WO2020025755A1

WO2020025755A1 - Devices and methods for testing dental implants

Info

Publication number: WO2020025755A1
Application number: PCT/EP2019/070783
Authority: WO
Inventors: Mikel ABASOLO BILBAO; Josu AGUIRREBEITIA CELAYA; Ibai CORIA MARTÍNEZ; Igor FERNÁNDEZ DE BUSTOS; Iker HERA MIGUEL
Original assignee: Euskal Herriko Unibertsitatea
Current assignee: Euskal Herriko Unibertsitatea
Priority date: 2018-08-01
Filing date: 2019-08-01
Publication date: 2020-02-06
Anticipated expiration: 2021-02-01
Also published as: EP4007900A1; ES2739878A1; ES2739878B2

Abstract

A device (10,11) comprising: a cam (20,21); a motor configured to rotate the cam (20,21); and at least one assembly (25a-25h) adapted to apply a load on a dental implant (55a-55h), each assembly (25a-25h) of the at least one assembly comprising: a support (50) adapted to support a dental implant (55a- 5h); a guide (38) arranged between the cam (20,21) and the support of the assembly (25a-25h); a first element (32) arranged on the guide (38) of the assembly (25a-25h) and adapted to contact the dental implant (55a-55h) in the support (50) of the assembly (25a-25h); a second element (34) arranged on the guide (38) of the assembly (25a-25h) and in contact with the cam (20,21), the second element (34) being adapted to move along the guide (38) of the assembly (25a-25h); and a spring (30) arranged on the guide (38) of the assembly (25a-25h) and comprising a first end and a second end, the first end being coupled to the first element (32) of the assembly (25a-25h) and the second end being coupled to the second element (34) of the assembly (25a- 25h). The invention also relates to a method for testing dental implants with the device.

Description

DEVICES AND METHODS FOR TESTING DENTAL IMPLANTS

Field of the invention

The present invention relates to the field of testing dental implants, and more specifically, to devices for testing dental implants.

Background of the invention

Dental implants which are installed in patients must be certified by means of fatigue and loosening tests, the strength of the dental implants with respect to these failures thus being assured. Such tests attempt to simulate the forces produced when chewing by means of a series of pulsating cyclic loads, i.e., a series of loading and unloading.

Direct tension machines, which apply a load on the test specimen by means of a linear actuator, have previously been used to perform tests of this type. Thus, direct tension machines for testing several devices have been adapted to enable dental implants to be tested. The costs of manufacturing such machines are high due to the components they include; furthermore, the machines are designed for testing a single dental implant.

New apparatuses have been developed in an attempt to lower the costs of testing dental implants.

Patent document MX-2010002975-A describes a chewing simulator, wherein a cam actuates a swinging arm which applies a load on a plurality of dental implants simultaneously. The cam must withstand the loading of all the implants simultaneously, which results in a high load which is variable over time, which in turn requires a high power motor to move the assembly. The dimensions and weight of the components and of the simulator generally result in high costs. Likewise, the loading cycles of the described chewing simulator do not exceed the frequency of 1.4 Hz, which slows down dental implant testing.

Patent document CN-101441158-A describes a chewing simulator, wherein a cam actuates a movable plate which is moved using several guide posts in order to apply a load on a plurality of dental implants simultaneously. A shock absorber is included for correct operation of the simulator. This simulator presents problems similar to those mentioned above in relation to the other chewing simulator in terms of complexity and sizing; likewise, the maximum load frequency is 2 Hz, which lengthens the dental implants testing time.

There is an interest in being able to perform fatigue and/or loosening tests in dental implants in an economical manner and in compliance with the standard regulation for such tests, for example standard ISO 14801 :2016 Dentistry -- Implants -- Dynamic loading test for endosseous dental implants. This standard establishes that tests of up to five million loading-unloading cycles can be performed on a dental implant at a maximum frequency of 15 Hz, resulting in an approximate duration of 4 entire days per dental implant tested. Therefore, on one hand, there is an interest in shortening the testing process time, but still complying with the standard regulation for such tests. On the other hand, there is also an interest in the economical manufacturing and maintenance of devices needed for performing the test process.

Description of the invention

The device and the method of the present disclosure attempt to solve one or more of the aforementioned problems in several embodiments of said device or method.

A first aspect of the invention relates to a device comprising: a cam; a motor configured to rotate the cam; and at least one assembly adapted to apply a load on a dental implant, each assembly of the at least one assembly comprising: a support adapted to support a dental implant; a guide arranged between the cam and the support of the assembly; a first element arranged on the guide of the assembly and adapted contact the dental implant in the support of the assembly; a second element arranged on the guide of the assembly and in contact with the cam, the second element being adapted to move along the guide of the assembly; and a spring arranged on the guide of the assembly and comprising a first end and a second end, the first end being coupled to the first element of the assembly and the second end being coupled to the second element of the assembly.

The device makes it possible to perform the testing of one or more dental implants according to the number of assemblies the device comprises.

The motor rotates the cam by means of a shaft and as the cam rotates, the second element of each assembly that is in contact with it gradually moves on the guide thereof, specifically it moves forwards and backwards on the guide in order to apply cyclic loading by way of loading and unloading. The second element follows the cam and compresses the spring of the assembly thereof in order to apply the load to the dental implant in the support when the second element moves forward, and decompresses the spring in order to stop applying the load on the dental implant when the second element moves backwards.

Compression of the spring results in a compressive force in the first element, and the first element applies said force on the dental implant. The compressive force is equal to the compression of the spring (the length that the spring is compressed is equal to the length that the second element travels when following the cam, therefore the length of the travel depends on the eccentricity of the cam) multiplied by the stiffness constant of the spring.

In some embodiments, the cam comprises one lobe.

One dental implant loading and unloading cycle is performed per revolution of the cam; therefore the frequency of cyclic loading is the number of revolutions per second of the cam.

In some embodiments, the motor is configured to rotate the cam at between 800 and 910 revolutions per minute, preferably at between 850 and 905 revolutions per minute, and more preferably at 900 revolutions per minute.

With a rotation speed of the cam of 900 revolutions per minute, the device produces 15 cyclic loads per second in the dental implant (given that the cam comprises one lobe); therefore, the fatigue test is performed in the most rapid manner possible complying with standard ISO 14801.

In some embodiments, the cam comprises two lobes.

In some embodiments, the motor is configured to rotate the cam at between 400 and 460 revolutions per minute, preferably at between 425 and 455 revolutions per minute, and more preferably at 450 revolutions per minute.

In some embodiments, the cam comprises three lobes.

In some embodiments, the motor is configured to rotate the cam at between 275 and 325 revolutions per minute, preferably at between 290 and 310 revolutions per minute, and more preferably at 300 revolutions per minute.

Two or three dental implant loading and unloading cycles are performed per revolution of the cam when the cam comprises two or three lobes, respectively. In order to produce 15 cyclic loads per second in each dental implant, as established as the maximum under standard ISO 14801 :2016, the motor must rotate the cam at a speed two or three times higher, respectively, with respect to the rotation speed when the cam has one lobe. In some embodiments, the device further comprises a reduction gear for the motor. In some embodiments, the device comprises a geared motor comprising the motor.

In some embodiments, the support of each assembly of the at least one assembly is adapted to support the dental implant forming a 30 degree angle with respect to the longitudinal axis of the guide of the assembly, i.e., with respect to the direction of the load, the load thereby being applied with a 30 degree angle on the dental implant as established under standard ISO 14801 :2016.

In standard regulations for testing dental implants, it may be established that the load to be applied on the dental implant must form an angle with respect to the axis of the implant. For example, standard ISO 14801 :2016 establishes that this angle must measure 30 degrees. By adapting the support to receive the dental implant such that said angle exists with respect to the longitudinal axis of the guide, the mechanism applying the load on the dental implant does not have to be altered.

In some embodiments, the support of each assembly of the at least one assembly comprises a tell-tale arranged to receive the load in the absence of or in the event of breaking of the dental implant.

When the device comprises a plurality of assemblies but there is not a plurality of dental implants to be tested, and even if each assembly has a dental implant installed therein and one of them breaks during the test, the tell-tale in each assembly may receive the load. The device can thereby operate continuously regardless of whether all the dental implants are present and have not broken. When any of the dental implants breaks during a fatigue test, since a tell-tale replaces them, the cam continues to be self-balanced and therefore does not affect the test conditions of the remaining implants.

In some embodiments, the second element of each assembly of the at least one assembly comprises a sheave in contact with the cam.

The sheave of each second element reduces the friction between the cam and the second element, which facilitates the travel of the second element and reduces the torque the motor must withstand.

In some embodiments, the first element and the second element of each assembly of the at least one assembly each comprise a carriage. These are commercial carriages for linear guides available on the market, therefore they are standard, reliable and economical elements.

In some embodiments, the at least one assembly comprises a plurality of assemblies.

The device allows several assemblies for testing multiple dental implants to be arranged (one per assembly) with the same cam of the device, which acts on all the assemblies.

In some embodiments, the plurality of assemblies is arranged around the cam such that the guide of each assembly of the plurality of assemblies extends from the cam radially.

The radial arrangement of each assembly (according to the guide of each assembly) facilitates the handling of the device and the dental implant test. The cam acts on the second element of each assembly since it is in the portion closest to the cam.

In some embodiments, the plurality of assemblies comprises eight assemblies; and each assembly is arranged such that the guide of the assembly forms an angle of between 40 and 50 degrees with respect to the guide of the two adjacent assemblies, and preferably forming a 45 degrees angle.

This distribution minimizes the power required for the drive motor. The equidistant arrangement of the assemblies around the cam causes the system to be as balanced as possible, thus reducing the torque that the motor must withstand.

In some embodiments, the at least one assembly comprises one assembly.

In some embodiments, the device further comprises a microcontroller configured to operate the motor.

The microcontroller can actuate the motor to switch on, to switch off and/or to make the cam rotate at a certain speed. The microcontroller can likewise receive the rotation speed from the motor and control the operation of the motor accordingly, particularly the microcontroller can control the number of loading-unloading cycles each implant withstands and adjust the speed of the motor in order to apply the desired number of loading-unloading cycles per unit of time for each dental implant.

A second aspect of the invention relates to a method comprising: providing a device according to the first aspect of the invention; situating a dental implant in the support of each assembly of the device; and activating the motor in order to rotate the cam of the device.

The method allows one or more dental implants to be tested and thus enables the fatigue and/or loosening strength of one or more dental implants to be checked. When the device comprises more than one assembly, it is possible to test a smaller number of dental implants than the number of assemblies of the device; for that purpose, a tell-tale can be situated in the support of each assembly wherein a dental implant is not going to be tested, such that the device can be operated even though only one dental implant or several dental implants are situated in the support of one or several assemblies of the device.

Advantages similar to those described for the first aspect of the invention also apply to this aspect of the invention.

Brief description of the figures

To complement the description and for the purpose of helping to better understand the features of the invention according to a practical embodiment thereof, a set of figures is attached as an integral part of the description in which the following is depicted in an illustrative and non-limiting manner:

Figures 1 and 2 show devices according to embodiments of the invention.

Description of embodiments of the invention

Figure 1 shows a device 10 for testing dental implants 55a-55b according to an embodiment of the invention.

The device 10 comprises a cam 20 with one lobe 23 which turns around a rotating shaft 22 as a result of a motor (not illustrated) of the device 10; the motor can be coupled to a reduction gear of the device 10 and connected to a microcontroller of the device 10 which controls it.

The device 10 further comprises two assemblies 25a-25b, both having the same features. A dental implant 55a-55b to be tested by the device 10 can be arranged in each assembly 25a-25b. Each assembly 25a-25b comprises a linear guide 38, a first element 32 arranged on the guide 38 in contact with the dental implant 55a-55b, a second element 34 movably arranged on the guide 38 and in contact with the cam 20, and a spring 30 coupled to the first element 32 and to the second element 34. The second element 34 of each assembly 25a-25b comprises a sheave 36 contacting the cam 20. The spring 30 is preferably a calibrated spring. Both the first element 32 and the second element 34 can be carriages, and they can be provided with balls for traveling along the guide 38.

The guide 38 of each assembly 25a-25b (and, therefore, each assembly

25a-25b) extends radially from the cam 20, the nearest end being the one at which the second element 34 is arranged. The guide 38 of each assembly 25a- 25b is preferably a rail of a guide with runners.

When the cam 20 rotates, the lobe 23 presses on the second element 34 of each assembly 25a-25b and moves it forwards on the guide 38 towards the first element 32, producing a compressive force on the spring 30 of each assembly 25a-25b. Since the spring 30 is coupled to the first element 32, the compressive force is transmitted to the first element 32 which in turn transmits the force to the dental implant 55a-55b. Therefore, the compression undergone by the spring is exerted by the followers of the cam 20, i.e., the second element 34 of each assembly 25a-25b. When the lobe 23 stops pressing on the second element 34, the second element 34 moves backwards along the guide 38, decompressing the spring 30.

The dental implant 55a-55b can be arranged in the assembly 25a-25b such that the axis thereof forms an angle with respect to the longitudinal axis of the linear guide 38, for example a 30 degrees angle, and the load is therefore applied to the dental implant 55a-55b with said angle.

Figure 2 shows a device 11 for testing dental implants 55a, 55c-55h according to one embodiment of the invention.

The device 11 comprises a support surface 15; the support surface can be, for example, a table with a plurality of legs 16. The device further comprises a cam 21 with three lobes 23 turning around the rotating shaft 22; the rotating shaft 22 is perpendicular to the support surface 15. Likewise, the device 11 comprises a motor (not illustrated) adapted to rotate the cam 21 around the rotating shaft 22, and in some examples, it also comprises a reduction gear coupled to the motor and/or a microcontroller connected to the motor. For example, the motor, the reduction gear and the microcontroller (in the event that the device 11 comprises either of the latter two or both) can be arranged behind the support surface 15; the shaft 22 to which the cam 21 is coupled can pass through a hole (not illustrated) in the support surface 15. The device 11 further comprises a plurality of assemblies 25a-25h arranged on the support surface 15 and around the cam 21. Each assembly 25a-25h comprises a support 50 adapted to support a dental implant 55a, 55c- 55h, the linear guide 38, the first element 32 arranged on the guide 38, a second element 34 arranged on the guide 38 such that it can move along the guide 38 and furthermore in contact with the cam 21 by means of the sheave 36 thereof, and the spring 30 (preferably a calibrated spring) coupled to the first element 32 and to the second element 34. The first element 32 of each assembly 25a-25h is arranged to contact the dental implant 55a, 55c-55h; when a dental implant 55a, 55c-55h is situated in the support 50, the first element 32 contacts the dental implant 55a, 55c-55h and can apply the load to the same.

Each assembly 25a-25h extends radially from the cam 21 by means of the respective guide 38. Likewise, each assembly 25a-25h is arranged forming a 45 degrees angle with respect to the adjacent assemblies (the closest assembly on either side). For example, a first assembly 25a is arranged at 45 degrees (defined from the rotating shaft 22 of the cam 21 ) in the counterclockwise direction with respect to a second assembly 25b and at 45 degrees (defined from the rotating shaft 22 of the cam 21 ) in the clockwise direction with respect to a third assembly 25h. This arrangement is advantageous for the device 11 since the power required for the motor actuating the system is as low as possible.

The support 50 of each assembly 25a-25h comprises a tell-tale 52 which receives the compressive force exerted by the first element 32 when there is no dental implant 55a, 55c-55h or the one situated in the respective support 50 is broken, for example, as illustrated according to the assembly 25b wherein no dental implant has been placed. As a result of the tell-tale 52, when an implant 55a, 55c-55h breaks (or in the absence of same) the tell-tale 52 replaces it and the first element 32 contacts the tell-tale 52, which allows continuing with the test such that the cam 21 is still balanced.

Each dental implant 55a, 55c-55h is subject to 15 loading and unloading cycles per second when the cam 21 rotates at 300 revolutions per minute.

The design of most or all of the components of the devices 10, 11 is conceived so that they can be commercial (can be selected from catalogues), which facilitates the manufacturing of the devices 10, 11 as well as the maintenance and/or replacement of said components, further offering economic savings. Likewise, the stress to which the cam 20, 21 is subjected is lesser compared to solutions from the prior art, which means that the dimensions of the cam 20, 21 can be smaller.

In this text, the word “comprises” and variants thereof (such as “comprising”, etc.) must not be interpreted in an excluding manner, i.e., they do not exclude the possibility that what is described may include other elements, steps, etc.

In turn, the invention is not limited to the specific embodiments that have been described but rather also covers, for example, those variants which may be made by a person with average skill in the art (for example, with respect to the choice of materials, dimensions, components, configuration, etc.), which can be inferred from the claims.

Claims

1. A device (10,11 ) comprising:

a cam (20,21 );

a motor configured to rotate the cam (20,21 ); and

at least one assembly (25a-25h) adapted to apply a load on a dental implant (55a-55h), each assembly (25a-25h) of the at least one assembly comprising a support (50) adapted to support a dental implant (55a-55h);

characterized in that each assembly (25a-25h) of the at least one assembly further comprises:

a guide (38) arranged between the cam (20,21 ) and the support of the assembly (25a-25h);

a first element (32) arranged on the guide (38) of the assembly (25a-25h) and adapted for contacting the dental implant (55a-55h) in the support (50) of the assembly (25a-25h);

a second element (34) arranged on the guide (38) of the assembly (25a- 25h) and in contact with the cam (20,21 ), the second element (34) being adapted to move along the guide (38) of the assembly (25a-25h); and

a spring (30) arranged on the guide (38) of the assembly (25a-25h) and comprising a first end and a second end, the first end being coupled to the first element (32) of the assembly (25a-25h) and the second end being coupled to the second element (34) of the assembly (25a-25h).

2. The device (11 ) according to claim 1 , wherein the cam (21 ) comprises three lobes (23).

3. The device (10,11 ) according to any of the preceding claims, wherein the motor is configured to rotate the cam (20,21 ) at between 275 and 325 revolutions per minute, and preferably at 300 revolutions per minute.

4. The device (10,11 ) according to any of the preceding claims, wherein the support (50) of each assembly (25a-25h) of the at least one assembly is adapted to support the dental implant (55a-55h) forming a 30 degree angle with respect to the longitudinal axis of the guide (38) of the assembly (25a-25h).

5. The device (11 ) according to any of the preceding claims, wherein the support (50) of each assembly (25a-25h) of the at least one assembly comprises a tell-tale (52) arranged to receive the load in the absence of or in the event of breaking of the dental implant (55a-55h).

6. The device (10,11 ) according to any of the preceding claims, wherein the second element (34) of each assembly (25a-25h) of the at least one assembly comprises a sheave (36) in contact with the cam (20,21 ).

7. The device (10,11 ) according to any of the preceding claims, the first element (32) and the second element (34) of each assembly (25a-25h) of the at least one assembly each comprise a carriage (32,34).

8. The device (10,11 ) according to any of the preceding claims, wherein the at least one assembly (25a-25h) comprises a plurality of assemblies (25a-25h).

9. The device (10,11 ) according to claim 8, wherein the plurality of assemblies (25a-25h) is arranged around the cam (20,21 ) such that the guide (38) of each assembly (25a-25h) of the plurality of assemblies extends from the cam (20,21 ) radially.

10. The device (11 ) according to claim 9, wherein the plurality of assemblies (25a-25h) comprises eight assemblies (25a-25h); and wherein each assembly (25a-25h) is arranged such that the guide (38) of the assembly (25a-25h) forms a 45 degree angle with respect to the guide (38) of the two adjacent assemblies (25a-25h).

11. The device according to any of claims 1 to 7, wherein the at least one assembly (25a-25h) comprises one assembly.

12. The device according to any of the preceding claims, further comprising a microcontroller configured to operate the motor.

13. A method comprising:

providing the device (10,11 ) according to any of the preceding claims; situating a dental implant (55a-55h) in the support (50) of each assembly (25a-25h) of the device (10,11 ); and

activating the motor to rotate the cam (20,21 ) of the device (10,11 ).