Dental Calculus Composition. 2. Subgingival Calculus: Ash, Calcium, Phosphorus, and Sodium

¹ Eastman Dental Dispensary, Rochester, New York

Subgingival calculus, obtained by deep scaling (marginal subgingival) and during gingivectomy (deep subgingival), was analyzed for loss in weight on ashing (900° C.), as well as content of calcium, phosphorus, and sodium. The mineral content of marginal subgingival calculus was quite variable. In contrast, deep subgingival calculus had a consistently high mineral content with a mean Ca: P ratio (weight) of 2.04 as compared to 1.89 for marginal calculus. The mean sodium content of ashed marginal calculus (1.87 per cent) was considerably lower than that of deep calculus (3.11 per cent). The composition of deep subgingival calculus tended to be related to the location in the mouth. However, marginal deposits from the upper molar areas had a lower mineral content than those from the lower lingual areas, except in subjects with subgingival calculus in one or the other area but not in both. In those subjects, the lower lingual calculus had a lower mineral content.