R., De Santis, M., Piras, F., Settanni, V., Mancini, A., Di Venere, D., Inchingolo, F., Inchingolo, A. D., Dipalma, G., & Inchingolo, A. M. (2023). Analysis of dental enamel remineralization: A systematic review of technique comparisons. Bioengineering, 10(4), 472. https://doi.org/10.3390/bioengineering10040472

Ontario Dental Association. (2025, June 26). Cavities and tooth decay. https://www.oda.ca/oral-health-basics/oral-conditions-diseases/cavities-tooth-decay/

Pitts, N. B., Zero, D. T., Marsh, P. D., Ekstrand, K., Weintraub, J. A., Ramos-Gomez, F., Tagami, J., Twetman, S., Tsakos, G., & Ismail, A. (2017). Dental caries. Nature Reviews Disease Primers, 3(1), 17030. https://doi.org/10.1038/nrdp.2017.30\

Rathee, M., & Sapra, A. (2023, June 21). Dental Caries. In StatsPearls. StatPearls Publishing. Retrieved February 23, 2026, from https://pubmed.ncbi.nlm.nih.gov/31869163/

Wilson , P. J. K., & Wilson , M. (2021). Tooth Decay. In Close Encounters of the Microbial Kind (pp. 273–291). Springer, Cham. https://doi.org/10.1007/978-3-030-56978-5_20.