Biological factors in dental caries: role of saliva and dental plaque in the dynamic process of demineralization and remineralization (part 1).

Dental caries is a complex disease process that afflicts a large proportion of the world's population, regardless of gender, age and ethnicity, although it does tend to affect more indivduals with a low socioeconomic status to a greater extent. The process of dental caries is dependent upon biological factors that are present within the saliva and dental plaque. There are many different agents within saliva and plaque that serve to protect the tooth surface against caries development. Salivary flow rate, buffering capacity, antimicrobial activity, microorganism aggregation and clearance from the oral cavity, immune surveillance, and calcium phosphate binding proteins all interact to inhibit or reverse demineralization of exposed tooth surfaces. Cariogenic bacteria levels within the saliva and plaque determine whether caries will occur or not, and the concentration in saliva and plaque are intimately related to the type of carbohydrate ingestion and the frequency of ingestion, as well as the oral hygiene practiced by the individual.