Invitro evaluation of cytotoxicity and elemental release of three types of Nickel - Chromium basemetal alloys

Dental alloys have a close contact to oral tissues. Following the corrosion phenomen the possibility of changes in surrounding tissues will exist. Due to different applications and suitable properties, dental alloys are very usefull, because of close relationship to restorative dentistry between alloys and tissues; they should be biocompatible & should not be cytotoxic. Base metal alloys are used in construction of prostheses frequently and are manufactured in Iran as well. Existence of some alloying elements such as Nickel or Beryllium has suitable effects like Protection against undesirable Oxidation or strengthening connection and also other profits. In parallel manner, they have some defects such as release Ion in oral environment and creation histotoxicity. The purpose of this study was to investigate and compare cytotoxicity of three types of nickel – chromium base metal alloys (Wirron 99, Verabond II, Supercast). With regard to different amounts of beryllium that have unique Delaminating properties, on mouse fibroblast cell (L922) In experimental study, 12 disks of each alloy with 5mm diameter and 2.5 mm thickness were prepared and placed in RPMI culture medium for 48 hours & 72 houres (extract medium). Then the extract mediums were diluted in two different dilutions of 200 & 40 and their cytotoxicity were evaluated by MTT assay and compare with two control groups consist of only culture media & culture media with teflon. The amount of Nickel, chronium, copper, zinc & silver released from each alloys were measured by flame atomic abosorption device. After 48 hours, no significant difference in cytotoxicity was found between samples and control groups (P>0.05). After 72 hours samples were not significantly different from each other in cytotoxicity, but there was a significant difference between samples and control groups. There was no significant difference in cytotoxicity with two dilutions of 200 & 40 between samples. Maximum release of nickel and chromium were observed from VeraBond II and zinc from Supercast. the cytotoxicity of three Nickel-Chromium alloys and one high noble which were used in this study was not different. There was some degree of cytotoxicity when the time duration of contact between cells and sampels were increased.