A dietary aspect of calculus.

M ANY investigations have been made to establish the relationships between the concentration of salivary components and the presence of caries. In recent years considerable effort has been expanded in attempts to correlate salivary composition with the presence or absence of calculus. Since calculus is composed mainly of calcium and phosphorus as the phosphate salt, it follows from various chemical laws that there must be a definite chemical relation between calculus and the calcium and phosphate ions in the surrounding saliva. This relationship has been elucidated by previous workers.' Suffice it to say here that when the product of the calcium-and phosphate-ion concentrations exceeds a certain value in a given sample of saliva, then there is a definite tendency toward the production of calculus by that saliva. Most of the investigations in this problem of calculus and salivary composition have been made upon saliva from fasting individuals. Conclusions from such investigations must of course apply to salivary conditions existing primarily under fasting conditions. Now most individuals have a habit of eating, and since food usually contains appreciable amounts of calcium and phosphorus in soluble form, it would seem logical that the ingestion of food might have an effect on the excretion of calcium and phosphate ions in the saliva, which in turn might increase or decrease the tendency of saliva to deposit calculus. This investigation therefore was undertaken to determine if dietary intake effects the calcium-and phosphate-ion concentrations in the saliva. For purposes of discrimination it was deemed necessary to know the fluctuations (if any) in salivary compositions that take place with the ingestion of Ca3(PO4)2 fortified solutions. This could then be compared with changes arising from the ingestion of a fortified test meal. Only the first part of this work, together with chemical and clinical results showing the relation of such changes to calculus formation, is reported in this paper. EXPERIMENTAL Ten normal, healthy, young adult male dental students were chosen and investigated under given conditions. Subjects reported at all times without breakfast. Following collection of the first saliva sample, they ingested various items and water. Then at ensuing 15-minute intervals for the first hour and 30-minute intervals for the second hour, saliva samples were collected and treated as follows.