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There is considerable variation in the composition of primary and secondary dentine. In general, secondary deposits, regardless of type, contain less calcium, phosphorous, and collagenous matrix per unit volume when compared to primary dentine. Fluoride levels show the reverse tendency. These observations suggest a more open, porotic structure for secondary deposits.

The nature and distribution of corrosion products in teeth restored with metal crowns retained by stainless steel posts were examined by means of energy-dispersive X-ray microanalysis, microradiography, and electron microscopy. The corrosion products consisted of calcium, phosphorous, iron, chromium, nickel, zinc, stannum and other elements. A possible root fracturing mechanism is discussed.

Quantitative measurements with Schiff reagent of the diffusion of aldehydes from endodontically prepared teeth were performed as a function of time, quantity, and concentration of the inserted drug, repeated sealing of the drug in the root canal, the age of the tooth, and the site of the diffusion. The measurements are based on the reaction of aldehydes with Schiff reagent. All teeth were permeable to formaldehyde-containing drugs. Diffusion of the formaldehyde could be detected within 1 minute. The bulk of the inserted formaldehyde diffused through the apical third, but in young teeth (less than 20 years) the whole root surface was permeable. A 2 percent solution of glutaraldehyde, unlike 10 and 25 percent studies, tended to permeate through the dentin and cementum.

Using electron probe microanalysis, the authors determined the calcium and magnesium contents in the incisors of rats treated with different doses of tetracycline and oxytetracycline, and in those of untreated rats. The contents of these elements were significantly lower in the dentine of the treated animals than in that of the control animals, whereas the enamel samples showed no statistically significant differences. The concentration tendency in different tooth sections, from the periphery to the pulp canal, i.e., decrease in calcium and increase in magnesium, was not influenced.