الفهرس 
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Abstract
The aim of this study was to detect the genotoxicity of zirconia ceramics under different conditions non-glazed,glazed before and after aging on human peripheral blood lymphocytes.
Specimen of zirconia was prepared according to the manufacturer’s instructions aseptically into discs (machine cut from the zirconia blocks) of 5mm diameter and 2mm thickness and surface area of 75 mm2.
A total of 24 zirconia discs and 6 sample solution were tested for genotoxicity and were divided into three main groups;groupI(n=6) control groupcell-culture medium (RPMI 1640) incubated under same conditions (has no genotoxic effects) ,group II (n=12) non aged group with two subgroups one non glazed subgroup IIa(n=6) other is glazedsubgroupIIb(n=6),group III(n=12) aged group with two subgroups one non glazed subgroupIIIa(n=6) other is glazed subgroup IIIb (n=6).
In subgroup IIb andIIIb specimens were glazed using (VITA AKZENT glaze powder and fluid VITA (VT), Zahnfabrik H. Rauter GmbH & Co. KG) mixed tillcreamy mix is obtained applied with suitable brush in one brush strokes in one direction then fired in Programat P300 furnace IvoclarVivadent (IV),Schaan, FL.
In group III specimens were aged by Accelerated aging in a steam autoclave (M 11 ultraclave autoclave. Midmark USA. (MD)) for 8consecutive cycles in 134°C 2 barpressure.
Each subgroup of specimens was sterilized in an autoclave in a separate sterilization packet as aseptic conditions are mandatory for cells growth in the next steps of cell culture.
Eluates of each group were prepared 24 hours after setting by placing each specimen in 1ml of extraction medium in microcentrifuge tube,extraction medium used was cell culture medium (RPMI 1640);with 100 IU/ml penicillin and 100 ug/ml streptomycin. All microcentrifuge tubes of eluates were incubated for 72 h at 37°C in CO2 incubator.
We took a total of 30 ml of venous blood using disposable sterile syringes from each individual (5ml for each experiment),samples were placed immediately after being taken in heparinized blood vaccutainers and kept in refrigerator.
Eluates of each subgroup was tested on lymphocyte cell culture of each donor.
Peripheral blood leukocytes were isolated by centrifugation (30 min at 1300g).After centrifugation, leukocytes in the buffy coat; were aspirated. Cell microgels were prepared onto a precleaned microscope charged slides then Lysis of cells, DNA unwinding, gel electrophoresis is donethen the microgels were neutralized and examined at 400× magnification using a fluorescence microscope to investigate the genotoxic effect caused by the eluates zirconia.
The results of this study showed that groupII with its two subgroups showing no deviation from negative control with its two subgroups and showing no DNA damage on culturedcells which indicate lack of genotoxicity of this group.
GroupIII showed increase in percentage of DNA damage which indicate genotoxicity of this group compared to other group and control group.