Dentistry – Orthodontics – By device having means to apply outwardly directed force
Reexamination Certificate
1998-10-14
2001-04-24
Wilson, John J. (Department: 3732)
Dentistry
Orthodontics
By device having means to apply outwardly directed force
Reexamination Certificate
active
06220856
ABSTRACT:
TECHNICAL FIELD
The invention has as its object a device for orthodontic or orthopedic correction of the maxilla and its dental units, as well as for orthodontic correction of the dental units in the mandible.
BACKGROUND OF THE INVENTION
Devices for orthodontic and orthopedic expansion or contraction of the maxilla are known. Such known devices may comprise means for anchoring the device to two or more molars positioned on opposite maxillary half-arches divided by the median antero-posterior axis. The devices further comprise thrust or traction agents affixed to the anchoring means and acting in a direction substantially perpendicular to the antero-posterior axis, i.e., in the direction of distancing the two anchoring molars from each other or of moving them closer together.
At present there are two known types of these devices. In a first known type, the thrust or traction agents are of the wrench or screw type. More particularly, a structure composed of conjunction and of stiffening elements connects the anchoring means of each of the two opposed molars to two terminals which each present at least one threaded opening coaxial respective to each other, with the threads running in opposite directions. A pin having two threaded ends, with the threads running in opposite directions, is engaged in the corresponding threaded openings of the two terminals. A middle portion of pin includes means for actuating the pin in rotation, such as with the use of suitable instruments. By rotating the threaded pin, it is therefore possible to move the two terminals farther away or closer together, to thereby control the expansion or contraction action of the maxilla.
Despite that the above-described types of devices make it possible to exert forces of expansion or contraction perfectly oriented in a direction perpendicular to the antero-posterior median of the maxilla (i.e., parallel to the direction of expansion or contraction desired), an appreciable disadvantage of these devices is that the expansion or contraction action is of very short duration once the “loading” action (i.e., the twisting of the pin) is terminated. The short duration is the result of the loading structure being essentially rigid. Moreover, these devices do not allow an expansion or contraction action of a desired amount to be exerted in a progressive manner. Rather, the traction or expansion force is exerted on the teeth in an almost “traumatic” manner (i.e., all at once or over an extremely limited length of time).
The application of these devices therefore is especially painful for the patient. Furthermore, this mode of operation of the device means that the medical personnel must execute frequent adjustments and trials with the thrust or traction means in order progressively to achieve, in small increments, the desired effect of expansion or contraction of the maxilla.
A second known type of device makes it possible to overcome the drawbacks of this first known type that relate to the rigid structure of the thrust and traction means. More specifically, in the second type of known device the thrust and traction means are made up of elastic elements that, in the application phase, are pre-loaded to a pre-set level. Presently, the elastic means are made up, however, of a metal wire that presents a certain elasticity and that is bent in such manner that it exerts an expansion or contraction force. To exert the force in the expansion direction, for example, the elastic metal wire may be bent in such manner as to form a handle with its terminal portions spread apart. While to exert a force of traction, the metal wire may be bent in such manner as to form, for example, a spiral with end parts that intersect each other.
These elastic means exert a progressive action of expansion and compression that, however, because of their structure, is of very short duration, requiring frequent interventions for additional loading of force by means of further deformations. This type of device presents an additional drawback of causing the support teeth to unacceptably tip from the desired vertical orientation and to cause an undesirable V-shaped gap in the arch form (anterior vestibulation).
It is therefore an object of the present invention to create an orthodontic and orthopedic device in such a manner that it does not suffer from the above-described drawbacks of the presently known devices. It is also an object of present invention to provide a low cost device that is simple to install and adjust.
SUMMARY OF THE INVENTION
The invention achieves the above ends with a device for making orthodontic or orthopedic corrections in a dental arch. The device includes thrust or traction means comprising at least one pair of terminals and an elastic means. The terminals of each pair are connected to means for anchoring them to at least one tooth on opposite sides of the dental arch or, alternatively, to two longitudinally spaced teeth on the same side of the dental arch. The two terminals of each pair telescopically engage each other in reciprocal sliding motion in a direction of expansion or contraction of the dental arch or, alternatively, in a direction of lengthening or shortening of the dental arch. The elastic means are positioned intermediate the two terminals of each pair and rest against stop elements which are adjustable to regulate a desired amount of thrust or traction force generated by the elastic means.
According to an improvement the terminals of each pair are constituted by a tubular element and an rod element sliding inside the tubular element.
According to a further improvement, each one of the two terminals carries at least one stop element, and the elastic means comprises a helix-shaped spring positioned between the two locating elements or radial enlargements. At least one of the stop elements can slide along the associated terminal and be locked into a desired position for setting the amount of force.
In a preferred form of execution, one of the stop elements comprises a small buckle that is slidable along the tubular terminal and which can be locked into position by tightening a radial screw or threaded pin screwed in a radial threaded perforation of the small buckle.
The terminals of the thrust or traction means may be either connected rigidly or elastically. For example, a rigid connection may be accomplished by soldering the thrust or traction means to the anchoring means or to a conjunction and stiffening structure affixed to the anchoring means, or an elastic connection may be accomplished by means of elastic ties that yield to pressure.
In order to guarantee that, as much as possible, the traction or expansion force is indeed exerted only in the desired direction (as is desirable to eliminate the effect of anterior vestibulation of the arch), it is possible to provide the anchoring on two teeth. That is, the device is anchored either on two molars, or two pre-molars (i.e., bicuspids), or on some combination thereof, with at least one tooth selected from each of the two dental half-arches. In this case, each pair of attachment points (e.g. wire hooks) symmetrically opposed with respect to the antero-posterior axis that defines the half-arch are connected together by means of a pushing device or with a traction means. The two pushing elements or the pair of traction means are oriented in parallel direction with respect to the direction in which they exert their thrust or contraction force.
The elements for attaching the pair of thrust elements or traction means onto the anchoring teeth either can be independent among themselves or they can form a type of framework. The framework can be a rigid connection because of the presence of the elastic means.
From the above, a number of the advantages of the present invention are made clear. First, the device according to the present invention provides an expansion or traction action or force which is progressive, thus overcoming the drawbacks of anterior vestibulation and of a slanting vestibule of the teeth. Moreover, the progressive nature of the force permits the maintaini
Carano Aldo
Testa Mauro
Foley & Lardner
Micerium S.R.L.
Wilson John J.
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