ABSTRACT
<p><b>OBJECTIVE</b>To evaluate the effect of SiO₂-ZrO₂slurry coating on surface performance of zirconia ceramic.</p><p><b>METHODS</b>Seventy pre-sintered zirconia discs were randomly divided into seven groups with 10 discs per group. Sample discs in each group received one of the following seven different surface treatments, namely, sintered (group AS), sand blasting after sintered (group SB), coated with slurry of mole ratio of SiO₂to ZrO₂2:1 (group 2SiO₂-1ZrO₂), coated with slurry of mole ratio of SiO₂to ZrO₂1:1 (group 1SiO₂-1ZrO₂), coated with slurry of mole ratio of SiO₂to ZrO₂1:2 (group 1SiO₂-2ZrO₂), coated with slurry of mole ratio of SiO₂to ZrO₂1:3 (group 1SiO₂-3ZrO₂), coated with slurry of mole ratio of SiO₂to ZrO₂1:4 (group 1SiO₂-4ZrO₂). Profilometer, X-ray diffractometer (XRD), energy dispersive spectrometer, scanning electron microscopy (SEM) were used to analyze surface performance.</p><p><b>RESULTS</b>The surface roughness of the discs in group AS was lower than those in the other groups [(0.33 ± 0.03) µm] (P < 0.05), there was no statistically significant difference (P > 0.05) among group 2SiO₂-1ZrO₂[(3.85 ± 0.38) µm], group 1SiO₂-1ZrO₂[(3.78 ± 0.56) µm] and group 1SiO₂-2ZrO₂[(4.06 ± 0.48) µm], and no difference (P > 0.05) was observed between group 1SiO₂-3ZrO₂[(1.02 ± 0.09) µm] and group 1SiO₂-4ZrO₂[(1.53 ± 0.23) µm] either. However, surface roughness in all coating groups was higher than those in group SB [(0.86 ± 0.05) µm] (P < 0.05). According to the XRD pattern, group AS and all coating groups consisted of 100% tetragonal airconia and monoclinic zirconia was detected at surface of group SB. Contents of surface silicon of coating groups increased significantly, however, no silicon was detected at sample surface of group AS and group SB. SEM showed that zirconia grains of coating exposed since part of silicon was etched by hydrofluoric acid, a three-dimensional network of intergrain nano-spaces was created.</p><p><b>CONCLUSIONS</b>SiO₂-ZrO₂slurry coating could make surface of zirconia rough and increase Si content without creating monoclinic zirconia.</p>
Subject(s)
Ceramics , Chemistry , Dental Etching , Hydrofluoric Acid , Pharmacology , Microscopy, Electron, Scanning , Random Allocation , Silicon Dioxide , Chemistry , Surface Properties , Zirconium , ChemistryABSTRACT
Objective:To evaluate the cytotoxicity of four dentin filling materials and two dentin adhe-sives with a dentin barrier test and to compare the results with those in a conventional filter diffusion test in order to investigate the advantages of the dentin barrier test.Methods: Eugenol cement, zinc phos-phate cement, adhesive glass ionomer cement, composite resin and two self-etching adhesives ( REMI BOND and Adper Easy One) were tested.In the dentin barrier test, L929 mouse fibroblasts were three-dimensional cultured in polystyrene meshes.The dentin disks were cut from the human third molars, near the pulp and in parallel with the occlusal surface, and their permeability within the measurement area was evaluated by a hydraulic permeability device.A mesh with the cells was placed in the “pulp cavity” of the chamber and one dentin disk was put on the cell mesh and its “pulp side” was in contact with the mesh.The test materials and controls were in contact with the“occlusal side” of the dentine disks for 24 h.The cell viability was obtained with MTT assay and the results were expressed as a percentage of con-trol tissues.The Mann-Whitney U test was used to make the statistical analyses.In the filter diffusion test, after a 24 h contact between the test materials and the filters with monolayer cells, the filters were dyed and the grades of cytotoxicity were decided.Results:A mean permeability of the dentin disks near the pulp was 0.293 μL/(min· cm2· cmH2O)(1 cmH2O=0.098 kPa);In the dentin barrier test, Eu-genol cement, REMI BOND and Adper Easy One respectively reduced the cell survival rates to 82%, 63%and 54%.Other materials showed no or very low toxic reactions; In the filter diffusion test, the light-curing composite resin was moderately cytotoxic, the dental adhesive glass ionomer cement was mild-ly cytotoxic and the others were severely cytotoxic;All the six materials in the dentin barrier test had low-er cytotoxicity than in the filter diffusion test.Conclusion:The cytotoxicity of the test materials using the dentin barrier test with three-dimensional cell cultures is lower than that in the filter diffusion test, which has good correlation with the clinical situation.