METHOD FOR THE REPEATED ACTIVATION OF AN ORTHODONTIC CORRECTION DEVICE

Abstract

The invention relates to a method for the repeated activation of orthodontic correction devices with a known critical temperature (Tkrit) and a glass transition temperature (Tg) lying above the critical temperature. In the method according to the invention, in order to guarantee gentle repeated activation, an orthodontic correction device is heated to a temperature that lies above the critical temperature but below the known glass transition temperature. The invention also relates to a device for performing the method.

Claims

1. A method for the repeated activation of orthodontic correction devices with a known critical temperature (Tkrit) and a glass transition temperature (Tg) lying above the critical temperature, in which an orthodontic correction device is heated to a temperature that lies above the critical temperature but below the known glass transition temperature.

2. The method according to claim 1, wherein the temperature lies by at least 2° C. below the known glass transition temperature.

3. The method according to claim 1, wherein the temperature is maintained for a predefined time, wherein the predefined time is at least 1 minute.

4. The method according to claim 1, wherein the heating is effected by a liquid medium, by a gaseous medium, by radiation, or hot air or by a combined application of at least two of the aforementioned liquid and gaseous media and radiation.

5. The method according to claim 1, wherein the repeated activation is effected a second time and each following time at a temperature that is in each case higher than the temperature of the previous activation.

6. The method according to claim 1, wherein a second and each following activation is effected at a predefined time interval.

7. The method according to claim 1, wherein the orthodontic correction device is manufactured from at least one material or a mixture of materials from the group that comprises a shape memory polymer, a mixture of shape memory polymers, a hydrogel and a metal or a shape memory alloy.

8. The method according to claim 1, further comprising a control unit that stores the temperature as well as the predefined time for heating and/or the time interval between two repeated activations for at least one further activation and that controls a means for heating.

9. The method according to claim 8, wherein a sensor captures the presence of the orthodontic correction device in a device for heating, and the control unit captures the signals of said sensor.

10. A device for heating an orthodontic correction device with a known critical temperature (Tkrit) and known glass transition temperature to a temperature that lies above the critical temperature and below the known glass transition temperature, comprising a receptacle for the orthodontic correction device as well as means (6) for heating.

11. The device according to claim 10, wherein the device comprises a control unit that is designed to control the means for heating for at least one further activation.

12. The device according to claim 10, wherein the receptacle is a frame or a basket, on or in which the orthodontic correction device is to be arranged for a further activation.

13. The device according to claim 10, wherein the means (6) for heating comprise a heater for a liquid or gaseous medium and/or a radiation source.

14. The device according to claim 10, wherein the device comprises a panel (5) for adjusting the control unit and for monitoring the further activation.

15. The device according to claim 10, wherein the device comprises means for capturing the presence of the orthodontic correction device in the device for heating.

16. The device according to claim 15, wherein the means for capturing the presence of the orthodontic correction device are configured as an optical, acoustic or contact sensor.

17. The method according to claim 4, wherein the liquid medium is water, a salt solution, a solvent or a mixture thereof, wherein the gaseous medium is water vapor, and wherein the radiation is infrared radiation.

18. The device according to claim 11, wherein the control unit is designed to control the temperature and the predefined time for heating and/or the time interval between two repeated activations.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Details of the invention are explained below with reference to an exemplary embodiment, wherein:

[0030] FIG. 1 shows a first exemplary embodiment of the device according to the invention;

[0031] FIG. 2 shows a second exemplary embodiment of the device according to the invention;

[0032] FIG. 3 shows a third exemplary embodiment of the device according to the invention;

[0033] FIG. 4 shows a flow chart for the optimized calculation of the length of time an orthodontic correction device is worn for.

DETAILED DESCRIPTION

[0034] The exemplary embodiment relates to an orthodontic correction device made of a SMP (alternatively, the correction device is manufactured from a hydrogel or SMA or a combination of at least two of the indicated materials, e.g., from Zendura® or Zendura FLX®). The orthodontic correction device is configured here as a dental splint. However, it can also be configured as a wire that is deployed in retainers on the teeth. A transparent SMP is preferably deployed so that the orthodontic correction device is likewise transparent and therefore inconspicuous during wearing.

[0035] The orthodontic correction device alters its shape under the action of an activation or of a stimulus in a first step. Thus, an orthodontic correction device can be manufactured in the future, desired position S4 of the corrected teeth and can be reshaped, prior to being worn for the first time, from the future desired position by the first activation into the shape S1 that corresponds to the current position of the teeth to be corrected. The activation is explained in greater detail below. Said orthodontic correction device is moreover configured so that, as a consequence of further activations, it assumes a shape S2 and, subsequently, S3 and, finally, S4 again, wherein the teeth to be corrected will have moved, for example, by 1 mm to 2 mm when the correction is finished by the shape S4 of the orthodontic correction device. It is expressly noted that the orthodontic correction device can require more or fewer activations depending on how many shapes it can or should assume from the original position of the teeth until it achieves the desired tooth position. In this way, an extensive correction of the tooth position, as a whole, can be achieved incrementally step-by-step by the orthodontic correction device, without the patient experiencing pain due to too great forces being exerted by the orthodontic correction device onto the teeth. At the same time, a relatively major alteration of the tooth position can thus be achieved with a single correction device.

[0036] In the case of this exemplary embodiment, it is supposed that the orthodontic correction device is to be worn in one of the shapes S1 to S4 in each case for 2 weeks by a patient, in order to achieve the desired tooth correction. In general, the duration of treatment, that is to say the time during which an orthodontic correction device in a given shape acts on the teeth to be corrected, can last from 5 days up to 3 months, wherein periods of time from one week up to two months are particularly usual.

[0037] In each case, after a phase of the treatment has been completed, a further activation of the orthodontic correction device takes place. According to the method according to the invention, the correction device is again subjected to a stimulus or an activation, e.g., by the action of heat, preferably transferred by a liquid medium, in particular water or an aqueous solution. Whilst the first activation according to the prior art per se requires that the orthodontic correction device is heated up to or above the glass transition temperature Tg, it has surprisingly emerged that a first activation can already be effected at a temperature clearly below the glass transition temperature, in this case, for example, at a temperature that lies 15° C. below the glass transition temperature indicated for the correction device to be activated. The further activation, that is to say the second or third or each following activation can be effected at a temperature that lies above the temperature of the first activation, however at least 2° C., but also alternatively at least 5° C., 10° C. or 20° C. below the known glass transition temperature Tg. If, for example, the glass transition temperature of the orthodontic correction device is 75° C., the temperature can be 60° C. for the first activation and can be 65° C. or 70° C. for the further activation. If multiple further activations are performed, the conditions for the further activation can be individually adjusted in the temperature range that lies between the temperature for the first activation and the known glass transition temperature Tg. The temperature is either further raised for an additional further activation, or the conditions can also be intensified by, e.g., holding the temperature at the same level and extending the time of the activation. The following table shows a selection of possible adjustments of temperature and time for the single or repeated activation of orthodontic correction devices:

TABLE-US-00001 TABLE 1 Adjustments of temperature and time for the activation of orthodontic correction devices Known Critical glass Temperature/ Temperature/ Temperature/ Temperature/ Temperature/ temperature transition time 1st time 2nd time 3rd time 4th time 5th Tkrit temperature Tg activation activation activation activation activation [° C.] [° C.] [° C./min] [° C./min] [° C./min] [° C./min] [° C./min] 53 60 55/15 — — — — 55 65 58/10 63/15 — — — 58 70 60/5  64/10 67/12 — — 55 75 60/10 65/10 65/20 70/15 — 57 75 60/12 65/12 70/15 70/30 73/20

[0038] In the case of PETG, a polyethylene terephthalate modified with glycol, or another thermoformable material, the glass transition temperature Tg usually lies between 72° C. and 75° C. For a thermoplastic material, the glass transition temperature Tg can, for example, also lie between 82° C. and 85° C. For numerous thermoplastic materials, the glass transition temperature can, however, also be modified and selectively adjusted, e.g., by deploying chemical components.

[0039] The above table clearly shows that the first activation is in each case effected with a temperature below the known glass transition temperature Tg. Said activation produces a modification in shape, the extent of which is predefined. Each further activation, in this case a second to a maximum of a fifth activation, is effected either at an increased temperature or at the same temperature but with a longer activation duration. As a result, it is guaranteed during each activation that a greater stimulus, which produces the next desired modification in shape, is set for the correction device.

[0040] The method of the further activation is preferably performed with the device according to the invention that is depicted, by way of example, in various embodiments in FIGS. 1, 2 and 3. Inasmuch as the devices have the same component parts, they are provided hereinafter with the same reference numerals.

[0041] The device 1 in accordance with FIG. 1 has a housing 2 into which a dish 3 is inserted as a receptacle. The dish 3 is, in this case, made of metal, but it can also be manufactured from plastic, glass or ceramic. It has a carrying capacity of 250 ml, but can, if required, be larger or smaller. A dish 3 of this size can receive multiple orthodontic correction devices. Water or an aqueous solution is located in the dish. E.g., cleaning agents, salts, solvents or the like can be added to the aqueous solution, wherein the proportion of water advantageously lies above 50 wt. % based on the total volume of the liquid. The dish 3 is advantageously covered by a lid 4. The housing 2 of the device 1 is preferably thermally insulated.

[0042] The orthodontic correction device is either placed directly into the dish 3 or inserted in a basket or frame into the dish 3 so that it is surrounded by the liquid medium or can be flowed around by a gaseous medium or it can be heated uniformly by a radiation source.

[0043] The dish 3 is heated by a heat source, preferably an electric heater that is arranged in the housing 2 and not depicted in greater detail in FIG. 1. The heat source has a power that is sufficient to heat the liquid medium to the predefined temperature that lies below the glass transition temperature. Usually, the heat source has a power of 100 W to 500 W. The current can be supplied by direct or alternating current. Alternatively, a heat source can be deployed for water vapor or heated air, wherein water vapor or heated air can then be guided, e.g., through a fan into the dish.

[0044] The device 1 according to FIG. 2 has all the features of the embodiment according to FIG. 1. In the housing, it comprises a control unit that is not depicted in greater detail, said control unit comprises a memory and is connected to a panel 5 having an On/Off switch as well as having an input device 5a and display device 5b, and to the means 6 for heating and, if applicable, further component parts that are arranged in or on the housing 2 in order to implement the method according to the invention. The memory of the control unit is either filled with defaults for the temperature that is to be achieved for further activation via the input device 5a of the panel 5, as well as, if applicable, with the time over which the temperature is to be maintained. Alternatively, the memory can be equipped with one or more programs that, in each case predefine, for specific further activations, a temperature and, optionally, a time, over which the predefined temperature is to be maintained. Optionally, the memory can also receive information regarding the spacing of the further activations, regarding cleaning or regarding cooling of the orthodontic correction device and, if applicable, integrate said information into the programs. Whereas experienced technical staff can operate the device directly by using the input device, it is by contrast advisable to save predefined programs in the memory when the patients utilize the device at home. The display device shows, e.g., a selection of input parameters for, for example, the temperature or time, the program or programs available for selection, the status of the device during operation with the display of the temperature and, if applicable, the remaining running time of the further activation.

[0045] The device 1, in particular the control unit, can be connected to external means for monitoring and controlling or checking the function of the device, which are not depicted in greater detail here. Thus, the device can be connected to an electronic unit such as a smartphone, a tablet or a computer and can be actuated, monitored, controlled and checked via this. This can be effected by way of special software, e.g., an app. Such an arrangement of the device in conjunction with an electronic unit is in particular sensible such that, e.g., technical staff can monitor or check the deployment of the device by patients. Patients can be informed, e.g., regarding the remaining running time of an activation operation or trigger such an operation, without having to actuate the device themselves.

[0046] The device 1 depicted in FIG. 2 has means 7 for cooling arranged in the housing, which cools the orthodontic correction device to the ambient temperature following the further activation. The device can, e.g., be configured so that, following the finish of the further activation, the liquid medium is removed from the dish, e.g., by opening a discharge, and air is subsequently blown through a fan onto the orthodontic correction device. The air can optionally be cooled, but already accelerated air has a cooling effect. In a simple embodiment, the device can also be equipped without means for cooling.

[0047] The device 1 optionally further has an ultrasonic source arranged in the housing 3, which is not depicted in greater detail here, that cleans the orthodontic correction device before, during or after the further activation.

[0048] The device 1 shown in FIG. 3 is in particular suitable for use in the professional environment. It comprises—except for the lid 4—all the features of the embodiment in accordance with FIG. 2. The device according to FIG. 3 can have a separate lid. However, at 400 ml, the dish 2 is more capacious than the dishes described above. A discharge 8 for the liquid deployed for heating as well as an inlet 9 for a cooling medium, in this case, e.g., cooled air or cold liquid, is provided at the bottom of the dish. The altered shape of the correction device is quickly fixed by the means for cooling, and the device is ready for the next activation operation, with which a further alteration in shape of an orthodontic correction device is to be produced.

[0049] FIG. 4 shows a flow chart that explains the method of operation of means for capturing the dwell time of an orthodontic correction device in a device for heating or activation. The means for capturing comprise, for example, an optical sensor such as an IR sensor that checks the presence of the orthodontic correction device in the device for heating, e.g., by activating the sensor within the interval of seconds or minutes and, in each case, emitting a sensor signal to the control unit, regarding the presence or the absence of the correction device in the device for heating. Alternatively, an ultrasonic sensor or another sensor that can detect the presence or the absence of the correction device can also be deployed.

[0050] If no correction device is detected, the monitoring continues running, regularly verifying the presence of the orthodontic correction device. If the correction device is captured in the device for heating, the control unit captures and stores, in each case, the time frame in which the correction device is located in the device for heating and connects this time frame to a predefined length of time. A second length of time that serves as a threshold can optionally be stored in the control unit. If the dwell time frame is shorter than the threshold, said dwell time is not stored and is not included in the subsequent calculations. A threshold can be, e.g., 20 minutes so that, for example, the insertion of the orthodontic correction device into the device for heating or activation during the length of time taken to clean teeth is not stored.

[0051] If the dwell time of the correction device in the device for heating is, on the other hand, longer than the length of time of the threshold, or if no threshold is entered, said length of time is captured and stored by the control unit. The control unit can either forward the captured dwell time of the correction device to a laboratory or a dental practice that utilizes said data for the recalculation or subsequent calculation of the length of time up to the next activation of the orthodontic correction device. The control unit can also forward the captured dwell time to a display or output unit that notifies the wearer of the orthodontic correction device how long the correction device has already been worn. The display or output unit can be the device for heating or activation, but it can also be an application (app) that is displayed on the wearer's computer, tablet or mobile phone. Said information can, e.g., also be reproduced in a graphical form that displays what proportion of the period of time for wearing the correction device predefined for the respective activation step has already been achieved. In this way, a tool is made available to the wearer of the correction device, with the aid of which he can optimize his behavior with respect to wearing the correction device.