WANNENMACHER, EUGEN Dental Institute, University of Berlin, Berlin, Ger­many (Sep. 20, 1938).

 [From translation by Rudolf Kronfeld.]

Caries develops only in areas of retention. This rule is also valid for hy­poplastic teeth. In enamel there is no true metabolism, but very slow processes of diffusion occur. Genuine caries of pregnancy is rare ; when it occurs, it begins in the gingival portion of enamel, and is associated with gingivitis. The parathyroids have a decisive influence upon mineralization of dental hard- tissues during the developmental period. In animal experiments, absence of parathyroids can be compensated with ” A.T. 10,” and also with liberal doses of calcium phosphate. [” A.T. 10 ” is the name of a preparation used mainly for the treatment of tetanus due to parathyroprivia.]

Evaluation of most reported statistical investigations on incidence of caries is difficult because of their incompleteness. A distinction should be made between number of individuals having caries and number of carious teeth. There should also be groupings in accord with the number of carious teeth ; e.g., group 1-3 carious teeth ; group 2-4-6 carious teeth ; group 3—more than 6 carious teeth. Divisions into fissure caries, approximal caries, and cervical caries are also required.

References: Collection Meusser, No. 29, 1937; No. 33, 1938.

WARD, MARCUS L.: School of Dentistry, University of Michigan, Ann Arbor, Mich. (Apr. 27, 1938).

Many fillings, which seem to be protecting teeth from further progress of caries, permit some liquids to pass between fillings and teeth. Why do teeth not decay under these conditions?

The author and co-workers have given considerable attention to development of materials that are not subject to excessive volume-change. In practically all cases slight increase in volume, rather than decrease, has been desirable after fill­ings have been inserted. Attempts to determine the amount of volume change that would not cause pressure upon the pulp, or other injury to the tooth, repeatedly raised the question whether there was leakage between filling and tooth-tissue even when there had been expansion of the filling material. There are differences in leakage when some materials are tested under water and then in air ; also differences in tooth tissue with respect to being wetted. The highly calcified tooth-tissue is apparently not wetted so easily as tissue that is poorly calcified (high in organic content). Gold-foil fillings, which are not subject to reactional volume-change and to only a small thermal-change, permit various dyes to pass between filling and tooth to the base of the filling, even when inserted in most favorable cavities and under most favorable conditions ; and also when the dentin is fairly high in organic content. But the same results have not been obtained for teeth that were highly calcified (low in organic content).

 

162                                SUMMARIES ON CARIES

Reference: American text-book of operative dentistry, Chapter VIII, 7th ed.—in press (Lea and Febiger, Philadelphia).

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