CN102319125A - Anti-loosing and corrosion-proof dental-implant central screw - Google Patents

Abstract

An anti-loosening and anti-corrosion central screw for dental implants, the small diameter of the thread is 1.5-2.5 mm, the height of the tooth form is 1/10 of the small diameter of the thread, and the surface is coated with a phosphorus-containing TiO ₂ film by the sol-gel method; The thread profile of the screw is triangular, the flank angle of the leading flank is 30°, and the flank angle of the following flank is 20°; It is arc-shaped, and the radius of curvature of these arcs is 1/50 of the small diameter of the thread; the pitch of the five threads of the central screw close to the nut is 0.4-0.5mm, and the bottom of the tooth is inclined inward along the direction of the nut, and is 10° to the thread axis. The included angle; the pitch of other threads is 0.8 ~ 1.0mm, and the bottom of the tooth is parallel to the axis of the thread. The central screw is not easy to loosen and corrode, has reliable performance and long service life, and can improve the long-term success rate of the dental implant.

Description

An anti-loosening and anti-corrosion dental implant central screw

technical field

The invention relates to a component of a dental implant for dental restoration, in particular to a central screw of the dental implant.

technical background

With the development and perfection of osseointegration theory and decades of clinical practice, dental implant has become one of the key restoration techniques for tooth loss. Compared with traditional removable dentures and fixed denture restoration methods, dental implant has the advantages of aesthetics and high comfort. , Stronger chewing function and other advantages. Although recent studies have shown that the five-year success rate of dental implants can reach 94.8% (upper jaw), 97.5% (lower jaw), and the overall success rate is 96.1%. However, with the further extension of service time, the long-term success rate of dental implants has a tendency to further decrease. The success rate of 16-year follow-up in foreign countries is 82.94%, and the success rate of 11-15 years in China is 62.5%. In many dental implant failure cases, failure phenomena such as loosening of the central screw are relatively common. Therefore, exploring anti-loosening countermeasures for the central screw of the dental implant has become a key technical issue to further improve the long-term success rate of the dental implant.

The central screw is an important component that connects the two major parts of a dental implant—the implant and the abutment. The threaded part of the central screw passes through the abutment to cooperate with the internal thread of the implant, and its nut cooperates with the inner wall of the abutment to realize the connection between the implant and the abutment. The central screw of the dental implant is small, with an average diameter of about 2 mm. In addition, the following factors make it very easy to loosen:

There are two contact interfaces between the central screw of the dental implant and other components inside the implant: 1. The lower central screw-implant interface, and 2. The upper central screw-abutment interface. In functional states such as chewing, the relative displacement of the two joint interfaces will occur in microns, and its motion amplitude is just within the range of motion amplitude of "fretting" in tribology. The damage caused by such fretting will be The loss of the screw contact surface material and the change of size lead to the loosening of the screw; and during the service process, the stress on the central screw is not uniform, and the stress is mainly concentrated at the crest of the thread and several threads near the root of the nut At the connection between the upper and central screws and the abutment, the main thread stress is about 200MPa, and the stress concentration in some places is serious, the maximum is 304MPa. These stress concentration parts are more likely to be damaged, which will lead to the loosening or even breaking of the central screw.

In addition, there are extremely small gaps (the width is generally in the range of 0.05-0.08 mm) between the above-mentioned interfaces. The central screw serves in a very special oral corrosion environment. A large amount of water and enzymes in the oral cavity, changing temperature and pH value, occlusal force and abnormal function, bad habits, etc. can cause fatigue and aging of the sealing material of the implant fixing screw hole. , leading to poor edge sealing, micro-leakage cannot be avoided, and corrosive media can easily penetrate into the extremely small gaps in the interface of the central screw; during the operation, the surface of the central screw will inevitably be affected by saliva, blood, intraoperative Contamination of liquids, etc. The above factors cause the central screw to be easily corroded, resulting in poor performance and failure; at the same time, corrosion will also accelerate the loosening of the central screw.

Contents of the invention

The object of the present invention is to design an anti-loosening and anti-corrosion dental implant central screw, which is not easy to loosen and corrode, has reliable performance and long service life, and can improve the long-term success rate of the dental implant.

In order to achieve the above object, the technical solution adopted by the present invention is a central screw for anti-loosening and anti-corrosion dental implant, the small thread diameter is 1.5-2.5 mm, and the height of the tooth form is 1/10 of the small thread diameter. Its structural characteristics yes:

The surface of the central screw is coated with a phosphorus-containing _TiO2 film by a sol-gel method; the thread profile of the central screw is triangular, the flank angle of the leading flank is 30°, and the flank angle of the following flank is 20°; the top of the tooth is arc-shaped, and the junction of the bottom of the tooth and the leading flank and the following flank is also arc-shaped. The radius of curvature of these arcs is 1/50 of the thread minor diameter;

Compared with prior art, the beneficial effect of the present invention is:

1. Anti-corrosion treatment was carried out on the surface of the central screw, that is, a uniform phosphorus-containing TiO ₂ film was prepared on the surface of the central screw by the sol-gel method, and the phosphorus-containing TiO ₂ film was used as a protective film on the surface of the central screw, which can significantly improve its corrosion resistance. Corrosivity, so that it has strong resistance to corrosive media in the interface gap during service, and can prolong its service life.

2. When the central screw of the present invention is screwed in, the leading flank facing the forward direction and the relative following flank are asymmetrical, and the flank angle of the leading flank (the angle between the leading flank and the perpendicular to the screw thread axis) is 30°, and the flank angle of the following flank (the angle between the following flank and the perpendicular to the screw thread axis) is 20°, so that the flank angle of the leading flank of the thread is greater than the flank angle of the following flank, so that Reducing the resistance of the thread to advance and increasing the resistance of the thread to retreat can effectively increase the bearing capacity of the screw and prevent the screw from loosening.

The top of the tooth is arc-shaped, and the junction of the bottom of the tooth and the leading flank and the following flank is also arc-shaped. The radius of curvature of the arc is 1/50 of the small diameter of the thread, so that all thread transition interfaces are arc-shaped and smooth transitions, avoiding The presence of any form of sharp corners can effectively reduce fretting damage; in addition, the arc-shaped transition surface enables the central screw surface to obtain a larger surface area, and the stress distribution in the contact area is more uniform without stress concentration.

In a word, the central screw of the present invention can well prevent loosening, has reliable performance and long service life, and can improve the long-term success rate of the dental implant.

The pitch of the above-mentioned five threads of the central screw close to the nut is 0.4-0.5mm, and the bottom of the tooth is inclined inward along the direction of the nut, forming an angle of 10° with the axis of the thread; the pitch of the other threads is 0.8-1.0mm, and the bottom of the tooth and Thread axes are parallel.

The five threads of the central screw close to the nut (that is, the junction with the abutment) are the main stress-bearing area during service. The thread pitch of this area is halved to 0.4-0.5mm to better disperse the stress; In addition, the bottoms of the five threads are inclined inwardly along the direction of the nut, forming an included angle of 10° with the thread axis, which further increases the retreat resistance, enhances the ability to bear loads, and better prevents the screws from loosening.

The lower surface of the nut of the central screw is inclined downwards, forming an included angle of 30° with the thread axis.

In this way, the junction of the nut and the root of the thread avoids forming a right-angle corner, which reduces the stress concentration at the corner, and at the same time increases the force-bearing area of the junction, which can withstand a larger tightening torque and make the connection more secure. firm.

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Description of drawings

Fig. 1 is a schematic structural diagram of an embodiment of the present invention.

FIG. 2 is an enlarged view of part A in FIG. 1 .

FIG. 3 is an enlarged view of part B in FIG. 1 .

Detailed ways

Example

Figures 1-3 show that a specific embodiment of the present invention is: a kind of anti-loosening and anti-corrosion dental implant central screw, the thread minor diameter D (the diameter of the cylinder tangent to the bottom of the tooth) is 1.5-2.5mm, The tooth profile height H is 1/10 of the thread diameter D, where:

The surface of the central screw is coated with a phosphorus-containing _TiO2 film by the sol-gel method; the thread profile of the central screw is triangular, the flank angle α ₁ of leading flank 3 is 30°, and the flank angle of following flank 4 α ₂ is 20°; tooth crest 1 is arc-shaped, and the junction of tooth bottom 2 and leading flank 3 and following flank 4 is also arc-shaped, and the radius of curvature of these arcs is 1/50 of the small diameter D of the thread;

Figures 1 and 2 show that the pitch of the five threads of the central screw close to the nut is 0.4 to 0.5mm, and the bottom of the tooth is inclined inward along the direction of the nut, forming an included angle γ of 10° with the thread axis; Figures 1 and 2 Figure 3 shows that the pitch of other threads in this example is 0.8-1.0 mm, and the root of the tooth is parallel to the axis of the thread.

Figure 1 also shows that the lower surface of the nut of the central screw in this example is inclined downwards, forming an included angle θ of 30° with the thread axis.

Claims (3)

1. An anti-loosening and anti-corrosion dental implant central screw, the thread diameter (D) is 1.5-2.5mm, and the tooth profile height (H) is 1/10 of the thread diameter (D), characterized in that: The surface of the central screw is coated with a phosphorus-containing TiO ₂ film by a sol-gel method; the thread profile of the central screw is triangular, and the flank angle (α ₁ ) of the leading flank (3) is 30°, following The flank angle (α ₂ ) of the flank (4) is 20°; the crest (1) is arc-shaped, and the junction of the tooth bottom (2) with the leading flank (3) and the following flank (4) is also Arcs, the radius of curvature of these arcs are 1/50 of the thread minor diameter (D); 2. A kind of anti-loosing and anti-corrosion dental implant central screw according to claim 1, characterized in that: the pitch of the five threads of the central screw close to the nut is 0.4-0.5 mm, and the bottom of the tooth is along the screw. The direction of the cap is inclined inwardly, forming an included angle (γ) of 10° with the thread axis; the pitch of other threads is 0.8-1.0mm, and the bottom of the tooth is parallel to the thread axis. 3. A kind of anti-loosening and anti-corrosion dental implant central screw according to claim 1, characterized in that: the lower surface of the nut of the central screw is inclined downwards, forming an included angle of 30° with the thread axis ( θ).

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