Abstract:
A bite correcting appliance for correcting an overbite or underbite condition of a patient includes upper attachment structure, lower attachment structure and a stretchable, close coil spring connected between the upper and lower attachment structures. The close coil spring exerts a pushing force on the lower jaw as the patient&#39;s mouth closes and is substantially non-prestressed or non-preloaded. At least one end of the appliance includes a deformable or crimpable portion allowing selective locking and unlocking to the corresponding attachment structure. Upper and lower attachment members are connected with the close coil spring by both threading and crimping to the spring.

Description:
This application is a continuation of application Ser. No. 09/307,403 filed May. 7, 1999 (now U.S. Pat. No. 6,113,390) 
    
    
     FIELD OF THE INVENTION 
     The present invention generally relates to orthodontic appliances and, more specifically, to appliances for treating malocclusions of the upper and lower jaws of a patient. 
     BACKGROUND OF THE INVENTION 
     Malocclusions between the upper and lower jaws of a patient generally fall within three classes. Class I malocclusions are those in which the individual teeth are not aligning well with each other and with the corresponding teeth in the opposite jaw. This malocclusion is commonly corrected with braces applied to the teeth for gradual realignment. Class II malocclusions relate to those cases in which the lower jaw is not developing in the manner which allows the upper and lower arches of teeth to come together with a proper bite or alignment to one another. More specifically, in this type of malocclusion an overbite condition exists and must be corrected by moving the lower jaw forward to obtain a proper bite. Corrective appliances are therefore used to hold the lower jaw in a proper bite position so that the jaw bones and muscles will support the proper bite. Class III malocclusions occur when the lower jaw is positioned too far forward with respect to the upper jaw. This condition, often referred to as an underbite, is typically corrected with the use of braces and rubber bands and, in some cases, through surgery. 
     The present invention generally relates to appliances for treating Class II or Class III malocclusions or, respectively, overbite and underbite conditions. In the past, rubber bands and springs extending in tension between upper and lower sets of brackets have been used to move the jaws into alignment as the patient closes their mouth. Over time, this corrective movement will permanently realign the upper and lower teeth of the patient through muscle development and/or proper bone growth. External head gear attached to the braces of the patient has been used for similar purposes. One main disadvantage with these treatment options is that they each require cooperation on the part of the patient. In other words, the patient is required to regularly maintain the rubber bands or head gear in place. Patients may choose not to apply the corrective appliances because they are unsightly or uncomfortable or may forget to apply them. In either case, the lack of diligence in using the corrective appliances reduces the effectiveness of the treatment. 
     Various bite fixing appliances have also been developed to overcome the disadvantages of rubber bands, springs, head gear or other methods of treating Class II and Class III malocclusions. Several of these appliances involve the use of coil springs connected between upper and lower sets of braces in a patient&#39;s mouth. Examples may be found in U.S. Pat. Nos. 3,618,214; 4,708,646; 5,352,116; and 5,846,074. These and other similar bite correcting appliances each suffer from various disadvantages. For example, the appliance described in U.S. Pat. No. 3,618,214 uses superimposed springs to pull a patient&#39;s lower jaw forward. This design is prone to mechanical failure and is undesirable for at least this reason. Also, this device is designed to apply a constant pulling force when the patient&#39;s mouth is in a closed position and this pulling force increases as the patient opens their mouth. This can be uncomfortable for many patients. 
     The device disclosed in U.S. Pat. No. 4,708,646 attempted to alleviate some of these concerns, however, the coil spring of this patent is an open coil spring secured within a resilient plastic so as to be nonstretchable. This design is prone to increased incidents of breakage or, in other words, subject to a short fatigue life. The open coil spring and the nonstretchable properties of the appliance increase the amount of stress on the spring and cause the stress to be applied over a shorter length of spring wire. Thus, the spring breaks with undesirable frequency. 
     U.S. Pat. No. 5,352,116 similarly relates to the use of a sheathed coil spring connected between upper and lower teeth of a patient to provide a pushing force to the lower jaw. As with the appliance shown in U.S. Pat. No. 4,708,646, this appliance can be difficult to install and reinstall. Also, although this appliance uses a stretchable spring, the spring is an undesirable open coil spring design. 
     U.S. Pat. No. 5,846,074 discloses the use of a coil wire sheath, however, the sheath is configured as an open coil compression spring. This spring presses against opposite connecting pieces as an internal straight wire spring element contained within the sheath is flexed when the mouth moves to a closed position. As stated in the patent, the coil spring does not supply significant pushing force and is not connected to the attachment structure at each end. The function of the coil sheath is to promote comfort and capture any broken pieces of the internal straight wire spring. 
     In general, the prior bite fixing appliances have provided inadequate treatment options for many patients and even the best appliances are in need of improvement in such areas as increasing fatigue life, easing installation and removal, and simplifying the overall construction. 
     SUMMARY OF THE INVENTION 
     The present invention generally relates to a bite correction appliance for overcoming various deficiencies of past appliances. In one aspect, the bite correction appliance of the invention generally includes a first attachment structure adapted to be secured to at least one upper or lower tooth of the patient and a second attachment structure adapted to be secured to a tooth of the opposite jaw which is located in a more forward position. The attachment structures may take many different forms and may be secured to the teeth either directly or indirectly. It is presently contemplated that orthodontic archwires, brackets and auxiliary wires or elements will be used as the attachment structures. In accordance with this aspect of the invention, a stretchable, close coil extension spring is connected between the first and second attachment structures for exerting a pushing force as the patient&#39;s mouth closes. When used to correct overbites, the spring will push the lower jaw forward. When used to correct underbites, the spring will push the lower jaw rearward. The close coil extension spring is substantially non-prestressed and includes a maximum gap of 0.015″ between adjacent coils in the preferred embodiment. This includes the case in which adjacent coils touch one another. 
     While typical extension springs may be prestressed or preloaded such that adjacent coils exert forces toward one another, the spring of the present invention is substantially non-prestressed. This, along with the additional wire resulting from the use of a close coil spring design, provides a longer fatigue life for the spring. In the preferred embodiment, the maximum gap between adjacent coils is 0.010″ and, more preferably, 0.005″. 
     To further increase the fatigue life of the spring, the spring is formed from double vacuum melted stainless steel. Another advantageous material for the spring is superelastic material such as nickel titanium. At least some of the adjacent coils are preferably exposed or not encased in other structure. This allows stretching of the extension spring during use. The appliance further comprises a flexible rod, such as a polymeric rod, contained within the adjacent coils. This rod prevents food from being entrapped with the spring and provides some support for the coil spring. 
     In another aspect of the invention, a coil spring assembly is formed with first and second attachment members affixed to opposite ends of the spring. The first attachment member is connected with the first attachment structure and the second attachment member is connected with the second attachment structure. At least one of the attachment members includes a connecting portion movable between locked and unlocked positions relative to its corresponding attachment structure. This allows at least one end of the spring to be selectively attached to and released from attachment structure, such as an archwire. In the preferred embodiment, the connecting portion is a deformable portion communicating with a hole in the first and/or second attachment member. This deformable portion may be moved between the locked and unlocked positions to allow connection and disconnection with respect to the corresponding attachment structure. 
     As another aspect of the invention, the first and second attachment members are threaded onto respective first and second ends of a coil spring, such as the close coil extension spring of the invention. After being rotated to the proper orientation with respect to one another, each of the attachment members is crimped to the coil spring to prevent further rotation relative to the coil spring. In this manner, flat connecting portions may be oriented, for example, approximately 90° with respect to each other about the axis of the spring. 
     These and various other objectives, advantages and features will become more readily apparent to those of ordinary skill in the art upon review of the following detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view of an appliance constructed in accordance with the preferred embodiment and shown partially connected to the braces of a patient; 
     FIG. 2 is a side elevational view similar to FIG. 1, but showing the appliance fully connected and correcting an overbite condition of the patient; 
     FIG. 2A is an enlarged view of encircled portion  2 A in FIG. 2; 
     FIG. 3 is a partially fragmented, side elevational view of the coil spring assembly of the appliance; and 
     FIG. 4 is a cross sectional view taken along line  4 - 4  of FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring generally to FIGS. 1 and 2, an appliance  10  is shown constructed in accordance with one preferred embodiment of the invention. Appliance  10  will be shown and described with respect to this preferred embodiment in terms of a device for correcting an overbite condition or Class II malocclusion. Those of ordinary skill in the art will readily appreciate that the device is easily adapted to correct underbite conditions or Class III malocclusions as well. Generally, the upper and lower connections of the device merely need to be reversed to reconfigure appliance  10  as a Class III corrective device. Other modifications of the structure and use of appliance  10  are also within the scope of the inventive concepts as will become more readily apparent upon reading the description of this preferred embodiment. 
     Appliance  10  generally includes upper attachment structure  12  and lower attachment structure  14 . In a typical case, this will include upper brackets  16  connected with an upper archwire  18  and lower brackets  20  connected with a lower archwire  22 . These comprise typical braces secured to upper and lower teeth  24 ,  26  of a patient. Other attachment structures may be substituted to perform this connecting function, for example, when braces are not worn by the patient. As shown in FIG. 1, the lower teeth  26  and lower jaw of the patient have an underbite with respect to the upper teeth  24  and upper jaw. A bracket  16  at the rear of the patient&#39;s mouth includes a tube  28  receiving a pin  30  having a hook-shaped portion  30   a . A ball or stop member  32  is disposed on the opposite end of pin  30 . A similar ball or stop member  34  is contained on lower archwire  22  at a more forward position. Appliance  10  further includes a close coil extension spring assembly  40  connected between the upper and lower attachment structures  12 ,  14 . More specifically, upper and lower attachment members  42 ,  44  are respectively connected to pin  30  and archwire  22  (FIG.  2 ). Thus, as the patient&#39;s mouth closes to the position shown in FIG. 2, a pushing force is exerted to the lower jaw in a forward direction against stop member or ball  34 . If a corrective device for Class III malocclusions is desired, then upper attachment member  42  would be connected to a lower tooth and lower attachment member  44  would be connected to an upper tooth. This would provide a forward pushing force to the upper jaw and a rearward pushing force to the lower jaw during mouth closure. 
     Referring to FIGS. 3 and 4, upper and lower attachment members  42 ,  44  each include flat portions  42   a ,  44   a  and internally threaded portions  42   b ,  44   b . Flat portions  42   a ,  44   a  include respective holes  46 ,  48  for connection with archwires  18 ,  22  (FIGS.  1  and  2 ). Hole  48  contained in flat portion  44   a  communicates with a slot  50  for attachment purposes as will be described below. FIG. 3 illustrates flat portions  42   a ,  44   a  in a preferred orientation rotated approximately 90° apart relative to the longitudinal axis of assembly  40 . Close coil spring  52  is formed by coils  54  either touching or spaced very closely apart by a gap D. Gap D is preferably less than 0.015″ and, most preferably, less than 0.005″. As shown in FIG. 3, coils  54  at opposite ends of spring  52  are threaded into threaded portions  42   b ,  44   b  of members  42 ,  44 . These coils are also very closely spaced or touching as previously described. A flexible rod  68  is contained with a close fit within spring  52 . Rod  68  may be formed of polyurethane and provides support for spring  52 . Rod  68  also prevents food from becoming trapped in spring  52 . 
     As best shown in FIG. 1, after attachment members  42 ,  44  are rotated to the proper orientation by threading onto the ends of spring  52 , attachment members  42 ,  44  are lightly crimped as indicated by crimps  60 ,  62  to retain the desired orientation. The crimping is preferably not forceful enough to retain members  42 ,  44  on the ends of spring  52  since the threading action will provide this function in a less stressful manner. Crimps  60 ,  62  are simply used to prevent further rotation of attachment members  42 ,  44  with respect to spring  52  as such rotation would inhibit the desired swivelling characteristics of spring assembly  40  during use. 
     Appliance  10  may be affixed to teeth  24 ,  26  in various manners other than the one shown in the drawings. Referring to FIG. 2, as one preferred manner, attachment member  44  is applied to lower archwire  22  by hooking archwire  22  into hole  48  and crimping flat portion  44   a  to a closed or locked position as shown in FIG.  2 A. Within this configuration, slot  50  is not large enough to allow archwire  22  to escape from hole  48 . The opposite attachment member  42  is then connected with pin  30  by sliding pin  30  through hole  46 . Pin  30  is then inserted into tube  28  and bent to form hook-shaped end  30   a . The distance of stop member or ball  32  from tube  28  may be adjusted to some extent to adjust the amount of forward pushing force provided by appliance  10 . To make this adjustment, pin  30  may be straightened and moved to the right or left as viewed in FIG.  2  and end  30   a  may be rebent to retain the adjusted position. 
     Thus, it will be appreciated that a forward pushing force on the lower jaw will be exerted through coil spring  52  as spring assembly  40  is retained between stop members  32  and  34  during mouth closure. When the patient&#39;s mouth is opened, spring  52  will stretch to some extent to relieve stress in the opposite direction. To remove coil spring assembly  40 , lower flat portion  44   a  is uncrimped or moved to an unlocked position as shown in FIG. 1 allowing removal from archwire  22 . Pin  30  may then be either clipped or straightened to allow removal from tube  28 . A new appliance  10  may then be easily applied in the manner described above. This aspect of the invention avoids the necessity to cut the archwire to remove the appliance. It will be appreciated that other quick release connectors are within the scope of this invention as well. 
     While the present invention has been illustrated by a description of the preferred embodiment and while this embodiment has been described in some detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. This has been a description of the present invention, along with the preferred methods of practicing the present invention as currently known. Various aspects of this invention may be used alone or in different combinations.