WO2009118741A2

WO2009118741A2 - Dental elevator

Info

Publication number: WO2009118741A2
Application number: PCT/IL2009/000345
Authority: WO
Inventors: Mordechai Findler; Efrat Broide; Alex Kuchuk
Original assignee: Efalmo Ltd.
Priority date: 2008-03-27
Filing date: 2009-03-26
Publication date: 2009-10-01
Also published as: WO2009118741A3; GB2458673A; GB0805543D0

Abstract

Dental elevator for tooth extraction has a movable beak that is capable of reciprocally and either concomitantly or independently axially rotating and linearly translating. The translational motion of the beak provides for a wedge action, whereas the concomitant rotation and translation provides for a wedge and lever action, applied onto the tooth to be extracted.

Description

DENTAL ELEVATOR

FIELD OF THE INVENTION

The present invention relates in general to dental elevators for tooth extraction. In more particular the present invention relates to a dental elevator for tooth extraction having a movable beak that moves in a rotational, linear and translational, and/or spiral motion.

BACKGROUND OF THE INVENTION

Dental elevator for tooth extraction normally has a hand held body to which a stem having a beak disposed at its distal end is attached. Dental elevators having a variety of beaks are common in the marketplace. Normally in a tooth-extracting operation using a dental elevator, the tip of the beak is forcefully inserted into the periodontal space at a targeted point of application adjacent to the targeted tooth. The tooth is dislocated by a wedge action and a lever action of the elevator. The dentist pushes and/or pulls the elevator and tilts it to disconnect the gingival fibers and dislocate the tooth. However, the beak may not firmly engage the tooth. Therefore even when the dental root is lifted by the lever action in which the periphery of alveolar bone located opposite to the surface of the root of the tooth is used as fulcrum, the dentist may have to repeat the lifting operations many times before completing the tooth extraction. Such operations require her or him to forcefully and simultaneously move and/or rotate the elevator in various directions. Unfortunately, such operations may involve accidental slip of the tip of the dental elevator off the place of application thereby severely damage surrounding soft tissues.

Contrary to elevators that normally provide for tearing and breaking the gingival fibers, thereby luxating a tooth to be dislocated and extracted, periotomes the blades of which are relatively thin provide for cutting the periodontal ligaments. Powered periotomes are known. Exemplary is a power periotome disclosed in US patent US6626670. A thin and preferably flexible blade, such that it can be bended to conform to the inwardly curved periodontal socket, reciprocally translating back and forth provides for cutting the gingival fibers. Moving the blade is accomplished by means of an integral motor. For dislocating a tooth off its socket the operator manually rotates the periotome to follow a desired track circumferential to the root of the tooth while the reciprocating motion of the blade is accomplished at a relatively high rate at frequencies in the range of a number of dozens of Hzs.

In US patent US1806592 a vibrating elevator the beak of which reciprocally rotates within a predefined range of rotational angles is disclosed. Rotating is effected by means of a lever laterally extending off the stem of the elevator. The end of this lever that is relatively distant from the axis of rotation is reciprocally moved along a predefined circular arc. The tip of the beak is manually forced into the periodontal space between the surface of the targeted tooth and the wall of its socket while is reciprocally swinging. Such swinging provides for a lever action by which disconnecting and tearing of the gingival fibers is accomplished. The rotary motion of the beak of the disclosed elevator is powered by means of a common dental engine that is normally available at dental clinics.

In British patent GB418588 an elevator powered by means of a pressurized fluid is disclosed. The beak of the disclosed elevator reciprocally and linearly translates along its axis. An integral piston pushed by means of the pressurized fluid hammers on the proximal end of the stem which is further distally pushed by the forcing piston. The tip of the beak is such forced into the periodontal space by the linear movement. The beak and the piston are pulled back by means of a biasing spring when the flow of the pressurized fluid is stopped. The gingival fibers are disconnected by the repeated wedge action applied by the distally moving beak that is further manually pushed and or tilted by the operator. An ultrasonic device providing for dislocating a tooth by means of ultrasonic vibrations is disclosed in Japanese patent JP10057401. The disclosed device consists of forceps having an oscillating chip that is activated by an ultrasound transducer housed in an arm of the forceps.

Any elevator providing a dentist for conveniently operating a tooth extraction, prevents him or her from exerting excessive forces, torques and/or power while concomitantly applying wedge and lever action for disconnecting the gingival fibers, as well as reducing hazards associated with difficulties and/or accidents in the tooth extraction, is beneficial.

SUMMARY OF THE PRESENT INVETION

It is an object of the present invention to provide a dental elevator having a replaceable beak that is detachably attached to the elevator's body. A beak that is reciprocally movable in any of the modes including spiral motion, rotational motion and linear translation. The parameters associated with such mode are changeable within respective and predefined ranges, at least one of which is suited to at least one targeted tooth.

The dental elevator of the present invention is provided with a motor electrically powered. The elevator is adapted and arranged for:

exerting torques onto a targeted tooth in a range, the upper limit of which is selectable by the user, the lower limit is in the range of 2.5 - 3 Newton meters (Nm);

reciprocally moving the beak at frequency levels within a range of a number of Hzs, the upper limit of which does not exceed two dozens of Hzs; rotating the beak within ranges of rotational angles respectively associated with a selected mode all of which are included in the range ±110°;

linearly moving the tip of the beak within a range of a number of milimeters.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is an isometric view of a dental elevator according to an embodiment of the present invention;

Figs 2A - 2B are two different side looking views of the distal segment of the beak shown in Fig.1 ;

Fig. 3 is a simplified graph of the rotational angle versus time of a rotating beak of a dental elevator according to an embodiment of the present invention;

Fig. 4A is a side looking view of a dental elevator according to a preferred embodiment of the present invention;

Fig. 4B is an elevational view of the distal end of the dental elevator shown in Fig. 4A;

Fig. 5A - 5B are elevational views of the proximal segment and the proximal end of the supporting lever shown in Fig. 4A respectively; Fig. 6 is an isometric view of a dental elevator according to another embodiment of the present invention;

Fig. 7 is a sectional view of the elevator body shown in Fig. 6; DETAILED DESCRIPTION OF THE PRESENT INVENTION

In accordance with the present invention a dental elevator for tooth extraction the beak of which is movable by rotating and/or linearly translating is provided. Rotating the beak provides for a lever action, whereas concomitantly translating and rotating the tip of the beak provides for a wedge and/or lever action applied onto the targeted tooth. Based on the experience of the inventor of the present invention the magnitude of torques exerted onto a tooth to be extracted are considerably high. Furthermore it was experimentally found that magnitudes that are lower compared to 2.5 NM are practically ineffective. However torques levels that are too high may tire the operator and deteriorate the efficacy of the extraction operation. Therefore the levels of torque exerted by the motor of the dental elevator of the invention are confined within ranges respectively associated with targeted teeth. Ranges of rotational angles within which the beak rotates and/or distances along which the tip of the beak linearly moves are similarly confined within respective limits associated with targeted teeth.

The body of a dental elevator of the invention can be oriented in any direction. Therefore the end of the elevator body that normally points towards the targeted tooth is termed hereinafter as distal, whereas the end of the elevator body that normally points towards the operator is termed hereinafter as proximal.

Reference is first made to Fig. 1 in which an isometric view of a dental elevator according to an embodiment of the present invention is shown. Dental elevator 20 has beak 22 disposed at its distal end. Stem 24 provides for connecting the beak to elevator body 24 as further detailed below. A stem having a beak disposed at its distal end is referred hereinafter as a beak. Elevator body 24 is structured and arranged for being snugly and firmly held by a hand of an operator. The beak is detachably attached to a movable shaft, not shown, housed within the elevator body by means of connector 28. Connector 28 can be moved between two positions. In the first position, which is the locked position, the beak is firmly secured to the shaft. In the second position the beak is released off the shaft, such that it can be removed. Any connector, such as a snap or rotating connector, which provides the operator for conveniently releasing the beak off the shaft, such as for its replacement, is in accordance with the present invention. An electric DC motor and a respective gear mechanism, not shown, both housed within the elevator body provide for reciprocally rotating the shaft and the attached beak, as indicated by double arrow 30, within a predefined range of rotational angles. The same motor, a cam and biasing spring or springs provide for linearly moving the shaft back and forth, as indicated by double arrow 32. This translational motion is effected along an interval of a predefined length coaxial with the beak. Operating keys 34 and an embedded electrical circuitry, not shown, provide for activating and controlling the motion of the beak. Electrical cable, not shown, connected at the proximal end of the elevator body provides for powering the motor by means of a remote power supply.

The rotational motion of the beak of a dental elevator of the invention provides for a lever action to be applied onto the desired tooth. Reference is now made to Figs 2A - 2B, in which the beak of the dental elevator shown in Fig. 1 is respectively shown in two different rotational angles. In Fig. 2A the planar face of beak 50 is contained in a plane inclined to the plane of the paper. Both planes mutually intersect along line 52, which is normal to axis 53. Axis 53, which is the axis of the beak, is contained in the plane of the paper. The line containing edge points 54 and 56, not shown, is parallel to the plane of the paper. In Fig. 2B the same beak is shown after being rotated around axis 53 by a given rotational angle in the direction shown by curved arrow 58. Such rotation causes the planar face of the beak to rotate relative to the plane of the paper by the same angle. The line along which the plane containing the face of the beak intersects the plane of the paper is respectively rotated to coincide with line 60. The line containing edge points 54 and 56 is also inclined to intersect the plane of the paper, such that edge point 54 is moved to a new location that is more distant from the face of the paper than the respective previous location. Point 56 is moved to a respective location placed below the plane of the paper. A tooth engaged with the planar face of the beak, such that it touches the surface of the beak at a point disposed between line 62, which coincides with the projection of axis 53 on the planar face and edge point 54, is forced to move along a respective distance off its previous location directed from the paper to its front.

According to the present invention the rotational angle of the beak reciprocally and repeatedly varies in time as long as the motor housed within the elevator body is activated. The rotational motion of the beak of a dental elevator in accordance with one embodiment of the present invention is hereby described with reference to Fig. 3 that is now made. Plot 70 is a segment of a simplified time profile of the rotational angle of a rotating beak. The beak rotates at respective rotational speeds having a fixed magnitude. However the rotational speed changes its direction at two extreme angles symmetrically disposed relative to a medial angle having a given value. The value of the medial angle is referred hereinafter as of zero degrees. Plots 72 and 74 respectively present the time profile of the extreme angles. Typically, the time profile of the rotational angle of a beak of the invention is rounded close to the respective turning points in which the rotational speed changes its sign. The magnitudes of the angular accelerations involved in practice are significantly lower than the levels associated with the linear segments shown in Fig. 3. The rotational acceleration along segment 76 is directed to the opposite direction of the respective rotational speed. The magnitude of the rotational acceleration monotonously increases along both segments 76 and 76A, thereby the magnitude of the respective rotational speed decreases along segment 76 down to zero, which is reached at a time corresponding to turning point 77. At this moment the speed changes direction, whereas its magnitude monotonously increases along segment 76A. Therefore the actual time profile of the rotational angle of the beak is rounded adjacent to the respective turning points, as respectively demonstrated by dashed segments 78, 78A, 78B. Therefore in such a case the magnitude of the respective extreme rotational angles decrease as shown by plots 72A and 74A. The azimuthal direction of the medial angle relative to the axis of the elevator body is optionally marked on its surface. In cases in which the beak does not have axial symmetry, such as the case described above with reference to Figs 2A, 2B, mounting such beak onto the elevator body is such constrained that the angular orientation of the beak conforms with the medial angle of the rotating mechanism, as further described infra. Typical values of the extreme angles are within the range of ±70° up to ±110°. The time scale of the graph is measured in cycle times of the oscillatory rotation. Typical cycle times are in the range of 0.05 - 0.5 seconds. A typical level of the maximal magnitude of the rotational velocity is of 17 radians per second.

The beak reciprocally moves in a translational motion according to the present invention along an interval having a predefined length, referred hereinafter as the translational step. The translational motion of a beak according to an embodiment of the present invention can be described by the same graph shown in Fig. 3, except that the ordinate measures the distance from the proximal end of the translational step (the end of the translational step that is closer to the elevator body). A simplified time profile of the distance of the tip from the proximal end of the translational step is similarly described by plot 70. The distances corresponding to the end points of the translational step are respectively presented by plots 72, 74. The value of the distance corresponding to plot 72 is zero. The time scale of this graph is similarly measured in cycle times whereas the distances are measured in tenths of millimeter. The beak is distally forced by the motor of the elevator at a velocity having a given time profile. A biasing spring proximally moves the beak back at a velocity having a magnitude having the same time profile but the opposite direction. Retaining the magnitude of the velocity at the same levels is effected by a cam coupled to the shaft of the driving motor thereby opposing the respective natural motion of the spring to get back to its rest position. The rotational motion and the translational motion of the beak are mutually synchronized such that changing the sign of the respective velocities concomitantly occurs.

Typical length of the translational steps are in a range of a few tenth of millimeters up to 2.5 mm. A key feature of the elevator of the invention that both the translational step as well as the extreme rotational angles are changeable while the beak continuously moves. Therefore the operator may momentarily change any of these levels either independently or simultaneously by respectively pressing an operating key installed on the elevator's body. For example it was experimentally found that towards the end of a process of tooth extraction the extreme angles are preferably increased by a significant percentage compared to their level along the entire process. Embodiment variants in which the operator can momentarily, or for a while, change either the length of the step, the magnitude of the extreme rotational angles, or synchronously both, are in accordance with the present invention. Such changes are similarly accomplished by pressing a key disposed at the elevator body.

A dental elevator in accordance with a preferred embodiment of the present invention is hereby described with reference to Figs 4A - 5B. The same numbers designates the same parts shown in Figs 4A - 5B. Dental elevator 80 is shown in Fig. 4A in its full length; the distal end of the elevator is shown in Fig. 4B. Connector 81 provides for connecting elevator body 82 to stem 84 of beak 86. Abutment 88 disposed at the distal end of supporting lever 90 provides for supporting the beak in place adjacent to the targeted point of application. For this purpose the operator presses it against the targeted tooth and/or against a surface located at its periphery. Supporting lever 90 is detachably attached to a displacement mechanism, not shown, that is secured to an inner surface of a sidewall of elevator body 82. Optionally one or more biasing springs associated with the displacement mechanism provide for pressing and tilting supporting lever 90 towards the beak. Clearance 91 disposed between the tip of beak 86 and abutment 88 has a changeable width. By suitably selecting the width of clearance 91, two opposing faces of the targeted tooth can be concomitantly engaged by the beak and the abutment respectively. The displacement mechanism operated by means of adjustment ring 92 provides for transversally moving the abutment relative to the tip of the beak thereby tuning the width of clearance 91. Tuning is accomplished by rotating the adjustment ring in one direction to extend this width, whereas rotating in the opposite direction provides for diminishing it. Such tuning might be required when the operator changes a point of application. Pad 94 the corners of which are rounded is made of, or at least upholstered with, a relatively soft material such as silicon. Pad 94 provides for minimizing hazards associated with excessive pressure exerted by abutment 88 onto the periphery of the targeted tooth.

In Figs. 5A - 5B a segment of supporting lever 90 and its proximal end are respectively shown. The geometrical shape of keying bracket 96 provides for securing supporting lever 90 to the displacement mechanism. A similar keying bracket or preferably one having a polygonal cross section the number of sides of which is uneven, such as a triangle or pentagon, is used for constraining the azimuthal direction of the beak to conform with the medial angle of the rotatable shaft. Spherical cap 98 resiliently attached to supporting lever 90 provides for locking it in place onto the displacement mechanism. The beak as well as the supporting lever having the abutment at its distal end are typically made of stainless steel, such that they can be autoclaved. Beaks made of plastic resins normally utilized for manufacturing disposable surgical equipment are in accordance with the present invention, as long as their structural strength meets the level of forces and moments involved. The elevator body is made of stainless steel and/or rigid plastic resins typically utilized for manufacturing medical equipment.

For operating a dental elevator according to one embodiment of the present invention the dentist first selects a mode in which the beak moves for dislocating a targeted tooth; then a set of working parameters associated with this mode are set by the operator. The various modes include spiral motion, rotational motion and linear translation of the beak relative to the elevator body. A set of working parameters associated with a specified mode that is accommodated to a targeted tooth, includes extreme levels of torques to be exerted by the motor driving the beak, extreme rotational angles between which the beak rotates and/or distances along which the tip of the beak linearly moves. Based on the experience of the inventor of the present invention some of the parameters that are suitable for extracting for example maxillary first premolar may differ from the respective parameters that are suitable for mandibular first premolar. The operator introduces the tip of the beak into the periodontal space at a targeted point of application, as known. The operator orients the axis of the elevator at a desired direction while firmly holding the elevator body such that he or she may resist any displacement of the elevator body off its targeted point of application, and/or a tilt off its desired direction. At this stage the operator activates the motor of the dental elevator thereby for example rotating the beak at a given direction concomitantly with automatically forcing the tip deeply into the periodontal space. The operator lets the reciprocal movement of the beak continue for a while. The rotational motion of the beak while its tip deepens into the periodontal space disconnects some of the gingival fibers. Additional fibers which are located at the other side of the tooth can be disconnected when the beak rotates at the opposite direction whilst proximally translating relative to the elevator body. The resisting force distally exerted by the operator provides for retaining the tip of the beak in its place during a cycle in which the beak automatically translates towards the elevator body. The operator may further tilt the axis of the elevator, thereby changing its fulcrum against a periphery of the alveolar bone, while distally pushing the elevator body to disconnect additional gingival fibers. He or she may pause for a while the motor for placing the tip of the beak at another point of application and further repeat the process as described above up to the point in which the tooth is dislocated off its socket. Activating the motor is accomplished according to a preferred embodiment of the present invention by pressing the respective operating key disposed at the surface of the elevator body. The motor is activated as long as the respective key is pressed on. When the operator releases the key the motor stops.

Following is a set of working parameters accommodated to various teeth according to an embodiment of the present invention.

Table 1 working parameters associated with exemplary teeth according to an embodiment of the present invention

EXAMPLE

A dental elevator according to another embodiment of the present invention was designed and manufactured to serve as a testing prototype. Reference is now made to Fig. 6 - 7 in which the setup of the testing prototype and a sectional view of its elevator body are respectively shown. The same parts have the same numbers in Figs 6 - 7. Flexible cable 110 connects a movable shaft installed within elevator body 112 to the shaft of DC motor 114. Cable 110 provides for transmitting the reciprocal rotational and translational motion as respectively shown by arrows 116, 118. Programmable controller 120 provides for activating the reciprocal rotation within a range of rotational angles, as known. The extreme rotational angles are selected by the operator who fixes their values during a setup session. The maximal magnitude of the rotational speed is controlled by manually varying the voltage of power supply 122. The length of the translational step is selectable by the operator within a range of a few millimeters and further controlled by controller 120. Operating keys and an associated display connected to the controller, not shown, provide the operator for inputting working parameters and for operating the elevator. Controller 120 provides for activating the reciprocal translational motion, by means of an embedded electrical actuator, such as a solenoid, not shown, and biasing springs 124. Sensors, not shown, connected to controller 120 provide for measuring the power consumed by, the temperature of, as well as instantaneous angular momentum exerted on, the electrical motor. Operational data, statuses, measurement data, as well as inputs from the operator are time tagged and stored in the memory of the controller to be uploaded to a remote computer for further analysis.

This dental elevator was used in clinical trials in which teeth of pigs were extracted. The experimental results clearly demonstrate a significant reduction in the time required to complete an extraction of any of the teeth involved. The measured angular moments exerted on the motor of this dental elevator are of a few, and up to five, Newton meters.

Claims

1. A dental elevator comprising o an elevator body structured and arranged for being held by a hand of an operator; o a movable beak distally disposed relative to said elevator body, and wherein said moving effected relative to said elevator body, and wherein said moving comprises any motion selected from a group of motions consisting of linear translation, rotation, spiral and any combination thereof.

2. A dental elevator as in claim 1 , wherein said moving reciprocally effected.

3. A dental elevator as in claim 2, wherein at least one of said motions effected at a predefined rate.

4. A dental elevator as in claim 1 , wherein said rotational motion effected within a predefined range of rotational angles.

5. A dental elevator as in claim 1 , wherein said rotational motion effected at a rotational speed the maximal magnitude of which is predefined.

6. A dental elevator as claim 4, wherein said range is changeable.

7. A dental elevator as in claim 6, wherein said translational and said rotational motions mutually synchronized.

8. A dental elevator as in claim 5, wherein said translational motion effected along a translational step having a predefined length.

9. A dental elevator as in claim 5, wherein said maximal magnitude is changeable.

10. A dental elevator as in claim 8, wherein said length is changeable.

11. A dental elevator as in claim 1, wherein said beak detachably attached to a shaft housed in said elevator body.

12. A dental elevator as in claim 1, further comprising abutment disposed adjacent to said beak, wherein said abutment provides for supporting said beak in place at a targeted point of application.