Glucose is considered the least cariogenic sugar because it is less readily fermented by oral bacteria compared to sucrose, fructose, and lactose. Sucrose is the most cariogenic sugar as it is metabolized by bacteria to produce sticky extracellular polysaccharides that enhance biofilm formation and acid production, leading to enamel demineralization. Glucose does not promote this sticky matrix formation, resulting in less plaque adherence and acid damage. Therefore, glucose poses a lower risk for dental caries development relative to the others listed.

Reference: Oral Pathology, Neville et al., 4th Edition.