Resting Plaque pH — NDEB AFK MCQ

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EasyCommunity Dentistry & EpidemiologyResting Plaque pHNDEB AFK

The pH of dental plaque at rest (before a carbohydrate challenge) is approximately which value?

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Correct answer: D — 6.5-7.0

The resting pH of dental plaque is approximately 6.5-7.0, close to neutral. This is maintained by salivary buffering (bicarbonate, phosphate) and metabolic activity of plaque bacteria. After a fermentable carbohydrate exposure, the pH drops rapidly below the critical pH for enamel demineralisation (~5.5) within 2-5 minutes (Stephan curve), then gradually recovers to resting levels over 20-60 minutes through salivary buffering and bacterial substrate depletion.

Reference: Fejerskov & Kidd – Dental Caries: The Disease and Its Clinical Management, 3rd ed., 2015