Which bacterium is most commonly associated with dental caries?

Which bacterium is most commonly associated with dental caries?

• A. Streptococcus mutans
• B. Lactobacillus acidophilus
• C. Porphyromonas gingivalis
• D. Actinomyces israelii

Answer: (A)

Streptococcus mutans is the bacterium most closely linked to the start of dental caries because it is highly adept at sticking to tooth surfaces and thriving in the sticky plaque that forms there. It uses enzymes to convert sucrose into extracellular glucans, creating a sticky biofilm that clings to enamel. Within this plaque, it rapidly ferments dietary sugars into lactic acid, driving down the local pH. This acidic environment causes enamel minerals to dissolve, initiating carious lesions. S. mutans is also an early colonizer of the oral biofilm and is especially tolerant of low pH, so it can persist as caries develop. Lactobacillus acidophilus is more linked to the progression of existing lesions rather than their initiation, thriving in the deeper, already-decayed areas. Porphyromonas gingivalis is associated with periodontal disease, not caries. Actinomyces israelii is known for actinomycosis, though other Actinomyces species can be involved in root caries, they are not the most common cause.

Streptococcus mutans is the bacterium most closely linked to the start of dental caries because it is highly adept at sticking to tooth surfaces and thriving in the sticky plaque that forms there. It uses enzymes to convert sucrose into extracellular glucans, creating a sticky biofilm that clings to enamel. Within this plaque, it rapidly ferments dietary sugars into lactic acid, driving down the local pH. This acidic environment causes enamel minerals to dissolve, initiating carious lesions. S. mutans is also an early colonizer of the oral biofilm and is especially tolerant of low pH, so it can persist as caries develop.

Lactobacillus acidophilus is more linked to the progression of existing lesions rather than their initiation, thriving in the deeper, already-decayed areas. Porphyromonas gingivalis is associated with periodontal disease, not caries. Actinomyces israelii is known for actinomycosis, though other Actinomyces species can be involved in root caries, they are not the most common cause.