A 13-year-old male attends for a check-up and cleaning. He drinks sodas and eats candy several times per week. Findings include generalized plaque, newly erupted permanent second molars, deep pits and fissures on the premolars and molars, and NO carious lesions. Sealants are placed on all erupted molars. This treatment is an example of:

Correct answer: C. Primary prevention

• A. Secondary prevention means early detection and treatment of disease that has ALREADY started — restoring an incipient lesion, scaling for early gingivitis, or screening. The stem explicitly rules this out by stating no carious lesions were found.
• B. Tertiary prevention rehabilitates a patient after disease has run its course and caused damage — dentures, implants, complex prosthodontics. Nothing here has been lost or needs replacing.
• C. CORRECT. Primary prevention stops disease BEFORE it occurs in a susceptible person. The key phrase in the stem is 'no carious lesions found' — there is no disease to detect or treat, and the sealant is placed on sound but vulnerable pit-and-fissure anatomy to prevent one developing. Sealants and community water fluoridation are the two textbook examples of primary prevention in dentistry.
• D. Primordial prevention targets the RISK FACTORS themselves before they take hold — dietary counselling about this boy's soda and candy habit, oral hygiene instruction, or a school policy limiting sugary drinks. Placing a sealant does nothing to the underlying dietary risk factor, so it is not primordial.

Note: The four levels with their dental examples: PRIMORDIAL — prevent the risk factor (education, access to care, sugar policy); PRIMARY — prevent the disease (sealants, water fluoridation); SECONDARY — detect and treat early (restorations, root canals, scaling); TERTIARY — rehabilitate after damage (dentures, implants). Note the trap: dietary counselling for this same patient would be primordial, while the sealant is primary.