Evaluation de l'étanchéité et des mécanismes de dégradations des systèmes adhésifs auto-mordançants modernes (étude in vitro)

L adhésion aux structures dentaires minéralisées repose aujourd hui sur l utilisation de deux familles de systèmes adhésifs : les systèmes M-R et les systèmes auto mordançants (SAM). Ces derniers, d apparition plus récente, permettent une plus grande rapidité, une facilité de mise en oeuvre et une réduction des sensibilités post-opératoires. Les premiers SAM apparus présentaient des résultats médiocres en tenues d étanchéité à court terme car des mécanismes de dégradation altéraient les joints adhésifs. Face à ce problème, la chimie des systèmes évolue en permanence. Nous nous proposons de réaliser une étude in vitro visant à étudier l étanchéité amellaire et dentinaire via une méthode de percolation d un traceur chimique ainsi qu à évaluer les mécanismes de dégradation via une méthodologie d observation en microscopie électronique à balayage de trois systèmes auto mordançants récents (Adper Easy BondiC G-aenial Bond®, OptiBond XTR®) en comparaison à un système auto-mordançant de référence (Clearfil SE Bond), gold standard des SAM. Cette étude nous permet de conclure que certains systèmes adhésifs auto-mordançants modernes présentent, en tenues d étanchéité, des résultats comparables aux systèmes adhésifs classiques mais qu entre eux des différences significatives existentPARIS7-Odontologie (751062104) / SudocSudocFranceF

Evaluation de l'étanchéité des restaurations adhésives (apport d'une méthodologie d'impédance électrochimique par rapport à une méthodologie conventionnelle de diffusion )

PARIS7-Odontologie (751062104) / SudocSudocFranceF

Effect of conditioners on dentin permeability using an impedance method

International audienceObjectives. 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.Materials and methods. Twenty-four 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 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

Effect of acids on dentin permeability using an impedance method.

International audienc

Evaluation of microleakage of composite resin restorations by an electrochemical technique: the impedance methodology

International audienceObjectives. The aim of our in vitro study was to quantitatively evaluate dentin microleakage by means of the impedance technique.Methods. Forty-five 2 mm thick dentin disks were embedded in a hollow polyurethane resin cylinder. The system used was a 'like' permeation cell. Standard cylindrical cavities (1.5 mm deep, 3.5 mm diameter) were prepared on the occlusal side of the disk. The current passing through the dentin was measured to calculate impedance and to establish resistance of the sample. The doses were then randomly divided into nine groups (n = 5). Each group was bounded with a different adhesive system and fitted with microhybrid composite resin (Filtek P60). The initial measurement with the empty cavity and the record measurement (t = 0) were performed to evaluate initial resistance after filling. Samples were then thermocycted.Results. At t = 0, the highest value was obtained with EP (550%), the lowest with PLP (115%). The values of other adhesives ranged in a group (350-450%) without statistical difference. After thermocycling, all groups exhibited no significant difference (350-230%) except PLP (50%). The tower joint degradation rate (5%) was obtained with OS with a significant difference for all systems, the higher with PLP (35%). The results for other adhesives ranged from 20 to 27% without significant difference.Significance. Dentin microleakage may be quantified with the impedance technique and this has shown that, except for PLP, the differences between the two families of adhesives are slight. This methodology is able to prove the influence of thermocycling in terms of joint degradation. (C) 2003 Academy of Dental Materials

Quantitative evaluation of self-etching primer action on dentin permeability: A correlation between impedance measurements and acidity

International audiencePurpose: 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

Toxicity Evaluation of Two Dental Composites: Three-Dimensional Confocal Laser Scanning Microscopy Time-Lapse Imaging of Cell Behavior

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