OBJECTIVE To evaluate the influence of three high-level chemical disinfectants for sterilization on cauterization of dental instruments.METHODS The measuring methods for disinfectants on cauterization of metal instruments,and usage indications for disinfectants followed Technical Standard for Disinfection published in 2002 by the Ministry of Health.Fourteen kinds of small instruments(grouped by 4 different metal materials) were analyzed on receipt and after sterilization by three high-level disinfectants(2% glutaraldehyde,chlorine dioxide, and symclosene),using cauterization rate.RESULTS Three high-level disinfectants had different cauterization rates,the cauterization rate was affected by concentration of disinfectant,sterilizing time,and morphology of instruments.The cauterization of chlorine dioxide was the strongest,followed by symclosene(trichloroisocyanuric acid),and then 2% glutaraldehyde.CONCLUSIONS In clinical sterilization,different materials of small instruments need proper disinfectants,concentration and sterilizing time for decreasing their cauterization.

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.