Studies of 4,335 persons—ages ranging from 7 to 65 years—in Norrbotten and Skane, Sweden, warrant the following groups of conclusions : (1) Increase in frequency, and development of severe types, of caries, are accompanied consistently by greater accumulations of materia alba (soft deposits) ; also, though to a less degree, of tartar (hard deposits). (2) Perfect rows of teeth, or such as have become only very slightly carious, may occur in mouths in which the teeth are never brushed or only occasionally. Frequent and careful brushing of the teeth may not prevent severe caries. (3) Immunity to caries is decreased when the color of the teeth changes from yellow or brown to white. (4) Increased detrition of milk-teeth is accompanied by decrease in frequency of gingival caries. After age of 30 years, there is a distinct antithesis between other types of caries and grade of detrition of the teeth. (5) Normal gums occur most frequently in mouths that are free from caries, or manifest only its simpler forms. Spontaneously- bleeding inflammation of gums follows the types of proximal and gingival caries, indicating a basic common cause. (6) Earlier views as to the injury caused to teeth by lacto-cereal diets—rich in carbohydrates—were partly confirmed. Frequency of caries decreases somewhat on a substantial meat diet. Caries arises independently of the amount of vitamin C in the diet. Tobacco-chewing deteriorates the gums, but possibly may prevent caries. Coffee does not appear to have any serious oral effect. (7) Hypoplasia—in 6 percent of the lacto-cereal group and 7 percent of the mixed-diet group—is equally distributed among the different varieties of caries. Individuals exhibiting early disturbances in the process of calcification do not appear, as a rule, to be subsequently disposed to advanced forms of caries. (8) Severe caries occurs most frequently when general nutritive condition is poor, but some types of caries are not related thereto. (9) Values obtained in determinations of vascular fragility (Hess test for bleeding tendency) are unrelated to existing types of caries. (10) Severe caries may be accompanied by reduction in percentage of hemoglobin. (11) In experiments on dogs, and after clinical studies in man, a very abundant intake of fruit having high acidity induced, in some cases, caries-like disintegration of dental hard-tissues.
References: Svenska Tand1.-Sallskapets Festsk., 1935; An investigation into questions of social hygiene in the Counties of Vdsterbotten andNorrbotten,Sweden (Part III, Chap. III), Royal Medical Board (1929-31), 1937.