The Preliminary Study Of Maxillofacial Prosthesis Based On Digital Computer Aided Design-3D Printing Technology And The Cytotoxicity Of 3D Printed Metallic Materials

Background:3D printing technology,also called rapid prototyping,is one of the most advanced additive manufacturing technology.With the development of the printing equipment,material and digital software,3D printing technology is becoming widly and efficiently applied in fields of oral and maxillofacial surgery,such as implant surgery guide,maxillofacial sugery guide, simulation and reconstruction of internal anatomy of root canal and so on. As the custom process of fabricating a maxillofacial prosthesis was complicated and lead a waste of materials and time,and the manual interval would affect the accuracy of prosthesis,maxillofacial prosthesis based on digital computer aided design and 3D printing technology emerged at the right moment.3D pringting technology can improve the accuracy of the prosthesis,simpilify complex process, save up materials and human resources.The materials must comply with the principle of biological compatibility when used in clinical.so this study choose cast nichrome, cobalt-chromium, pure titanium for reference,to test the cytotoxicity of 3D printing material of nichrome, cobalt-chromium, titanium alloy.Objective:The purpose of this study is to manufacture the framework of maxillofacial prosthesis by 3D printing technology,with the artificial teeth and base plate decorate in conventional method.The cytotoxicity of 3D printing metallic material of nichrome, cobalt-chromium, titanium alloy were tested by MTT with cell line of L929 mouse fibroblasts.Methods:1) Subject was a maxillary malignant tumor patient with postoperative maxillary defect, the STL data was obtained by scanning gypsum model using 3 shape D700 scanner.2) Geomagic and Rihnoceros software was used to design the framework of the prosthesis.3) Renishaw AM250 SLM as the 3D printer,combining with exclusive 3D printing materials were to print out the framework.And,the framework was post-processed after then.4) The traditional method of making the prosthesis was combined to complete the final prosthesis.Then compare the 3D printed framework wear with the traditional framework and conclude advantages and disadvantages of 3D printing framework..5) The standard samples of nichrome, cobalt-chromium, titanium alloy were manufactured by Renishaw 250 SLM, using traditional casting method manufactured nichrome, cobalt-chromium, pure titanium standard samples, test their cytotoxicity by MTT method. Set up a negative control group and a positive control group.Results:1) The framework manufactured by 3D printing technology could be fit in patient’s oral well.The patient was comfortable about the final prosthesis with its conformity, masticatory efficiency, retention force and its function in facial appearance.2)The result of MTT show that compared with casting nichrome, cobalt-chromium, pure titanium, the three kinds of nichrome, cobalt-chromium, titanium alloy of 3D printed metal materials had no obvious toxic, both within the permitted in clinical application, can meet the demands of dental metallic materials cytotoxicity.Conclusion:3D printing technology applied in the manufacturing the framework of prosthesis is feasible; Nichrome, cobalt-chromium, titanium alloy of Renishaw metal material for 3D printing technology can be used in clinical without safety problem.