Cavities are caused by the bacterial imbalance/infection known as “caries.” Dental caries is a transmissible bacterial infection of the teeth that leads to net mineral loss in the teeth, resulting in white spot lesions, cavitation, and potential tooth loss. This disease is prevalent in all age groups and a chronic disease among many patients.^[1] Historically, the disease model involved two primary pathogens, Mutans streptococci and Lactobacillus; however, additional pathogens are being identified every year, and some 40 different bacteria within the oral biofilm have now been implicated in this disease.^{[2, 3]}

…dental caries is a pH dysfunction of the normal biofilm on the teeth.

All humans have a small layer of bacteria on their teeth. This layer of bacteria is called a biofilm. A biofilm is a community of microorganisms meshed together in a sticky film, and caries is now understood to be a biofilm disease. In recent years, as our understanding of the complexity of biofilms has increased significantly, so has our appreciation for the complexity of this disease. Current biofilm studies suggest that dental caries is a pH dysfunction of the normal biofilm on the teeth.^[4]

What this means is that prolonged periods of low (acidic) pH in the mouth provide the biologic oral environment that selects for the growth of cavity causing bacteria and at the same time is responsible for the demineralization and net mineral loss of the teeth (See Figure 2).^[5] The bacteria that play a role in dental caries are acidogenic and aciduric. This means that they produce acid as a by-product when they metabolize or digest food sources, and unlike healthy, desirable bacteria, they are uniquely adapted to live and thrive in an acidic environment. By producing lots of acid, they create an environment within the biofilm that does not allow for healthy bacteria to survive. Unfortunately, this acidic environment is also responsible for the breakdown of the tooth structure. This production of acidic conditions in the biofilm eventually creates a shift in the bacterial makeup, favoring more acidic bacteria, which results in yet more mineral loss on the teeth.^[6]

These cavity-causing bacteria in biofilms are strongly resistant to antibodies, antibiotics, and antimicrobial agents.^[7] Consequently, biofilm diseases do not respond to surgery, vaccinations, or antibiotic/antibacterial strategies that target one species of bacteria. In order to effectively treat dental caries, not only must we restore the teeth to function, but the dental biofilm needs to be restored to health and the pH dysfunction corrected.^[8]

1. R.A. Bagramian, F. Garcia-Godoy, and A. R. Volpe, “The GlobalIncrease in Dental Caries: A Pending Public Health Crisis,” Am J Dent22, no. 1 (February 2009): 3–8.
2. A. C. Tanner, J. M. Mathney, R. L. Kent Jr., et al., “Cultivable AnaerobicMicrobiota of Severe Early Childhood Caries,” J ClinMicrobiol 49, no.4 (April 2011): 1464–74.
3. V. K. Kutsch, C. L. Kutsch, and B. C. Nelson, “A Clinical Look atCAMBRA,” DPR 41, no. 8 (August 2007): 62–67.
4. N. Takahashi and B. Nyvad, “The Role of Bacteria in the CariesProcess: Ecological Perspectives,” J Dent Res 90, no. 3 (March 2011):294–303.
5. P. D. Marsh, “Dental Plaque as a Biofilm: The Significance of pH inHealth and Caries,” CompendContinEduc Dent 30, no. 2 (March 2009):76–8.
6. N. Takahashi and B. Nyvad, “The Role of Bacteria in the Caries Process:Ecological Perspectives,” JDR 90, no. 3 (March 2011): 294–303.
7. P. E. Kolenbrander, “Oral Microbial Communities: Biofilms,Interactions, and Genetic Systems,” Annul Rev Microbiol 54 (2000):413–437.
8. O. Fejerskov, and E. Kidd, Dental Caries: The Disease and Its ClinicalManagement (Oxford, UK: Blackwell Munksgaard, 2003), 4–5.