Which bacteria in saliva are associated with caries initiation and progression?

• A. Mutans Streptococci and Lactobacilli
• B. Staphylococcus Aureus
• C. Pseudomonas Aeruginosa
• D. Lactobacillus Only

Answer: (A)

Streptococcus mutans and Lactobacillus species work together across the stages of caries in saliva. Streptococcus mutans is especially good at initiating decay: it sticks to the tooth surface, forms sticky glucan-rich plaque from sucrose, and produces acid that lowers the local pH. This combination makes it a primary initiator of enamel lesions. Once a lesion has started, Lactobacillus species—being highly acid-tolerant and persistent—tend to thrive in the acidic environment and continue producing acid, driving the lesion deeper and promoting progression into dentin. That’s why this pair best explains both initiation and progression of caries.

Staphylococcus aureus and Pseudomonas aeruginosa aren’t the typical drivers of dental caries in saliva, and Lactobacillus alone mainly aligns with progression rather than initiation.