Dental plaque is the prerequisite for the development of smooth surface caries. The presence of extracellular polysaccharides (like glucans and levans) have been clearly demonstrated in dental plaque. Glucans, especially their water-insoluble fraction, can serve as a structural component of plaque matrix and help in adhering certain bacteria to the teeth. Even though the ability to produce acid may be a prerequisite for caries induction, but not all acid producing organism are cariogenic.