WO2013033856A1

WO2013033856A1 - Handpiece for an endodontal instrument for drilling root canals

Info

Publication number: WO2013033856A1
Application number: PCT/CH2012/000212
Authority: WO
Inventors: Jean-Claude Rouiller; Olivier Breguet
Original assignee: Fkg Dentaire S.A.
Priority date: 2011-09-09
Filing date: 2012-09-06
Publication date: 2013-03-14
Also published as: CH705479A1

Abstract

The present invention relates to a handpiece (10) equipped with an instrument holder head (11) comprising a retaining support (12) for the attachment of the end piece (13) of an endodontal instrument (14). This instrument is designed to change shape as a function of a change in temperature and comprises a working zone (15) which is designed to mill a root canal (16) of a molar (17). In a conventional way, the instrument (14) is rotationally driven to file the walls of the root canal and extract the dentine in order to prepare the space intended to be filled with a root treatment compound. The handpiece (10) is also equipped with a heating unit (18), arranged at the base of the instrument holder head (11) and provided with a central bore (19) through which the retaining support (12) passes. This heating unit (18) comprises at least one reel (20) of resistive wire supplied with alternating current from two terminals (21) housed in the handpiece (10). It allows energy to be supplied to the instrument (14) if necessary in order to bring about a change in temperature liable to alter the shape of the working zone (15) thereof while it is being used.

Description

HANDPIECE FOR AN ENDODONTIC INSTRUMENT FOR DRILLING RADICULAR CHANNELS

Technical area

The present invention relates to a handpiece, commonly called "contra-angle", arranged to support an endodontic instrument for the boring of root canals, said handpiece being provided with an instrument holder head equipped with a support for holding and fixing said endodontic instrument, this instrument being designed to change shape according to a temperature change.

Prior art

The cleaning and shaping of the root canals for receiving the filling substances is carried out by the use of boring instruments having an active part, called a working part, the purpose of which is to shape and clean the root canal to prepare it for receiving treatment and sealing materials. The root canals have often particular geometries and present complex curvatures, reduced sections in the form of constrictions or oval areas, which are not well suited to the introduction of preparation and shaping instruments. This is why instruments called limes must have sometimes opposite characteristics. These files must be thin but strong, flexible enough to follow the curvature of the root canal and reach its end while remaining hard enough to cut and cut the walls of this canal. These requirements impose on the odontologist a process of preparation and treatment of the root canal during which he is forced to use a whole range of tools with progressive action, to adapt to the morphology of the canal, this range of tools with structural and dimensional variations. To facilitate the introduction of these instruments into the root canal by minimizing the risk of screwing when said instrument support is a rotating mandrel, new instruments have been developed. These instruments have at least one working area arranged to have a retracted shape when in the rest position and an expanded structured shape when in the working position. When the instrument is made of a metal alloy whose particularity is the shape memory, the passage from the retracted position to the expanded position can be obtained by a simple variation, for example a rise in temperature.

It has been found that in some cases the temperature rise required for the instrument's working zone to change from its retracted position to its expanded form can be generated naturally by the heat of the patient's body.

However, this heat input may be insufficient or too slow to generate the increase in temperature required to ensure the shape of the instrument and it is then essential to provide an external heat source.

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Presentation of the invention

The handpiece of the invention provides several solutions to the problem of providing sufficient heat for the instrument to move its working area from its retracted position to its expanded form in accordance with the physical shape memory characteristics of the material. used to produce this instrument.

For this purpose, the handpiece according to the invention as defined in the preamble is characterized in that it comprises means arranged to bring to said instrument the energy required to generate said temperature change likely to modify the shape of its zone working and control means arranged to trigger said energy supply.

According to a first embodiment of the handpiece, said means arranged to supply energy to said instrument comprise at least one coil of resistive electric wire. Said coil of resistive electric wire may advantageously be arranged in a heating block mounted under said instrument holder.

Said heating block is then preferably traversed by the support for holding the instrument.

In order to allow the user to initiate the process of raising the temperature of the instrument, the handpiece preferably comprises a switch arranged to control the power supply of said resistive electrical wire coil.

According to another embodiment of the handpiece, said means arranged to supply energy to said instrument comprise at least one nozzle for supplying a heating liquid which is advantageously provided with a central channel coupled to a source of energy. supply of heating liquid.

According to an advantageous embodiment, said handpiece contains an electric micro-pump connected to said heating liquid supply source, said electric micro-pump being controlled by a switch fixed on said handpiece.

According to a first variant embodiment, said heating liquid can undergo a rise in temperature following a chemical reaction. According to a second variant embodiment, said heating liquid may undergo a rise in temperature following electric heating by Joule effect.

According to other embodiments, the means arranged to provide said energy instrument may comprise an ultrasonic wave generator, an infrared radiation generator or a high frequency wave generator. Advantageously, said holding support is a rotating mandrel. Brief description of the drawings

The present invention and its main advantages will become more apparent in the description of various embodiments, with reference to the accompanying drawings, in which: FIGS. 1 and 1A respectively show a view of a handpiece according to the invention carrying an instrument right, at the time of its introduction lo in a root canal of a tooth, and a sectional view along the line AA of this instrument in the root canal of the tooth, Figures 2 and 2A respectively represent a view of the piece to Figure 1A hand carrying a twisted instrument, initially straight after its introduction into the root canal of a tooth, and a sectional view along line BB of the instrument of Figure 2 into the root canal of the tooth FIG. 3 represents a view of the preceding handpiece according to the invention with another twisted instrument, at the time of its insertion into a root canal 0 of a tooth, FIGS. 4, 4A and 4 B represent respectively the previous handpiece with the instrument of Figure 3, after its introduction into a root canal of a tooth, and sectional views, respectively along the line CC and the line D-5 D, of the 4, in the root canal of the tooth, and FIGS. 5 and 5A respectively represent a second embodiment of a handpiece according to the invention carrying a right instrument, at the moment of its introduction into a root canal of a tooth, and a view in section along the line EE of the instrument of Figure 5 in the root canal of the tooth. Best ways to achieve the invention

FIGS. 1 to 4, and more particularly FIG. 1, show a handpiece 10 equipped with an instrument head 11, comprising a holding support 12 which may be a rotary mandrel intended for training and training. attachment of the end tip 13 of an endodontic instrument 14. This endodontic instrument 14, which is a file, comprises a working zone 15 arranged for milling a root canal 16 of a tooth 17, in the particular case a molar. In a conventional manner, the instrument 14 is rotated to file the walls of the root canal 16 of the tooth and extract the dentin to prepare the space to be sealed by a root treatment paste.

Since the root canals are rarely rectilinear and have very irregular sections, it is advisable, on the one hand, to dig the canal by

15 respecting the natural configuration of this channel and, on the other hand, to avoid screwing the instrument into the dentine and thus risking the rupture of the file. To this end, a new type of instrument has been proposed to provide health care personnel with a more universal tool than the files currently used. These instruments allow each to replace a whole range of files of different sizes due to their deformation capacity in use. They are actually preformed and can change shape when they undergo a change in temperature. These instruments are made of a shape memory material and preferably have a first form when they are at room temperature and a second form, different from the first form, when they are at the working temperature, the latter being generally above room temperature.

For some shape memory type alloys, the temperature rise provided by contact with the patient's body may be sufficient to move the instrument work area from its first form to its second form. However, in most cases, it is necessary to have a source of thermal energy sufficient to effect this transformation. The The handpieces described in the context of the present invention have the particularity of comprising means making it possible to supply the energy necessary to change the shape of the instrument from the rest position, that is to say to introduce in the root canal, at the working position, that is, milling the walls of the canal.

For this purpose, the handpiece 10 is equipped with a heating block 8, disposed at the base of the instrument-holder head 11, this block being provided with a central bore 9 through which the holding support 12 passes. heating block 18 comprises î o at least one coil 20 consisting of a resistive wire winding, for example AC powered from two terminals 21 housed inside the handpiece 10. A switch 22, for example in the form of a push-button or the like, is mounted on the handpiece 10 to close two contacts 23 when the practitioner wishes to feed the coil 20 in order to

By Joule effect, to bring the temperature increase required to cause the change in shape of the working zone 15 of the instrument 14. This temperature increase is shown schematically by the arrow M. 0 FIG. a sectional view along the line AA of Figure 1, which illustrates the cross section of the working area 15 of the instrument 14 in the root canal 16. It will be noted that the section of the instrument is relatively small compared to the section of the channel, so that the instrument can be introduced without difficulty in the latter.

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FIG. 2 shows the working zone 15 of the instrument 14 after a temperature increase undergone by heating caused by the temperature rise of the Joule coil 20. It will be noted that the shape of the working zone 15 is twisted and substantially conical between the upper end fixation of the instrument 14 and its tip engaged at the bottom of the root canal 16 of the tooth 17. FIG. 2A is a cross-sectional view along the line BB of the root canal, showing the section of the working area 15 of the instrument 14. Note that this section is larger than that of the view of FIG. The twisted form allows scraping, filing or cutting of the dentin to prepare the root canal 16 for root treatment closure of the tooth 17.

FIG. 3 shows the same handpiece 10 equipped with an instrument 24 whose working zone 25 is twisted when it is introduced into the root canal 26 of a tooth 27. This instrument has a substantially rectilinear shape and this Geometry allows easy introduction into the channel that has complex geometry. The rectilinear form is that of the cold instrument, that is to say prior to its temperature rise caused by the Joule effect coil 20.

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FIG. 4 shows the handpiece 10 equipped with the instrument 24 after its introduction into the root canal 26 of a tooth 27 and after the temperature rise generated by the Joule effect coil 20. In this case the hand is used as a heating medium and is not necessarily rotated. The increase in temperature caused a considerable deformation of the shape of the working area 25 so that it adapted to the walls of the channel, despite the complexity of shape of the latter. The loops of the instrument in the working area rely on the walls of the channel and the scraping can then be done by a simple movement back and forth5 without engaging the rotation. However, the rotation of the instrument allows you to file, scrape or mill the dentin and prepare the canal in one operation instead of using a range of different instruments. As a result, the operation of preparing the root canal is greatly simplified. Figure 4A shows a sectional view along the line CC of the tooth 27, the root canal 26 and the working area 25 of the instrument 24. In this case the root canal is relatively narrow. Figure 4B shows a sectional view along the line DD of the tooth 27, the root canal 26 and the working area 25 of the instrument 24. In this case the root canal is wider.

Figure 5 shows a second embodiment of a handpiece according to the invention. This handpiece 30 is equipped with an instrument holder head 31, comprising a holding support 32 for fixing the end piece 13 of the endodontic instrument 14 as described in FIGS. 1 and 2. handpiece 30 is substantially identical to the handpiece 10 described above. However, it is also equipped with a nozzle 33 disposed at the base of the instrumentation head 31. This nozzle 33 is provided with a central channel 34 for supplying a heating liquid to cause a sufficient temperature rise of the instrument for generating the change of shape of the working zone 15. A switch 42, in the form of a pushbutton or the like, is mounted on the handpiece 30 to close two contacts 43 when the practitioner wishes to generate a jet of liquid through the nozzle 33. These two electrical contacts 43 are part of a supply circuit of an electric micro-pump 44 fed, for example, with alternating current and which is coupled to a reservoir of heating liquid (Not shown) as shown by the arrow R. The temperature of the heating liquid can be increased following a chemical reaction or following electric heating by Joule effect. Some liquid compounds used in dental treatment may heat up in the air and this heating may be sufficient to cause the desired heating to change the shape of the instrument.

Other heating means for providing said instrument with energy to generate said temperature change that may change its shape may be used. Among these means there may be mentioned an ultrasonic wave generator, an infrared radiation generator and a high frequency wave generator. These different generators exist in sufficiently miniaturized forms and have a weight and volume appropriate to be implanted in the door-angle. These means can be used alone or in combination. Their power is adapted to the energy required to heat the instrument sufficiently to change its shape.

Figure 5A shows a sectional view along the line E-E of the tooth 17, the root canal 16 and the working area 15 of the instrument 14 during its introduction and before any change in shape.

The present invention is not limited to the embodiments described, but may undergo various modifications or variations obvious to those skilled in the art. Thus the means for heating the instrument can be varied depending on the alloys used for the realization of the shape memory instruments.

Claims

claims

A handpiece, commonly referred to as a "contra-angle", arranged to support an endodontic instrument for boring root canals, said handpiece (10; 30) being provided with an instrument head (1; 31) provided with a holding bracket (12; 32) for driving and securing said endodontic instrument (14; 24), said instrument being adapted to change shape according to a temperature change, characterized in that it comprises means arranged to bring to said instrument the energy required to generate said temperature change likely to modify the shape of its working area (15; 25) and control means arranged to trigger said energy supply.

Handpiece according to claim 1, characterized in that said means arranged to supply energy to said instrument comprise at least one coil (20) of resistive electric wire.

Handpiece according to claim 2, characterized in that said coil (20) of resistive electrical wire is disposed in a heating block (18) mounted under said instrument head (11).

Handpiece according to claim 3, characterized in that said heating block (18) is traversed by the holding support (12) for driving the instrument.

5. Handpiece according to claim 1, characterized in that it comprises a switch (22) arranged to control the power supply of said coil (20) of resistive electric wire.

6. Handpiece according to claim 1, characterized in that said means arranged to supply energy to said instrument (24) comprise at least one nozzle (33) for supplying a heating liquid.

7. Handpiece according to claim 6, characterized in that said nozzle (33) is provided with a central channel (34) coupled to a heating liquid supply source.

8. Handpiece according to claim 7, characterized in that it contains an electric micro-pump (44) connected to said source of heating liquid supply.

9. Handpiece according to claim 8, characterized in that said electric micropump (44) is controlled by a switch (42) fixed on said handpiece (30).

10. Handpiece according to claim 6, characterized in that said heating liquid undergoes a rise in temperature following a chemical reaction.

1. A handpiece according to claim 6, characterized in that said heating liquid undergoes a rise in temperature following electric heating by Joule effect.

12. Handpiece according to claim 1, characterized in that said holding support (12; 32) is a rotary mandrel.

13. Handpiece according to claim 1, characterized said means arranged to provide said energy instrument comprise an ultrasonic wave generator.

14. Handpiece according to claim 1, characterized in that said means arranged to provide said energy instrument comprise an infrared radiation generator. 15. Handpiece according to claim 1, characterized in that said means arranged to provide said energy instrument comprise a high frequency wave generator.