Cytotoxicitic detection of laser welding between NiTi shape memory alloy and stainless steel in vitro / 中华口腔医学杂志

ABSTRACT

<p><b>OBJECTIVE</b>To investigate the cytotoxicity of laser-welded nickel titanium (NiTi) and stainless steel composite archwire.</p><p><b>METHODS</b>The NiTi and stainless steel composite archwire (CoAW) laser-welded with pure copper inrerplayer was studied with methyl thiazolyl tetrazolium (MTT) test in vitro. The cytotoxicity of CoAW was compared with stainless steel archwire and NiTi archwire. Two tests were carried out. Test 1 the immersed solution of CoAW was diluted to five grades (50%, 40%, 30%, 20%, 10%). The cytotoxicity in vitro of these agents was assayed on murine fibroblast cell L929 line with MTT test at 24 and 48 hours. Test 2 the immeresed solution of CoAW, NiTi archwires and stainless steel archwires was diluted to four grads (100%, 75%, 50%, 25%). The cytotoxity of three kinds of material was compared at 48 hours.</p><p><b>RESULTS</b>The results of all samples revealed level 0-1 cytotoxicity. In test 1, the same grade solution optical density (except 20%) at 24 hours was statistically lower than at 48 hours. In test 2, the optical density of CoAW solution (1.964 ± 0.122, 2.084 ± 0.056, 2.056 ± 0.071, 2.096 ± 0.050) was statistically lower than the same grade solution of stainless steel archwire (2.168 ± 0.091, 2.227 ± 0.160, 2.302 ± 0.052, 2.301 ± 0.060) and NiTi archwire (2.138 ± 0.105, 2.262 ± 0.050, 2.271 ± 0.082, 2.294 ± 0.056) (P < 0.05).</p><p><b>CONCLUSIONS</b>The MTT test of CoAW in vitro showed that cytotoxicity was related to concentration and time. The cytotoxicity of the CoAW was more serious than that of stainless steel and NiTi archwires. However, CoAW belonged to secure rang of material toxicity reaction.</p>