CN1462612A - Laser stereo shaping method for preparing buccal metal prosthesis - Google Patents

Abstract

The invention discloses a laser three-dimensional forming preparation method of oral metal prosthetics. The laser three-dimensional forming technology is combined with dental computer-aided design and manufacturing technology to establish a new technology for directly manufacturing oral metal prosthetics from metal powder. The 3D CAD model of the restoration is generated in the computer, and then the model is layered and "sliced" according to a certain thickness, that is, the 3D information is converted into a series of 2D contour information, and then the laser coating method is used to accumulate metal layer by layer according to the contour trajectory Powder material, resulting in dental restorations that require only minimal processing. This invention will open up a new method for the production of dental restorations; it can also be extended to the rapid and accurate production of restorations in orthopedics, plastic surgery and other fields.

Description

Preparation method of laser three-dimensional forming of oral metal restoration

1. Technical field

The invention belongs to the field of stomatology or biomedical engineering, and relates to a method for preparing oral dentures or denture parts, in particular to a method for preparing oral cavity metal restorations by laser three-dimensional forming.

2. Background technology

Tooth and dentition defect is a common and frequently-occurring disease in the department of stomatology, accounting for about 24%-53% of natural persons. When the disease occurs, fixed restorations are usually selected for restoration by hand-made individual methods. The prosthetics are manufactured using the precision casting method, which is cumbersome, slow, and inefficient, and the number of visits to the doctor is high and the time is long. It is imperative to change the traditional production method.

Since the 1980s, CAD/CAM technology has been introduced into the field of prosthodontics. France, Switzerland, Germany, and the United States have successively developed dental CAD/CAM systems, among which the German CEREC--CAD/CAM system is the most famous and popular. More than 5,000 units have been sold, capable of producing ceramic inlays, veneers and full crowns. The technology is considered a revolutionary breakthrough in the field of stomatology. However, because the processing method adopts the lost material milling method, there are the following problems: first, the matching machining material must be prepared in advance, and the volume of the machining material must be larger than the cutting molding to leave enough machining allowance. It will inevitably cause a lot of waste of materials; secondly, due to the limitation of the performance of machined materials, only small and simple restorations can be made, such as single crowns and simple fixed bridges, and the application range is very limited; thirdly, the material of machined materials Single, either metal or ceramic, does not have the ability to make composite restorations.

3. Contents of the invention

In order to overcome the disadvantages of poor performance, low material utilization rate, long processing cycle, and simple forming shape in the prior art, the purpose of the present invention is to establish a laser three-dimensional forming preparation method for oral metal restorations. This method is to apply advanced laser stereoforming technology to the manufacture of oral metal restorations. It is expected to lay a theoretical and technical foundation for replacing traditional casting methods or innovating existing computer-aided manufacturing methods for oral restorations. The production opens up a new processing technology.

In order to achieve the above object, the technical solution of the present invention is to first generate a three-dimensional CAD model of the oral metal restoration in the computer, and perform layered slice processing on the model according to the processing accuracy requirements, and convert the three-dimensional CAD model of the shape of the oral metal restoration The data is converted into a series of two-dimensional plane data; then, according to the plane data of each layer, the trajectory of the laser beam scanning is determined, the processing program is generated, and it is transmitted to the CNC workbench; the laser beam is determined by the CNC workbench according to the processing program. The scanning trajectory scans on the substrate, and at the same time, the metal/alloy powder is fed into the laser molten pool through the powder feeder, so as to obtain a coating consistent with the plane shape; after the laser beam scans a layer, the laser head and The powder feeding nozzle rises along the Z axis for a distance ΔZ (its value is equal to the thickness of the CAD two-dimensional slice model), and then scans according to the scanning trajectory of the next layer. When all the planes are scanned, the three-dimensional entity is obtained Oral metal restorations. (Figure 1). During the manufacturing process, the powder feeding volume of different powder feeders can be adjusted according to the needs, so that different parts of the oral metal restoration have different components and tissues, so as to achieve the best combination of material/performance/use environment.

The method of the present invention will open up a new processing method for computer-aided design and production (CAD/CAM), which is more in line with the individualized production requirements of each dental restoration; it can also process and produce a variety of materials, and is expected to produce composite Material restoration; the material performance of the processed restoration will be far superior to existing materials; it can save expensive dental materials, and compared with cutting processing methods, it has a wider application range and higher practical value. Just like the modern laser phototypesetting technology replaces the traditional typesetting and printing technology, it greatly improves the automation and production efficiency of oral restorations, meets the rapid restoration needs of the majority of patients with tooth defects, and can extend this technology to orthopedics, plastic surgery and other disciplines. The rapid and accurate production of solid and precision medical devices has huge economic and social benefits. In addition to the general characteristics of saving materials and being able to process arbitrary shapes, this method also has the advantages of being able to manufacture composite restorations and their physical, chemical and mechanical properties can be controlled artificially, which greatly expands the types and scope of computer-aided restorations.

4. Description of drawings

Figure 1 Schematic diagram of the principle of laser stereoforming technology;

Figure 2 is a schematic diagram of the system used in the experiment; the symbols in the figure indicate laser 1, reflective focusing mirror 2, powder feeder 3, substrate 5, molten pool 4, and CNC workbench 6.

Fig. 3 is the three-dimensional reconstruction figure of the wax-type;

Figure 4 is an SLC file distributed by layers;

Fig. 5 is SLFC hierarchical data file;

Figure 6 shows that the STL file is generated after Rpdata processing;

Fig. 7 The picture of the nickel-chromium alloy crown prepared by laser stereoforming technology.

5. Specific implementation

The present invention will be described in further detail below in conjunction with the accompanying drawings and the embodiments given by the inventor. 5.1 Experimental equipment

Referring to FIG. 2 , the laser processing experimental equipment includes a laser 1 , a reflective focusing mirror 2 , a powder feeder 3 , a substrate 5 , a melting pool 4 , and a numerical control workbench 6 . The data acquisition equipment includes Taiwan-made four-axis CNC laser scanning system and IntelPIV2.0G computer. Software: SURFACER 10.5, SDBC (Structural Dynamics Research Corporation) company; Cloud Date Process software, software developed and designed by Xi'an Jiaotong University to process point cloud data; MIMICS software, Belgium Materialize company; RP daba software, designed by Xi'an Jiaotong University, slices CAD The model is converted to STL format software. 5.2 Experimental materials

Rene95 alloy powder is selected, and its composition is shown in Table 1. The particle size is -200 mesh to +300 mesh, the powder particles are spherical, and the fluidity is better. Design and manufacture micro powder feeder, the range of powder feeding volume is 1.0--10g/min, and the powder feeding accuracy is ±3%. The selected substrate is disc-shaped carbon steel with a diameter of 120 mm and a thickness of 8 mm, and its light-receiving surface is blackened to increase the light absorption rate.

Table 1: Rene95 Alloy Composition

C Cr Cr Co Co Al Ti Ti Mo Mo W Nb Zr B Ni

0.04～ 12～14 7～ 3.3～ 2.3～ 3.3～3.7 3.3～3.7 3.3～ 0.03～0.07 0.006～0.015

0.09 9 3.7 2.7 3.75.3 Experimental method

(1). According to the requirements of prosthodontics, the artificial full crown tooth body is prepared, the impression is taken, the superhard plaster model is reproduced, and the removable model is prepared using the plaster model. Make full crown wax-up with inlay wax. Spray the wax type with HD-EV universal flaw detection developer evenly, let it stand for 10 minutes, and the surface is dry. Put the wax-up on the scanning platform, and control the movement of the mechanical platform through the computer. The platform translates in the direction of X-Y axis and rotates in the direction of Z-axis, so as to measure the various surfaces of the wax-up. The laser emitting device generates a laser beam, and the incident laser and The horizontal plane is vertical, and the angle between the receiving beam and the incident beam of the dual CCD is 45 degrees. The laser beam is projected in a linear shape. When the linear beam is projected onto the surface of the wax pattern and reflected, the reflected light is received by the sensor receiving device and input to the computer. With the continuous rotation of the platform in the Z-axis direction, the 360-degree contour of the wax-up is gradually measured to obtain all the data of the wax-up, and the scanning step is 0.01mm.

The computer system processes the data measured by the laser scanner into point cloud data and SCN data format. The data can be processed by SURFACER software to form a three-dimensional wax-shaped reconstruction, as shown in Figure 3.

Process the above SCN point cloud data with Cloud Data Process software to form SLC format files distributed by layers. See Figure 4.

Process the SLC file with MIMICS software and turn it into a binary SLFC file, which is a rapid prototype layered data file. See Figure 5.

Process the SLFC file with Rpdata software, and finally generate the STL format file. See Figure 6.

The three-dimensional reconstruction of the molar crown is realized by laser scanning measurement method, and the CAD model of the crown is obtained, and the file format is STL format.

(2). Preparation of equipment and materials: Prepare Rene95 alloy powder with a particle size of -200 mesh to +300 mesh. The powder particles are spherical and have good fluidity. Design and manufacture micro powder feeder, the range of powder feeding volume is 1.0～10g/min, and the powder feeding accuracy is ±3%.

(3). Input the CAD solid model of the crown into the laser stereoforming equipment. The equipment software cuts the CAD solid model of the crown into 0.1mm thick slices, and converts the data of each slice into numerical control processing commands to control the laser stereoforming system.

(4). The laser beam 1 forms a molten pool 4 of a certain size on the surface of the substrate 5 after passing through the reflective focusing mirror 2, and is driven by the numerical control workbench 6, and is processed by numerical control according to the scanning trajectory line generated in step (3). command, scan the surface of the substrate 5 . While the laser beam is scanning, the powder feeder 3 feeds the metal/alloy powder into the molten pool 4, that is, synchronous powder feeding and coating are carried out, and a layer of material is obtained after condensation. After scanning one layer, the laser beam 1 and the powder feeder 3 rise a distance ΔZ along the Z-axis according to the setting output in step (3), and then coat the next layer of material according to the scanning trajectory of the next layer. After all layers have been applied, a three-dimensional solid part is obtained.

(5). The parameters selected in the experiment are: laser power 3300w ~ 4000w, scanning speed 5mm/s ~ 10mm/s, powder feeding volume 10g/min ~ 20g/min, protective gas flow rate 3.5l/min ~ 6.5l/min . 6 layers of laser cladding for each layer, with an overlap rate of 40%. The artificial tooth crown is obtained, and its accuracy is ±1mm/100mm in the x-y direction, and ±1mm/200mm in the z direction. The mechanical properties of the material are: the room temperature yield strength reaches 850MPa, the tensile strength reaches 950MPa, the elongation exceeds 10%, and the fatigue performance reaches the level of forged materials. 5.4 Example: Application of laser three-dimensional forming technology to prepare oral nickel-chromium alloy crown

Material: Nickel-chromium alloy powder (Rene95 alloy powder, Beijing Iron and Steel Research Institute) was selected, and its composition is shown in Table 1.

Refer to the experimental method in 5.3 to obtain a nickel-chromium alloy crown. Figure 7.

The present invention opens up a new processing method for computer-aided design and production (CAD/CAM system), which is more in line with the individualized production requirements of each oral restoration; it can also process and produce a variety of materials, and it is expected to produce composite material restorations. body; the material performance of the processed restoration will be far superior to existing materials; it can save expensive dental materials, and compared with cutting processing methods, it has a wider application range and higher practical value. Just like the modern laser phototypesetting technology replaces the traditional typesetting and printing technology, it greatly improves the automation and production efficiency of oral restorations, meets the rapid restoration needs of the majority of patients with tooth defects, and can extend this technology to orthopedics, plastic surgery and other disciplines. The rapid and accurate production of solid and precision medical devices has huge economic and social benefits.

In addition to the general characteristics of saving materials and being able to process arbitrary shapes, this method also has the advantages of being able to manufacture composite restorations and their physical, chemical and mechanical properties can be controlled artificially, which greatly expands the types and scope of computer-aided restorations.

Claims (1)

1. the laser solid forming preparation method of oral cavity metal restoration is characterized in that, may further comprise the steps at least:

1) at first in computer, generates the three-dimensional CAD model of oral cavity metal restoration, and according to requirement on machining accuracy this model is carried out hierarchy slicing and handle, the 3 D stereo data transaction of oral cavity metallic prosthetic shape is become a series of two dimensional surface data;

2) then, determine the track of laser beam flying, generate processor, and it is passed to numerical control table, NC table according to the panel data of each layer; Realize that by numerical control table, NC table track while scan that laser beam determines according to processor in the enterprising line scanning of base material, simultaneously, sends into the metal/alloy powder by powder feeder, thereby obtain the coating consistent with this flat shape in laser molten pool; Behind the intact one deck of laser beam flying, laser head and powder-feeding nozzle are along the Z axle segment distance Δ Z that rises, and its numerical values recited equates with the thickness of CAD two dimension slicing model; Track while scan according to following one deck scans again, after all planes have all been scanned, promptly obtains three-dimensional entity oral cavity metal restoration.

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