FR2516376A1 - DENTAL PROSTHESIS PIVOT AND KEY FOR ITS PLACEMENT - Google Patents

Abstract

THE INVENTION AIMS AT A PIVOT 10 OF A SINGLE PERFECTED HOLDER FOR A DENTAL PROSTHESIS INCLUDING A ROD 12 WITH SENSITIVELY PARALLEL THREADED SIDES SUBDIVIDED LONGITUDINALLY IN SEPARATE BRANCHES 20, 22 TO BE INSERTED BY SCREWING INTO A DENTAL CANAL 19. WITH A WRENCH THAT APPLIES A PREDETERMINED MAXIMUM TORQUE TO THE DENTAL PIVOT TO SCREW IT INTO THE DENTAL ROOT IN ORDER TO REALIZE THE CROWN.

Description

The present invention relates to a dental prosthesis pivot

  perfected intended to be introduced

  in a dental root canal in order to make volu-

  me to the dental root to operate a crown reconstruction, and to a torque wrench intended to be

  used in conjunction with this one.

  In the past, solid and rigid dental pivots were made. Some dental pivots of this kind had conical threaded surfaces, as in

  provides an example, U.S. Patent No. 4,239,459.

  Others had elongated surfaces of continuous diameter substantially along their entire length, as exemplified by United States patents n

  3,524,255, 3,656,256 and 3,861,043 Certain pivots den-

  even suggested the arrangement of a slit extending

  spanning the length of the side of these, as is the case in United States Patent No. 644,804 United States Patent No. 838,296 and United States Patent No. 4,239,489 supra describe hollow pivots ie US Patent No. 4,234,309 exemplifies the teaching of the combination of a key intended to be used in conjunction with a dental pivot, while in the

  Swiss Patent No. 562,605, which has substantially the same 9 m

  jet, the threads provided on the dental pivot end before the head end of the pivot where the force is created

greatest retention.

  In each of the examples of provisions of the prior art recalled above, the nature of the dental pivot is such that, when it is screwed

  in the root canal of the tooth, the forces applied

  quées by the thread of the pivot against the walls cooperated

  tooth rants exert outward expansion forces on the tooth root, and this can sometimes

  give rise to a fracture thereof The teeth fractu-

  these are irreparable, and it is therefore important to avoid fracturing the dental root when applying the dental pivot therein, and even

  during the subsequent use of the tooth once the tooth

  vot and the dental crown were assembled at the root.

  The pivots of dental prosthesis of the tecnmique an-

  also led to the fracture of the racial

  not dental due to the application to the pivot of lateral forces and constraints during chewing. The present invention aims to solve the above-mentioned problems of dental pivots in the art

  The present invention provides a dental pivot.

  re which is about to be introduced by screwing into the root canal using a calibrated key so as to apply a predetermined torque to the dental pivot in order to avoid the application of excessive forces and stresses to the walls of the dental root and to allow the

  tooth pivot to be screwed into this root without fracture

  ture of the tooth, however, that the dental pivot is in-

  troduit in the tooth, it is anchored by cementing so as to avoid the establishment of anti-rotation forces which

  could normally tend to cause the pivot to come off

  screws from its seat into the root of the tooth These forces

  of anti-rotation are all the more eliminated by the expan-

  normal zion of the threaded branches of the dental pivot which brings them into closer friction contact with the threads of the root canal of the tooth They are further assisted by the cement which takes hold in the irregularities of the dentine wall and in the slit

existing between the branches.

  The provisions described above, as well as

  other purposes, features and benefits of this

  te invention, will emerge more fully from the description

  detailed description of an embodiment of the invention which, although currently preferred, is given only

  title of nonlimiting example The description refers

  in the attached drawing, in which: Fig 1 is an enlarged elevation view and in part

  in cross section of a dental prosthesis pivot arranged

ment to the invention;

  Fig 2 is a perspective view of a cushioned element

  impact weaver intended to be used in conjunction with the dental pivot of fig 1; Fig 3 is a perspective view of the dental pivot

  of fig 1 shown in combination with a dyna- key

  mometric according to the invention; Fig 4 is an enlarged elevational view of another embodiment of the dental pivot; Fig 5 is a vertical sectional view of the key, substantially along line 5-5 of Fig 3;

  Fig 6 is an enlarged perspective view of an au-

  be dental pivot; and Fig 7 is an elevational view of a dental pivot according to the invention screwed into a tooth root and capped

of a crown.

  As can be seen by referring to FIGS. 1, 2 and 3 of the drawing, the dental prosthesis pivot which is represented by these is designated as a whole by the reference and comprises a rod 12 formed integrally with a body 14 and a crown anchoring means generally designated by the reference 16 The rod 12, the body 14 and the crown anchoring means 16 are all integral with the

  from each other and form a single structure.

  So while these items have separate markers,

  none of them is to be considered as normally susceptible

  separation from others.

  In the case where the rod 12 ′ is of greater length,

  re to that of the root canal in which it is

  suitable for insertion by screwing, it can be

  cut to a length less than that of the root canal using a diamond-tipped dental bur After the pulp has been removed from the root canal 19 (Fig 7?) and

  that the channel has been closed, it is bored to a diameter

  be corresponding to that of the wall of the rod 12.

  The rod 12 is subdivided or separated into a desired number of branches, represented in the drawing by the

  two branches 20 and 22 mutually separated by a window

  through you 24 which extends over the entire length of the rod and extends beyond it penetrating into the body 14 to end in an enlarged curved opening 26 The fact of providing the end of the slot 24 with the curved commissure 26 eliminates the risk of a fracture occurring at the closed end of the slot 24 when compression forces are applied to the branches

  and 22 in a manner which will be described later.

  Not only does the enlarged end 26 of the slot 24 eliminate the risk of fracture of the dental pivot 10 at the end of the slot, but it also provides a means by which the branches 20 and 22 of the pivot rod are able to flex and move-one by

  relation to the other so as to be able to crash while relating

  proceeding from each other in a radial direction.

  Thus, the connection provided between the branches 20 and 22 at the surface surrounding the hollowed out end or enlarged commissure 26 of the slot plays the role of an elastic articulation around which the branches flex and

play elastically.

  As we will see, the slot 24 provides enough space

  pace to allow the branches 20 and 22 to approach and move away radially from each other It also serves to absorb the radial forces which are applied to the branches when the latter are screwed into the root canal 19 of a tooth root 25 (If G.

  7) L Ability of branches to bend as well as to

  approaching and moving away from each other allows them to

  po-us r irregularities of the thread 17 of the root canal

  laire This movement allows the branches to absorb the

  constraints and forces which would otherwise be applied

  located on the walls of the root canal 19 and would be

  likely to cause tooth fracture.

  As will also be seen, the longitudinal extent

  the slot 24 formed between the branches 20 and 22 ends at a point 26 which is located inside the body 14 and provides an essential advantage compared to the prior art The space of the slot 24 establishes a passage d evacuation for dental debris, and

  this causes the hydraulic and pneumatic forces to disappear.

  ticks which normally tend to develop below the dental pivot 10 when the latter is screwed with cement into the root canal of the tooth Ia slot 24 which allows the branches to undergo a relative displacement, and which is longer that the rod 12, now establishes

  an evacuation route from the bottom of the root canal

  area 19 of the tooth and below the distal end or insertion end of the rod 12 and rising to the surrounding atmosphere The space 24 allows debris,

  air, fluids and gases to accumulate in it

  and be evacuated from channel 19 without damaging it

root of the tooth.

  The thread 18 of the rod 12 extends over the entire length thereof and over the entire length of the body

  wider 14, partly on each branch 20, 22 The former

  lower end 28 of the body 14 can decrease or curve as shown in fig 1 of

  so as to allow him to marry the conic

  tee or the curvature of the milled dental root

  25 in which the rod and the body must be screwed So, when the rod 12 and the body 14

  are fully screwed into the root canal 19, the end

  conical or curved half 28 of the body 14 comes to bear

  be the milled inner surface of the tooth to fit into -

  ter and take a seat against it by marrying it without creating constraints The wider threaded body 14 adapts with tight fit inside the milled coronary aspect to establish a grip therewith

  retention of complete and larger surfaces

  This avoids the application of lateral centripetal stressing forces against the cooperating surface of the dental root 25 which could otherwise tend to fracture the tooth when the latter thus cooperates with the

  Prior art dental pivots.

  Although it has been found in practice that the pro-

  shaping wire 28 of the body 14 prevents fracture of the dental root when it bears against it, the scope of the invention includes the possibility of using a washer or elastic joint 50, visible more clearly in FIG 2, in association with the dental pivot 10 The washer or seal 30 can be 9 in all

  desired elastic or resilient material, such as "Si-

  lastic "When the washer 50 is screwed upwards to 516376 along the threads 18 of the t Life 12, it stops coming to bear against the underside of the body 14 adjacent

  at the curved or conical surface 23 thereof.

  When the rod 12 and the body 14 are fully screwed into the root canal 19, the washer 30 is compressed by engaging in the coronary aspect of the dental root 25 to form an airtight seal between the root dental and the surface 28 of the body 14 When it is thus engaged and compressed, it

  also plays the r 8 the shock absorber to absorb

  elastically ber the stresses and forces which would otherwise be applied during the screwing of the dental pivot 10 in the root canal 19 of the tooth Once the pivot 10 is implanted by screwing in the root canal 19 and that a crown 31 is located built and anchored around the root and around

  of the anchoring portion 16 of the dental pivot 10, the round

  delle sealing 30 has the effect of absorbing the stresses

  quotes and forces that are applied to the crown 31 and to the dental root 25 through the dental pivot 10 during chewing and other movements

grinding of the tooth.

  The dental pivot 10 can do without the washer or seal 30 in certain cases where the seat and the nesting ensured between the body 14 and the root

  are considered sufficient and adequate in his absence.

  In other conditions of use, it may be

  haitable to add the washer 30 to ensure effective

  cement tightness and absorption of forces.

  Once the pivot 10 is permanently screwed inside the dental root 25, it provides the dental root with a volume sufficient to allow restoring a crown to the dental root.

  around the anchoring means 16 The anchoring means shown

  felt here is designated as a whole by the reference 16 and extends outwards from the dental root in

  the opposite direction to the threaded rod 12.

  As shown in the drawing, the anchoring means 16 comprises a series or multiplicity of c 8 truncated nes 32, wider than the body 14 and the rod 12, which are separated from each other in the longitudinal direction of the

  dental pivot 10 by extensions or separators 34 for-

  més in one piece Each of the elements in c 8 not truncated 32 is arranged so that the largest diameter of its conical outer surface is from the c 8 tee of the rod

  of the pivot which is adapted to be screwed into the ra-

  diculaire 19 This downward and outward orientation

  taper of the conical surfaces of the elements in c 8 do 32 promotes the use of the pivot 10 in a manner which will be described later If it turns out that the height of the means

  anchor 16 is greater than that desired for the rec-

  crown titution, this can be shortened by

  simple grinding wheel removal of the number of anchoring elements

  ge in c 8 only truncated 32 and separators 34 which are esti-

surplus and superfluous measures.

  The application and insertion by screwing of the rod 12 and of the body 14 into the root canal of the tooth is carried out with self-tapping formation of the thread 17 of the root canal, the sides of which are substantially parallel to and precisely match that self-tapping thread 18 and the external c 8 tees of the rod 12 and of the body 14 of the dental pivot 10 Dental cement is poured into the root canal 19 and can also be applied to the rod 12 and to the body 14 so

  to be in intimate contact with all the surfaces of the

  letter 18 Although in the arrangements shown, the rod is subdivided into two branches, the scope of the invention includes the subdivision of the rod into any number of branches formed by space

  of elasticity and evacuation 24 or the like therebetween

  ci Once the cement is applied to the rod 12 and

  to the body, these are ready to be introduced by screwing

  age in the root canal 19 of the tooth.

  According to conventional techniques of the prior art,

  this was done by hand or using a tool-

  tine to rotate the dental pivot 10 by lowering it along the tapped or non-tapped root canal of the tooth It has been found that the application of too much torque to the dental pivot 10 tends to break the tooth if it ci exceeds a given value for which the lateral forces generated exceed, the lateral mechanical resistance of the dental root or the resistance force that the tooth exerts against the rod 12 and the body 14 when they are screwed into it Consequently, the scope of the present invention encompasses the possibility of screwing the dental pivot 10 into the

  root canal of the tooth using a dynamo wrench

  torque limiting metric which is represented by

  Figs 3 and 5 and designated as a whole by the repè-

  re 40 The key 40 is suitable for applying to the pivot 10 a tightening torque which will be less than that for which the resistance to fracture of the dental root is exceeded. The torque wrench 40 comprises a screw wheel 42 which can rotate by manual rotation, the interior of which is hollowed out to form a chamber 44 as shown in FIG. 5 The lower end of the

  chamber ends with a closing wall 46 which pre-

  feels a central hole 48 through which a driven shaft 50 exits the wheel 42 The driven shaft 50 has an enlarged head 52 whose underside constitutes a clutch surface or active surface which cooperates with

  the active surface facing the wall 46 The surfaces

  these active elements of the head 52 and of the wall 46 act

  clutch means for transmitting the action of the

  screwing thread 42 to the driven shaft 50 These surfaces are relatively smooth, which therefore allows them to slide relative to one another when it is desired and necessary.

  The inner chamber 44 of the wheel 42 is ta-

  raudée as shown in 54 in order to receive a

  threaded setting element formed by a nut 56 in the

  which can advantageously be provided with a slot for

  ception of screwdriver 58 Between the taring element 56 and the head 52 of the driven shaft 50 is contained an elastic biasing or force application means formed by a spring 60 The spring 60 is trapped between the taring element 56 and the t 9 te 52, and its tension can be modified by adjusting the axial position of the element 56 located inside the chamber 44 of the screwing boot 42.

  The inside of the key Must be protected from

  untimely gliding by application of a closure cap 62 applied to the thread 54 The driven end of the shaft 50 can be provided with any suitable gripping means for driving the dental pivot 10 during its rotation of screwing in the root canal of the

  To facilitate representation and understanding

  sion, this means is shown as having a simple screwdriver blade 64 At its top, the dental pivot 10 is provided with a complementary grip slot 66 for

  receive the blade 64 It will appear to the qualified technician

  try to use other agencies

  to achieve the torque limitation according to the pre-

invention.

  Before screwing on the dental pivot

  in the root canal 19, adjust the nut

  rage 56 of the torque wrench 40 so as to make it compress the spring 60 so that it applies a predetermined elastic force against the head 52 of the driven shaft 50 in order to force the latter to cooperate by taking

  surfaces with the wall 46 Once the drnamom key 4-

  stick 40 is tared, it is ready to be used

sée.

  Align the rod 12 of the dental pivot with the

  root nal 19 of the tooth The initial rotation of the dental pivot 10 can be carried out with the fingers of the hand to set up the dental pivot and its rod 12 in the channel 19 Following this, we screw more fully with auto - tapping the dental pivot in the root

  25 using the torque wrench 40 in engagement

  managing the blade 64 of the torque wrench in the slot

  receiving 66 of the dental pivot 10 and turning

the dial 42.

  As the rod 12 and the body 14 are gradually screwed into the root canal 19 and form the internal thread 17, all possible fluids, debris, gs or air trapped below the end

  distal or insertion end of the stem

  wind admitted or discharged to the atmosphere during such an introduction with self-tapping in the manner which was previously exposed, until the joint 26 also ends up being surrounded by the outlet of the

  channel 19 The elastic joint formed between the branches

  ches 20 and 22 allows the branches to flex radially inwards while approaching each other, by marrying and absorbing the irregularities which can occur during the engagement of the threading 18 against

the root canal 19.

  In this way, all the creative forces of

  fracture likely to appear during such an

  screw connection are now absorbed by the radial deflection towards the inside of the branches in the direction of one another which the split space 24 separates them spares Having a memory, the articulation 26

  by nature behaves like a return spring towards the ex-

  constantly imposes on the thread 18 of the rod 12

  and of the body 14 to move radially outwards

  eur to come into screwing engagement in intimate contact with the thread 17 that it forms in the root canal 19 This always guarantees obtaining the most complete benefit of the screwing cooperation between the two

threads 17 and 18.

  When a washer 30 of the sealing type is used, as shown in FIG. 7, this is compressed between the exposed wall of the root

  dental and the body 14 to completely seal the es-

  pace separating them and to form a shock absorber at its level When the sealing washer 30 is omitted, the adjacent surface of the body 14 abuts with full seat and in cooperation with the obturation of the wall inside the wall root canal countersunk 19

of the tooth.

  Although the dental cement previously applied to the rod 12 and to the body 14 as well as to their thread 18 is sufficient to retain them in cemented friction cooperation with the root canal 19, when

  the cement hardens, any tendency on the part of the pivot

  shut up 10 to turn later in opposite direction to get out of the dental root 19 is thwarted

  by the elastic force directed radially outwards

  which is applied to branches 20 and 22 at the level

  of the elastic joint 26 located between them.

  Thus, the elastic joint 26 provides a memory which tends to bring the branches 20 and 22 into contact with hard surfaces and in anti-rotation cooperation with the

  thread 17 of the root canal 19.

  If it appears on the pivot 10 and therefore on the shaft 50, during the screwing of the rod 12 and of the body 14 in the root canal 19, a resisting torque exceeding the setting torque given by the spring 60 contained in the torque wrench 40, the spring 60 allows the wall 46 of the thumb wheel 42 and the adjacent active surface of the head 52 of the driven shaft 50 to slide one relative

  to the next It follows that it is not possible to

  follow the screwing of the rod 12 and the body 14 in the root canal 19 using the torque wrench as long as the resistance force existing between the threads 17 and 18 has not disappeared or has been reduced

  therefore, the rotation of the dental pivot

  re 10 by means of the driven shaft 50 stops Continuing the rotation of the wheel 42 does not give rise to any deeper screwing of the pivot 10 in the channel

  root 19 as long as the creative resistance forces

  these fracture exerted on it are not removed

  mées. It is clear from the above that, as soon as the adjustment of the element 56 located in the knob 42 of the torque wrench is carried out so that the spring 60 does not create, between the head 52 of the driven shaft

  and the surface of the wall 46 of the wheel 42 a

  ple likely to cause the tenacity to be exceeded

  mechanical tee and the fracture resistance of the tooth, the tooth will not fracture while using the

  wrench 40 Continued rotation of the screw wheel

  sage 42 will not lead to any further engagement of screwing the rod into the dental root 19 because the clutch surfaces will slide and rotate relative to one another without any work transmission occurring between those Therefore, even if the rod 12 and the body 14 are able to absorb the stressing forces creating fractures applied between them and the dental root 19, the use of the torque wrench 40 provides additional assurance. that at no time of the use of the key on the dental pivot 10, the latter will not exert efforts on the dental root causing the resistance to be exceeded

of the dental root.

  After dental pivot 10 has been applied to the

  dental root 25 as described, this is found

  ve ready for the application of a crown 68 at the root

  dental 25 at the location of the anchoring means 16 of the

  your dental 10 Crown 68 is shaped as follows

  classic to allow it to adapt precisely

  sion at the dental root 25 It presents the classic hollow interior intended to take place around the means

  anchor 16 and over it.

  The crown 68 is shown diagrammatically in FIG. 7 Its arrangement details can be modified,

  and they are not necessarily limited to those shown

  felt here Before applying the crown 68 by means of anchor 16, a dental or composite cement is applied

  inside it Dental cement or composite

  te can also be applied around exposed surfaces

  anchor elements in c 8 not truncated 32 and around

  separators 34 and the body 14 of the dental pivot 10.

  The anchoring means with c 8 multiple truncated nes 16 is

  unusually well suited for use in restaurants

  ration of old and already worn bridges and crowns.

  It was noted above that the small diameter ends of the truncated c 8 nes 32 extend on the opposite side to the rod 12 facing the interior opening of

  the crown 68, while the ends of gra ddiamè-

  tre cones 32 extend down from the c 8 tee of the body 14 and of the rod 12 The c 8 tees from below the large bases of the anchor cones 32 act as surfaces below which the dental cement or composite flows and against which it hardens by making engagement therewith The cones are decreasing in the way

  represented and described in order to establish a natural flow

  of dental cement along a path starting from the narrower portions of the truncated anchor cones 32, along the flared surfaces, then ending in the spaces provided by the dividers 34 located between

each of the conical elements.

  In practice, it has been found that when dental cement is compressed, it flows along the path of least resistance going from the narrow ends of the

  conical truncated anchor elements 32 towards the ends

  wide tees then ending in the spaces provided by the separators 34 located between them The initial application of dental cement in such spaces provided

  by the separators 54 is even more fully compressed during and during the application of the crown 68 over

* all the anchoring means 16 The forces applied by the crown cause the cement to flow

  in all the spaces that exist below the large

  bases of the c 3 nes truncated 32 so as to make it

  nir in complete engagement and cementing with them This ensures a suitable and long-term connection and engagement between the crown 68 and the anchoring means 16 as well as the elimination of air pockets inside

of the crown.

  The embodiment of the dental pivot represents

  tée by fig 4 is designated as a whole by the reference numeral 110 The last two numbers used in this embodiment correspond to the homologous structural elements described with regard to embodiment 10 represented by fig 1 and 3 and described with reference to these figures Consequently, for the sake of convenience, all the reference numerals 1 ′

  used with regard to the description of the form

  110 of fig 4 are formed by adding

to the previous ones.

  Fig 4 differs from that of the embodiment

  tion 10 previously described in that it does not include the two-stage body 14 Unlike the

  prior embodiment, the pivot 110 is inu-

  only well suited to be used in association with teeth with several roots, in which two or more of these pivots 110 can be used. The embodiment 110 comprises a threaded rod 112 with substantially parallel sides, the thread 118

  extends around each of the representatives of the multipli-

  city of branches 120 and 122 As in embodiment 10, the branches are separated and spaced

  from each other by an evacuation slot 124 which extends

  stretches across much of the length of the stem and

  ends near the far end of the ti-

  ge by the elastic memory recall joint

gie 126.

  In embodiment 110, the extent longi-

  tudinal of the rod 112 is such that its coro-

  naire ends at the outlet of the root canal 19.

  Similarly, the evacuation slot or passage

  124 establishes an escape route to the appropriate atmosphere

  quat starting from the distal end, or end of in-

  troduction, stem 112 during its introduction with

  self-tapping in channel 19 until the articu-

  lation 126 is ultimately enclosed in the root canal

  The dental pivot 110 consists of a single te-

  nant, and it comprises a crown anchoring means 116 which is shaped and behaves substantially in the same way as the crown anchoring means 16 of the form

  of embodiment 10 previously described For this reason

  sound, we will not make a detailed description of it-

repetitive strain.

  To ensure that the dental pivot 110 is correctly screwed into the root canal 19 of the tooth with application to the latter of a torque which does not risk

  not cause the mechanical resistance to be exceeded

  that of tooth 25, the torque wrench 40 can be used in the manner previously described. To allow the use of the wrench 40, the embodiment 110 comprises

  te a complementary screwdriver slot 166 which is a-

  suitable for receiving the screwdriver type blade 64.

  It will go without saying for those skilled in the art that the representation

  tation and description of blade 64 and slot 66

  or 166 with complementary profiles cannot

  themselves constitute a limitation of the scope of the invention

  It is open to any other means

  of additional socket to operate the commitment of vis-

  wise of the dental pivots according to the invention in the root canal 19 with a force not likely to exceed

  the mechanical strength of the dental root 25.

  As you can see now referring to fig 6,

  the embodiment represented by this corresponds to

  pond for many of its essential provisions to the embodiment 10 described with reference to FIGS. 1 and 3 Consequently, the last two digits of the numerical marks designating the details of the homologous arrangement are the mgmes, and all the marks are taken in the

series starting from 200.

  The similarity of embodiment 210 with embodiment 10 cannot escape the first glance. The rod 212 of the latter ends in the body 214, and these two elements are split at 224 to form the multiplicity of branches 220 and 222 which are separated so as to be able to move elastically with respect to each other to absorb shocks and

  the forces likely to be applied to their threading

  ge 218 during the introduction of self-tapping screwing

  age of the dental pivot 210 in the root canal 19.

  Like the previously described embodiments, the embodiment 210 is in one piece conformation comprising a body 214 in which the walls delimiting the enlarged opening 226 behave so as to keep the memory of the separation of the multiplicity of branches 220 and 222 It also ensures the reception of debris and the establishment of a passage

  venting from the end of the intro

  duction of the rod 212 during the screwing of the rod and of the body in the milled coronary aspect complementary to the root 19 As visible in FIG. 6, the embodiment 210 may use a washer or seal 230 in "Silastic", as described in what

  relates to embodiment 10.

  Embodiment 210 differs from Embodiment 10 in the details of conformation of the means

  anchor 216 Embodiment 210 is unusual -

  suitable for fitting a new crown prosthesis.

  For this reason, the anchoring means 216 eliminates the

  multiplicity of anchors in c 8 not truncated 32 dis-

  placed at a distance from each other and converts it

  ci in a c 8 ne single truncated smooth side 232 Its ex-

  the narrow end is located at a distance from the rod 212, while its wide end is located at the side of its connection in one piece with an extension of the

body 214.

  The implementation of the dental pivot 210 is carried out in a manner substantially identical to that previously described with regard to the preceding embodiments With regard to the pivot 210, the element

  anchor 232 is provided with a slot 266, similar to the windows

  tes 66 and 166, which receives the end 64 of

  the driven shaft 50 of the torque wrench 40 The applica-

  tion and screwing of the rod 212 of the dental pivot 210 into the root canal 19 takes place in a manner substantially identical to those previously described

  as for the implementation of the torque wrench 40.

  The blade 64 is engaged in the slot 266 of the anchoring element 232 to cause the latter to penetrate by rotation into the root canal 19 of the tooth Si, at an instant

  any during such self-tightening engagement

  tapping, is applied to the branches of the

  rod 212 a torque which exceeds the set torque set

  nor by the spring 60 on the torque wrench 40, tared

  by adjusting the adjustable nut 56 contained therein

  ci, the clutch surfaces cooperating between the wall 46 and the head 52 begin to slide one relative

  to the other This guarantees that at no time the applica-

  Torque to the dental pivot will only cause the mechanical strength of tooth 25 to be exceeded and only

  the pivot exerts no fracture-creating forces

  be the walls of the root canal 19 thereof.

  As described above, the branches 220 and 222 bend and move independently with respect to each other in reaction to any forces being exerted on them during such a screwing operation. This aptitude of the branches of the rod to yield in reaction to the screwing forces allows them to behave as a shock and force damper which transmits such forces to the branches of the rod to make them absorb them In the absence of such a force damper , the forces are exerted towards

  the exterior against the newly tapped wall of the

  root nal 19 of the tooth, and they give rise to

  fracture of tooth 25 if they cause a protrusion

  mechanical strength of the tooth.

  In each of the embodiments, the multipli-

  city branches are normally located at

  from each other by the slit formed between it

  these In each case, the branches flex relative to each other in reaction to the forces which

  are applied to them to deal with irregularities

  countries in their self-tapping movement along

of the root canal 19 of the tooth.

  In each case, the spring return articulation provided by the walls surrounding the wider opening 26, 126, 226 located at the end remote from the slot exerts on the branches a restoring force which makes them

  tend to assume their normal relative position of parallel

  lélisme This outward biasing force exerted at the elastic articulation 26, 126, 226, brings the threading 18, 118, 218, of each of the dental pivots in fuller and more complete grip relationship with the complementary surfaces of the filetae 17 that they form in the root canal 19 of the

  tooth The spring effect of the branches allows them to be uniform

  even to absorb the stresses over their entire length and on the slit portion of the body This has the effect of ensuring greater cooperation and retention between the dental pivot to restore volume and

  the thread 17 formed by the latter on the tooth 25 Ce de-

  more complete grasp also opposes anti-rotation

  or at the risk of the dental pivot leaving accident

  so much the root canal 19 of the tooth, while ensuring a complete casing cooperation

and forces between them.

  We have just shown, described and underlined the fundamental new characteristics of the invention in its application to preferred embodiments thereof, but it should be understood that various

  deletions, substitutions, modifications and combinations

  sounds as to the form and details of the device represented

  felt and its implementation can be brought by the experienced technician without leaving it

  of the scope of the invention, which is therefore not to be considered

  me limited only by the scope of the appended claims.

  This is how we could combine the

  three embodiments with respect to the rod, to the body

  intermediate and to the structure of the anchoring means.

16376

Claims (15)

  1. Dental pivot (10; 110; 210) intended to be   introduced into a dental root canal (19), charac-   terized by: a rod (12; 112; 212) suitable for being   screwed into the root canal   (19) and having substantially parallel threaded sides   leles starting from the insertion end of the said   rod and extending at least over the entire length of the   said rod to be introduced by screwing into the root canal (19); a slot (24; 124; 224) provided   in said rod, starting from said insertion end   tion and extending over a relatively large length thereof to subdivide said split rod into a multiplicity of elongated threaded branches (20, 22; 120, 122; 220, 222) separated from each other by a space delimited by said slot (24; 124; 224) for allowing said branches to move mutually to absorb the fracture-creating forces which are applied to them during the screwing of said rod   in the dental root caml (19); and a means of anchoring   ge (16; 116; 216) integral with said rod (12; 112; 212) and intended to anchor a dental crown (31) to it.   2. Dental pivot according to claim 1, charac-   terized in that said anchoring means (16; 116) forms an integral part of said pivot (10, 110) and is located at   the opposite of said insertion end of said ti-   ge (12, 112), said anchoring means comprising a multi-   plicity of truncated conical elements (32; 132) located at   distance from each other and each presenting a di-   meter decreasing when moving away from said rod.   3. Dental pivot according to claim 1, charac-   terized by a threaded body (14; 214) interposed between and   forming a single piece with said rod (12; 212) and the   said anchoring means (16; 216), and having a width   greater than that of said rod.   4. Dental pivot according to claim 3, charac-   terized in that said body (14, 214) is rounded adjacent to said rod (12; 212) to avoid fracture   of the tooth (25) during its engagement with it   ci during the introduction of said rod and said body in the tooth.   5 dental pivot according to one of claims   3 and 4, characterized by force absorbing means (30; 230) disposed between said body (14; 214) and said   rod (12, 112, 212), said absorption means being com-   pressible between said body and the dental root when screwing said rod and said body therein   to absorb the forces applied between the raci ne and the pivot.   6. Dental pivot according to one of claims   3 to 5, characterized in that said slot (24; 224) extends   tends beyond said rod (12; 212) entering said body (14; 214) and ending therein by an enlarged curved opening (26; 226) which prevents fracture of said body at the ends of said slit and promotes the relative displacement of said branches (20, 22; 220, 222).   7. Dental pivot according to one of claims   3 to 6, characterized in that said anchoring means (216) is a c-shaped extension 8 not truncated from said body (214) wider than said body located at c 8 opposite t said rod (212).   8. Dental pivot according to one of claims   I to 6, characterized in that said anchoring means (16;   116) is formed by c 8 nes truncated (32; 132) mutual- spaced apart.   9 Dental pivot (10; 110; 210) intended to cooperate   rer with a tooth root canal (19), characterized   in that it comprises: a rod (12; 112; 212) present   both substantially parallel flanks and being threaded along said flanks over a length of the rod allowing it at least to be screwed completely into the root canal (19), said rod being relatively spaced and subdivided into a multiplicity of branches (20, 22; 120, 122; 220, 222) mutually joined in one piece at their ends remote from the distal end of said thread (18; 118; 218) of said rod   so as to be able to undergo a mutual displacement of compress-   elastic tension, each of said branches comprising a   portion of said thread (18; 118; 218) so that when   that said rod is screwed into the root curry (19), said branches spring out towards the inside, approaching each other within said space (24; '124; 224) to absorb forces which tend to fracture the   dental root, however, that said joint remains   fate (26; 126; 226) urges said branches (20, 22;, 122; 220, 222) in screwing cooperation with the root canal (19) in order to oppose that said rod accidentally unscrewing of it; and anchoring means (16; 116; 216) connecting to said   rod for anchoring a dental crown (31) thereto.   10. Dental pivot according to claim 9, ca-   characterized in that said space (24; 124; 224) separating   each of the branches (20, 22; 120, 122; 220, 222) of the-   so-called multiplicity of branches starts from the far end   the of the threaded rod (12; 112; 212) and extends beyond it in order to establish an evacuation passage going from said distal end to the atmosphere in order to pocket the development of forces in said root canal (19) at said distal end of said rod.   11. Dental pivot according to one of claims   I to 10, characterized in that, for its installation by screwing, a key is used which comprises: an operating member (42) manually movable in rotation; a tree   (50) movable in rotation under the action of said ma-   work and with respect thereto, said shaft and said drive member having mutually cooperating surfaces for the purpose of rotating said shaft in correspondence with the manual rotation of said drive member; and a biasing means (60) applying   a force urging said surfaces to cooperate together   ble to rotate jointly and adapted to yield to allow said surfaces to rotate relative to each other when a torque applied to said shaft (50) and opposing its rotation exceeds a predetermined torque defined by the biasing means (60) , and in that it   is provided on said shaft (50) and on said dental pivot   re (10; 110; 210) gripping means (64, 66; 64, 165 o; 64, 266) adapted to cooperate removable so as to rotate said rod (12; 112; 212) to screw it into   said tooth root canal (19).   12. Dental pivot according to claim 11,   characterized in that said key (40) further comprises an adjustable calibration means (56) arranged on said operating member (42) so as to allow the force applied by said biasing means (60) to be modified so   that said surfaces rotate relative to each other   when the resistive torque applied to said rod   (12; 112; 212) during its screwing into the root canal   the area (19) exceeds said predetermined torque.   13. Dental pivot according to one of claims   11 and 12, characterized in that said pivot (10; 210) comprises a body (14; 214) located between said rod (12; 212) and said anchoring means (16; 216), and in that said thread (18; 218) formed along said rod   is self-tapping and extends along said body.   14. Assembly consisting of a dental pivot (10,, 210) intended to be introduced by screwing into a   root canal (19) of tooth and a torque wrench   that (40) for fitting thereof, characterized in that: said dental pivot (10; 110; 210) comprises a   distal end intended to be introduced by screwing   ge in the tooth root canal (19) and an anchoring means (16; 116; 216) formed integrally with said dental pivot and intended to anchor a dental crown (31) thereto; said dental pivot has an elongated outer surface with substantially parallel flanks carrying a longitudinal thread (18; 118; 218) and being subdivided into a multiplicity of branches (20,   22; 120, 122; 220, 222) mutually spaced and mutual-   Lely movable at said distal end, said branches being joined together at a distance from said distal end to ensure said mutual movement; said key (40) comprises a pivoting screw shaft (50) and a rotary actuator (42) each having surfaces (52, 46) flexibly urged to come into mutual drive engagement in order to rotate said shaft (50 ) under the action of the rotation of said operating member (42); an elastic means (60) is arranged   in said operating member (42) and intended to stress   flexibly ter said surfaces to establish said drive grip; and cooperating means (66, 64; 166, 64;   266, 64) are provided on said anchoring means and on the   said pivot screw shaft for enabling active transmission of the torque from said actuator (42) to said dental pivot (10; 110; 210) and for eliminating said active transmission when the resisting torque applied to said dental pivot exceeds torque   taring motor of said operating member (42).   15. The assembly of claim 14, character-   in that said cooperating means provided on said anchoring means and on said pivot screw shaft comprise means with mutual engagement (66, 64; 166,   164; 266, 264), in particular with conjugate profiles, for example- full slotted and screwdriver blade.   16. Torque wrench (40) for driving in a dental pivot (10; 110; 210), with torque limitation, characterized in that it comprises: an organ   manually movable maneuver in rotation (42) comprising   as a driving means (46), a driven shaft (50) comprising a driven means (52); a biasing means (60) adapted to flexibly bias said driving and led means (46, 52) to come into mutual engagement in order to rotate said shaft (50) with said operating member (42) and to yield in reaction to the tree audit application (50)   of a resistive torque greater than the defective setting torque   nor by the means of solicitation (60) to make yield   said means of solicitation by allowing the establishment   ment of a slip between said means leading and led   (46, 52) during the continued rotation of said organ-   maneuvering (42), and a conjugation means (64) provided on said driven shaft and adapted to mate with a 16376   24. dental pivot to rotate it under the effect of   the rotation of said operating member (42).   17 Torque wrench according to claim 16, ca-   characterized in that said driving and driven means (46, 52) are relatively smooth surfaces.   18 Torque wrench according to one of the claims   tions 17 and 18, characterized in that said operating member (42) comprises a chamber (44) in which a limiting wall (46) comprises an opening (48) through which said driven shaft (50) exits from said member (42) ,-and   in that said driving means (46) of said operating member   vre is formed by a wall of said chamber.   19 Torque wrench according to claim 18, characterized in that said biasing means is a spring (60) disposed inside said chamber (44), said spring biasing said driving means and   led (46, 52) to engage with each other.   Torque wrench according to claim 19, characterized in that it also comprises a calibration means (56) provided on said operating member (42) and adjustable so as to allow the stressing force of said spring (60) to be modified to fix the couple   for which said driving and driven means (46, 52) are   move and rotate relative to each other.