Abstract:
In order to design a device for the destruction of a tooth free from transverse forces and bending moments comprising a destruction bolt which can be introduced into a bore of the tooth such that a destruction of the tooth is possible without transverse forces and bending moments being exerted on the patient it is suggested that the outer dimensions of the destruction bolt be increasable in such a manner that the tooth is broken and thereby split open by means of internal pressure due to application of symmetric forces in the bore.

Description:
[0001]    The present disclosure relates to the subject matter disclosed in International Application No. PCT/EP00/03531 (WO 00/66024) of Apr. 19, 2000, which is incorporated herein by reference in its entirety and for all purposes.  
         BACKGROUND OF THE INVENTION  
         [0002]    The invention relates to a device for the destruction of a tooth free from transverse forces and bending moments, comprising a destruction bolt which can be introduced into a bore of the tooth.  
           [0003]    One complication during the extraction of wisdom teeth can be the impacted position of the tooth, i.e. the wisdom tooth lies more or less horizontally in the jaw socket, the roots pointing towards the mandibular joint. During the extraction of these impacted wisdom teeth a standard method is commonly used: Since the tooth can scarcely be removed as a whole from the jawbone, it is split into several pieces. Once the cavity of the tooth has been opened by cutting open the cover over the tooth, an approximately cylindrical hole is introduced into the tooth of approximately 2 to 3 mm diameter by means of drilling or cutting. Usually, a bolt fitting into the bore and having a length of approximately 15 to 20 cm, at the rear end of which a knob-like handle is seated, is now used and the bolt forcefully bent back and forth in the bore using transversely directed manual forces and utilizing the lever action of the knob-like handle for such a time until the tooth breaks. Additional bores and additional crowbar-like leverage are mostly necessary until the tooth is split into sufficiently small pieces and until all the parts of the tooth can be removed from the tooth socket cavity with forceps or pincers.  
           [0004]    The forceful effect on the tooth as described has, of course, a further effect on the jaw and the head of the patient. The consequences of this robust treatment can be manifold:  
           [0005]    1. On account of the tooth cavity being cut open the jaw is weakened by the notch effect at this point, and the risk of the jaw being fractured, which is therefore already great as such, is increased even more due to the forces and bending moments introduced.  
           [0006]    2. Since the patient cannot absorb the effective bending moments even when he is anesthetized, these bending moments are conducted further and absorbed by the neck and spinal column. The result can be intensive hematomas in the neck and larynx area.  
           [0007]    3. If the patient is not anesthetized, he experiences the effect of force and is fully aware of the bone-breaking, grinding noises. This can lead to documented, traumatic conditions following the operation.  
           [0008]    It is the object of the invention to design a device of the generic type such that a destruction of the tooth is possible without transverse forces and bending moments of the type described being exerted on the patient so that the disadvantages and consequences which are described and sufficiently known can be avoided.  
         SUMMARY OF THE INVENTION  
         [0009]    This object is accomplished in accordance with the invention, in a device of the type described at the outset, in that the outer dimensions of the destruction bolt can be increased in such a manner that the tooth is broken and thereby split open by means of internal pressure due to application of symmetric forces in the bore.  
           [0010]    In contrast to the known destruction bolt which can be introduced into the bore and merely serves to act upon the tooth with transverse forces and bending moments, the destruction bolt introduced into the bore of the tooth is, therefore, in the case of the device described, increased in its outer dimensions such that it exerts internal forces on the tooth which widen the bore, finally break the tooth and thus split it into parts. In this respect, no bending moments or transverse forces at all are exerted on the patient, the forces acting on the tooth are absorbed solely by the tooth itself which does not, however, experience any external forces which endeavor to displace it in relation to the jaw.  
           [0011]    This principle of the application of force by means of internal pressure which is free from transverse forces and thus bending moments is adequately known in technology as such, e.g. during the splitting of blocks of stone by way of water pressure in bores or by way of quick-frozen water or also only for the broadening without destruction during conical press fitting by means of pressure oil.  
           [0012]    In a first preferred embodiment it is provided for the destruction bolt to comprise two parts which can be moved relative to one another and have sliding surfaces which slide on one another during the movement of the parts relative to one another and as a result increase the outer dimensions of the destruction bolt.  
           [0013]    For example, one part can be a slotted sleeve and the other a central drawing or pressure bolt which can be displaced therein and has a conical extension which forms a sliding surface. If the drawing or pressure bolt is displaced in relation to the slotted sleeve, the conical extension enters the interior of the slotted sleeve and widens this. The sleeve itself can likewise have a conical sliding surface.  
           [0014]    In another configuration, one part is designed as a stationary half bolt and the other part as a displaceable drawing or pressure bolt, wherein both parts bear wedge surfaces sliding on one another as sliding surfaces. If the two parts are displaced in axial direction relative to one another, the wedge surfaces slide on one another and press the two parts apart, thereby increasing their outer dimensions.  
           [0015]    In a further, preferred embodiment the two parts can be designed like blind rivets. This design makes it possible, in particular, to initiate a uniform pressure via the circumference of the bore.  
           [0016]    It is particularly advantageous when the device is a forceps-like tool which is designated in the following as a pair of breaking forceps and when the two parts can be moved relative to one another by means of two forceps handles of the breaking forceps pivotable relative to one another. It is then possible in a very simple manner to move the two parts relative to one another simply by pivoting the forceps handles relative to one another such that the outer dimensions of the parts can be increased for the purpose of breaking the tooth.  
           [0017]    In a preferred embodiment, it is thereby provided for the breaking forceps to include a ratchet mechanism, by means of which the complete stroke of the forceps handles is transformed into a small partial stroke of the two parts relative to one another. During the increase in the outer dimensions of the parts due to relative displacement of the two parts in relation to one another, the operating surgeon can proceed very delicately in that he does not bring about the complete displacement of the two parts relative to one another in a single stroke but rather that he makes a plurality of small partial strokes one after the other, wherein the forceps handles are repeatedly moved through their complete stroke. The ratchet mechanism can comprise an elbow lever which engages in teeth with its free end.  
           [0018]    It is also advantageous when the two forceps handles can be pivoted into a release position, in which the two parts are displaced relative to one another in such a manner that their outer dimensions are reduced. This is of advantage, in particular, when the widened destruction bolt has to be removed again from the bore, for example, when the tooth has not been successfully split apart. As a result of a corresponding movement of the two parts relative to one another which is triggered by the pivoting of the forceps handles into the release position, the outer dimensions of the two parts are reduced and so the force-locking engagement of the two parts on the inner wall of the bore in the tooth is discontinued.  
           [0019]    In a particularly preferred embodiment it is provided for the two parts to be movable away from one another towards opposite sides during the increase in the outer dimensions and for the destruction bolt to be mounted on the device so as to be rotatable about its longitudinal axis. With such a configuration, the breaking forces exerted on the tooth are essentially transferred to the tooth in a plane which is defined by the movement of the two parts. This plane can likewise be turned due to rotation of the destruction bolt about the longitudinal axis and this leads to the operating surgeon being able to adjust the direction of the breaking forces.  
           [0020]    In a further, preferred embodiment, it may be provided for the two parts to be movable relative to one another by means of a hydraulic drive for altering the outer dimensions of the destruction bolt.  
           [0021]    This hydraulic drive may preferably comprise a pump driven by a motor or a hydraulic piston operated by hand or foot for generating the actuating pressure for the hydraulic drive.  
           [0022]    In this respect, it is advantageous when the device has a housing which bears the destruction bolt and accommodates an actuating and supply unit and when the housing forms a forceps-like tool together with a hand lever mounted thereon. This results in a very manageable tool which can be operated like a pair of forceps and displaces the parts of the destruction bolt hydraulically relative to one another.  
           [0023]    In a different embodiment, it may be provided for the drive to be connected to an actuating and supply unit via a hose. In this respect, the connection between the hose and the actuating and supply unit may preferably be designed as a plug-in connection.  
           [0024]    In a further configuration of a device with parts displaceable hydraulically relative to one another, it may be provided for the hydraulic drive to comprise a piston sealingly displaceable in a bushing, one of the two displaceable parts being held on the piston, i.e. a hydraulic piston-cylinder unit.  
           [0025]    In this respect, a particularly simple construction results when a supply line for a hydraulic medium is arranged in the bushing on one side of the piston and when the piston is displaceable in the bushing contrary to the action of a spring during supply of hydraulic medium via this supply line. With such a configuration, the piston is therefore displaced in one direction due to supply of hydraulic medium but in the opposite direction by a spring which is tensioned during the displacement of the piston by the hydraulic medium.  
           [0026]    In another configuration, it may, on the other hand, be provided for a supply line for a hydraulic medium to be arranged in the bushing on both respective sides of the piston; the piston is therefore driven by hydraulic medium in a double-acting manner.  
           [0027]    A particularly favorable design results when the piston is sealed in relation to the bushing by means of an expansion bellows. It is then possible to use as hydraulic medium not only physiologically harmless liquids, for example, water but also other liquids which should not come into contact with the body, for example, synthetic liquids.  
           [0028]    In a further, preferred embodiment, it is provided for the hydraulic drive to comprise a bellows which is arranged between the two parts, can be filled with hydraulic medium and moves the two parts away from one another during filling, thereby increasing their outer dimensions. This bellows is blown up like a balloon during filling with hydraulic medium and therefore pushes the two parts apart. These abut as a result on the inner wall of the bore in the tooth and transfer breaking forces to the inner wall of the bore.  
           [0029]    The two parts may, in particular, be mounted so as to be pivotable away from one another.  
           [0030]    It is also favorable when the two parts are spring-assisted so that during emptying of the bellows the two parts are brought closer to one another again whilst reducing their outer dimensions.  
           [0031]    In a further, preferred configuration of an inventive device, the destruction bolt comprises a bellows which can be filled with a hydraulic medium. This bellows can be introduced directly into the bore of the tooth and abuts on the inner wall of the bore during filling with hydraulic medium; during further filling breaking forces are exerted as a result on the inner wall of the bore of the tooth which finally split it apart.  
           [0032]    The bellows can, for example, be of a ball-shaped design or a cylinder-like design.  
           [0033]    It is favorable when the bellows bears notched pieces added laterally which come to rest on the inner wall of the bore and assist in the destruction of the tooth.  
           [0034]    The bellows is preferably of an expandable design.  
           [0035]    The following description of preferred embodiments of the invention serves to explain the invention in greater detail in conjunction with the drawings.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0036]    [0036]FIG. 1 shows breaking forceps in a side view;  
         [0037]    [0037]FIG. 2 shows a first preferred embodiment of the forceps head of the breaking forceps marked in FIG. 1 with a circle;  
         [0038]    [0038]FIG. 3 shows a view similar to FIG. 2 in a modified embodiment of a forceps head;  
         [0039]    [0039]FIG. 4 shows a schematic side view of a breaking unit with a breaking head, a supply and actuating unit and a hose connection between breaking head and supply and actuating unit;  
         [0040]    [0040]FIG. 5 shows a view similar to FIG. 3 in a modified embodiment of a breaking unit;  
         [0041]    [0041]FIG. 6 shows a view similar to FIG. 4 in a further, preferred embodiment of a breaking unit;  
         [0042]    [0042]FIG. 7 shows a sectional view of a first preferred embodiment of a breaking head with a double-acting hydraulic drive;  
         [0043]    [0043]FIG. 8 shows a view similar to FIG. 7 with a modified design of the destruction bolt;  
         [0044]    [0044]FIG. 9 shows a view similar to FIG. 7 with an expansion bellows seal;  
         [0045]    [0045]FIG. 10 shows a view similar to FIG. 8 with an expansion bellows seal;  
         [0046]    [0046]FIG. 11 shows a view similar to FIG. 7 with a single-acting hydraulic drive and a restoring spring;  
         [0047]    [0047]FIG. 12 shows a view similar to FIG. 8 with a single-acting hydraulic drive and a restoring spring;  
         [0048]    [0048]FIG. 13 shows a view similar to FIG. 9 with a single-acting hydraulic drive and a restoring spring;  
         [0049]    [0049]FIG. 14 shows a view similar to FIG. 10 with a single-acting hydraulic drive and a restoring spring;  
         [0050]    [0050]FIG. 15 shows a diagrammatic illustration of a supply and actuating unit for a double-acting hydraulic drive with a pump driven by a motor;  
         [0051]    [0051]FIG. 16 shows a diagrammatic view of a supply and actuating unit for a double-acting hydraulic drive with a pump operated by hand;  
         [0052]    [0052]FIG. 17 shows a view similar to FIG. 15 for a single-acting, hydraulically acting drive;  
         [0053]    [0053]FIG. 18 shows a view similar to FIG. 16 for a single-acting, hydraulically acting drive;  
         [0054]    [0054]FIG. 19 shows a schematic view of a screw connector for the connection of a destruction bolt in the form of a bellows;  
         [0055]    [0055]FIG. 20 shows a longitudinal sectional view through a first, preferred embodiment of a bellows-like destruction bolt fillable with a hydraulic medium;  
         [0056]    [0056]FIG. 21 shows a view similar to FIG. 20 in a modified embodiment of a destruction bolt;  
         [0057]    [0057]FIG. 22 shows a view similar to FIG. 21 with a destruction bolt bearing notched pieces;  
         [0058]    [0058]FIG. 23 shows a sectional view along line  23 - 23  in FIG. 22; and  
         [0059]    [0059]FIG. 24 shows a breaking element in a drilled tooth.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0060]    [0060]FIG. 1 shows by way of example a whole breaking forceps in the side view with the variation of the forceps head in accordance with FIG. 3. A forceps handle  4  is located  
         [0061]    at A in an initial position  
         [0062]    at B at the end of a stroke  
         [0063]    at C in a release position.  
         [0064]    [0064]FIG. 2 shows the forceps head with the destruction bolt: drawing bolt  2  and slotted sleeve  3  which effect the actual splitting open of the tooth in a symmetric design.  
         [0065]    [0065]FIG. 3 shows the forceps head with the destruction bolt: stationary half bolt  13  and drawing bolt  12  in a non-symmetric design.  
         [0066]    Depending on the design, the destruction bolt  1  is pushed as far as possible into the prepared bore in the wisdom tooth. The forceps handles  4 ,  4   a  are then actuated. A lever  7  presses under the drawing bolt  2  and  12 , respectively, via the forceps joint  5  and by means of the joint bearing  6 . Since a stationary part is held by the front part of the forceps handle  4   a , the drawing bolt  2  and  12 , respectively, is displaced relative to it.  
         [0067]    With the design according to FIG. 2: As the drawing bolt  2  has a conical extension  8  at its free end, it can press the slotted sleeve  3  apart. As a result, two symmetric forces are introduced into the tooth bore in longitudinal direction of the tooth and these forces break the tooth when they are of a suitable magnitude. The sleeve can also have a conical sliding surface.  
         [0068]    With the design according to FIG. 3: Stationary holding bolt  13  and drawing bolt  12  are designed as half cylinders and both have a respective wedge surface  14  at the free end so that during the displacement of the drawing bolt  12  the wedge surfaces can slide on one another and the distance between the outer edges increases. In this case, as well, two symmetric forces are introduced into the tooth bore in longitudinal direction and these forces then break the tooth when the forces are of a suitable magnitude.  
         [0069]    In order to prevent the tensioned manual force from pressing the tooth parts unnecessarily far apart at the moment the tooth breaks, a ratchet mechanism, which includes a ratchet nose  15 , a forceps joint  5 , a ratchet pawl  9 , ratchet teeth  10 , and a restoring spring  11 , is integrated into the handle of the forceps. As a result, the stroke of the forceps handle  4  can be limited and the breaking forces are generated by a plurality of small manual strokes, whereby any springing back or uncontrolled splitting stroke is prevented.  
         [0070]    If the forceps handle  4  is moved into release position C, the drawing bolt  2 ,  12  can be moved back into its initial position with the lever  7  and the forceps is removed from the tooth. This possibility is important, in particular, at the time when the breaking of the tooth has not succeeded, for whatever reasons, in order to then prevent the tool from jamming in the bore.  
         [0071]    Since the making of the bore in the tooth by means of a cutting tool, drill or wheel stone need not lead to a precise diameter, it is also conceivable for the forceps to possibly have to be exchanged for forceps with a thicker drawing bolt measurement after the first attempt. In this case, as well, the return to the initial state is indispensable.  
         [0072]    The destruction bolt  1  may be turned about its axis by means of a gripping surface  16  so that the direction of the breaking force generated is altered and thus breaking of the tooth in a specific direction can be brought about.  
         [0073]    [0073]FIG. 4 shows a complete, hydraulically assisted breaking unit in its operating position. The breaking head  19 , together with a hose  22 , is coupled to a surgical supply system  23 , which is already present, via a hydraulic plug-in system  26 .  
         [0074]    The drilled wisdom tooth is located in the lower jaw  20  and the lower, cylindrical attachment  21  of the breaking head  19  (FIGS.  7  to  14 ) is introduced into the tooth. A hose  22 , in which the supply lines are located, makes a large treatment area possible and connects the breaking head to the supply and actuating unit  23  (FIGS. 15, 17) which makes a well regulated and delicate breaking of the tooth possible.  
         [0075]    [0075]FIG. 5 shows a forceps-like tool in its operating position.  
         [0076]    The drilled wisdom tooth is located in the lower jaw  20  and the lower, cylindrical attachment  21  of the breaking head  19  (FIGS.  7  to  14 ) is introduced into the wisdom tooth. The supply lines run through the housing  24  from the breaking head to the rear section, in which the cylinder  46  (FIG. 16) is located which generates the hydraulic supply pressure for the breaking and return strokes via the hand lever  25 .  
         [0077]    [0077]FIG. 6 shows an almost identical tool to FIG. 5 but, in this case, the breaking heads  19  (FIGS.  11  to  14 ) have been provided with a supply concept for a controlled breaking stroke and a spring-assisted return stroke which brings about differences in the area of the supply lines and the cylinder  46  (FIG. 18) in the area of the hand lever  25 .  
         [0078]    The Breaking Heads  
         [0079]    [0079]FIGS. 7 and 8 show the hydraulically (water) assisted breaking head in a symmetric (FIG. 7) and non-symmetric (FIG. 8) design with controllable breaking and return strokes.  
         [0080]    In the symmetric design, the drawing bolt  2  is pressed hydraulically upwards; the slotted sleeve  3  is thereby spread apart and symmetric forces introduced into the jaw which split the tooth open. The supply of the hydraulic medium (water) takes place via a lower connection (breaking stroke); subsequently, it is conducted via a control bushing  30  to the lower piston side of the drawing bolt  2 , whereby the breaking stroke is carried out. The upper piston side of the drawing bolt  2  is supplied via an upper connection (return stroke).  
         [0081]    A cover  31  is provided with a return flow bore and a cover  32  offers the contact edge for the slotted sleeve.  
         [0082]    In the non-symmetric design, the drawing bolt  12  is pressed hydraulically upwards and the half bolt  13  performs a lateral stroke on account of the wedge surface, whereby symmetric forces are introduced into the tooth in this case, as well. The supply of the hydraulic medium (water) takes place in the same way as with the symmetric design, i.e. the following individual parts are identical:  
         [0083]    the control bushing  30   
         [0084]    the cover  31  as well as  
         [0085]    the cover  32 .  
         [0086]    All the seals of the designs according to FIG. 7 and FIG. 8 are based on the use of the hydraulic medium water, wherein an exiting of small amounts of water into the mouth area is admissible.  
         [0087]    [0087]FIGS. 9 and 10 show the hydraulically (synthetic liquid) assisted breaking head in a symmetric (FIG. 9) and non-symmetric (FIG. 10) design with controllable breaking and return strokes.  
         [0088]    The design of FIG. 9 has the same operating principle as that of FIG. 7, the decisive difference lies in the seals used which, in this design, represent an absolutely leak-free unit on account of an expansion bellows  33 .  
         [0089]    The non-symmetric design (FIG. 10) is comparable to that of FIG. 8; in this case, as well, the medium used (synthetic liquid) shows its effects. An expansion bellows  33  creates the high sealing effect.  
         [0090]    [0090]FIGS. 11 and 12 show the hydraulically (water) assisted breaking head in a symmetric (FIG. 11) and non-symmetric (FIG. 12) design with a controllable breaking stroke and spring-assisted return stroke.  
         [0091]    The design of FIG. 11 is comparable to that of FIG. 7; in this respect, the return stroke of the drawing bolt  2  has, however, been realized via a pressure spring  34 . As a result, the hydraulic drive and the required return flow bores in the cover  31  are omitted. The same changes, pressure spring  34  and cover  31 , have been made in the version of FIG. 12 which otherwise is absolutely identical to the version of FIG. 8 on account of the unchanging medium (water).  
         [0092]    [0092]FIGS. 13 and 14 show the hydraulically (synthetic liquid) assisted breaking head in a symmetric (FIG. 13) and non-symmetric (FIG. 14) design with a controllable breaking stroke and spring-assisted return stroke.  
         [0093]    The constructional criteria of the absolutely leak-free unit have been combined in the designs of FIGS. 13 and 14 with a spring-assisted return stroke so that the expansion bellows  33  and the pressure spring  34  have been included in the symmetric design and in the non-symmetric design the expansion bellows  33  and the pressure spring  34 .  
         [0094]    The Supply and Actuating Unit  
         [0095]    [0095]FIG. 15 shows a hydraulically schematic overall concept for the remote-controlled breaking heads of FIGS.  7  to  10  with controllable breaking and return strokes.  
         [0096]    The supply and the generation of the hydraulic pressure for the drive of the breaking heads of FIGS.  7  to  10 , which are illustrated in FIG. 15 as a double-acting cylinder  39 , is undertaken by an electrical drive unit  40  which comprises:  
         [0097]    electric motor  41   
         [0098]    hydraulic pump  42   
         [0099]    pressure limiting valve  43   
         [0100]    container  44 .  
         [0101]    The actuation and control of the breaking and return strokes is brought about via a 4/3-way acting valve  50  which is designed for operation by hand or foot.  
         [0102]    The fine adjustment of the breaking stroke is ensured via the throttle check valve  49 .  
         [0103]    The elements  40 ,  49  and  50  are located in the supply and actuating unit  23  of FIG. 4.  
         [0104]    [0104]FIG. 16 shows a hydraulic concept for the remote-controlled breaking heads of FIGS.  7  to  10  with controllable breaking and return strokes.  
         [0105]    The generation of the hydraulic pressure for the drive of the breaking heads of FIGS.  7  to  10 , which are illustrated in FIG. 15 as a double-acting cylinder  39 , is applied via a manually operated unit  46 . The fine adjustment of the breaking stoke is regulated via the control unit  49 .  
         [0106]    The elements  46 ,  49  are located in the housing  24  and the actuation of the cylinder or hydraulic piston  46  takes place via the hand lever  25  (FIG. 5).  
         [0107]    [0107]FIG. 17 shows a hydraulically schematic overall concept for the remote-controlled breaking heads of FIGS.  11  to  14  with a controllable breaking stroke and spring-assisted return stroke.  
         [0108]    The concept of FIG. 17 differs due to the single-acting cylinder  38  with spring resetting, the symbolic illustration of the breaking heads of FIGS.  11  to  14  from that of FIG. 15. The actuating unit represents a 3/2-way acting valve  51 ; additional circuitry symbols have an identical designation and function to that of FIG. 15, the same way as the connection to FIG. 4, i.e. the switching elements  40 ,  49 ,  51  are accommodated in the unit  23 , is given in this case.  
         [0109]    [0109]FIG. 18 shows a hydraulic concept for the remote-controlled breaking heads of FIGS.  11  to  14  with a controllable breaking stroke and spring-assisted return stroke.  
         [0110]    [0110]FIG. 18 represents the same basic principle as FIG. 16 in that the hydraulic pressure is applied via the actuating unit  46  and the fine regulation of the breaking stroke is undertaken by the control unit  49 ; the essential change is to be seen in the controlled breaking heads which have a spring-assisted return stroke.  
         [0111]    The arrangement of the units  46 ,  49  is clearly shown in FIG. 5.  
         [0112]    FIGS.  20  to  23  show three different forms of breaking elements, the main function of which, to introduce a rotationally symmetric pressure into the tooth, is provided by way of an expandable bellows  60 .  
         [0113]    The bellows  60  of FIG. 20 is a ball-shaped bellows which is introduced into the tooth bore. The bellows is connected via an adhesive connection  61  to a hose  62  and a screw connector  63  (FIG. 19), whereby a possibility is created of connecting a hydraulic supply and actuating unit  23  (FIGS. 17, 18).  
         [0114]    If the bellows is acted upon with pressure, it expands for such a time until it abuts in the tooth bore on all sides and the pressure is transferred to the tooth; following a slow and delicate increase in pressure, the tooth subsequently breaks.  
         [0115]    The bellows  60  of FIG. 21 is a cylinder-shaped bellows which differs from that of FIG. 20 only in the shape of the bellows.  
         [0116]    The bellows  60  of FIG. 22 is a cylinder-shaped bellows with notched pieces  64  adhered to the sides which encourage breaking in a specific direction as a result of their acute-angled shape (FIG. 23).  
         [0117]    [0117]FIG. 24 shows a breaking element in a drilled tooth  65  which introduces a rotationally symmetric pressure into the tooth by means of bellows  66  and by means of segment pieces  67 .  
         [0118]    The required pressure is supplied via a screw connector  68 , which can be combined with a supply and actuating system  23 , to a control bushing  69  and thus to the bellows  66 . If the bellows expands on account of the slowly increasing pressure, the segment pieces  67  which are pivotally mounted and spring-assisted are pressed apart. The individual segment pieces  67  press against the tooth bore and thus transfer the pressure which finally leads to the tooth breaking.