Dentistry – Orthodontics – Means to transmit or apply force to tooth
Patent
1990-11-23
1993-02-02
Mancene, Gene
Dentistry
Orthodontics
Means to transmit or apply force to tooth
A61C 300
Patent
active
051833883
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a mobile hinge as used in orthodontic appliances where arch wires on the upper and lower jaw are interconnected by a rod unit that normally consists of two telescopically movable parts.
FIELD OF THE INVENTION
Previous designs for a telescopic unit and other accessories have been described in the following U.S. Pat. Nos.: 3,028,671 to Berger, 4,462,800 to Jones and 2,959,856 to Gurin. The Berger patent discloses slotted screw and a nut. The Jones patent employs a hinge-screw combination. The Gurin patent employs a hinge without collar but with set screw. Similar constructions can be derived from U.S. Pat. Nos. 2,959,856, 3,158,934, 3,238,619, 4,462,800, 4,551,095 and 4,795,342.
BACKGROUND OF THE INVENTION
All these hinges that are also commercially available have the disadvantage to use screws either to fasten the rod unit to the wire or to retain the hinge member in the bearing aperture of the rod unit. As the jaws move forward and backward, the screws have the tendency to become loose. If the screw is used to fasten the wire, another drawback consists in that the masticatory load, already under normal jaw movements, provides a tremendous amount of pressure acting onto the wire at the contact area with the screw, thus resulting in a metal fatigue and eventual breakage of the wire. The use of a screw implies also that very fine threads have to be manufactured which constitutes a relatively costly procedure. In many cases, the use of a screw results in a bulky construction which causes an irritation of the soft tissue. If the screw is connected to the wire, the lateral movement of the rod unit is restricted, thus increasing the patient's discomfort. Certainly, in U.S. Pat. No. 4,583,944 there is a hinge member consisting of a stud that is connected to a tube extending normally to its smaller shank. There is no screw and no separate part. However, such a design is not only bulky and, therefore, disagreable to the patient, but it is also difficult to manufacture, because the tube will usually be connected to the stud by soldering. Even if it were produced by other methods, it would always involve difficulties. Moreover, the telescopic unit of the Herbst appliance can only be stripped over the head portion of the stud, thus allowing that it can be stripped off by movements of the patient's jaws. Therefore, it never came into practice.
SUMMARY OF THE INVENTION
It is an object of the present invention to simplify the construction and to make it more reliable. Inconveniences to the patient should be avoided.
This object is achieved according to the invention by a movable hinge member in which a shaft portion of generally cylindrical shape is integrally formed with a head portion of larger width to retain the hinge member within the bearing aperture on one side, while it is retained by the wire itself or by a little pin on the other side. The wire may be inserted into the end opposite to the head portion by providing a hole or a slot that may be closed by suitable means. In this way, the connection with the wire may be effected in a surprisingly simple manner.
In principle, the head portion could be T-shaped; however, it is preferred to have it circular, when seen in the direction of the longitudinal axis of the shaft portion, because in this way, it is less irritating to the patient. For the same reasons, a cylindrical head can have at least one circular edge, especially on its front surface, rounded, whereby the front surface may outwardly be dished.
When a screw was used in known hinge members to retain it in the bearing aperture, it generally has an incision in its front surface for enabling insertion of a screw driver. Such incisions (or protrusions) are not only inconvenient for the patient, but it may also constitute a hygienic problem, since it may cause particles of food to be caught on. With a hinge member according to the invention, it is easily possible to form it free of incisions and/or protrusions.
BRIEF DESCRIPTION OF THE DRAWINGS
Further details of the inventio
REFERENCES:
patent: 711948 (1902-10-01), Dodge
patent: 886904 (1908-05-01), Wagner
patent: 1525408 (1925-02-01), Miller et al.
patent: 1761581 (1930-06-01), Northey et al.
patent: 2140820 (1938-12-01), Summerhays
patent: 2383068 (1945-08-01), MacLean, Jr.
patent: 3357292 (1967-12-01), Falkenberg
patent: 4462800 (1984-07-01), Jones
patent: 4472139 (1984-09-01), Rosenberg
patent: 4496318 (1985-01-01), Connelly, Jr.
Lucchesi Nicholas D.
Mancene Gene
Ortho-Dent
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