WO2019095660A1

WO2019095660A1 - 3d printing method for dental implant abutment

Info

Publication number: WO2019095660A1
Application number: PCT/CN2018/087871
Authority: WO
Inventors: 张志霄; 刘睿诚; 邹善方; 吴利苹; 姚圳珠; 曾益伟
Original assignee: 成都登特牙科技术开发有限公司
Priority date: 2017-11-15
Filing date: 2018-05-22
Publication date: 2019-05-23
Also published as: CN107900332B; CN107900332A

Abstract

A 3D printing method for a dental implant abutment, the method comprising three-dimensional scanning, three-dimensional designing, data processing, 3D printing, and component post-processing. The method is characterized in that: for the three-dimensional scanning, overall profiles of a three-dimensional model are first obtained by means of blue-light scanning, and then fine scanning of an interface portion of the implant abutment is performed by means of probe-based scanning; burr compensation is not included in the three-dimensional design, and for data processing, smooth surface structures free of additional support members are provided at the interface where the dental implant abutment is connected to an implant, at the interior of the interface, and at the periphery of the interface. The 3D printing method for a dental implant abutment significantly improves the molding precision of the dental implant abutment, enables the implant abutment to better meet detail requirements, and simplifies a molding process of selective laser melting, thereby greatly shortening the production period for implant abutments and improving molding efficiency.

Description

3D printing method for dental implant bracket

Technical field

The present invention relates to a 3D printing method, and in particular to a 3D printing method for dental implant holders.

Background technique

Dental implant surgery is currently the most effective method of repairing the missing tooth. The connection between the implant and the implanted superstructure needs to be repaired with a precision implanted stent. Cobalt-chromium alloys and titanium alloys are widely used in the field of denture restoration because of their excellent mechanical properties in strength, hardness, wear resistance, and toughness. Among them, local implants and full-mouth implants are the most common metals. Denture implant brackets.

At present, the commonly used dental metal implants are processed by mechanical cutting, but this molding method takes a long time, has low utilization rate of raw materials, and is lacking in precision. At present, the precision of burs cutting can reach 60μm, and the accuracy and quality of dental implants will be reduced due to the loss of cutting burs. In the process of cutting, the knives cannot be cut in the cutting process, and the accuracy of adjacent places is not Good, the abutment and the implant, the abutment and the upper restoration cannot be precisely fitted, affecting the accuracy and the overall quality of the planting and restoration.

The most commonly used metal for planting brackets is titanium alloy. Titanium alloys tend to have the following problems during the cutting process: the hardness of titanium alloy is too large to make it difficult to cut, and the deformation coefficient of titanium alloy is less than or close to 1, which often aggravates tool wear. At the same time, due to the small elastic modulus of the titanium alloy, bending deformation is easily generated under the action of radial force during processing, causing vibration, increasing tool wear and affecting the accuracy of the part. Due to the high chemical activity of titanium, it is easy to absorb oxygen and nitrogen in the air to form a hard and brittle outer skin at high cutting temperatures; at the same time, plastic deformation during cutting also causes surface hardening. Therefore, the cutting manufacturing method is not suitable for high-performance, automatic and rapid production of the planting bracket.

3D printing is another name for additive manufacturing. It rebuilds the 3D digital model and uses the metal powder layer-by-layer principle to manufacture solid parts, making the entire manufacturing process truly intelligent and digital. Laser selective melting is the most widely used laser selective melting technology. It is a technology based on laser melting metal powder. It integrates laser technology, digital intelligent control technology, computer aided design analysis and rapid prototyping. It can directly manufacture metallurgical bonding. Metal parts with compact structure, good mechanical properties and high precision.

Laser selective melting technology has the advantages of high degree of individuality, simple process, short production cycle and high material utilization rate. It can meet the technical requirements of personalized, complicated and difficult oral repair, and at the same time make up for the shortcomings of the prior art. Because of the various effects of cutting temperature. Therefore, laser selective melting has been applied more and more to the manufacture of dental prostheses, and has become an indispensable emerging technology for oral digital processing.

However, when the laser selection is melted in the processing of metal materials, due to the forming mechanism of the sudden heat and quenching, the thermal stress of the planting bracket is large during the processing, and it is easy to be deformed; after the support of the processing planting bracket is added for 3D printing, the post-processing is time consuming. It is easy to affect the accuracy of the interface with the implant, so it is very difficult to melt the metal implant bracket by laser selection. Since the parts currently melted by the laser selection usually require low precision, the edge of the part has a burr and other uneven structure after the one-time laser scanning, which is also not allowed in the dental implant bracket.

Summary of the invention

The invention provides a 3D printing method for a dental implant bracket, which improves the forming precision of the dental implant bracket and simplifies the molding process of laser selective melting.

The 3D printing method of the dental implant bracket of the invention comprises three-dimensional scanning, three-dimensional design, data processing, 3D printing and post-part processing. In the three-dimensional scanning, the global shape of the three-dimensional model is obtained by blue light scanning, and then the probe scanning pair is obtained. The interface part of the implant bracket is finely scanned, and the burr compensation is not set in the three-dimensional design. In the data processing, the interface between the dental implant bracket and the implant body, the interface inside and the interface edge are smooth surfaces without support. structure.

In an alternative manner, when the data processing position is placed, the long axis of the three-dimensional model and the horizontal axis of the substrate are between 30° and 60°.

Preferably, the long axis of the three-dimensional model is at an angle of 45° to the horizontal axis of the substrate.

Further, in the three-dimensional design, the interface edge of the three-dimensional model is used as a reference to locate the interface position in the three-dimensional model, so that the designed three-dimensional model and the base station are closely matched.

Further, when the three-dimensional model is exported, all the shells included in the three-dimensional model are merged, and then the chord height of the triangular patch in the three-dimensional model is set to be less than 0.1 mm to ensure the accuracy of the three-dimensional model.

Further, in 3D printing, at least two laser scans of the interface are performed by laser selective melting.

Optionally, during the laser scanning, the interface is first subjected to 4 to 6 repeated scans with a low line energy density laser having a line energy density of 0.1 to 0.3 J/mm, and then the line energy density is controlled. The dense remelting is performed at a high line energy density laser of 0.5 to 1 J/mm.

On this basis, in 3D printing, orthogonal continuous scanning is applied to the local implanted stent, and the full-port implanted stent is scanned by a checkerboard type partition, and the support forming portion is scanned by a barrier layer.

The 3D printing method of the dental implant bracket of the invention can greatly improve the forming precision of the dental implant bracket, and can make the planting bracket better meet the requirements in the detail part, and also simplifies the molding process of the laser selection melting, so that the stent is planted. The production cycle has been greatly shortened, effectively improving the molding efficiency.

The above content of the present invention will be further described in detail below with reference to specific embodiments of the embodiments. However, the scope of the above-mentioned subject matter of the present invention should not be construed as being limited to the following examples. Various alterations and modifications may be made without departing from the spirit and scope of the invention.

DRAWINGS

1 is a flow chart of a 3D printing method of a dental implant holder of the present invention.

Figure 2 is a schematic view of the position of the three-dimensional model.

Detailed ways

The 3D printing method of the dental implant bracket of the invention comprises three-dimensional scanning, three-dimensional design, data processing, 3D printing and part post-processing. Among them, three-dimensional scanning is the first step in dental digital processing, and the patient's oral condition can be obtained through three-dimensional scanning. The three-dimensional scanning of dentistry is divided into two types: gypsum model scanning and patient intraoral scanning. The present invention uses a gypsum model scanning method. The gypsum model scanning process uses a rapid solidification material such as silicone rubber to take out the impression from the patient's mouth, and then injects the plaster model through the impression, and then scans the three-dimensional shape of the plaster model with a scanner. The scanning accuracy at this stage will directly determine the molding accuracy of the entire machining process. Therefore, in order to improve the scanning accuracy, the global shape of the three-dimensional model is obtained by blue-ray scanning in the three-dimensional scanning, and then the interface portion of the implanting bracket is finely scanned by the probe scanning, thereby realizing the scanning reproduction of each small feature, and the scanning precision can be Within 2μm, the final design of the implant support can better meet the patient's needs in the details. Although both blue light scanning and probe scanning are prior art, in the conventional dental implant stent 3D printing process, only one scanning mode is adopted as needed, and the present invention uses two scanning methods according to different parts and needs. Combined use, the scanning accuracy of the whole and the details is greatly improved, which lays a foundation for the final high-precision printed product.

The 3D design is to import the scanned oral 3D data into dental design software such as 3shape or EXOcad, and design the implant bracket according to the position of the implant, the shape of the restoration and the size of the implant. The thickness of the crown and the bracket can be as low as 0.15mm, which is lighter, and the burr compensation is not set in the three-dimensional design, which eliminates the complicated and time-consuming process of the bur cleaning, and the production cycle of the planting bracket is greatly improved. shorten. The bur compensation described therein is a default value in the design software. In the conventional dental implant brackets that are formed by cutting, in order to compensate for the lack of precision due to the diameter of the bur itself, more cutting is performed at a precise position such as a cut end, so that the joint is better adhered to the base. In the 3D printing, the bur is not involved, but it is usually customary to perform the bur compensation in the three-dimensional design, and this will affect the precision of the final molding. Therefore, the present invention cancels the option and improves the accuracy of the 3D printing. At the same time, the integrity of the designed planting bridge is also guaranteed. In the three-dimensional design, the shape of the restoration is designed according to the actual situation, and then the suitable planting bracket is designed by the back-cutting. When the foundation bridge is designed, sufficient space of 1.5-3.0 mm is reserved for the upper restoration. The position of the interface in the 3D model is located by using the interface edge of the 3D model and the geometric edge of the abutment as a reference, so that the designed 3D model and the abutment are precisely matched. When exporting to STL format, merge all the designed shells, and then set the STL triangle facet height below 0.1mm to ensure the accuracy of the 3D model in the STL file.

Data processing is the process of data inspection and repair, position placement, support addition and slicing in the designed 3D model in the data processing software. In the position placement, the three-dimensional model of multiple STL files printed at the same time is typeset and placed, and it is necessary to ensure that no contact occurs between the three-dimensional models, the distance boundary is at least 10 mm, and the distance between them is >1 mm. When placing the position, the principle that the support surface is as small as possible and the height in the vertical direction is as small as possible is to improve the molding efficiency. When the position is placed, the long axis of the three-dimensional model and the horizontal axis of the substrate are at an angle of about 45°, which can enhance the ability of the printed planting bracket to resist the lateral force from the blade during the spreading process, so that the forming process of the planting bracket more stable.

In the support addition part of the data processing, it is required to ensure that the printed planting bracket can be firmly supported, and the planting bracket is also easily removed after molding. The interface between the implant and the implant is removed, and the support members in the interface and the edge of the interface are eliminated, so that the inside of the interface and the edge of the interface are smooth surface structures without additional support members, and the interface is obtained by increasing the density of the support members around the interface. Good support to ensure the quality of the interface.

In 3D printing, printing is performed using a laser selective melting process. In order to improve the printing effect, the accuracy of the printing part is improved. At the time of laser scanning, at least two laser scannings are performed on the position of the interface to completely melt the metal powder at the place, and the interface surface is smooth and flat, thereby greatly improving the precision of the interface. The laser energy of each scan may be the same or different. For example, the scanning position may be repeated 4 to 6 times with a low line energy density laser having a line energy density of 0.1 to 0.3 J/mm, and then the line may be used. The energy density is controlled by a high linear energy density laser of 0.5 to 1 J/mm for dense remelting. Orthogonal continuous scanning is applied to the local implanted stent, and the full-port implanted stent is scanned by a checkerboard type partition, and the support forming portion is scanned by a compartment. The laser focused beam has a diameter of 40 to 100 μm, a laser power of 100 to 300 W, a scanning speed of 700 to 2000 mm/s, and a scanning pitch of 0.1 to 0.16 mm.

After the 3D printing is completed, the comprehensive performance of the planting bracket is improved by post-processing.

Example 1:

This embodiment takes the preparation of a titanium alloy full-mouth implanted stent as an example.

The 3D printing method of the dental implant bracket of the present invention as shown in FIG. 1 includes:

Three-dimensional scanning: After the impression is taken from the patient's mouth by silicone rubber, the plaster model is infused through the impression. In order to improve the scanning accuracy, a combination of blue light scanning technology and probe scanning technology is adopted. Firstly, the shape of the model is scanned by a 3shape blue light scanner to obtain the global topography of the three-dimensional model, and then the Nobel probe scanner is used to implant the stent. The interface part performs fine scanning to realize the scanning reproduction of each small feature at the neck edge and the implant interface, and the final scanning precision can reach 2 μm.

Three-dimensional design: After obtaining the three-dimensional data inside the patient's mouth, the oral three-dimensional data is imported into the EXOcad dental design software, and the implant stent is designed according to the shape of the implant and the shape of the restoration and the axial direction of the two. Depending on the thickness of the stent in the mouth and the patient's tolerance, the crown and stent have a thickness of 0.5 mm, which ensures strength and is also lightweight. No burr compensation is set during the design process. During the design process, it is necessary to confirm the boundary line of the interface between the opening and the abutment interface to ensure accurate 3D printing.

After the dental implant bracket completes the 3D design, it is exported as an STL format file containing 3D model data. Then, the shells of all the designs in the 3D model are merged, and the triangular shape of the 3D model in the STL is set to be less than 0.1 mm to ensure the accuracy of the 3D model.

Data processing: After the 3D design is completed, the STL format file of the implanted bracket is obtained, and the STL file of the implanted bracket is imported into the magic data processing software for data inspection and repair, position placement, support addition, slicing and scanning strategy planning, etc. step.

The data inspection and repair part is to check whether the three-dimensional model in the three-dimensional STL file has defects such as holes and bad edges, and if the defect is found to be repaired, the three-dimensional model in the STL file is a complete and closed casing. .

In the position placement part, the multiple STL files printed at the same time are typeset and placed, and it is necessary to ensure that no contact occurs between the three-dimensional models, the distance boundary is at least 10 mm, and the distance between them is >1 mm. As shown in Fig. 2, the position should be placed as small as possible and the height in the vertical direction should be as small as possible to improve the molding efficiency. When the position is placed, the angle α between the long axis of the processed three-dimensional model 2 and the horizontal axis of the substrate 1 is about 45°, which can enhance the ability of the stent to resist lateral force, make the molding precision higher, and print When the powder spreading blade 3 of the printing device moves in the direction of the arrow to perform powdering, the powder scraping blade 3 can be respectively contacted with the three-dimensional model 2 at different positions, thereby avoiding the uneven contact at the same position and causing uneven wear, and at the same time minimizing The small powder scraper 3 is subjected to the resistance of the three-dimensional model 2 when it is running.

When the support is added, it is easy to remove the support after the molding is completed while ensuring that the planting bracket can be firmly supported. For different types of scrapers in 3D printing devices, you can choose the appropriate support type. This embodiment uses a rigid blade with the added support being a block support. The interface between the implant and the implant eliminates the support in the interface and the edge of the interface, so that the inside of the interface and the edge of the interface are smooth surface structures without additional support members, and the interface is obtained by increasing the density of the support around the interface. Good support ensures the quality of the interface.

The slice portion is obtained by passing a three-dimensional model in the STL file to obtain slice data, and the slice thickness in the embodiment is set to 30 μm.

The scanning strategy planning part is to plan the scanning method of each slice to determine the separation distance between the scanning lines and the offset distance of the contour lines. In this embodiment, an orthogonal continuous scanning strategy is employed.

3D printing: After the data processing is completed, the data is imported into a laser-selected 3D printing device and printed. The printing material is made of micron-sized spherical metal powder. The laser scans the powder of each layer of the cross-section on the substrate by scanning, and then superimposes the layers as a planting support. The diameter of the laser focused beam of the 3D printing apparatus was set to 80 μm, the laser power was set to 120 W, and the control precision of the screw motor was within 1 μm. The exposure parameters inside the printing implant bracket are: scan spacing 0.14mm, speed 1200mm/s, intensity 270W, offset compensation 0.08mm, stripe width 5mm, hop scan, rotation; the exposure parameters of the upper part of the print implant bracket are: distance 0.14mm The speed is 1300mm/s, the strength is 300W, and the thickness is 0.06mm. The exposure parameters of the lower part of the implant bracket are slightly weaker than the upper exposure parameters, and the speed and the exposure intensity are reduced. The aim is to shorten the time and improve the efficiency under the condition of molding quality.

The Ti6Al4V titanium alloy powder material is produced by plasma atomization. The sphericity is above 90%, the powder particle size ranges from 15 to 45 μm, the powder Hall fluidity data is less than 40 s/50 g, and the powder oxygen content is 1000 ppm.

TC4 (Ti6Al4V) is selected as the substrate material to ensure good wettability between the molding material and the substrate, ensuring a firm bond between the substrate and the part without cracking.

In the molding process, according to the difference of materials and layer thickness, the laser power, scanning speed and other molding processes of the 3D printing device are adjusted to ensure that the laser beam can completely melt the metal powder to form a continuous smooth melting channel. In order to prevent the printing powder from oxidizing during the melting process, the printing powder is protected by nitrogen gas during the molding process, and the nitrogen gas pressure is 5 bar. In order to prevent the dust generated in the molding process from contaminating the printing powder, a dust filtering device is disposed in the 3D printing device.

Post-processing of parts: After 3D printing is completed, post-processing is required to improve the overall performance of the parts. Since the laser selective melting is a rapid thermal quenching process, there is residual stress inside the molded stent. In order to prevent deformation, the molded part needs to be placed in an atmosphere-protected muffle furnace together with the substrate before cutting, and an annealing heat treatment is performed to remove residual stress inside the implant holder.

The treatment process is: heating in a muffle furnace from normal temperature to 800 ° C for two and a half hours, then holding for two hours, and then naturally cooling to 380 ° C, the whole process is protected by argon gas, and the flow rate of argon gas is controlled at 0.5 m 3 / h.

After the annealing treatment is completed, the implant holder can be cut from the substrate, and then the support is removed, and then the surface is subjected to sandblasting, polishing, polishing, etc., and the interface is closely adhered to the gap after the post-processing is completed, and the molding effect is good. . The comprehensive performance test is shown in Table 1. Compared with the mechanical cutting technology, the technique adopted by the invention has higher precision and better mechanical properties, and the release of the metal ions in the mouth of the prosthesis is less, and the safety hazard to the patient is smaller.

Table 1:

参数parameter	本实施例的方法Method of this embodiment	机械切削Mechanical cutting
材料material	Ti6Al4V球形粉末Ti6Al4V spherical powder	Ti6Al4V圆形切削盘Ti6Al4V circular cutting disc
精度Precision	误差在20μm以下The error is below 20μm	一般在60～120μmGenerally in 60 ~ 120μm
抗拉强度tensile strength	1100Mpa1100Mpa	780Mpa780Mpa
屈服强度Yield Strength	1050Mpa1050Mpa	580Mpa580Mpa
断后延伸率Post-break elongation	>10％>10%	5％～7％5% to 7%
口内金属离子释放量Intraoral metal ion release	少于1μg./cm ³ Less than 1μg./cm ³	10μg./cm ³ 10μg./cm ³

Example 2:

This embodiment takes the preparation of a pure titanium full-mouth implanted stent as an example.

Three-dimensional design: After obtaining the three-dimensional data inside the patient's mouth, the oral three-dimensional data was imported into the EXOcad dental design software, and the planting bracket was designed according to the position of the implant, the shape of the restoration and the size of the implant. According to the thickness of the implanted stent in the mouth and the patient's tolerance, the thickness of the crown and the stent is 0.05 mm, which not only ensures the strength, but also meets the lightweight design. No burr compensation is set during the design process. During the design process, it is necessary to confirm the boundary line of the interface between the opening and the abutment interface to ensure accurate 3D printing.

In the position placement part, the multiple STL files printed at the same time are typeset and placed, and it is necessary to ensure that no contact occurs between the three-dimensional models, the distance boundary is at least 10 mm, and the distance between them is >1 mm. As shown in Fig. 2, the position should be placed as small as possible and the height in the vertical direction should be as small as possible to improve the molding efficiency. When the position is placed, the angle between the long axis of the processed three-dimensional model and the horizontal axis of the substrate is about 45°, which can enhance the ability of the stent to resist lateral force and make the molding precision higher.

The scanning strategy planning part is to plan the scanning method of each slice to determine the separation distance between the scanning lines and the offset distance of the contour lines. In this embodiment, a checkerboard partition scanning strategy is used to reduce thermal stress during molding and prevent deformation.

3D printing: After the data processing is completed, the data is imported into a laser-selected 3D printing device and printed. The printing material is made of micron-sized spherical metal powder. The laser scans the powder of each layer of the cross-section on the substrate by scanning, and then superimposes the layers as a planting support. The diameter of the laser focused beam of the 3D printing apparatus was set to 80 μm, the laser power was set to 120 W, and the control precision of the screw motor was within 1 μm. The exposure parameters inside the printing implant bracket are: scan spacing 0.14mm, speed 1500mm/s, intensity 290W, offset compensation 0.08mm, stripe width 5mm, hop scan, rotation; the exposure parameters of the upper part of the print implant bracket are: distance 0.14mm The speed is 1500mm/s, the strength is 300W, and the thickness is 0.03mm. The exposure parameters of the lower part of the implant bracket are slightly weaker than the upper exposure parameters, and the speed and the exposure intensity are reduced. The aim is to shorten the time and improve the efficiency under the condition of forming quality.

The pure titanium powder material is selected by plasma atomization, the sphericity is above 90%, the powder particle size ranges from 15 to 45 μm, the powder Hall fluidity data is less than 40 s/50 g, and the powder oxygen content is 1200 ppm.

The treatment process is: heating in a muffle furnace from normal temperature to 800 ° C for two and a half hours, then holding for 1 to 2 hours, then naturally cooling to 380 ° C, the whole process is protected by argon gas, and the flow rate of argon gas is controlled at 0.6 m 3 / h.

After the annealing treatment is completed, the implant stent can be cut from the substrate, and then the support is removed, and the surface is subjected to sandblasting, polishing and polishing to obtain a pure titanium full-mouth implant stent.

Claims

The 3D printing method of the dental implant bracket includes three-dimensional scanning, three-dimensional design, data processing, 3D printing and post-processing of parts. The feature is: the three-dimensional model is first scanned by blue light to obtain the global shape of the three-dimensional model, and then scanned by the probe. The interface part of the implanted bracket is finely scanned, and the burr compensation is not set in the three-dimensional design. In the data processing, the interface between the dental implant bracket and the implant body, the inside of the interface and the interface edge are smooth without support. Surface structure.
A 3D printing method for a dental implant holder according to claim 1, wherein the angle between the long axis of the three-dimensional model (2) and the horizontal axis of the substrate (1) is (α) when placed at the position of data processing. 30 ° ~ 60 °.
A 3D printing method for a dental implant holder according to claim 2, wherein the long axis of the three-dimensional model is at an angle of 45 to the horizontal axis of the substrate.
The 3D printing method for a dental implant holder according to claim 1, wherein in the three-dimensional design, the interface edge of the three-dimensional model is positioned by using the interface edge of the three-dimensional model and the geometric edge of the base as a reference, so that the design is good. A precise fit between the 3D model and the abutment.
A 3D printing method for a dental implant holder according to claim 1, wherein: when the three-dimensional model is exported, all the shells included in the three-dimensional model are merged, and then the triangular surface of the three-dimensional model is merged. The string height is set to less than 0.1 mm to ensure the accuracy of the 3D model.
A 3D printing method for a dental implant holder according to any one of claims 1 to 5, wherein in the 3D printing, at least two laser scans of the interface are performed by laser selective melting.
A 3D printing method for a dental implant holder according to claim 6, wherein at the time of said laser scanning, a low line energy density laser having a line energy density of 0.1 to 0.3 J/mm is used for said interface. After 4 to 6 repeated scans, the dense line energy density laser with a line energy density of 0.5 to 1 J/mm is used for dense remelting.
The 3D printing method for a dental implant holder according to any one of claims 1 to 7, wherein in the 3D printing, orthogonal continuous scanning is applied to the local implant support, and the full-port implant support is performed by using a checkerboard type partition scan. The forming part is supported and scanned by a compartment.