This invention relates to an adjustable strip metal element for dental purposes, specifically for use as an adjustable fixing and supporting element, which is intended to be fitted around a tooth and to be connected to an orthodontic or prosthetic appliance to hold it in position.
An element of that kind described in U.S. Patent Application Ser. No. 792,193 filed Apr. 29, 1977, has end portions provided with bevelled surfaces for forming a scarfed joint and with slide-snap fastener parts. Owing to the geometric configuration of the known strip metal element, the fastener is disposed on the mouth side in a lingual position relative to that tooth surface which faces the tongue. When the element is fitted around a molar tooth, which is rectangular, there is sufficient space for accommodating the slide-snap fastener. Incisors have a configuration which is similar to an ellipse, one radius of which is buccal and the other lingual relative to the cheek. At relatively small teeth, the space which is available on the lingual side is hardly sufficient for accommodating a slide-snap fastener. In the use of the known strip metal element it is also difficult to apply the force required to close the slide-snap fastener in the patient's mouth.
A main object of the invention is to provide a strip metal element which is of the kind described in the above-mentioned prior application and has an improved slide-snap fastener, which can be disposed on the lingual side as well as on the buccal side and which can also be closed more easily and can be combined with retaining elements, if this is desired.
In a strip metal element which is of the kind described first hereinbefore and has end portions provided with slide-snap fastener parts and preferably with bevelled surfaces for forming a scarfed joint, this object is accomplished according to the invention in that a tunnel member is provided on one strip end portion and has at its end a detent spring which is laterally bent in the direction of movement of the other strip end portion as the latter enters the tunnel member, whereas the other strip end portion comprises oblique barblike detent teeth for a snap engagement with the detent spring, which yields as said other strip end portion is moved into the tunnel member, so that an adjustable slide-snap fastener is obtained. Each strip end portion is preferably provided with a raised abutment, which has an undercut for engagement by a forceps as the fastener parts are fitted one into the other. One of said abutments constitutes the tunnel member and the other abutment holds a detent bar.
According to another feature of the invention, the strip metal element is provided with a plurality of buttons, each of which has an enlarged base portion mounted on an associated strip end portion and an enlarged head portion opposite to the base portion in an arrangement in which one base portion is preferably formed with a tunnel passage provided with a detent leaf spring for interlocking with detent teeth provided on the other strip end portion. Strip metal elements provided with such buttons may be applied to two or more teeth which are to be corrected by elastic strips laid around the buttons.
Further details of the invention will be described hereinafter with reference to embodiments shown by way of example on the accompanying drawings, in which
FIG. 1 is a perspective view showing a first embodiment of a strip metal element which is provided with a slide-snap fastener and applied around a tooth,
FIG. 2 is a perspective view showing a second embodiment of a strip metal fastener which is provided with a slide-snap fastener and has been applied around a tooth and is being tightened,
FIG. 3 is a perspective central sectional view showing on a still larger scale than the preceding figures a strip metal element provided with a slide-snap fastener,
FIGS. 3a and 3b are enlarged perspective central sectional views showing another embodiment of a metal strip element provided with a slide-snap fastener and the use of that embodiment for tooth correction,
FIGS. 4 and 5 are, respectively, a sectional view and a top plan view showing a slide-snap fastener part which constitutes a bracket,
FIG. 6 is an elevation showing a forceps for tightening the fastener shown in FIGS. 4 and 6, and
FIGS. 7 and 8 are, respectively, an elevation and a sectional view showing another forceps, which is shown in FIG. 7 in position for use.
FIG. 1 shows a strip metal element 2 which is to be applied around a tooth 1 and has a scarfed joint 3 formed by bevelled end portions. The strip end portions carry respective abutments 4 and 6, which constitute fastener parts and comprise respective baseplates 4a and 6a welded to the strip metal element. The fastener part 4 constitutes a tunnel member, which is provided with a laterally bent detent spring 5, which is shown in FIG. 3. The other fastener part 6 is provided with a tongue 7a having detent teeth 7, which interengage with the detent spring 5 in the tunnel passage 36 of the tunnel member 4 as shown in FIG. 3. Each of the fastener parts 4 and 6 has an undercut 8 for engagement by a forceps as shown in FIG. 2. It is apparent from FIG. 1 that the tunnel member 4 has in its surface remote from the strip metal element 2 a longitudinal recess 9 for receiving retaining or anchoring elements, which are soldered to the tunnel member and may consist, e.g., of a tubular member 10 for tooth-correcting strips or wires.
FIG. 2 shows a strip metal element 2 which has been applied around a tooth 1 and has a scarfed joint formed by bevelled end portions 3, which are respectively provided with fastener parts 4 and 6 having baseplates 4a and 6a, respectively, which are welded to the strip metal element. The fastener part 4 constitutes a tunnel member, which is provided in its tunnel passage with a laterally bent detent spring 5, which is shown in FIG. 3. The other fastener part 6 is provided with a serrated detent bar 7, which cooperates with the tunnel member 4 as a slide-snap fastener. To close the fastener, a forceps 11 may be used, which has two relatively slidable gripping jaws 12 for engaging undercuts 8 of the parts 4 and 6.
FIG. 3 is a sectional view showing the strip metal element 2 forming a scarfed joint 3 and provided with a tunnel member 4, which has in its tunnel passage 36 a laterally bent detent spring 5, and a second fastener part 6 provided with a tongue 7a having detent teeth 7, which can be caused to interengage with the detent spring 5 by means of a forceps, which engages with the undercuts 8.
FIG. 3a is a sectional view showing a strip metal element 2 which forms a scarfed joint 3 and is provided with fastener parts consisting of buttons, each of which comprises an enlarged base portion 4a or 6a and an enlarged head portion 4b or 6b and a neck portion between the base and head portions. The base portion 4a, 4b provided on one strip end portion constitutes a tunnel member and is formed in its base portion 4a with a tunnel passage 36, in which a laterally bent leaf spring 5 extends, which interengages with detent teeth 7 of a tongue 7a with which the second strip end portion is provided. Each of these buttons mounted on the end portions of strip metal elements 2 applied around teeth 1 or may be used for a correction of teeth by means of elastic strips 13 applied around the button between its enlarged head and base portions. These buttons are so small that they may be disposed on the inside of teeth and may be used for instance, for turning molar teeth 1 and for other purposes.
FIGS. 4 and 5 show a fastener part 14 which consists of a tunnel member and is provided in its tunnel passage 36 with a laterally bent detent spring 15. The tunnel member 14 cooperates with a fastener part 6, which is of the type described hereinbefore and provided with a serrated detent bar 7. In the present embodiment, the tunnel member 4 consitutes also a bracket. The bracket may be provided with a longitudinal groove 17 for slidably receiving an orthodontic appliance, and with a clamping device 16, which projects over said groove and is selectively angularly movable to positions for slidable and clamping engagement, respectively, with an orthodontic appliance 19 received in said groove so that the clamping device 16 is adapted to secure said bracket to said orthodontic appliance 19 in a selected position. The clamping device 16 may comprise a rotatable plate, which has portions differing in thickness and protruding over said groove 17, or may comprise a plurality of radial clamping arms, which differ in thickness and are angularly spaced apart, each of said arms being selectively angularly movable to a position in which it protrudes over said groove 17. The bracket may also comprise laterally disposed, longitudinally extending grooves defined by shoulders 20 and adapted to receive tying elements for securing orthodontic arches as has been described in the above-mentioned application. In this embodiment, one and the same member serves both as a bracket and as part of the fastener and also, on the bracket end, for the connection of a tying wire to a tooth without need for additional means for fixing the tying wire. In the embodiment shown, the combined tunnel-and-bracket member 14 has also an undercut 18 for engagement by a forceps 11.
As shown in FIG. 4, the clamping device 16 may be rotatably mounted in the bracket by means of a rotatable stub shaft 21, the clamping device 16 axially fixed to the shaft 21. A snubbing spring 22, curved toward the bracket, is riveted to the free end of shaft 21 and tends to hold the same and the clamping device 16 in a predetermined axial position relative to the bracket. On the other side or opposite side of longitudinal groove 17, the bracket is provided with a transversing recess 23 for receiving shaft 21. Recess 23, at its lower end, communicates with tunnel passage 36.
Clamping device 16 is disposed above the upper part of recess 23, and snubbing spring 22 is disposed at the lower end of recess 23.
FIG. 6 shows the forceps 11 having two gripping jaws 12, which are displaceable relative to each other. One gripping jaw 12 is carried by a tube 21, which slidably surrounds a rod 22 carrying the other jaw 12. The rod 22 is surrounded by a spring 23, which urges the gripping jaws 12 axially apart. The forceps 11 is provided with a ring member 24 and with a ball end 25, which are axially movable relative to each other to move the gripping jaws 12 towards each other against the force of the spring 23 so that the fastener consisting of the members 4 or 14, on the one hand, and 6, on the other hand, can be closed. This enables a simple fixation of the strip metal element 2 around the tooth 1 by means of the slide-snap fastener.
Another forceps 26 is shown in FIGS. 7 and 8 and comprises a gripping jaw 27, which is movable toward the second gripping jaw 30 against the force of a spring 31 by means of a cable 28 extending in a flexible metal tubing 29, which is connected to the gripping jaw 30, whereas the cable 28 is connected to the gripping jaw 27 and to a finger ring 32, which is displaceable against the force of the spring 31. The flexible metal tubing 29 is connected to a head member 33 by a guide tube 34, on which the finger ring 32 is fitted. The latter carries a pin 34, which extends in a slot 35 of the guide tube 34 so that the parts 32 and 34 are axially slidable relative to each other within limits defined by a pin-slot joint 34, 35. The spring 31 tending to return the finger ring 32 is accommodated in the guide tube 34, as is apparent from the sectional view of FIG. 8.