Kt. Maciel et al., THE EFFECTS OF ACETONE, ETHANOL, HEMA, AND AIR ON THE STIFFNESS OF HUMAN DECALCIFIED DENTIN MATRIX, Journal of dental research, 75(11), 1996, pp. 1851-1858
During resin-bonding procedures, dentin surfaces are treated with acid
ic conditioners to remove the smear layer and decalcify the surface to
expose the collagen fibrils of the underlying matrix. These decalcifi
ed surfaces are then either air-dried or treated with dehydrating solv
ents, procedures which may modify the physical properties of the denti
n matrix. The purpose of this study was to evaluate the effects of deh
ydration on the stiffness of the decalcified dentin matrix. Small (8 x
1.7 x 0.9 mm) beams of dentin were prepared from mid-coronal, dentin
of extracted human molars. The ends were covered with varnish for prot
ection, and the specimens were placed in 0.5 M EDTA for 5 days to deca
lcify. The stiffness was measured by both the cantilever technique and
by conventional stress-strain testing. Specimens tested by the cantil
ever technique were sequentially exposed to water, acetone, alcohol, H
EMA, and glutaraldehyde. Specimens tested by conventional stress-strai
n testing were exposed either to water, acetone, or HEMA, or were allo
wed to air-dry. The results indicate that the stiffness of decalcified
human dentin matrix is very low (ca. 7 MPa), if the specimens are wet
with water. As they are dehydrated, either chemically in water-miscib
le organic solvents or physically in air, the stiffness increases 20-
to 38-fold at low strains or three- to six-fold at high strains. These
increases in modulus were rapidly reversed by rehydration in water. E
xposure to glutaraldehyde also produced an increase in stiffness that
was not reversible when the specimens were placed back in water.