2 research outputs found
Influence of Different Etching Times on Dentin Surface Morphology
The aim of this study is to investigate the influence of different etching times on demineralized dentin surface morphology
using scanning electron microscopy and qualitative line microanalysis of chemical structure. Two sample
groups, consisting of 30 first premolar teeth in each group, were established. Teeth were cut at the half-distance between
the enamel-dentin junction and the pulp. The first group of specimens was etched for 10 seconds and the second group
for 30 seconds. 37% ortophosphoric acid was used. SEM (scanning electron microscopy) was utilized to observe the following
parameters: number and diameter of dentinal tubules, dentinal and intertubular dentinal surface percentage, appearance
of the dentin surface porous zone containing smear layer and demineralized residual collagen particles with
dentin demineralization products in acid globules, and dissolved peritubular dentin cuff. After calculating measurements
of central tendency (X,C, Mo, SD), Kolmogorov-Smirnov and Student t-test were performed to confirm the quantitative
results, and the cĀ²-test was run to produce qualitative data. In contrast to the 10-second etching time, the increased
etching time of 30 seconds resulted in the following findings: (1) an increased number of dentinal tubules (p<0.05), (2)
an increase in dentinal tubule diameter (p<0.05), (3) an increase in dentinal tubule surface percentage (p<0.001), (4) a
decrease in intertubular dentinal surface percentage (p<0.001), (5) appearance of dentin surface porous zone containing
smear layer and demineralized residual collagen particles with dentin demineralization products in acid globules (p<
0.001), and (6) completely dissolved peritubular dentin cuff (p<0.001). Therefore, different etching times using the same
phosphoric acid concentration result in different morphological changes in demineralized dentin surface. Moreover,
based on a comparison with current studies, prolonged etching time causes morphological changes to dentin surface.
Such changes, have, in turn, negative effects on the dentin hybridization process
Biological Bases of Dentin Hybridization
The aims of this study were threefold: (1) to characterize and quantify the number, diameter and surface area of exposed
dentinal tubules on the cross section of the human coronal dentin; (2) to determine if any such differences in these
properties arise in relation to the distance from the dentinoenamel junction; and (3) to evaluate whether such differences
can influence dentin hybridization. To accomplish these aims, scanning electron microscopy comparative observation
was carried out on 60 prepared human premolars, which were divided into three groups of 20 samples each. The three
sample groups were cut as follows: (1) in the central fissure region, one millimeter from the enamel-dentine junction; (2)
halfway between the enamel-dentine junction and the pulp; and (3) one millimeter from the roof of the pulp chamber.
Using one-way analysis of variance (one-way ANOVA) and a regression linear model, the data enumerated below were
obtained. First, the mean number of the tubule openings was 19600/mm2 on the first level, 32400/mm2 on the second and
42300/mm2 on the third. The mean tubule diameter on the first level was 0.67 mm, 1.52 mm on the second and 2.58 mm on
the third. Finally, exposed tubules on the first level occupied 2.79% of of total dentinal surface area, 23.90% on the second,
and 87.78% on the third level. Therefore, significant statistical differences (p<0.01) between all three groups of the
specimens for all three properties were observed, as well as positive correlation between the dentin depth and each of these
properties. This indicates that the dentin structural variety, which ultimately determines adhesion to dentine, involves a
complex interaction between biological material (dentin) and the particular adhesion system applied