How are extracellular polysaccharides in dental plaque primarily formed?

Extracellular polysaccharides in dental plaque are primarily formed from bacterial action on sucrose. When sucrose is available, certain bacteria in the oral cavity can metabolize it to produce polysaccharides such as dextran and levans. These polysaccharides serve as a matrix for plaque formation, providing structure and stability to the biofilm that coats the teeth. This process is crucial because it promotes the retention of bacteria in the oral environment, facilitating the bacterial community's growth and leading to dental issues such as cavities and periodontal disease.

The role of sucrose as a substrate is significant because it provides the sugar necessary for the bacteria to synthesize these extracellular polysaccharides, which would not occur to the same extent with other carbohydrates or materials.