Critical pH for initiation of caries in dentin is:: (A) 4.3-4.5, (B) 5.2-5.5, (C) 4.9-5.1, (D) 6.2-6.5
Answer is D. Critical pH for initiation of caries in dentin is 6.2-6.5.
In addition, the critical pH for dentin is higher than for enamel, so demineralization is likely to start even before the pH reaches the critical level for enamel (pH = 5.5).