Porous zirconia ceramic as an alternative to dentin for in vitro dentin barriers cytotoxicity test.

OBJECTIVES: This study assessed the potential of porous zirconia ceramic as an alternative to dentin via an in vitro dentin barrier cytotoxicity test. METHODS: The permeability of dentin and porous zirconia ceramic was measured using a hydraulic-conductance system, and their permeability was divided into two groups: high and low. Using an in vitro dentin barrier test, the cytotoxicity of dental materials by dentin and porous zirconia ceramic was compared within the same permeability group. The L-929 cell viability was assessed by MTT assay. RESULTS: The mean (SD) permeability of the high and low group for dentin was 0.334 (0.0873) and 0.147 (0.0377) µl min-1 cm-2 cm H2O-1 and for zirconia porous ceramic was 0.336 (0.0609) and 0.146 (0.0340) µl min-1 cm-2 cm H2O-1. The cell viability of experimental groups which are the low permeability group was higher than that of the high permeability group for both dentin and porous zirconia ceramic as a barrier except for Maxcem Elite™ by porous zirconia ceramic. There was no significant difference between dentin and porous zirconia ceramic in cell viability, within either the high or low permeability group for all materials. The SD for cell viability of the porous zirconia ceramic was less than that of the dentin, across all materials within each permeability group, except for Maxcem Elite™ in the high permeability group. CONCLUSIONS: Porous zirconia ceramic, having similar permeability to dentin at the same thickness, can be used as an alternative to dentin for in vitro dentin barrier cytotoxicity tests. CLINICAL RELEVANCE: In vitro dentin barrier cytotoxicity tests when a standardized porous zirconia ceramic was used as a barrier could be useful for assessing the potential toxicity of new dental materials applied to dentin before applying in clinical and may resolve the issue of procuring human teeth when testing proceeds.

The evaluation of the desensitization effect of a desensitizing agent and desensitizing toothpastes in vitro.

This study was evaluating how three desensitizing toothpastes used at home influence the effect associated with desensitizing agents after application in the clinic. Fifty dentine disks measure it permeability and 32 dentine disks with similar permeability levels were selected. Following Dental desensitizer treatment, dentine disks were randomly divided into three subgroups (n=10) that received applications of three toothpastes, respectively. The permeability (Lp) of each specimen was measured after each treatment. One specimen was selected from each group for scanning electron microscopy (SEM) observation. After each treatment, the Lp values decreased significantly for each group (p<0.05) and either completely or partially blocked the dentine tubules upon SEM observation. However, no significant differences in Lp values were observed amongst subgroups (p>0.05). After using the Dental desensitizer, Sensodyne, Crest and Colgate desensitizing toothpastes both can continued to reduce the permeability of the dentine disk, and no significant differences were found amongst them.