Inductively Coupled Plasma-atomic Emission Spectrometry Measurements Of Elemental Release From NiCrBe Alloy Into Different Media

[Background] Because of its good physical and mechanical properties,dental casting alloys have been used in clinical field for decades. However different kinds of alloys have different biocompatibilities which are determined by the quality and quantity of the released cations. It has been documented in vitro and in vivo that some of the released elements have allergic properties, immunological and bacterialogical effects even have carcinogenic or mutagenic possibilities, mostly among the base dental alloys. Quantitative measurements of elemental release are the base for further research about dental alloy biocompatibilities. Limited by the shortage of advanced testing instrument, only a few institutes in our nation developed such research and none of them based their research on long-term tests which was thought by foreign experts to be very important in predicting biocompatibilities of alloys.[Purpose]The aim of the current study is to test whether time and differentimmersion media are factors influencing elemental release from a base dental alloy: Nickel-Chromium-Beryllium alloy and in what degree those factorsinfluencing it. We will also try to find the stable time for each metal when the releasing rate no more increase.As a result,give more support to future research of biocompatibilities and provide guidance for the application of such alloy in clinics.[Material and methods] Standard sized casting NiCrBe alloy were put into different immersion media (physiological saline solution or artificial saliva) randomly. ICP-AES was used to test the elemental release of each component. Observe the surface of alloy before and after immersion by scanning electron microscope.[Results](1) Except the release of Ni in the artificial saliva, all the other elements remain unchanged statistically in the first week.(2) After one month the elemental release of Cr in both media and Ni in the artificial saliva increase statistically.(3) After three months all the elemental release increased significantly among which even the most stable elements: Co in physiological saline solution and Be in artificial saliva have some quantitative release.(4) More elemental release of Ni and Be was found in the physiological saline solution than in the artificial saliva and more elemental release of Al and Cr was found in artificial saliva than in physiological saline solution.(5) Detected by the scanning electron microscope, surface corrosion became severer when the immersion time increased and severer corrosion was found on the testing sample immersed in physiological saline solution than in artificial saliva.(6) The total elemental release in the physiological saline solution is larger than those released in the artificial saliva.[Conclusions](1) With the increase of immersion time, more types of elements were detected and the quantity of each element released were also increased.(2) The total amount released from physiological saline solution is larger than those from the artificial saliva: Ni>Be>Cr>Al>Co>Mo in physiological saline solution and Ni>Al>Cr>Be>Co=Mo in the artificial saliva.(3) The result of comparative research through scanning electron microscope conforms to the total quantity of elemental release.