Effect of conditioners on dentin permeability using an impedance method.
OBJECTIVE
The aim of our in vitro study was to contribute to an elaboration of a protocol to evaluate the permeability of dentin and the effect of different acid conditioners by means of the electrochemical impedance technique.


METHODS
Twenty-four 1.1mm 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 dentin conditioners.


RESULTS
The highest resistance decrease was obtained with 32% phosphoric acid and 10-3 solution which improved the permeability, respectively, 9.0 and 6.9% with no significant difference. The acidic monomer can be considered as intermediate (4.3%) between 10-3 solution and the polyacrylic acid (2.8%) with no significant difference.


CONCLUSIONS
By measuring electrical resistance of dentin disks with the impedance method, we can evaluate the ionic conduction through the sample and achieve quantitative values about permeability. The action of dentin conditioners can be significantly evaluated regarding their action in terms of resistance of the etched zone (REZ) and increasing dentin permeability.
Pradelle-Plasse
Nelly
N
Hôtel Dieu, Université Denis Diderot, Service d'Odontologie Garancière, Departement of Restorative Dentistry and Endodontics, Paris, France. nx.pradelle@oreka.com
Wenger
François
F
Colon
Pierre
P
D000134:Acid Etching, Dental / Q000379:methods*; D000180:Acrylic Resins / Q000494:pharmacology; D000704:Analysis of Variance; D002712:Chlorides; D019343:Citric Acid / Q000494:pharmacology; D003804:Dentin / Q000187:drug effects*; D003806:Dentin Permeability / Q000187:drug effects*; D015194:Diffusion Chambers, Culture; D017097:Electric Impedance; D004563:Electrochemistry / Q000295:instrumentation; D005290:Ferric Compounds / Q000494:pharmacology; D006801:Humans; D008689:Methacrylates / Q000494:pharmacology; D010756:Phosphoric Acids / Q000494:pharmacology; D012815:Signal Processing, Computer-Assisted; D016369:Smear Layer; D013223:Statistics as Topic
D000180:Acrylic Resins; D002712:Chlorides; D005290:Ferric Compounds; D008689:Methacrylates; D010756:Phosphoric Acids; C008384:methacrylic acid; D019343:Citric Acid; C006903:carbopol 940; C024555:ferric chloride