Dental Caries

Dental caries, commonly called tooth decay, is a biofilm-mediated, diet-dependent, multifactorial, and dynamic disease that results in the net loss of mineral from the hard tissues of the tooth. Left uncontrolled, it progresses from an early subsurface lesion to a visible cavity and can ultimately involve the dental pulp.

Definition

Dental caries is the localized destruction of susceptible dental hard tissues by acidic by-products from the bacterial fermentation of dietary carbohydrates, producing a progressive net loss of mineral that, if unchecked, leads to cavitation of the tooth.

Scope

This entry covers caries as a disease process: its multifactorial cause, the demineralization-remineralization dynamic that drives lesion progression and arrest, how lesions present at different stages, and the global burden the disease imposes. It treats caries as a topic for understanding rather than a clinical protocol, and connects to companion entries on classification, cavity preparation, and restoration.

Core questions

• What factors must coincide for caries to develop?
• How does the demineralization-remineralization balance determine whether a lesion progresses or arrests?
• How do caries lesions present and progress through enamel and dentine?
• Why is caries considered preventable and, in early stages, reversible?
• How large is the global burden of dental caries?

Key concepts

• Biofilm (dental plaque)
• Fermentable dietary carbohydrates
• Demineralization and remineralization
• White-spot (early) lesion
• Cavitation
• Lesion activity (active vs. arrested)
• Fluoride and the protective factors
• Caries risk factors

Key theories

Chemoparasitic (acidogenic) theory

The long-standing explanatory model holds that oral bacteria ferment dietary carbohydrates into acids that dissolve tooth mineral; contemporary accounts refine this into an ecological, biofilm-centered view in which a sugar-driven shift in the microbial community favors acid production and demineralization.

Mechanisms

Caries arises from the interaction of a susceptible tooth surface, a cariogenic biofilm, fermentable carbohydrates, and time. When the biofilm metabolizes sugars, the resulting acids lower local pH and dissolve calcium and phosphate from the tooth surface (demineralization); when the acid challenge subsides, saliva and fluoride favor redeposition of mineral (remineralization). The net direction of many such cycles determines whether a lesion forms, progresses, arrests, or reverses. Early lesions appear as subsurface mineral loss (a white spot) beneath a relatively intact surface; continued net loss leads to surface breakdown and cavitation, after which the lesion can extend through dentine toward the pulp.

Clinical relevance

Because caries is a dynamic and largely preventable process, recognizing it as a continuum — rather than only as an established cavity — underlies modern prevention and minimally invasive management. This description is provided to explain the disease and its evidence base, not to guide the diagnosis or treatment of any individual.

Epidemiology

Untreated caries of the permanent teeth is repeatedly identified as one of the most prevalent health conditions worldwide, affecting people across all regions and age groups; systematic Global Burden of Disease analyses document its high and persistent prevalence and the substantial disability burden of oral conditions.

Evidence & guidelines

Authoritative reviews characterize caries as a biofilm-mediated, sugar-driven, dynamic disease and frame prevention around controlling the biofilm, limiting fermentable carbohydrate exposure, and exploiting fluoride and remineralization; these principles inform contemporary preventive and minimally invasive management.

History

The bacterial-acid (chemoparasitic) explanation of caries is associated with Willoughby D. Miller's late-nineteenth-century work and dominated thinking for decades. Twentieth-century research reframed caries as a dynamic, ecological process of mineral loss and gain, a view consolidated in reference texts such as Fejerskov and Kidd's Dental Caries and in later authoritative reviews that emphasize biofilm and dietary sugar as central drivers.

Key figures

• Willoughby D. Miller
• Ole Fejerskov
• Edwina Kidd
• Nigel Pitts

Seminal works

• selwitz-2007
• pitts-2017
• fejerskov-2015

Frequently asked questions

Is early dental caries reversible?

Early, non-cavitated lesions reflect subsurface mineral loss and can re-mineralize when the balance shifts back toward mineral gain; once the surface has cavitated, the lost structure does not regrow, although the lesion can still be arrested.

What makes a tooth surface develop caries?

Caries requires a susceptible surface, a cariogenic biofilm, repeated exposure to fermentable carbohydrates, and time; removing or reducing any of these factors shifts the balance away from decay.