Final answer:
The enzyme sucrase or invertase converts sucrose into glucose and fructose, with glucose being used to form dextran, contributing to the formation of dental plaque and tooth decay.
Step-by-step explanation:
The enzyme used to convert sucrose to glucans and fructans, which are extracellular polysaccharides that help bacteria stick to the tooth, is known as sucrase or invertase. The process involves the hydrolysis of sucrose into glucose and fructose. The glucose is then used to make dextran, a glucan which is part of the extracellular matrix of biofilms on teeth, also known as dental plaque. The fructose, on the other hand, is fermented to produce organic acids like lactic acid, which can demineralize tooth enamel and lead to tooth decay. Bacteria like Streptococcus mutans are primarily responsible for this process in the oral cavity, contributing to cariogenic activities.