Dimensional changes of demineralized dentin treated with HEMA primers.
OBJECTIVE
The purpose of this study was to measure the dimensional changes of demineralized dentin before and after application of HEMA (2-hydroxyethyl methacrylate) by confocal laser scanning microscopy (CLSM).


METHODS
The middle portion of bovine dentin was ground, polished, and covered with a vinyl tape with a 4-mm hole punched through it. A strip of polysiloxane impression material was then placed across the center of the dentin surface to preserve a strip of the original unetched surface. Dentin surfaces were etched with 32% phosphoric acid for 60 s and rinsed with water. The impression material was then removed and the following sequential steps were performed: the dentin surface was mildly air-dried, then strongly air-dried, then treated with either 35 wt.% HEMA/water or 100 wt.% HEMA and mildly air-dried, and then strongly dried again. The shrinkage of the demineralized dentin surface from the original unetched level was measured by CLSM in each step and results analyzed by one-way ANOVA.


RESULTS
The dimensional changes of demineralized dentin after mild air drying were approximately -1 micron and, following strong air drying, resulted in -5 microns shrinkage. Following the application of 35 wt.% HEMA/water, the height of the demineralized dentin changed to a level of -3.3 microns, but then shrank to -4.8 microns after strong drying. ANOVA indicated that re-expansion of the shrunken etched dentin was significant (p < 0.05); however, the treated surface collapsed when it was strongly dried again (p < 0.05). 100% HEMA did not re-expand the shrunken demineralized dentin under any of the application on protocols (p > 0.05).


CONCLUSIONS
Thirty-five wt.% HEMA in water re-expanded the collapsed demineralized dentin matrix, however not to the original level. One hundred wt.% HEMA did not cause any re-expansion.
Nakaoki
Y
Y
Cariology and Operative Dentistry, Department of Restorative Sciences, Graduate School, Tokyo Medical and Dental University, 5-45 Yushima 1-chome, Bunkyo-ku, Tokyo 113-8549, Japan.
Nikaido
T
T
Pereira
P N
PN
Inokoshi
S
S
Tagami
J
J
D000134:Acid Etching, Dental; D000818:Animals; D002417:Cattle; D003094:Collagen / Q000737:chemistry / Q000187:drug effects; D003804:Dentin / Q000737:chemistry / Q000187:drug effects*; D003806:Dentin Permeability; D017220:Dentin-Bonding Agents / Q000494:pharmacology*; D003890:Desiccation; D008689:Methacrylates / Q000494:pharmacology*; D018613:Microscopy, Confocal; D019279:Resin Cements / Q000494:pharmacology*; D014867:Water
D017220:Dentin-Bonding Agents; D008689:Methacrylates; D019279:Resin Cements; D014867:Water; C005044:hydroxyethyl methacrylate; D003094:Collagen