US3377704A - Apparatus for the removal of a cemented dental structure - Google Patents

Description

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April 16, 1968 BRODIE ETAL 3,377,704

APBARATUS FOR THE REMOVAL OF A CEMENTED DENTAL STRUCTURE Filed Nov. 19, 1964 4 Sheets-Sheet l iftifil j/z/vs/v TUFFS 5 5 EQUINE H1175: L./=1 Lns n F, 7" UFPNEIH April 16, 1968 s. s. BRODIE ETAL 3,377,704

APPARATUS FOR THE REMOVAL OF A CEMENTED DENTAL STRUCTURE Filed Nov. 19, 1964 4 Sheets-Sheet 2 April 1 s. s. BRomE ETAL 3,377,704

APPARATUS FOR TEE REMOVAL OF A CEMENTED DENTAL STRUCTURE Filed NOV. 19, 1964 4 Sheets-Sheet 3 Pom-4 50 0/36 J\ lmmli A ril 16, 1968 s. s. BRODIE ETAL 3,377,704

APPARATUS FOR THE REMOVAL OF A CEMENTED DENTAL STRUCTURE Filed Nbv. 19, 1964 ?1 QLEE 4 Sheets-Sheet 4 United States Patent 3,377,704 APPARATUS FOR THE REMOVAL OF A CEMENTED DENTAL STRUCTURE Sidney Steven Brodie, 720 Fort Washington Ave., New

York, N.Y. 10040, and Albert de la Lastra, l9 Cambridge Ave., Bethpage, N.Y. 11714 Filed Nov. 19, 1964, Ser. No. 412,540

Claims. (Cl. 32-43) ABSTRACT OF THE DISCLOSURE This invention relates to an apparatus for the removal of a cemented dental structure in which a mechanical arrangement capable of transmitting mechanical energy along the longiutdinal axis of the structure uses a variety of magnetically operable means for imparting impacting forces to the mechanical arrangement. The magnetically operable means include a controlled source of magnetic energy selectively activating movable masses of magnetic material to vary the frequency and phase of the impacting sequence.

This invention relates to improvements in dentistry and more particularly to improvements in apparatus for the removal of a cemented dental structure.

Dental structures such as bridges and crowns are bonded to natural tooth roots by cements. It is well known, that the removal of cemented dental structures may be necessary for one or more of the following reasons:

(a) The occurrence of dental decay.

(b) To examine the vitality and pulpal involvement of a prepared tooth.

(c) To repair cemented dental structures made defective by the wear of materials.

(d) The loss of selected supporting teeth.

It is also known that natural tooth roots are connected to bone structure by a matrix of connecting fibers. The connecting fibers exhibit a resultant vector force which holds the tooth root in place, which vector force operates substantially along a longitudinal axis in the direction of the top to bottom of the tooth. Thus, properly directed impacting forces permit the use of high force magnitudes to break the cement bonds holding the dental structure to the tooth root without substantial detrimental eifect to the fibers or natural tooth roots.

In the prior art, removal of dental structures such as bridges and crowns was achieved by sacrifice of the tooth, or, by application of a rigid grasping means to the structure followed by the manual application of an impacting or leverage force in an attempt to break the cement bonds. However, prior art devices could apply only in exact magnitudes of impacting forces since manual means were used. Such manual means were further limited in that the oral cavity is not large enough to permit easy direct impacting to those dental structures located near the rear of the cavity. Other consequences of the use of prior art apparatus are patient discomfiture, and inconvenience to the dentist occasioned by the cumbersome mechanical apparatus.

It is accordingly an object of this invention to provide a more efiicient apparatus for the removal of a cemented dental structure.

It is another object of this invention to provide an apparatus for the removal of a cemented dental structure using precisely regulated impacting forces directed along the longitudinal axis of said structure.

It is still another object of this invention to provide an apparatus for the removal of a cemented dental structure operable in confined regions of the oral cavity.

3,377,704 Patented Apr. 16, 1968 It is an object of this invention to provide an automatic apparatus minimizing manual intervention for eifecting the removal of a cemented dental structure.

It is another object of this invention to provide an apparatus for the removal of a cemented dental structure, which apparatus includes control means remote from the oral cavity.

It is still another object of this invention to provide an electrically operable apparatus for the removal of a cemented dental structure.

It is yet another object of this invention to provide an apparatus for the removal of a cemented dental structure, which apparatus may be selectively coupled to any one of a plurality of permanent bridge or crown arrangements.

As previously mentioned the direction of application of impacting must be translated along the longitudinal axis of the cemented dental structure so as to avoid the tearing or twisting of the fiber matrix which secures the tooth root to the fiber matrix which secures the tooth root to the bone.

It is accordingly a feature of this invention that the apparatus comprises means for coupling the structure capable of transmitting mechanical energy along the longitudinal axis of said structure; and magnetically operable means for imparting forces to the coupling means.

The magnetic actuation of the impacting forces permits the use of a wide variety of electro magnetic control arrangements with the advantage of precision and flexibility. The coupling means translates the impacting forces and applies said forces to the cemented dental structures which avoids injury to the fiber matrix.

It is another feature of this invention that the mecha nism for generating the impacting forces comprise at least one movable magnetically responsive mass operating within a controlled field of magnetic energy, the mass being guided to impact upon the coupling means by selective actuation of the controlled field. Thus, by modulating the magnetic field, it is now possible to control the acceleration and direction of the mass to achieve selectively varying impacting frequencies and force magnitudes.

It is another feature of this invention that the mass can be disposed within a variety of inductive winding arrangements.

It is a feature of this invention that the means for coupling the cemented dental structure capable of transmitting mechanical energy along the longitudinal axis of said structure comprise a rigid member, means for grasping the structure, and a pivotably supported lever linking the rigid member and the grasping means.

It is evident that the impacting of the mass against a portion of the rigid member will cause the translation of force through the rigid member of the grasping means by motion of the pivotably supported lever.

It is accordingly another feature of this invention that the means used to reposition the mass upon alteration of the magnetic field comprise selective combinations of permanent magnetic and magnetically permeable materials, or, bistable remanent magnetic materials.

It is another feature of this invention that two movable masses may be used to sequentially impact upon the coupling means. Advantageously, during each impacting cycle two impacts can be delivered in a variety of timed relations without increasing the frequency of the source. Additionally, rapid successive impacting tends to limit the ability of the dental structure to return to its original state.

Restated, the above described arrangements increase the flexibility of control and frequency of impacting because the motion of one or more masses causing the impacting is responsive only to an applied magnetic field. Additionally, magnetic means can be used to selectively reposition one or more masses.

Other objects, features, and advantages of this invention will become apparent from the following description and accompanying drawings in which:

FIGURE 1 is a sectional view of one embodiment of the invention.

FIGURE 2 is a simplified diagrammatic illustration of the embodiment shown in FIGURE 1.

FIGURE 3A is another illustration of the embodiment shown in FIGURE 1 emphasizing the coupling means.

FIGURE 3B shows an alternative embodiment of the coupling means.

FIGURE 4 shows an alternative embodiment to that shown in FIGURE 3A.

FIGURE 5A shows the use of two movable masses in another embodiment of the invention.

FIGURE 5B is a diagrammatic illustration of the embodiment shown in FIGURE 5A.

FIGURE 5C shows the use of two masses in an embodiment alternative to that shown in FIGURE 5A.

FIGURE 6 shows another embodiment of the invention having two movable masses with permanent magnetic portions thereof.

FIGURE 7 shows another embodiment of the invention using a single mass having a permanent magnetic portion thereof.

FIGURE 8 shows another embodiment of the invention using a single movable mass formed from bistable remanent magnetic material.

FIGURE 9 illustrates the magnetic interactions of the embodiments shown in FIGURE 8.

In FIGURE 1, the coupling means comprises rigid bar 2 having a hook or grasping means 1 at one end thereof. The hook or grasping means may be any one of a number of dental implements which can be conveniently affixed to firmly grasp a dental crown. The rigid bar is slidably mounted within a movable mass 7. The translation of the bar relative to the mass is limited by a stop collar 3 fixed to the bar. The mass 7 is formed from any one of a number of magnetically permeable materials such as soft iron. Surrounding a portion of the bar and the mass is an inductive winding 16. The inductive winding 16 is enclosed within a magnetically permeable casing 9 which supports and completes the magnetic flux path through the movable mass. One end 11 of the movable mass 7 is formed into a conical shape which is intended to nestle against a conically shaped indentation of the casing 9. The conically shaped indentation is fonmed from a static mass portion. It should be noted, that one end of the rigid bar 2 has a large cross section area 4, the motion of the bar being limited by stop collar 5.

When a magnetic field generated from winding 16 is applied, the field intercouples movable mass 7 causing the movable mass to move toward impact surface 4 of the rigid bar and toward the static mass portion of casing 9.

As is illustrated in the figure, the movable mass will first impinge upon the impact surface 4 moving the rigid bar until the mass impinges upon the static mass 10, the stop collars 3 and 5 being so disposed as to permit movement of the bar relative to the static mass until the movable mass closes the air gap between 10 and 11.

In order to reposition the movable mass 7, it is not sufficient to merely reverse the polarity of the applied magnetic field. This is because the movable mass is attracted to the stationary mass It due to the relative attractive polarity difference; i.e., north-south, or south-north. By reversing the polarity of the magnetic field, the same attractive polarity difference exists. These facts necessitates the repositioning of the movable mass by means other than the varying of the polarity of the applied magnetic field. Advantageously, the repositioning of the movable mass can be accomplished by use of a spring bias 14. The spring 14 causes the movable mass to push against stop collar 3 thus moving rigid bar 2. The motion of rigid bar 2 is limited by stop collar 5 impinging upon static mass 10.

FIGURE 2 is a simplified representation of the dy- 4 namics of the movable mass, spring and impact surface 4 of the rigid bar 2 shown in FIGURE 1. When the magnetic field is applied, movable mass 7 translates to the left against spring bias 14, making initial impact upon surface 4- of the rigid bar and continuing to translate to the left until the movable mass is stopped by static mass 10.

In FIGURE 3A the coupling means comprises a pivotable lever 21 coupling the rigid bar 2 at a first pivot point 23. Additionally, a support member 27 is rigidly connected between the casing 9 and a second pivot pin 22. The hook or grasping means 1 is coupled to a third pivot point 24. Guiding the u and down motion of hook 1 are guide means 25 and 28 afiixed to a support member 27. When a magnetic field is applied to movable mass 7, said movable mass translates to the left impinging upon surface 4 of rigid bar 2. This causes lever 21 to rotate counterclockwise around pivot point 2 2. The rotation of lever 21 pulls hook 1 in an upward direction. Similarly, as described in connection with FIGURE 1 when the movable mass is repositioned, it pushes against stop collar 3 (see FIGURE 1) causing rigid bar 2 to rotate lever 21 in a clockwise direction. This forces hook I in a down ward direction. The measured motion of the hook 1 in actual practice need be only a few tenths of a millimeter in both the upward or downward direction.

In FIGURE 38 the hook or grasping means 1 is guided in its upward and downward motion by use of a guide bushing 25 supported by member 28 coupled to support member 27 In all of the embodiments, the movable mass 7 can be conveniently supported by easing 9. Additionally, the air gap design between the movable mass 7 and the stationary mass 8, can optimize the concentration of flux lines by any one of a number of well known configurations. This fact is illustrated conveniently in FIGURE 1 by the conica'lly shaped air gap.

Self-evidently, movable mass 7 can impact upon the rigid bar 2 in either a compressive or tensional sense.

FIGURE 4 shows the movable mass 7 applied in a compressive sense against rigid bar 2. In this embodiment, the rigid bar is connected to the lever at pivot point 23, while two support members 27a and 27b are used. Support member 2712 is coupled to pivot point 22, while support member 27a positions the guide bushing 25.

In FIGURE 5A two movable masses 7a and 7b are shown slidably mounted upon rigid bar 2. Two independent inductive windings 16a and 1611 are used. The magnetic flux path generated by windings 16a substantially couples mass 7a through casing 9 and static mass 10. Similarly, the main flux path including movable mass 7b comprises the entire extent of casing 9, static mass 10, and movable mass 7a. The windings 16a and 1611 are electrically connected to phase control means 50. Operatively, windings 16a are actuated first. This causes movable mass 7a to impinge upon member do. After the field has been iemoved from windings 16a, a field is applied through windings 16b causing mass 7b to impinge upon element 4b. The magnetic field strength emanating from windings 16b can be used to maintain both masses in contact relation with each other and with static mass 10. Repositioning means, not shown, are used in a similar arrangement as that shown in FIGURE 1. Advantageously, the excitation of windings 16a and 1611 can be made in different predetermined patterns with respect to time to achieve a wide variety of rhythmic variations.

FIGURE 5B is a simplified schematic of the relations between movable mass 711 and 7b together with rigid bar 2.

FIGURE 5C is an embodiment showing two movable masses 7a and 7b impacting upon rigid bar 2 in compressive relation. In this embodiment movable mass 7b is slidably mounted upon rigid bar 2, while movable mass 7a impacts directly upon element 4a.

As previously mentioned, each movable magnetically permeable mass must operate against a spring bias, or, more generically a restoring force. Advantageously, the

use of permanent magnetic material or bistable remanent magnetic material may provide a restoring force to replace the spring bias.

FIGURE 6 shows two movable magnetic masses 7a and 7b slidably mounted on rigid bar 2. Each movable mass is formed from a portion of permanent magnetic material such as Alnico and a magnetically permeable portion formed from soft iron. Additionally, the static mass is formed from the same permanent magnetic material such as Alnico. All the permanent magnetic material exhibits the same magnetic polarity. Furthermore, the permanent magnetic material forms the outer face of static mass 10 and is disposed opposite the permanent magnetic face of movable mass 7a.

The magnetic field emanating from winding 16a is of sufiicient magnitude to overcome the repulsive magnetic fields existing between the permanent magnetic faces on the static mass 10 and the movable mass 7a. A somewhat larger field (due to the longer flux path) is necessary to move mass 7b towards mass 10. When the applied magnetic fields are reduced, the repulsive fields existing between the permanent magnetic faces will cause the masses 7a and 7b to be repositioned. This may be seen more clearly in FIGURE 7.

In FIGURE 7 a single mass is shown with the air gap ends 9a and 9b of the casing extending over the magnetically permeable portions of the movable mass 7. In this embodiment, as in the embodiment shown in FIG- URE 6, the applied magnetic field must be of sufiicient intensity to overcome the repelling field between the oppositely disposed permanent magnetic faces of the static mass 10 and the movable mass 7.

FIGURE 8 shows an embodiment identical with that shown in FIGURE 7 except that the movable mass 7 is formed from bistable remanent magnetic material and the static mass 10 is formed from magnetically permeable material. Any one of a number of well known ferrites having substantially square hysteresis loops may be used for the bistable remanent material.

The operation of the embodiment in FIGURE 8 may be understood by also considering FIGURE 9. It should be recalled that square loop material exhibits two magnetic states. The material may be driven into a first stable state by the application of magnetic field of a first polarity and into a second stable state by the application of a magnetic field of opposite polarity.

FIGURE 9A shows that when mass 7 is in a first stable state, the applied field through static mass 10 is in a series aiding direction. This causes mass 7 to move towards the static mass 10. When the applied magnetic field is removed, as is shown in FIGURE 9B, the masses are attractively connected.

It is well known, that there is a phase lag in driving remanent magnetic material from a first into a second stable state and vis-a-vis. As a consequence when a magnetic field of opposite polarity is applied, a repulsive force exists between the two masses separating mass 7 from mass 10. This is because the movable mass 7 has not changed state while an opposite polarity has been induced in the static mass 10. With the continued application of the oppositely poled magnetic field, mass 7 is driven into a second stable state and is series aiding with respect to the flux in static mass 10. This causes mass 7 to move toward the static mass. These interactions are shown in FIGURES 9C and 9D respectively. Consequently, sensitive frequency control may be obtained through the use of bipolar current pulses applied to windings 16.

It is understood that there are numerous arrangements for affixing a hook or other grasping implement to the crown or other cemented dental structure and various changes in the details, arrangements of parts, which have herein been described may be made by those skilled in the art without departing from the principle and scope of the invention.

What is claimed is:

1. An apparatus -for the removal of a cemented dental structure comprising:

means for coupling the structure capable of transmitting mechanical energy along the longitudinal axis of said structure;

a first and a second movable magnetically permeable mass;

means for guiding the first and second mass to impact upon the coupling means;

a controlled source of magnetic energy for selectively generating magnetic fields intercoupling the masses and for accelerating the masses toward the coupling means, the controlled source including phase control means for regulating the magnetic fields such that the first mass is accelerated independent 01 the second mass; and

means for repositioning the masses along the guide means upon alteration of both fields.

2. An apparatus for the removal of a cemented dental structure comprising:

means for coupling the structure capable or transmitting mechanical energy along the longitudinal axis of said structure;

a first and second movable mass each having a magnetically permeable portion and a permanent mag netic portion, the permanent magnetic portions being of the same polarity;

means for guiding the masses to impact upon the coupling means; and

means for impressing a magnetic field of sutficient intensity to accelerate the masses "toward the coupling means;

the permanent magnetic portions of each mass being of sufiicient intensity to reposition the masses along the guide means upon removal of the magnetic field.

3. An apparatus for the removal of a cemented dental structure comprising:

means for coupling the structure capable of transmitting mechanical energy along the longitudinal axis of said structure;

a movable mass having a magnetically permeable portion and a permanent magnetic portion thereof;

means for guiding the mass to impact upon the coupling means;

magnetically permeable means magnetically linking the mass and having a portion of its extent formed from permanent magnetic material disposed near the mass;

means for impressing a magnetic field to accelerate the mass in a first direction along the guide means;

the permanent magnetic portions emanating fields of sufficient intensity to accelerate the mass in a second direction along the guide means upon the removal of the magnetic field.

4. An apparatus for the removal of a cemented dental structure comprising:

means for coupling the structure capable of transmitting mechanical energy along the longitudinal axis of said structure;

a movable mass formed from bistable remanent magnetic material;

means for guiding the mass to impact upon the coupling means;

magnetically permeable means magnetically linking the mass having a portion of its extent formed from permanent magnetic material;

means for inducing a first stable state in the bistable magnetic mass accelerating the mass in a first direction along the guide means; and

means for inducing a second stable state in the bistable magnetic mass for accelerating the mass in an opposite direction.

7 5. An apparatus according to claim 4, characterized in that:

the means for establishing the first and second stable states comprising a winding surrounding the mass; and a source of bipolar current pulses coupled to the winding arrangement.

References Cited UNITED STATES PATENTS 8 2,628,319 2/1953 Vang 3l0-15 2,640,266 6/ 1953 Sarti 32-43 2,777,198 1/1957 Wallace 32-61 3,129,347 4/1964 TOgnOla 31015 FOREIGN PATENTS 316,478 8/ 1929 Great Britain.

RICHARD A. GAUDET, Primary Examiner.

10 J. W. HINEY, Assistant Examiner.

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