Name a caries-associated genus and describe its role in progression.

Name a caries-associated genus and describe its role in progression.

• A. Porphyromonas gingivalis is primarily associated with periodontal disease rather than caries.
• B. Actinomyces species are described as the main caries-causing organisms.
• C. Lactobacillus species are the sole drivers of caries progression.
• D. Streptococcus mutans forms robust biofilms and produces acid via carbohydrate metabolism, driving demineralization.

Answer: (D)

Dental caries arise from acid-generating, acid-tolerant bacteria within a dental biofilm that adheres to the tooth surface. Streptococcus mutans embodies this principle. It forms robust, sticky biofilms on enamel through production of extracellular polysaccharides that help it stick and persist in plaque. When fermentable carbohydrates are present, S. mutans metabolizes them to acids like lactic acid, lowering the local pH. This acidification dissolves tooth minerals as demineralization occurs; repeated or sustained acid production leads to lesion progression.

Other choices don’t fit as well: Porphyromonas gingivalis is more closely tied to periodontal disease rather than caries; Actinomyces species can be involved in early colonization and root caries but are not the main drivers of coronal caries; Lactobacillus species contribute to progression once lesions are established but aren’t the primary initiators. S. mutans uniquely combines strong biofilm formation with high acid production to drive caries progression.