Further Experiments with Intact Teeth Placed in Various Buffer Solutions

Abstract

Decalcification of teeth by acids is relevant to evaluation of food habits, use of soft drinks, and methods of prevention. Expts. were designed to study the dissolution rate at short intervals of time. The dissolution curve in vitro has a sigmoid form. The initial "lag period" is accounted for by the fact that enamel is a compact structure, requiring time for acid diffusion to take place. The time that the acid must be in contact with the tooth to produce decalcification in vivo depends on the quality of tooth structure, crystal size, presence of organic channels for diffusion, concn., rate of salivary flow,etc. Enamel caps bathed in lactic acid buffers of pH 3.95 for 15 min. lose about 0.1% of their wts. Such erosion, if repeated, may make the tooth more susceptible to bacterial attack and actual decay. The gravimetric method with air-dried specimens may lead to false detns. because of increased imbibition of the specimen through continued demineralization.