Figure 11. Relation between the pH of the supernatant of whole saliva (after 10,000 g centrifugation) and aggregation of its constituents. A high-pH plaque favors formation of a higher calcium phosphate and lower carbohydrate protein containing aggregate; a low-pH plaque favors the reverse. Indicated in the Fig. are pH ranges of different kinds of plaque. Possible variation in saliva pH is shown in Fig. 13 (from Kleinberg et al., 1977).