Etiology
The caries process requires the simultaneous presence of four factors: a susceptible host (tooth), cariogenic bacteria, fermentable carbohydrates, and sufficient time.
Streptococcus mutans is the primary cariogenic organism. It produces lactic acid from dietary sugars, adheres strongly to tooth surfaces via glucan synthesis, and survives in acidic environments.
Lactobacillus species play a significant role in caries progression once cavitation occurs. Other acidogenic species include Streptococcus sobrinus and various Actinomyces species.
Dietary factors are central: frequency of fermentable carbohydrate intake is more important than total amount. Sucrose is particularly cariogenic as it serves as a substrate for glucan synthesis.