Restorative & Materials · single question
Which organism contributes chiefly to the PROGRESSION of a carious lesion rather than to its initiation?
Show answer and explanation
Correct answer: A. Lactobacillus species
- A. CORRECT. LACTOBACILLUS is a poor adherer to smooth enamel but thrives in the retentive, acidic environment of an established cavity. Its numbers rise once a lesion has cavitated, and it is strongly acidogenic and aciduric, so it drives the lesion DEEPER. Salivary Lactobacillus counts therefore correlate with the number of active cavities rather than with the risk of new ones.
- B. Actinomyces viscosus is associated principally with ROOT surface caries and with early plaque formation.
- C. Streptococcus mutans is the INITIATOR. It adheres to the pellicle, synthesises adhesive glucans from sucrose via glucosyltransferase, and begins demineralisation on an intact surface.
- D. Porphyromonas gingivalis is a periodontal pathogen of the red complex, not a cariogenic organism.
Note: The pairing to remember: S. mutans INITIATES, Lactobacillus PROGRESSES. Actinomyces is the organism of root caries.
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