Dentistry – Orthodontics – Including extra-oral force transmitting means
Reexamination Certificate
1999-12-17
2001-04-10
Wilson, John J. (Department: 3732)
Dentistry
Orthodontics
Including extra-oral force transmitting means
Reexamination Certificate
active
06213765
ABSTRACT:
TECHNICAL FIELD
This application is directed to an orthodontic protraction appliance in which a rod is braced between a patient's forehead and chest (sternum). Elastics are mounted between the rod and orthodontic braces on the patient's teeth to apply the desired protracting force.
BACKGROUND
Orthodontists frequently find it necessary to apply protracting forces to a patient's teeth over prolonged periods of time. In some cases, the desired forces are preferably forwardly directed to urge the teeth outwardly away from the patient's mouth. The present invention provides a simple, stable device for applying such forces.
The prior art has evolved a variety of orthodontic protraction appliances. For example, U.S. Pat. No. 862,881 Case discloses a protraction appliance in the form of a headgear anchorage for applying corrective forces to the teeth. A retruding bow is held in front of the patient's mouth by elastic straps which form part of the headgear. The retruding bow can be connected to braces fixed to the patient's teeth to apply various forces to the teeth. Because the retruding bow is elastically supported at the back of the patient's head, Case's device is best suited to application of rearwardly directed forces and is generally incapable of applying significant forwardly directed forces in the manner of the present invention.
U.S. Pat. No. 2,334,894 Atkinson discloses an appliance having a frame which is strapped to a patient's head to position a spaced apart pair of parallel, vertical arms in front of the patient's face. A cross member extends horizontally between the arms. The ends of the cross member slidably engage the arms, allowing the cross member to be raised or lowered to position it at a desired level in front of the patient's mouth. Elastic bands, hooks, etc. can then be mounted between the cross member and braces applied to the patient's teeth, to apply the desired protracting force. Unlike the present invention, which provides secure bracing at the patient's forehead and sternum, Atkinson's device is braced between the patient's forehead and chin. Forehead-chin bracing is adequate to sustain application of corrective forces which are effective in some orthodontic correction procedures. However, forces imposed on the patient's lower jaw by an Atkinson type device can cause undesirable tempero mandibular joint displacement. This is preferably addressed by moving the maxillary posterior teeth forward, but such movement is not adequately achieved by the prior art.
SUMMARY OF INVENTION
The invention provides an orthodontic protraction appliance in which an upper portion of a vertically extending rod is supported against a patient's forehead, with the lower portion of the rod being supported against the patient's chest. An elastic support is coupled to a central portion of the rod to anchor a plurality of elastic bands connected to braces attached to the patient's teeth.
In a first embodiment, the elastic support is slidably positionable along and releasably fastenable to the first rod. The first support preferably includes a head band coupled to the upper portion of the rod. The head band encircles the patient's head to support the upper portion of the rod against the patient's head. The second support preferably includes a breast plate coupled to the lower portion of the rod. The breast plate supports the lower portion of the rod against the patient's chest. The opposed ends of a chest strap are coupled to the breast plate, and the chest strap is fastened to encircle the patient's chest and support the breast plate. A shoulder harness can be coupled between the breast plate and the chest strap, such that the shoulder harness extends over the patient's shoulders to further support the breast plate.
The first support further includes a first strut coupled between the upper portion of the rod and the head band. The second support further includes a second strut coupled between the lower portion of the rod and the breast plate. The first strut is coupled to the upper portion of the rod to permit unimpeded vertical movement of the rod with respect to the head band. This may be accomplished by fixing one end of the first strut to the head band and fixing an opposed end of the first strut to a first ring which encircles the upper portion of the first rod.
A second embodiment of the invention includes a second vertically extending rod. An upper portion of the second rod is coupled to the first support and a lower portion of the second rod is coupled to the elastic support. In the second embodiment: the elastic support is slidably positionable along and releasably fastenable to the second rod; and, head band additionally supports the upper portion of the second rod against the patient's head. The elastic support is coupled to the central portion of the first rod to permit unimpeded vertical movement of the first rod with respect to the elastic support. This may be accomplished by including in the elastic support further a second ring encircling the central portion of the first rod. Preferably, the upper portion of the second rod is pivotally coupled to the first support.
A third embodiment of the invention includes a lateral alignment mechanism coupled between the central portion of the first rod and the lower portion of the second rod to maintain lateral alignment of the elastic support with respect to the first rod as the first rod moves vertically with respect to the elastic support. The lateral alignment mechanism may be a sector with a vertical, concave groove in a rearward facing, convex arc portion of the sector. The groove is positioned against the central portion of the first rod to permit the sector to rotate along the groove with respect to the central portion of the first rod. A forward facing portion of the sector is pivotally coupled (preferably eccentrically) to the lower portion of the second rod. The elastic support and the sector's forward portion are slidably positionable along and releasably fastenable to the second rod. Advantageously, a second ring encircles the central portion of the first rod and further encircles the arc portion of the sector.
In a fourth embodiment of the invention, a lower end of the upper portion of the first rod is pivotally connected to an upper end of the lower portion of the first rod to permit lateral movement of the upper and lower portions of the first rod with respect to the patient, while substantially preventing forward or rearward movement of the upper or lower portions of the first rod with respect to the patient. Advantageously, the upper portion of the first rod is shaped to conform generally to a central vertical side profile of a human face, enabling the upper portion to be positioned closely to the face and thus reduce obstruction of the patient's vision. A universal joint pivotally couples the lower end of the lower portion of the first rod to the breast plate. The universal joint permits lateral movement of the lower portion of the first rod with respect to the patient, while substantially preventing forward or rearward movement of the lower portion of the first rod with respect to the patient. A spring coupled between the universal joint and the lower end of the lower portion of the first rod, biases the lower portion of the first rod away from the universal joint as the lateral movement increases, and assists in retracting the lower portion of the first rod toward the universal joint as the lateral movement decreases.
REFERENCES:
patent: 862881 (1907-08-01), Case
patent: 2151458 (1939-03-01), Allen
patent: 2334894 (1943-11-01), Atkinson
patent: 2735424 (1956-02-01), Benjamin
patent: 3391693 (1968-07-01), Georgiade et al.
patent: 4951655 (1990-08-01), MacMillan et al.
patent: 5531229 (1996-07-01), Dean et al.
patent: 5810583 (1998-09-01), Doyle
Fetchko Eric B.
Standerwick R. William
Bumgarner Melba
Oyen Wiggs Green & Mutala
Standerwick R. William
Wilson John J.
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