Sugar frequency, not just amount, drives tooth decay
Caries is not a mysterious rot—it is acids from plaque bacteria dissolving enamel, dentin, and cementum. By 2016 roughly 3.6 billion people had decay in permanent teeth. The earliest clue is often a chalky white spot, long before a dark hole opens.
Tooth decay, also called dental caries, happens when bacteria ferment sugars on the tooth surface and release acids—mainly lactic acid—that strip minerals faster than saliva can put them back. Four ingredients are needed: a tooth surface, cariogenic microbes, fermentable carbohydrates such as sucrose, and time, plus a sheltered biofilm niche. Mutans streptococci, especially Streptococcus mutans and Streptococcus sobrinus, and lactobacilli are the microbes most often blamed; they thrive when sugar is frequent and brushing is sparse. Sucrose is particularly cariogenic because bacteria convert it into sticky dextran that glues plaque in place.
Demineralization begins as a white spot lesion. Active cavities tend to look dull and lighter; a dark brown shiny patch may mean past decay that has halted. Once enamel is breached, dentinal tubules open toward the nerve, so heat, cold, or sweets sting. Untreated, bacteria can kill the pulp, leave the tooth tender to pressure rather than temperature, and seed abscesses—or, rarely, life-threatening spread such as Ludwig angina. Root surfaces lose mineral about 2.5 times faster than enamel; proximal lesions in permanent teeth take on average four years to cross enamel.
Prevention stacks cleaning, less sugar, and fluoride from water, salt, or toothpaste. Brushing twice daily and daily floss are standard advice; treating a mother's cavities may cut bacteria she passes to children. Risk climbs with dry mouth from diabetes, Sjögren syndrome, or drugs such as antihistamines and antidepressants, and with poverty and poor access to care. WHO notes treatment is often scarce in developing regions even though sugar-rich diets make caries most common in the developed world. Large lost tooth substance cannot yet be grown back; fillings, restorations, or extraction manage what remains.
Source: Tooth decay
