RESUMO
PURPOSE: To test the effects of sequential application of potassium oxalate gel/adhesive agent on in vitro dentin permeability. MATERIALS AND METHODS: Full crown preparations were made in extracted human molars to expose deep coronal dentin. The roots and pulp were removed and the resulting crown segments were connected to a special device (Flodec) to permit the measurement of the permeability of the specimens before and after treatments. Minimum and maximum permeability were recorded after smear layer and phosphoric acid treatment. A new smear layer was created and the permeability measured after the crowns were bonded with Single Bond (3M ESPE), One-Up Bond F (Tokuyama), and AdheSE (Ivoclar Vivadent), either according to manufacturer's instructions or after treating the acid-etched dentin with a 3 wt% potassium oxalate gel. The results were expressed as a percentage of maximum permeability values. Impressions and epoxy resin replicas from the crown segments were produced for SEM examination. RESULTS: None of the adhesives were able to eliminate the fluid flow through dentin. Two-way ANOVA revealed that the application of potassium oxalate prior to the bonding procedures was the most effective technique in reducingthe dentin permeability (p < 0.05), regardless of the adhesive used. SEM micrographs showed that transudation of dentinal fluid could be identified on the surfaces of all replicas. CONCLUSION: The use of potassium oxalate gel was effective in reducing the permeability of bonded dentin.
Assuntos
Permeabilidade da Dentina/efeitos dos fármacos , Adesivos Dentinários/farmacologia , Oxalatos/farmacologia , Substâncias Redutoras/farmacologia , Condicionamento Ácido do Dente , Resinas Acrílicas/química , Bis-Fenol A-Glicidil Metacrilato/química , Coroas , Colagem Dentária , Dentina/efeitos dos fármacos , Dentina/ultraestrutura , Líquido Dentinal/efeitos dos fármacos , Géis , Humanos , Teste de Materiais , Metacrilatos/química , Microscopia Eletrônica de Varredura , Ácidos Fosfóricos/farmacologia , Camada de Esfregaço , Propriedades de Superfície , Preparo Prostodôntico do DenteRESUMO
OBJECTIVES: The aim of this study was to evaluate the variation of fluid filtration across dentin treated with different formulations of potassium oxalate gels and one gel of acidified sodium fluorophosphate, under five different pre-conditioned dentin surfaces. METHODS: The methodology used for the measurement of hydraulic conductance of dentin in the present study was based on the model suggested by Pashley, Stewart and Galloway [Arch Oral Biol 29 (1984)379]. Two hundred dentin discs 1 mm in thickness, obtained from human extracted third molars, were divided into 20 groups of ten specimens each. The groups corresponded to the following experimental materials: 3% potassium oxalate gel-pH 4; 6% potassium oxalate gel-pH 4; 3% potassium oxalate gel-pH 2.5 and 1.23% fluoride gel (APF gel)-pH 3.6-3.9, applied to dentin under the following surface conditions: air-dried, blot-dried, wet, EDTA air-dried; EDTA blot-dried. General MANOVA and post-hoc Duncan tests were performed on the data. RESULTS: Regardless of surface pre-treatment the 3% potassium oxalate gel-pH 2.5 produced the greatest reduction in dentinal filtration (p<0.05) even after citric acid challenge. In general, air-drying the dentin was the best surface pre-treatment (p<0.05). The interaction between the material and surface pre-treatment showed values of hydraulic conductance similar for most of the combinations, but the 3% potassium oxalate gel-pH 2.5 under wet conditions produced the largest reduction in hydraulic conductance. The APF gel produced the smallest reduction in hydraulic conductance when compared with the other materials, regardless of surface pre-treatment. SIGNIFICANCE: the potassium oxalate gels studied in this investigation have a great potential for tubule occlusion and, consequently, should be effective treatments of dentinal hypersensitivity, regardless of dentin wetness.