ORTHODONTIC ELASTOMERIC LIGATURE MANIPULATOR

Abstract: A head (9) projecting from the end of a rod body (1') or from the apex of a flat trifurcated quadrant body (1) has an offset fixed prong (10) projecting from its end which is crossed by a movable prong (22) carried by a rocker (20) mounted on the head and tiltable to alter the spacing between the prongs. The tip portions (13 and 25) of the prongs have notches (14 and 26) facing away from each other to hold a ligature ring (37) in stretched condition for application to the wings (44 and 45) of an orthodontic tooth bracket (39). The tip portions of the prongs are canted relative to the prong shanks to be disposed in parallel planes and a line passing through the notches is at an angle to one edge of the body. The notch (26) in the movable prong (22) is deeper than the notch (14) in the stationary prong (10) and the portion of the shallower notch (14) adjacent to the tip of the prong forms the prong tip as a probe. A spring (28) presses the rocker to urge the tip of the movable prong away from the tip of the fixed prong.

Description: Description Orthodontic Elastomeric Ligature Manipulator Technical Field This invention relates to a manipulator for orthodontic elastomeric ligatures of the ring type, or which include a ring component, and can be utilized for applying such a ligature to the wings of an orthodontic tooth bracket for the purpose of holding an arch wire in the slot between such wings, and for removing such a ligature ring from tooth bracket wings. Background Art Elastomeric ligature ring appliers proposed or available heretofore have been of two principal types, namely, the pliers-type and the tweezers-type. Both of these types are represented in Cusato United States Patent 4,001,940, issued January 11, 1977, the tweezers-type being shown in Figures 1 to 5, 5A and 6, and the pliers-type being shown in Figures 14 to 21. Patents showing previous pliers-type of apparatus cited against the application resulting in the aforesaid United States Patent 4,001 ,940 are Belgian Patent 523,365 of October 1953, United Kingdom Patent 764,150 of December 1956 and United Kingdom Patent 921,015 of March 1963. Prior patents showing tweezers-type apparatus cited against the application resulting in United States Patent 4,001,940 are Engelsman United States Patent 955,955, issued April 26, 1910, and Gardella United States Patent 1,974,106, issued September 18, 1934. Patents issued later than United States Patent 4,001,940 showing pliers-type of apparatus are Dragan United States Patent 4,106,374, issued August 15, 1978, and Frajdenrajch United States Patent 4,310,305, issued January 12, 1982. The pliers-type of device includes jaws that are spring-pressed toward each other having tips that can be inserted into the aperture of an elastomeric ligature ring element after which the pliers handles can be pressed toward each other to spread the tips and thereby stretch and hold the ligature ring between the tips. United States Patent 4,001,940 in Figures 17 and 18 provides a latch that can be engaged between the handle elements of the pliers to hold such elements in contracted position for maintaining the tips in spread condition to hold a ring stretched. The tips of a tweezers-type of device are normally urged apart by the resiliency of the tweezers and the tips can be pressed together for engagement with a ligature ring and then released to spread and hold the ring. Such tweezers may have a latch to hold the legs of the tweezers apart for maintaining a ring in stretched condition, as shown in the Engelsman United States Patent 955,955. It is difficult to stretch and hold an elastomeric ring in stretched condition by manipulation of a pliers-type instrument when applying such a ring to the wings of an orthodontic bracket, and it is also difficult to manipulate latch mechanism for holding apart the jaws of such a pliers instrument and for releasing the jaws from a ligature ring. Moreover, such latch mechanism is intended to hold the pliers jaws spaced apart only a predetermined distance, whereas it may be desirable to stretch ligature rings different amounts depending on the type of bracket to which the ring is to be applied. The tweezers-type of ring-holding instrument is difficult to hold firmly in the hand, and it is more difficult to hold such an instrument securely while manipulating latch mechanism to hold the legs of the tweezers in spaced relationship. Disclosure of the Invention In accordance with the present invention, a manipulator has a body that can be grasped between the thumb and one or more fingers of a hand, and such body may be furcated to provide one or more throats or crotches into which the web of the hand between the thumb and forefinger can be fitted as the manipulator is grasped. The body of such manipulator carries a fixed prong projecting from it and an adjacent movable prong which prongs can engage, stretch and hold a ligature ring between them while the manipulator is manipulated to apply such ligature ring to the wings of an orthodontic tooth bracket. The shanks of the prongs may be crossed and their tip portions may be canted relative to their shanks in parallel relationship and offset from the handle to enable the body of the manipulator and the operator's hand grasping it to be held out of the operator's line of sight to the ring as it is applied to tooth bracket wings. Also the tips may be arranged at an angle relative to the body to improve vision and facilitate holding and manipulation of the manipulator. The tip portions of the prongs have notches opening away from each other for cradling opposite sides of a ligature ring, one notch being relatively deep and the other notch being relatively shallow and located in its prong tip portion sufficiently close to the prong tip as to shape the end of such tip as a generally straight probe• Advantages of the manipulator of the present invention are that it is easy to hold securely in the hand and can be manipulated conveniently to apply ligature rings to the ears or wings of an orthodontic bracket, even though the orthodontic brackets are of different widths, which brackets may be on teeth in various portions of a mouth. A further advantage is that the applicator can be used to apply ligature rings to tooth brackets without applying substantial pressure or tooth bracket or arch wire which can cause patient discomfort. Brief Description of Drawings of the Preferred Embodiment The details of the invention will be described in connection with the accompanying drawings of my. preferred embodiment in which, Figure 1 is a top perspective of the manipulator, Figure 2 is an enlarged fragmentary side elevation of the head portion of the manipulator with parts broken away, Figure 3 is a side elevation similar to Figure 2 but with parts shown in a different relationship, Figure 4 is an end elevation of the head portion of the manipulator viewed from line 4—4 of Figure 2, Figure 5 is a plan of the head portion of the manipulator, Figures 6, 7 and 8 are top perspectives of the head portion of the manipulator illustrating sequential conditions of the manipulator in picking an elastomeric ligature ring from a ring storage or supply spindle, Figures 9 and 10 are side elevations of the head portion of the manipulator holding a ring stretched to different degrees. Figure 11 is a detail plan and Figure 12 is a detail elevation of the tip portions of manipulator prongs on an enlarged scale illustrating an initial positioning of a ring alongside a tooth bracket, Figure 13 is a plan and Figure 14 is an elevation of the tip portions of the manipulator prongs corresponding to Figures 11 and 12, respectively, but showing the prongs in a sequential position for applying a ring to wings of a tooth bracket, Figure 15 is a plan, Figure 16 is a side elevation and Figure 17 is a perspective of the head portion of the manipulator shown executing the step illustrated by Figures 13 and 14 in applying a ring to tooth bracket wings. Figure 18 is a plan and Figure 19 is an elevation of the tip portions of the manipulator prongs illustrating a further sequential step in applying a ligature ring to the wings of an orthodontic tooth bracket, Figure 20 is a plan, Figure 21 is an elevation and Figure 22 is a top perspective of a portion of the manipulator head shown as executing substantially the step illustrated in Figures 18 and 19 in applying a ligature ring to the wings of an orthodontic bracket, Figure 23 is a plan and Figure 24 is an elevation of the tip portions of manipulator prongs corresponding to Figures 11 and 12, Figures 13 and 14 and Figures 18 and 19 illustrating still a further sequential step in applying a ligature ring to the wings of a tooth bracket, Figure 25 is a plan, Figure 26 is an elevation and Figure 27 is a top perspective of a portion of the head of the manipulator showing the prongs executing the step illustrated by Figures 23 and 24, Figure 28 is a plan and Figure 29 is an elevation of the tip portions of prongs of the manipulator illustrating an initial step in withdrawing the prongs from a ligature ring applied to the wings of a tooth bracket, Figure 30 is a plan and Figure 31 is an elevation illustrating the prongs releasing the ligature ring in place on the tooth bracket wings, Figure 32 is a plan and Figure 33 is an elevation of the manipulator prongs immediately following full release of the ligature ring in place on the tooth bracket wings, Figure 34 is an elevation and Figure 35 is a top perspective of a portion of the head of the manipulator showing it in relationship to a tooth bracket corresponding to the illustration of Figures 32 and 33, Figure 36 is an elevation of the manipulator illustrated as being held in one position by an operator's hand shown in phantom. Figure 37 is a corresponding view illustrating the manipulator as being held in a different position by an operator's hand and Figure 38 is a similar view illustrating the operator's hand as holding the manipulator in still a different position, Figure 39 is a plan of a portion of the head of the manipulator shown with " the prongs in relationship to wings of a tooth bracket attached to a tooth having overgrown gum tissue, Figure 40 is a top perspective of a portion of the manipulator head illustrating the application of rings of an orthodontic ligature chain " to the wings of tooth brackets, Figure 41 is a top perspective of a manipulator having a modified shape of handle, and Figure 42 is a side elevation of such manipulator, Figures 44, 45 and 46 are fragmentary side elevations of a portion of the manipulator of Figure 41 showing parts in different positions, Figure 47 is a top perspective of a third form of manipulator having prongs of different shape, Figure 48 is a fragmentary side elevation and Figure 49 is a fragmentary top plan of such third form of manipulator. Best Mode for Carrying Out the Invention Orthodontic elastomeric ligature rings require very delicate and precise manipulation in applying them to and removing them from wings of tooth brackets. The rings shown in Figures 6, 7 and 8 are on an enlarged scale. Typical ligature rings have an external diameter of approximately 3 millimeters and an internal diameter of approximately 1 millimeter. The wings of an orthodontic tooth bracket shown in Figures 11 and 12, for example, are approximately 1 millimeter in width in a direction parallel to the arch wire and are spaced apart lengthwise of the wire approximately 1 millimeter. The wings of a tooth bracket for a molar may be approximately 1 1/2 millimeters in width and adjacent wings may be spaced apart approximately 2 millimeters so that the overall span of a pair of such wings is approximately 5 millimeters. Because of the dimensions stated above, an applier or manipulator for orthodontic elastomeric ligature rings should be compact and must be capable of precise operation if it is to be able to pick and stretch a ring, to apply the ring to tooth bracket wings and then to be released from the applied ring reliably, easily and quickly. The manipulator of the present invention has such capabilities. A preferred type of ligature ring manipulator is shown in Figures 1 to 38. As shown best in Figures 1 to 5, inclusive, such manipulator includes a flat or plate body 1 made of molded plastic which preferably is of trifurcated quadrant profile including two edges 2 and 3 which are generally linear and substantially mutually perpendicular and which body has three furcations between such edges. Such furcations include a furcation 4, formed partially by or located adjacent to one generally linear edge 2 of the body, a second furcation 5 formed by or located adjacent to the other generally linear edge 3 of the body and a third furcation 6 projecting radially from the body substantially midway between the furcations 4 and 5. A crotch or throat 7 is formed between the adj cent furcations 4 and 6 and a crotch or throat 8 is formed between the furcations 5 and 6. Such body is adapted to be held clamped between a user's thumb engaging one body face and a user's first and second fingers engaging the opposite face of the body. The manipulator includes a head 9, which may be made of molded plastic, integral with and projecting from the apex of the quadrant body generally in prolongation of edge 3 of the body as shown in Figures 1 and 2, the length of the head extending transversely of the other edge 2 of the body as shown in Figure 2. Such head carries prongs which can be used to pick and stretch a ring and hold the ring in such stretched condition automatically while the manipulator is being . manipulated to apply the ring to the wings of a tooth bracket. Such prongs include a fixed prong 10 shown best in Figure 2 as having an anchored end portion 11 embedded in the projecting end of the head 9, a shank 12 bent relative to the length of the head and projecting away from the body and a tip portion 13 bent transversely of the shank 12 at an angle of 90 degrees to 115 degrees, preferably about 105 degrees. The tip portion of the fixed prong, which is offset from its embedded end portion 11 by the shank 12, has in it a shallow notch 14 adjacent to the tip 15 which notch opens away from the body. Such notch forms the tip 15 as a probe which is substantially pointed and further forms a shoulder 16 at the side of the notch opposite the tip 15. The tip portion 13 of the probe is canted relative to the shank at an angle of 20 to 60 degrees, preferably approximately 40 degrees, relative to the plane of the body 1 by a bend 17, as shown best in Figure 5. From the opposite sides of the head 9, ears 18 spaced transversely of the body project beyond the edge of the head remote from the body to form a recess 19 between them for receiving a rocker 20. Such rocker is secured in such recess by a pivot 21 extending between the ears 18 through a transverse bore in the rocker located generally centrally between its ends. From the end of the rocker 20 remote from the body 1 projects a prong 22 movable with the rocker and having an anchored end portion 23 embedded in the end of the rocker remote from the body 1 , so that the rocker constitutes a mounting member for the movable prong. A shank 24 of the prong pro ects from such anchored end portion into substantially mutually perpendicular crossing relationship with the shank 12 of fixed prong 10. In the tip portion 25 of movable prong 22 is a notch 26 opening away from the tip portion 13 of prong 10. Such notch is adjacent to the tip of prong 22 and is deeper and narrower than the notch 14 in the tip 13 of prong 10. The tip portion 25 of movable prong 22 is canted relative to its shank 24 and the central plane of body 1 by a bend 27 through an angle of 20 degrees to 60 degrees, preferably approximately 40 degrees, so that . the tip portion of the two prongs are in substantially parallel planes, as shown in Figure 5. The crossing relationship of the shank 12 of fixed prong 10 and the shank 24 of movable prong 22 can be changed, preferably even into the uncrossed position shown in Figure 3, by tilting rocker 20 about its pivot 21 relative to head 9 and body 1. The rocker is urged toward its limiting position shown in Figure 2 by a spring which may be a helical compression spring 28 having one end seated in a socket 29 in the bottom of recess 19 and its other end seated in a socket 30 in the end portion 31 of the rocker 20 at the side of pivot 21 remote from prong 22. Since the notch 26 forms a hook engageable with a ligature ring, constituting a load, and it is at the side of pivot 21 remote from spring 28 applying a force to- the rocker 20, such rocker constitutes a lever of the first class. The underside of the portion 31 of rocker 20 at the side of pivot 21 adjacent to the body makes an angle of 20 degrees to 40 degrees, preferably about 30 degrees, to the bottom of the recess 9 so that the rocker can rock relative to the head 9 and body 1. The edge of the head facing the rocker is crowned with a ridge adjacent to the pivot 21 so that the portions of such edge at opposite sides of the pivot form an included angle of 140 degrees to 160 degrees, preferably approximately 150 degrees, so as to enable the rocker to rock relative to the head for changing the relationship of movable prong 22 relative to fixed prong 10. Spring 28 urges the rocker toward the limiting position shown in Figure 2, but it can be rocked into its other limiting position shown in Figure 3 by the tip '* ■ :-*-7 - '~ of a finger F of the operator pressing on the end portion 31 of the lever. The tip of lever portion 31 preferably has an upswept crest 33 providing a surface 34 against which pressure can be exerted by the tip of the forefinger to press the end portion 31 of the lever away from the edge 19 of the head if desired. Also, a thumb-receiving recess 35 in the side of the body and an adjacent thumb-engageable rib 36 on the side of the body may be provided, if desired. Figures 6, 7 and 8 illustrate a procedure for using the manipulator to pick a ligature ring 37 off a spindle 38. Such rings may be disconnected or may be connected by a thin strand. The first step is for the hook formed by notch 26 of the movable prong 22 to hook one portion of the ring loop as shown in Figure 6. The manipulator is then pulled away from the spindle 38 in the direction indicated by the arrow in Figure 6 to stretch the ring until the manipulator can be inclined to the position shown in Figure 7. The force exerted on the movable prong by the ring as the manipulator is thus pulled and inclined will tilt the rocker 20 relative to the head 9 to the position shown in Figure 7 in opposition to the force exerted by spring 28. With the rocker in that position, the probe tip 15 of prong 10 can be poked into the slot to which the aperture of the ring is deformed, as shown in Figure 7. The notch 14 of prong 10 can then engage the side of the uppermost ring loop generally opposite the portion of such ring loop engaged by the notch 26 of prong 22. When the ring is held between the notches 26 and 14 of the prongs 22 and 10 in stretched condition, the manipulator can be lifted from the position shown in Figure 7 to the position of Figure 8 to withdraw the uppermost ring easily from the spindle 38, breaking any strand connecting adjacent rings. The notch 26 of prong 22 is not -deep enough to engage the next lower ring and, when the uppermost ring is stretched, the probe tip 15 can easily be inserted between the uppermost ring and -1 1 - the next lower ring without disturbing such next lower ring. The spring 28 is designed so that the rocker 20 will assume an attitude of equilibrium relative to the head 9 substantially in the position shown in Figure 9 when a ligature ring has been picked and is being held by the prongs as shown in that figure. In such an attitude of rocker 20, the force exerted by spring 28 multiplied by the distance between the spring and the rocker pivot 21 will produce a moment equal to the moment produced by the force exerted by the stretched ring 37 multiplied by the distance between notch 26 gripping such ring and the pivot 21. The force produced by compressed spring 28 should be related to the resistance to stretching of ring 37 with respect to the lever arms of such forces such that the spacing of the prong tips 13 and 25 will be slightly greater than 3 millimeters, which is the approximate composite width of the wings and spacing of a tooth bracket. The rocker will be maintained in the attitude relative to head 9 shown in Figure 9 automatically without the application of finger pressure to the rocker. If the ligature ring is to be applied to a tooth bracket having a greater composite width of the wings and spacing, such as a molar tooth bracket, the operator may press his finger against the end surface 34 of the rocker crest 33 to assist the spring 28 in rocking the rocker 20 farther to increase the spacing between the tips 13 and 25 of the prongs as shown in Figure 10. If the pressure of the finger on the surface 34 is removed, the tension of the ligature ring will not draw the movable hook 26 toward the fixed hook 14 again to the positions shown in Figure 9, because the additional stretching of the ring will subject the material to some permanent deformation. If the ring is somewhat overstretched, therefore, the new force equilibrium position of the prongs without further application of finger pressure to the rocker will be such that their spacing will be maintained automatically slightly greater than the spacing required to place the ring on the wings of a molar tooth bracket, such as slightly in excess of 5 millimeters. Alternatively the rocker end 31 may be pressed with the finger to reduce the force of spring 28 on the rocker to some extent to reduce the stretch of the ring. Thus the prongs can be adjusted infinitely to any desired extent so as to be stretched between the limits of tilt of the rocker 20. A tooth bracket, which is not a molar tooth bracket, to which it is desired to apply a ligature ring is shown in Figures 11 to 35. The base of the tooth bracket 39 is bonded to the face of the tooth 40 by a layer of adhesive 41. The bracket is applied to the tooth so that the length of the groove 42 in its outer face extends circumferentially of the tooth arch to receive in it an arch wire 43. The bracket has a pair of wings 44 at one side of the groove 42 and a pair of wings 45 at the other side of such groove which the ligature ring can encircle spanning the groove 42 to hold the arch wire 43 in the groove. After a ligature ring has been picked from a ring supply, such as in the manner illustrated and described in connection with Figure 6, 7, 8 and 9, the tips of the manipulator prongs can be placed against the arch wire with the stretched ring straddling the tooth bracket 39, as shown in Figures 11 and 12. Without appreciably changing the tilt of the prongs relative to the bracket, the manipulator can then simply be pushed toward the tooth so that the shoulders of the notches remote from the prong tips will push one stretch of the ring against the wings 44 to be wedged away from the prongs 10 and 22 by engagement with the curved outer sides of the adjacent wings 44, as shown in broken lines in Figure 13, so that such stretch Of the ring will slide away from the groove 42 over the tips of those wings and snap in behind the curved wings, as shown in Figures 13 and 14. If the ring is not stretched quite O eo t to cπ en o cπ o en o β X Hi O ^ X Φ TJ y H < P- P- 3 TJ ii o φ eQ 3 O Φ φ 3 li 0 eQ β H li tn eQ . * - rt ft Φ tr TJ CO tr tr X ^ 0 φ Φ — . y H tr ■I- y J ft •* <. rt tr «> P i ii p. o 2! li Φ o rt o φ 0 ) Φ 01 01 3 a rt X Ω 3 TJ oi Φ 3 * rt XT O ii β O •*• φ β Φ ii Hi 3 rt iQ ft ) Φ o 01 f 1" tr Pi • 71 rt tr - X O P- P- P- t> y rt rt H) eQ o Hi a O 4 0 3 ft a •XI Φ rt H φ ( 01 φ tr Φ P- Pi 3 • 3 t) Φ P i P- ft ) P, -_ . P 1 ft TJ tr O Pi 00 β o β y 3 P- 01 P i φ •X) <! ft ) ft rt ft ) 01 Φ 3 H tr rt rt ti Oi ft ) Φ O a- ft ) eQ rt H ro β Φ P- Φ o rt 3 3 Pi TJ P- i O rt TJ 01 P- 3 ■ 71 tr o 3 ft ) TJ P- • 01 TJ ■ X) rt ϋ eQ P- β P- O 0 tr rt P i 01 Ω 3 li li Φ P 1 rt ft ) ιQ Φ 0 φ l P i 01 01 XT 01 Pi Φ P 1 φ P- rt O to 3 P> 01 Ω •*• 3 O Φ tr y P- ft ) ft ft ) P- O eQ rt 01 tr 3 3 Hi ar O φ Oi φ ft 01 01 rt p i 01 a 4 t t tr • - i O H — * • P- Φ P- X ft ) 3 ft ) Qi a Ω ft ) X Φ ft rt li ft ) P- Φ O 3 * Ω - * < 3 rt φ tr of 20 to 40 degrees relative to the plane of the tooth arch during the procedure of applying a ligature ring to a tooth bracket by the procedure described so that the hand of the operator and the manipulator will not obscure the line of. vision of the operator to the ligature ring and the tooth bracket. Because the angle of tilt of the manipulator need not be changed appreciably, if at all, during most procedures for applying a ligature ring to the wings of a tooth bracket, as indicated by Figures 15, 20 and 25, the line of vision of the operator remains unobstructed during the entire operation of applying a ligature ring to the wings of a tooth bracket. In describing the prongs of the manipulator in connection with Figure 2, it was noted that the movable prong 22 was shorter than the fixed prong 10 # so that a line connecting their tips was disposed at an angle of 10 to 30 degrees, preferably about 20 degrees, relative to the edge 2 of the quadrant body 1. This angle may increase slightly as the rocker 20 is rocked to move the tip portion 25 of the prong 22 toward the tip portion 13 of prong 10. Such angular relationship will determine the attitude of the body 1 relative to the tooth arch when a ligature ring is being placed on the wings of a tooth bracket because, as shown best in Figures 16, 21 and 26, the manipulator is held with the line joining the prong tips disposed substantially parallel to a tangent to the curved arch wire and tooth arch at the location of the tooth bracket to which the ligature ring is being applied. Consequently, during such ring application, the body 1 of the manipulator will be held relative to the arch wire and tooth arch, as indicated in Figure 21 , with the edge 2 of the manipulator quadrant at an angle of 10 to 30 degrees to the tangent to the arch wire and the tooth arch at the location of the tooth bracket to which the ligature ring is being applied. Thus, the attitude of the manipulator •body during such applying operation will be governed by the angular relationship between the tips of the prongs and the edge 2 of the manipulator body. Such angular relationship enables the manipulator to be held more conveniently by the operator, enables the body of the manipulator and the hand holding it to be more easily positioned out of the line of vision of the operator to the ligature ring and retracts the cheek to facilitate access. The offset of the fixed prong also contributes to the convenience with which the manipulator can be held and to keeping it out of the line of vision of the operator and also assists in retracting the cheek. When the application of the ring to the wings of a tooth bracket has been completed, as shown in Figures 23 to 27, it is then necessary to release the hooks 14 and 26 of the manipulator from the applied ring. The sequence of steps to effect releasing of the manipulator hooks from the ring is illustrated in Figures 28 to 35. The hooks of the manipulator prongs can be removed from the ligature ring placed on the orthodontic bracket without appreciably changing the attitude of the body relative to the arch wire and tooth arch, as will be evident particularly from a comparison of the body positions shown in Figures 21 and 34. Moreover, the hooks of the manipulator prongs can be released from a ligature ring after it has been applied to a tooth bracket merely by tilting the rocker 20 relative to the body by applying pressure with the forefinger to the crest 33 of the rocker in the manner illustrated in Figures 3 and 34. By such pressure, the rocker will be tiled from its position shown in Figures 16, 21 and 26 to the position of Figure 34. The sequence of movements of the prong hooks relative to the ligature ring as such hooks are withdrawn from the ring begins with the step illustrated by Figures 28 and 29 in which the manipulator is simply pulled slightly away from the tooth after the final step of applying the ring illustrated by Figures 23 and 24. As the prongs are then moved toward each other by finger pressure on the crest 33 of the rocker- 20 to tilt the rocker for moving movable prong tip 25 toward stationary prong tip 13, such tips may engage opposite sides of the bracket wings and by pressure on such sides actually wedge the tips away from the bracket. As the rocker 20 is rocked farther the deep notch 26 of the shorter movable prong 22 is withdrawn from the ligature ring by movement of the prong tip generally parallel to the arch wire 43, as shown in Figures 30 and 31. When the tips of prongs 22 and 10 are in this relationship relative to the applied ligature ring, farther withdrawal of the manipulator in the direction indicated by the arrow in Figure 31 , away from the arch wire and bracket, will pull the probe 15 of the fixed prong out of the other side of the ligature ring, as shown in Figures 32 and 33. It can be seen from Figure 31 that it is not necessary to tilt the rocker 20 relative to the body to the point where the tip portion 25 of the movable prong overlaps the tip portion 13 of the fixed prong in order to withdraw the manipulator hooks from the ligature ring which has been applied to the wings of a tooth bracket, but it is easier for the operator simply to tilt the rocker substantially fully relative to the manipulator body so that the tip portions 25 and 13 of the prongs pass each other as shown in Figures 3, 34 and 35. Such uncrossing of the prongs is particularly beneficial to facilitate release of the prong tips from the ligature ring where the bracket is very narrow, such as a single bracket. As has been explained in connection with Figures 21 and 26, a line joining the tips of movable prong 22 and fixed prong 10 during the application of a ligature ring to the wings of a tooth bracket is substantially parallel to a tangent to the arch wire arch and to the tooth arch at the location of the tooth' bracket to which the ring is being applied. Consequently,- the attitude of the manipulator relative OMPI *,..-*, • co co to to cn cn o en o cn order for its arch wire slot to be substantially in the plane of the remainder of the arch wire arc. In such instances, the cant of the prong tip portions 25 and 13 relative to the shanks 24 and 12 of their respective prongs facilitates insertion of the prong tips between the gum G and the gingival wing of the tooth bracket, as illustrated in Figure 39. While the foregoing description has described the application of single ligature rings to the wings of O tooth brackets, the manipulator can also be used conveniently to apply to tooth brackets the rings of twin rings connected by a tie, or multiple rings connected by ties to form a chain, as shown in Figure 40. Such interconnected rings can be applied, respectively, to successively adjacent tooth brackets around a tooth arch, or successive rings can- be applied to tooth brackets which are spaced from each other by one or more intermediate brackets. In any of such instances, any of such interconnected rings can be 0 distended individually and applied to the wings of a selected tooth bracket, as indicated in Figure 40, in the same manner as described above as being utilized in applying individual ligature rings to tooth brackets. In addition, the probe end 15.of such fixed 5 prong 10 may be used as a ligature director and can also be used to pick ligature rings off the wings of a tooth bracket when it is desired to remove such rings. In the manipulator shown in Figures 41 to 46, inclusive, the body of the manipulator adapted to be 0 held clamped between a user's thumb and the first and second fingers is of rod shape instead of being a flat or plate body. Such rod is preferably of isosceles triangular cross section, as shown best in Figure 43. The body 1 ' has a head 9 at one end including ears 18 5 spaced transversely of the body to form a recess between them for receiving the rocker 20. Such rocker" is similar to the rocker of the manipulator described in connection with Figures 1-to 4. OMPI CO eo to to — __ cπ cn o cn o cπ o projecting in cantilever fashion from the central portion of the end of the manipulator head 9. The end of such shank carries divaricated outcurved, oppositely extending prong elements 53. The end of each prong element has a hook 54 opening away from the movable prong 51 when the rocker 20 is in its limiting position engaged with the head 9, as shown in Figure 48. The prong portions 53 are curved outward away from each other and from the end of shank 52 backward toward the body 1 ' „ The movable prong means 51 carried in cantilever fashion by the rocker 20 includes two prong - shanks 55 straddling the fixed shank 52. The prong shanks 55 are offset away from the fixed prong members 53 so that the prong members 56 carried by shanks 55 are spaced farther from the prong members 53 than they would - otherwise be. The movable prong members 56 carried by the prong shanks 55 are outcurved away from each other and back toward the manipulator body 1 ' , as shown best in Figure 49. The tips of the prong members 56 have hooks 57 opening away from the fixed prong members 53. The lengths of the fixed prong members 53 and of the movable prong members 56 are generally equal so that the hooks 54 of the stationary prong members and the hooks 57 of the movable prong members are in substantially overlying relationship as shown in Figure 49. The shanks 55 of the movable prong members preferably are somewhat shorter than the shank 52 of the fixed prong members so that the hooks 57 of the movable prong members are located closer to the manipulator head 9 than are the hooks 54 of the fixed prong members, as shown best in Figure 48. The manipulator shown in Figures 47 to 49 can be operated to apply ligature rings to the wings 45 of the tooth bracket 39 in generally the manner described in connection with Figures 11 to 35, but the type of manipulator shown in Figures 47 to 49 -is especially designed to be used for applying ligature rings 'to and • removing such rings from the wings of tooth brackets applied to the lingual faces of teeth. The manipulator of Figures 47 to 49 has two sets of hooks to facilitate manipulating ligature rings on the left side and on the right side of the teeth arches, respectively.

Claims: Claims 1. An orthodontic elastomeric ligature ring manipulator comprising a body adapted to be grasped between the thumb and at least one finger of a hand, said body having two prongs projecting therefrom in adjacent relationship and the tips of said prongs having hooks directed away from each other for holding a ring extending between said hooks. 2. The manipulator defined in claim 1 , in which a first one of the prongs is fixed relative to the body and the second one of the prongs is movable relative to the first prong. 3. The manipulator defined in claim 2, and spring means urging the second prong to move its tip portion away from the tip portion of the first prong. 4. The manipulator defined in claim 2, and a mounting member pivotally supported from the body and carrying the second prong for movement relative to the first prong. 5. The manipulator defined in claim 4, in which the mounting member is a rocker. 6. The manipulator defined in claim 1 , in which one of the prongs is an offset prong. 7. The manipulator defined in claim 6, in which the offset prong includes a shank and a tip portion disposed at an angle to said shank and the other prong includes a shank crossing said shank of the offset prong. 8. The manipulator defined in claim 1, in which each prong has a shank portion and a tip portion and said tip portions are canted respectively in the same direction relative to said shank portions of the prongs. 9. The manipulator defined in claim 1 , in which one prong is shorter than the other prong. 10. The manipulator defined in claim 1 , in which the notch in one prong is deeper than the notch in the other prong. 11. The manipulator defined in claim 1 , in which the notch in one prong is sufficiently close to the tip of that prong and is sufficiently shallow that the tip of such prong forms a probe extending lengthwise of the prong tip portion. 12. The manipulator defined in claim 1 , in which the prongs include shank portions and tip portions and the shank portion and tip portion of one of said prongs are bent relative to each other to form an offset prong. 13. The manipulator defined in claim 1, in which the two prongs have shanks disposed in crossed relationship. 14. The manipulator defined in claim 1, in which a first one of the prongs is fixed relative to the body and the second one of the prongs is movable relative to the first prong, and spring means urging the second prong away from the first prong toward a limiting position, the ring extending between the hooks being operable to hold said second prong away from its limiting position nearer said first prong. 15. The manipulator defined in claim 1, in which the body is a substantially flat trifurcated --- - . 'Jis .- quadrant body having a head projecting from the apex. - thereof generally in prolongation of one edge of said body. 16. The manipulator defined in claim 15, in which the body has one of its furcations adjacent to each of the edges of the body and its third furcation is substantially midway between said edge furcations.

Inventors: ARMSTRONG MACLAY M, HOUSER STEVEN A, ARMSTRONG, MACLAY, M., HOUSER, STEVEN, A.
Applicants: ARMSTRONG M M, ARMSTRONG, MACLAY, M.
Application year: 1984
Main classification: A61C3
IPC codes: A61C7