Permeability Tests on Teeth with Pulpal Involvement

Abstract

Tests of the permeability of teeth may be made to compare teeth of youth, where diffusional processes are involved in active metabolism, with teeth of maturity, where metabolic activities are greatly reduced or absent. Experiments have shown that irritations cause obliteration of dentinal tubules. Tests may therefore be made to determine the extent of such changes, to learn whether teeth under certain conditions are incapable of reacting to irritation. The last mentioned aim is the basis of this report on teeth that were extracted because of caries. In tests of this kind it is desirable to depend on physical forces in diffusional phenomena, such as osmotic pressure and capillarity, rather than on chemical affinity for components of tissues. If the disclosing fluid is properly selected, physical forces cause relatively quick impregnation of interstices and areas of loose molecular structure. Chemically active stains, on the other hand, may vitiate the experiment by combining with normal tissue. Experience has shown that alcoholic basic fuchsin, early used by Caush, fulfills reasonable requirements. It enters the interspaces, yet does not combine with mature intact enamel, cementum, or dentinal ground-substance, after weeks of exposure. Results due to its action are therefore especially noteworthy. Experiments of this kind were undertaken on a small scale in 1916,2 and continued since 1929. The ensuing observations suggested the concept of tooth maturation, first presented in 1930. The study of maturation has graphically demonstrated the existence of the physiologically scle-