| Laser rapid forming (LRF) is a new and advanced manufacturing technology combined with rapid prototype and laser cladding technique. A full density complex metal component can be rapidly fabricated without molds by LRF. LRF is a promising manufacturing technology because it has several advantages, such as low cost, short cycle times and excellent physical properties.LRF is an add-material automatic processing.It can overcome the defect of Titanium casting and save more materials than numerical control milling.So the potential of LRF applied in dentistry may be available. The object of this experimental study is to probe the feasibility of the Titanium coping fabricated with LRF in order to make the foundation for the LRF application in dentistry in the future.The main methods and contents of this research were showed in this paragraph.Firstly,To evaluate the precision of 3D reconstructing abutment by laser scanning.Then,the aluminium abutment die were scanned by 3D laser scanner and the 3D shape of the coping was designed base on the digital abutment by Reverse Engineering software SURFACER Secondly, Titanium single cladding tests were carried out by orthogonal experimental design.Optimized technologic parameters of Titanium coping were picked up after multi-layer cladding test and gradient forming test.Finally,Titanium copings were fabricated with LRF and the fabricating precision of the LRF was evaluated through marginal adaptation test.Conclusions presented in this paper can be summarized as follows:1.The 3D laser scanner is reliable and repeatable in reconstructing abutment model.The error of measurement is-0.16㎜~+0.16㎜. The precision of 3D laser scanner is.excellent2.The aluminium abutment die was designed according to the data of Wang Huiyun's teeth survey and statistics.Aluminium abutment die was scanned by 3D laser scanner and the 3D shape of the coping was designed base on the digital abutment by Reverse Engineering software SURFACER The digital coping with smooth surface and distinct shoulder was prepared for the next experiments.3 . The processing parameters were picked up employing orthogonal experimental design.The parameters of Titanium coping were optimized as follows:laser power:400W ~550W, scanning speed: 8mm/s~10mm/s, powder feeding rate:2.8g/min~3.2g/min,spot diameter: 0.8mm, Argon shielding gas: 4L/min ~8L/min,single layer thickness: 0.1mm.4.Titanium copings were fabricated with LRF base on the CAD coping data. Titanium coping with equal thickness and smooth internal surface has a little sticking powder on external surface The dimension of Titanium coping were height 5.57±0.21mm;diameter of undersurfacer 5.52±0.15 mm;, diameter of apicalside 4.78±0.15 mm. The dimension meet the request of design.This research verified the feasibility of LRF fabricating Titanium coping5.The fabricating precision of the LRF was evaluated through marginal adaptation test. By 6-point measuring method (A,A'at the edge of occlusion surface, B,B'in the middle of axial wall, C,C'on the shoulder), gap between coping intelnal surface and die was measured.The results showed that the mean value of A,A',B,B',CandC'was 86.36±20.17μm,82.14±17.97μm,47.83±17.99μm,62.36±24.53μm,53.62±23.21μm,53.92±21.22μm The result of statistics showed the experimental data significant less than 120μm which accepted by clinical.The precision of LRF can meet the request of clinical. |
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