feldspar and thiazolyl-blue

To assess qualitative and quantitative cytotoxicity effect on permanent prosthetic materials to human gingival fibroblasts.. Human gingival tissues were collected (with informed consent) from patients undergoing periodontal surgical procedures and fibroblasts were cultured in vitro. Cell type was determined by performing proteomic analysis. Selected prosthetic materials including titanium, feldspathic ceramic, gold and chrome-cobalt alloy specimens (5×2 mm) were fabricated. The toxicity of prepared specimens was tested by exposing them to cell culture medium for 48, 72, 96 and 120 hours at 37°C under sterile conditions. Cell viability was estimated using MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay. The data concerning cell viability were statistically analyzed using two-way ANOVA test and Tukey multiple comparison test.. Results obtained after 48 hours showed no toxic effect of titanium compared to control group. Cytotoxic effect was observed in gold alloy and feldspathic ceramic, however, it was not significant compared to control group. Chrome-cobalt alloy significantly reduced cell viability compared to control group (p≤0.001). Cytotoxicity diminished with increasing incubation time of specimens. After 120 hours of incubation all tested materials, except chrome-cobalt alloy, had no cytotoxicity.. Titanium proved to be non-toxic. Gold alloy and feldspathic ceramic had short-term cytotoxic effect. Chrome-cobalt alloy had highest cytotoxic effect on fibroblast cells.

Topics: Aluminum Silicates; Cell Adhesion; Cell Proliferation; Cell Survival; Cells, Cultured; Chromium Alloys; Colorimetry; Coloring Agents; Dental Materials; Dental Porcelain; Dental Prosthesis; Fibroblasts; Gingiva; Gold Alloys; Humans; Materials Testing; Potassium Compounds; Temperature; Tetrazolium Salts; Thiazoles; Time Factors; Titanium

A wide variety of dental ceramics compositions have been introduced in dental clinical practice in order to combine desired aesthetics with superior mechanical performance. The aim of the present study was to investigate the microstructural changes in three dental ceramics after their sintering according to manufacturers' instructions and to comparatively evaluate some of their physical, mechanical and biological properties.. The analysis of the phases present in each material before and after sintering was performed with scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction analysis (XRD). The thermal properties of ceramic specimens were evaluated with differential thermal and thermogravimetric analysis (TG-DTA). The mechanical properties evaluated were fracture toughness, Young's modulus and microhardness with the Vickers indentation method. MTT assay was used for cell proliferation assessment. One-way analysis of variance (ANOVA) with Bonferroni multiple comparisons tests was used to determine statistically significant differences (significance level of p<0.05).. Results showed a remarkable variation among the three ceramic compositions of leucite content in the starting unheated ceramic powders ranging between 14 and 32 wt.% and in the respective sintered powders ranging between 15 and 41 wt.% The low fusing glass-ceramic and the high fusing leucite-based ceramic presented significantly higher fracture toughness (p<0.001) and microhardness and lower modulus of elasticity (p<0.05) compared to the low fusing feldspathic ceramic. The three ceramics were almost equivalent concerning their in vitro biological behavior.. Variations in crystal structure, distribution and composition are related to differences concerning mechanical properties of dental ceramics.

Topics: Aluminum Silicates; Apatites; Biocompatible Materials; Cell Proliferation; Cells, Cultured; Coloring Agents; Dental Porcelain; Dental Prosthesis Design; Differential Thermal Analysis; Elasticity; Fibroblasts; Glass; Hardness; Hot Temperature; Humans; Materials Testing; Metal Ceramic Alloys; Microscopy, Electron, Scanning; Periodontium; Potassium Compounds; Spectroscopy, Fourier Transform Infrared; Stress, Mechanical; Surface Properties; Tetrazolium Salts; Thermogravimetry; Thiazoles; X-Ray Diffraction

The biocompatibility of new dental ceramics has not been assessed with the same scrutiny as has been applied to alloys and composites. Yet, the biocompatibility of ceramics is critical to the long-term success of dental prostheses because ceramics are in close contact with oral tissues for extended periods.. Five dental ceramics (2 traditional feldspathic veneer porcelains [Vita Omega and Duceragold], 2 lithium disilicate pressable materials [Stylepress and Empress-2], and a pressable leucite-based material [Empress-1]) were tested for their ability to alter cellular mitochondrial dehydrogenase activity after fabrication using a tetrazolium assay, after aging for 2 weeks in a biologic solution and after post-aging polishing with either a fine diamond or diamond polishing paste. Cellular responses were compared with polytetrafluoroethylene controls (analysis of variance, Tukey pairwise post-hoc comparison, alpha=.05).. The feldspathic porcelains caused only mild (<25% of controls) mitochondrial suppression regardless of aging or polishing. The pressable leucite-based material initially caused a 5% stimulation (not significant) of mitochondrial activity, which decreased significantly (P<.05) by 30% with aging to levels comparable to the feldspathic porcelains, and did not change with polishing. Both lithium disilicate materials caused an initial suppression of mitochondrial activity that decreased significantly with aging, but Empress-2 was severely cytotoxic initially (<20% of controls, P<.01), and became more cytotoxic again after polishing. Stylepress was less cytotoxic initially (85% of controls, not significant) and did not become cytotoxic again after polishing.. Dental ceramics are not equivalent in their in vitro biologic effects, even within the same class of material, and biologic safety should not be assumed. Most ceramics caused only mild in vitro suppression of cell function to levels that would be acceptable on the basis of standards used to evaluate alloys and composites. However, 1 Li-disilicate material (Empress-2) exhibited cytotoxicity that would not be deemed biologically acceptable on the basis of prevailing empirical standards for dental alloys and composites.

Topics: Aluminum Silicates; Analysis of Variance; Animals; BALB 3T3 Cells; Biocompatible Materials; Ceramics; Coloring Agents; Dental Materials; Dental Polishing; Dental Porcelain; Lithium Compounds; Matched-Pair Analysis; Materials Testing; Mice; Mitochondria; Polytetrafluoroethylene; Potassium Compounds; Succinate Dehydrogenase; Surface Properties; Tetrazolium Salts; Thiazoles; Time Factors