Estudio "in vitro" de catorce productos propuestos para el tratamiento de la sensibilidad dentinaria mediante el uso de un sistema de perfusión de dentina y microscopía electrónica de barrido.

Abstract

This thesis studies the in vitro capability of fourteen systems, proposed to treat dentin sensibility (DS), to seal dentine tubules, to reduce dentin permeability and to evaluate the effect of wetness and tooth brushing on these agents. MATERIALS AND METHODS: 140 dentin samples, obtained from human third molars, were divided into fourteen groups of 10 each. Ten discs from each group were mounted in a perfusion device based on the Pashleys system. Each disc was etched with 35% phosphoric acid. Permeability was measured for the disc and this value was considered the reference value (100%). After treatment with each agent, permeability was measured again after one hour. One was studied under SEM. After this, nine were water washed, and then, flow was measured. One was studied under SEM. Eight molars were subjected to simulated tooth brushing equivalent to three weeks of normal brushing, permeability was measured, and samples studied under SEM. The agents studied were Ami-dent-Sealant, KDM-Flustady, Systemp-desensitizer, Excite, Scotchbond-1, Seal&Protect, Promp-L-pop, Clearfill-SE Bond, Duraphat, NMTD-4. RESULTS: Tooth brushing increased tubular permeability in all cases. Seal&Protect showed the greatest amount of tubular occlusion among the unbrushed and brushed samples, and the lowest dentinal perfusion rates. DISCUSSION: A great number of adhesives have been proposed to treat DS based on successful studies in perfusion and SEM. Using the same methodology we had found worse results. The only explanation could be that we worked with a positive pressure device. The use of a wet dentin and the flow of dentinal tubules havent been considered in previous studies of DS. Tay studies new adhesives working with positive pressure and found the presence of Osmotic Blistering and Water Trees in the depth of dentin adhesives that can justify the post operative sensitivity of composite restorations. Osmotic blistering can explain lacuna defect images in the adhesive samples that we find; this indicates that positive pressure should be incorporated in the new in vitro studies of DS to simulate the oral conditions. CONCLUSIONS: All systems reduced dentinal perfusion when applied. After brushing, all systems increased perfusion. Best results are obtained by specific adhesive systems with filler.