INCREASE IN HARDNESS OF DENTIN ON DRYING

¹ Department of Biochemistry and Pharmacology, School of Medicine and Dentistry, the University of Rochester, Rochester, N.Y.

(1) In each tooth, the average width of the microcut was less for the dried dentin than for the moist.

(2) The changes in the dentins on drying were as follows: 4 teeth had a decrease in microcut widths of 5µ; 1 tooth had a decrease of 4µ; 5 teeth had a decrease of 3µ; 4 teeth had a decrease of 2µ; and 4 teeth had a decrease of only 1µ.

(3) The average width of the microcuts for all moist dentins was 12µ, for all the dried dentins was 9µ (average difference—3µ; average per cent difference—33).

(4) The dentin microhardnesses according to the Bierbaum scale was increased on drying from 75 to 129 (average increase—54; average per cent increase—42).