Quantitative evaluation of self-etching primer action on dentin permeability: a correlation between impedance measurements and acidity.
OBJECTIVE
To evaluate quantitatively the effect of six contemporary self-etching systems on dentin permeability by means of the electrochemical impedance technique and to correlate these results with their acidity.


METHODS
36 1.1 mm thick dentin disks were embedded in a hollow polyurethane resin cylinder. The system used was a "like" permeation cell: two electrodes immersed in a 10(-1) KCl solution were attached to a potentiostat. It was connected to a microcomputer controlled frequency response analyzer, and a 10 mV sinusoidal voltage signal over a frequency range of 1 Hz to 65 kHz was applied between the electrodes. The current passing through the dentin was measured to enable a calculation of impedance expressed in a complex number. To establish an evaluation of permeability variation, the resistance was noted for all specimens before and after the application of self-etching adhesive. A pH meter used with a combined glass-electrode measured the pH of all the systems.


RESULTS
The higher decrease of the resistance of dentin samples was obtained with Experimental (EXP), which presented no significant difference with Touch and Bond (TB), Etch and Prime 3.0 (EP), and Etch Free Tenure (EF). These acidic monomers improved the dentin permeability respectively to 6.7, 5.1, 5.0 and 5.0%. The lowest values were obtained with Clearfil SE Bond (SEB) (2.0%), which showed significant difference with all the other systems. Prompt L-Pop (PLP) with 4.3% showed significant difference with EXP and SEB and no significant difference with the three other systems. The pH and permeability variation were not systematically correlated.


CONCLUSIONS
Significant differences, in terms of quantitative evaluation of demineralization for self-etching systems on dentin, are of interest to clinical practitioners. Dentin bonding efficiency for this sort of adhesive system is not specifically related to this parameter, but low aggressiveness could be an area of concern on enamel.
Pradelle-Plasse
Nelly
N
Department of Operative Dentistry and Endodontics, Faculty of Dental Surgery Paris 7, France. nx.pradelle@oreka.com
Colon
Pierre
P
Wenger
François
F
Picard
Bernard
B
D000134:Acid Etching, Dental; D000269:Adhesives; D000704:Analysis of Variance; D003806:Dentin Permeability / Q000187:drug effects*; D017097:Electric Impedance; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008963:Molar; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted; D016369:Smear Layer; D013499:Surface Properties
D000269:Adhesives