Which combination of salivary characteristics is MOST associated with high caries risk?

Correct answer: D. Low flow rate, low pH, and low buffering capacity

• A. High buffering capacity partially compensates for low flow, making this less risky than the correct answer.
• B. High pH is protective, and viscosity alone is not the dominant factor.
• C. This is the PROTECTIVE profile associated with low caries risk.
• D. CORRECT. All three protective functions are lost together. LOW FLOW removes the mechanical clearance of sugars and bacteria and reduces delivery of calcium, phosphate, and antimicrobial proteins. LOW pH shifts the equilibrium toward demineralization (critical pH 5.5 for enamel, 6.2 for dentin/root surface). LOW BUFFERING capacity (bicarbonate, phosphate, urea) means the pH stays depressed for longer after each acid challenge — the area under the Stephan curve grows.

Note: Stimulated flow below 0.7 mL/min or unstimulated below 0.1 mL/min defines hyposalivation. Ask about medications — polypharmacy is the leading cause of dry mouth.