Tooth decay begins with bacteria, primarily Streptococcus mutans, that naturally live in your mouth. These bacteria thrive on sugars and starches from the foods you eat, producing acids as a byproduct. In a healthy mouth, saliva helps neutralize these acids and remineralize enamel. However, when acid production outpaces your mouth's natural defenses, the enamel begins to break down at a molecular level.
The decay process follows a predictable pattern. Bacteria form a sticky film called plaque on tooth surfaces within hours of eating. If plaque is not removed through brushing and flossing, it hardens into tartar within 24 to 48 hours, creating a shield that protects bacteria and makes them harder to remove. The acids trapped beneath plaque and tartar slowly dissolve the minerals in your enamel.
Once enamel is compromised, decay progresses more rapidly through the softer dentin layer beneath. Dentin contains microscopic tubes that connect directly to the tooth's nerve center, which is why cavities that reach this layer often cause sensitivity and pain. Without treatment, decay can reach the pulp, the innermost part of the tooth containing nerves and blood vessels.
