| The most commonly used method of making metal dental prostheses is still investment casting. It can not meet the demands of fast and efficient prostheses making nowadays, due to its time-wasting and defects in casting.Though the application of CAD/CAM has greatly increased the efficiency, only crown or fixed bridge could be made for its special process. With the emergency of LRF, fast making metal prosthesis with free-defects is becoming possible. The objective of this research is to devolope a newly CAD-based, laser rapid forming method in making Ti base.The main methods and contents of this research were showed in the following sentences. Firstly, we made the comparision of accuracy between two models data acuquired by different 3D scanning systems, in order to ensure the precision of later CAD processing. Secondly, the proper overlap rate was to be ensured. Divided by the orthogonal design method, the processing parameters of LRF was to be optimizied. The maximum of curving slope was firstly acquired through the forming process of arc plate, which was used to avoid failure in forming Ti base .Thirdly, the digitized base was then to be designed by the RE software and fabricated by the LRF. The adaptation of 2 different made Ti base was then compared. Finally, 2 patients were selected and their Ti bases of complete denture were to be made by LRF. After that, clinic effects was recorded and analyzied. Results presented in this paper can be summarized as follows,1. The plaster model of mandibular dentition was scanned separately by the laser and grating projection systems and the data was obtained. The comparison results of accuracy showed that there was no statistics significance(P>0.05)between 3 models, and the newly grating projection system has better precision(P≈0.822).2. The overlap experiment showed that the cladding surface quality was good. The height was about 2.06mm and the width 1.32mm(single height 0.1mm, 20 layers cladded).3. Based on the orthogonal design method, the processing parameters were optimized and assured. Under the parameters that laser power was 750~850W, powder feeding rate 4.0~4.5A, scan speed 700~800mm/min, the cladding had better H and W, which is 88.53μm and 1284.17μm. The different level of each factor had statistics significance (p<0.05).4. The maximum of curing solpe in LRF process was ensured for the first time and the value was 0.85. The curved object with lower curve slope can be successfully formed.5. The upper edentulous model was scanned by the grating projection system. The digitized model was reconstructed and then the digitized base was designed by the RE software. The height was 43.1mm; thickness of base and resin-retainer parts was about 1.2mm and 0.7mm. The average adaptation errors were about 0.021mm and -0.0196mm.6. The Ti base was fabricated by the LRF and the fitness of 2 different made plates by traditional and an LRF method was compared. The results showed that average adaptation errors of traditionally made plate were about 0.135mm, while that of the LRF was about 0.334mm.7. Two upper edentulous patients were chosen and the two Ti base plates were designed and made by previously new process. The upper complete denture was then fabricated. The clinic effects were recorded and the results showed that the patient satisfaction value was improved to 8~8.5 during 1st and 3rd month with traditional way. While with LRF made denture, the value only raised during 3rd month and the average value was about 6.5~7.5. The satisfaction of LRF was lower than the traditional way, especially in stability and mastication.Conclusions: The new grating projection system had better acquiring precision; under the suitable processing parameters, the LRF has better quality in forming small, curved object. Based on the digitized base, the Ti base was fabricated by LRF system for the first time and the forming process saved much time compared with the traditional way. We are going to believe that the LRF making process is totally feasible, and with further study on the forming properties and betterment of equipment, LRF will lead to the renovation of oral prosthodontics.
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