Saliva pH — MFDS Part 1 MCQ

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ModeratePhysiologySaliva pHMFDS Part 1

Unstimulated whole saliva is collected from a healthy adult at rest and its pH is measured promptly. Which range is most consistent with normal resting saliva?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: D — 6.0–7.4

Explanation lettering: D = shown as A · E = shown as B · A = shown as D · B = shown as E

The correct answer is A. Resting, unstimulated whole saliva is normally mildly acidic to approximately neutral, with a usual physiological range of about pH 6.0–7.4. Prompt measurement is relevant because sample handling and loss of carbon dioxide can alter the recorded pH. Ranges B and C are too acidic to represent normal resting saliva and may instead suggest an acidic oral environment or recent acid exposure. Ranges D and E are excessively alkaline for normal unstimulated saliva. Salivary pH varies with flow rate, time of day, diet and collection technique, so it should be understood as a physiological range rather than a single fixed value.

Reference: Health Education England, Mouth Care Matters: A Guide for Hospital Healthcare Professionals, section 6.2, 2019. https://mouthcarematters.hee.nhs.uk/wp-content/uploads/sites/6/2020/01/MCM-GUIDE-2019-Final.pdf