Abstract:
A jaw exerciser for providing passive motion therapy such as that used to treat trismus is provided. The jaw exerciser has a user-adjustable distance between the upper jaw support and the lower jaw support. The jaw exerciser includes a shaft, a first or upper jaw support frame including a first jaw support, a second or lower jaw support frame including a second jaw support, a distance adjuster which may be in the form of a jack screw for manually adjusting the distance between the first jaw support and the second jaw support, and a retaining screw. The jack screw may be received by the second or lower jaw support frame and engage the first or upper jaw support frame. Removable bite pads may optionally be provided for installing on the first jaw support and the second jaw support.

Description:
FIELD OF THE INVENTION 
     The present specification relates generally to jaw exercisers and more specifically relates to a passive motion therapy jaw exerciser having a user-adjustable distance between the upper jaw support and lower jaw support. 
     BACKGROUND OF THE INVENTION 
     Certain ailments or treatments of ailments may cause patients to lose range of motion in their jaw as well as diminish their jaw and joint function. The inability to open one&#39;s mouth fully is a condition referred to as trismus (sometimes referred to as “lockjaw”). For patients with trismus, jaw motion may be partially or fully rehabilitated by passive motion therapy in which the jaw muscles are passively stretched, i.e. without activating jaw muscles to perform the movement. This can be accomplished by the patients using their hands to pull their lower jaw open and holding the stretch for a predetermined duration, for example, 30 seconds. Over time, the patient gradually opens his or her mouth further and further thereby increasing the range of motion of his or her jaw. 
     Certain devices are available to assist with passive motion therapy so that the user need not use their hands to hold their jaw open, but instead may use their hands for other activities while maintaining their jaw in a passive stretched position. Such devices may include upper and lower jaw supports in which the distance between the upper and lower jaw supports is adjustable. As passive range of motion stretching may be done, for example, 10 times per day, the patient may wish to take the device with them outside of the home. However, presently available devices are bulky and typically involve the use of separate carrying cases to transport them while not in use. Some patients may find transporting such devices inconvenient and may choose not to take them outside of the home. This may reduce the frequency with which they perform the passive stretching exercises and consequently slow their rehabilitation process. 
     Accordingly, there remains a need for improvements in the art. 
     SUMMARY OF THE INVENTION 
     In accordance with an aspect of the invention, there is provided a compact passive motion therapy jaw exerciser that may be quickly assembled and disassembled and thereby may be conveniently carried on one&#39;s person, such as in a jacket or pant pocket, without the need for a separate carrying case. 
     According to an embodiment of the invention, the present invention provides a jaw exerciser comprising: a shaft; a first jaw support frame in sliding frictional engagement with the shaft and extending substantially perpendicularly to the shaft, the first jaw support frame including a first jaw support; a second jaw support frame in sliding frictional engagement with the shaft and extending substantially perpendicularly to the shaft, the second jaw support frame including a second jaw support; and a distance adjuster received by the first jaw support frame and engaging the second jaw support frame so as to be substantially parallel to the shaft, the distance adjuster being configured to adjust the distance between the first jaw support and the second jaw support. 
     According to a further embodiment, the present invention provides a kit for assembling a jaw exerciser, the kit comprising: a shaft; a first jaw support frame including a first jaw support, the first jaw support being configured to slidingly frictionally engage the shaft; an adjustable second jaw support frame including a second jaw support, the adjustable second jaw support being configured to slidingly frictionally engage the shaft; and a jack, the jack being configured to engage the first jaw support frame and be received by the adjustable second jaw support frame so as to be substantially parallel to the shaft and to adjust the distance between the first jaw support and the second jaw support. 
     According to a further embodiment, the present invention provides a method for assembling a jaw exerciser, the method comprising: positioning a first jaw support frame including a first jaw support, on a shaft in sliding frictional engagement; positioning an adjustable second jaw support frame including a second jaw support, on the shaft in sliding frictional engagement; engaging a retaining screw with the shaft to prevent the first jaw support frame and the adjustable second jaw support frame from disengaging from the shaft; and engaging a jack with the first jaw support frame through the adjustable second jaw support frame, the jack for adjusting the distance between the first jaw support and the second jaw support. 
     Other aspects and features according to the present application will become apparent to those ordinarily skilled in the art upon review of the following description of embodiments of the invention in conjunction with the accompanying figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference will now be made to the accompanying drawings which show, by way of example only, embodiments of the invention, and how they may be carried into effect, and in which: 
         FIG. 1  is an exploded view of a jaw exerciser according to an embodiment; 
         FIG. 2A  is a bottom right side perspective view of a straight first jaw support according to an embodiment and  FIG. 2B  is a top right side perspective view of the straight first jaw support of  FIG. 2A ; 
         FIG. 3A  is a top left side perspective view of a straight second jaw support according to an embodiment and  FIG. 3B  is a bottom left side perspective view of the straight second jaw support of  FIG. 3A ; 
         FIG. 4A  is a bottom right side perspective view of an arched first jaw support according to an embodiment and  FIG. 4B  is a top right side perspective view of the arched first jaw support of  FIG. 4A ; 
         FIG. 5A  is a top left side perspective view of an arched second jaw support according to an embodiment and  FIG. 5B  is a bottom left side perspective view of the arched second jaw support of  FIG. 5A ; 
         FIG. 6A  is a bottom right side perspective view of an extended arched first jaw support according to an embodiment and  FIG. 6B  is a top right side perspective view of the extended arched first jaw support of  FIG. 6A ; 
         FIG. 7A  is a top left side perspective view of an extended arched second jaw support according to an embodiment and  FIG. 7B  is a bottom left side perspective view of the extended arched second jaw support of  FIG. 7A ; 
         FIG. 8A  is a back perspective view of the mini-sized shaft of the jaw exerciser of  FIG. 1 ,  FIG. 8B  is a bottom left side perspective view of the mini-sized shaft of  FIG. 8A ,  FIG. 8C  is a back right perspective view of a shaft according to another embodiment and  FIG. 8D  is a bottom left side perspective view of the shaft of  FIG. 8C ; 
         FIG. 9A  is a front view of a jack according to an embodiment and  FIG. 9B  is a front view of the mini-sized jack of the jaw exerciser of  FIG. 1 ; 
         FIG. 10A  is a front view of the retaining screw of the jaw exerciser of  FIG. 1  according to an embodiment and  FIG. 10B  is a bottom front perspective view of the retaining screw of  FIG. 10A ; 
         FIG. 11A  is a top perspective view of a pair of straight bite pads according to an embodiment,  FIG. 11B  is a top perspective view of a pair of extended arched bite pads according to an embodiment,  FIG. 11C  is a top perspective view of a pair of arched bite pads according to an embodiment,  FIG. 11D  is a bottom left side perspective view of the arched bite pad of  FIG. 11C  shown separated prior to being installed on the arched jaw support, and  FIG. 11E  is a bottom left side perspective view of the arched bite pad shown installed on the arched jaw support; 
         FIG. 12A  is a back right side perspective view of the jaw exerciser of  FIG. 1  in an open position according to an embodiment and  FIG. 12B  is front right side perspective view of the jaw exerciser of  FIG. 12A  in an open position; 
         FIG. 13A  is a top right side perspective view of the jaw exerciser of  FIG. 1  in a closed position according to an embodiment and  FIG. 13B  is a bottom left side perspective view of the jaw exerciser of  FIG. 13A  in a closed position; 
         FIG. 14  is a right side view of a jaw exerciser according to an embodiment shown deployed in a model of a human jaw classified as normal bite; 
         FIG. 15  is a right side view of a further embodiment of the jaw exerciser configured for users with overbites shown deployed in a model of a human jaw with an overbite; and 
         FIG. 16  is a right side view of a further embodiment of the jaw exerciser configured for users with underbites shown deployed in a model of a human jaw with an underbite. 
     
    
    
     Like reference numerals indicate like or corresponding elements in the drawings. 
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     According to an embodiment as shown in  FIGS. 1, 12A, 12B, 13A, and 13B , a jaw exerciser such as jaw exerciser  100  is generally configured to allow a user, namely a human, to use passive motion therapy to exercise his or her jaw. The jaw exerciser  100  may comprise a shaft  116 , a first jaw support frame  120  in sliding frictional engagement with the shaft  116 , an adjustable second jaw support frame  112  in sliding frictional engagement with the shaft  116  and a distance adjuster such as a jack, for example, a jack screw  130  which may be received by, engage or connect to the first jaw support frame  120  and also engage the second jaw support frame  112  so as to be substantially parallel to the shaft  116 . The first jaw support frame  120  may include a first jaw support  126  and the second jaw support frame  112  may include a second jaw support  113 , each jaw support  126  and  113  being for insertion into a user&#39;s mouth. The distance adjuster such as jack screw  130  may be configured to adjust the distance between the first jaw support  126  and the second jaw support  113  using a knob  135  included at the top of the jack screw  130 . According to an embodiment, turning the knob  135  in a first direction lowers the adjustable second jaw support frame  112  thereby increasing the distance between the first jaw support  126  and the second jaw support  113 , while turning the knob  135  in the opposite direction to the first direction lowers the jack screw  130  thereby allowing the user to push the adjustable second jaw support frame  112  towards the first jaw support frame  120  in order to reduce the distance between the first jaw support  126  and the second jaw support  113 . 
     According to an embodiment, the jaw exerciser may also include a retaining means such as retaining screw  140 . According to an embodiment as shown in  FIGS. 10A and 10B , the retaining screw  140  may be removable such that temporarily removing it may allow the first jaw support frame  120  and the second jaw support frame  112  to be placed on, or removed from, the shaft  116 , during assembly or disassembly of the jaw exerciser  100 . According to an embodiment, a retaining cap  121  may be provided on shaft  116  to prevent the first jaw support frame  120  and the second jaw support frame  112  from disengaging with shaft  116 . According to an embodiment, retaining cap  121  may be integrally molded with the shaft  116 . According to an embodiment, a scale such as distance scale  117  may be provided on the shaft  116  that visually conveys the distance between the first jaw support frame  120  and the second jaw support frame  112 . According to an embodiment, each line on the distance scale  117  may be 2 mm from the next line. According to an embodiment, an indicator  104  may be provided on the first jaw support frame  120  and an indicator  105  may be provided on the second jaw support frame  112  to help the user differentiate between the first and second jaw support frames. According to an embodiment, indicators  104  and  105  may be shapes such as an inverted triangle and a diamond. According to a further embodiment, letters, such as T for top and B for bottom may be used as indicators  104  and  105 . According to a further embodiment, both shapes and letters may be used as indicators  104  and  105 . 
     According to different embodiments of the invention, the maximum distance between the first jaw support  126  and the second jaw support  113  may vary in order to accommodate users with different jaw sizes. For example, one embodiment of the jaw exerciser using shaft  116  and jack  130  as shown in  FIGS. 8C, 8D, and 9A , may, for example, open up to 53.4 mm (2.1 inches) wide (a “standard” size), while another embodiment of the jaw exerciser using mini-sized shaft  116   a  and mini-sized jack  130   a  as shown in  FIGS. 8A, 8B, and 9B , may, for example open up to 33.4 mm (1.3 inches) wide (a “mini” size). Note that  FIGS. 8A, 8B, and 9B  denote corresponding parts  116 ,  117 ,  119 ,  121 ,  130 , and  135  in a mini-sized shaft and jack to the parts  116   a ,  117   a ,  119   a ,  121   a ,  130   a , and  135   a  of the standard-sized shaft and jack. Other maximum distances are possible according to further embodiments of the invention; for example, a mini-sized version may suitably support a maximum distance of between about 10 mm and about 33.4 mm. 
     According to the embodiments as shown in  FIGS. 2A to 7B , different shaped jaw supports may be used. Certain shapes may be more suitable for some applications or purposes than others. A straight first jaw support  113   a  and straight second jaw support  126   a  as shown in  FIGS. 2A to 3B  may be used, for example, to keep a user&#39;s mouth open during medical examinations. The lack of an arched shape more readily allows visual examination of inside the user&#39;s mouth on either side of the straight supports. An arched first jaw support  113  and arched second jaw support  126  as shown in  FIGS. 4A to 5B  may provide improved support than the straight supports during a user&#39;s daily stretches, and an extended arched first jaw support  113   b  and an extended arched jaw support  126   b  as shown in  FIGS. 6A to 7B  may be most appropriate for use by users with a more limited ability to open their mouth (i.e. a more severe case of trismus). According to further embodiments, mini-sized embodiments for each of different shaped jaw supports, which may also reduce the length of the extension of the associated jaw support frames, may also be employed. Parts  104   a ,  105   a ,  112   a ,  113   a ,  118   a ,  120   a ,  122   a ,  124   a ,  125   a ,  126   a ,  153   a , and  154   a  in the straight shape correspond to parts  104 ,  105 ,  112 ,  113 ,  118 ,  120 ,  122 ,  124 ,  125 ,  126 ,  153 , and  154  in the arched shape and to parts  104   b ,  105   b ,  112   b ,  113   b ,  118   b ,  120   b ,  122   b ,  124   b ,  125   b ,  126   b ,  153   b , and  154   b  in the extended arched shape. 
     According to an embodiment as shown in  FIGS. 11A to 11E , bite pads  146 ,  147 , and  148 , molded to the shape of the corresponding jaw support, may be used to increase comfort for the teeth of a user. Bite pads  146 ,  147  and  148  are optional, but may be preferred by users that have sensitive teeth, users that have teeth that do not line up properly, or users whose dentist may recommend use of bite pads  146 ,  147  or  148 . A pair of straight jaw support bite pads  146  may consist of a top bite pad  146   a  and a bottom bite pad  146   b  which may be used on the first straight jaw support  126   a  and a second straight jaw support bite pad  146   b  may be used on the second straight jaw support  113   a . Further, an arched jaw support bite pad  148   a  may be used on the arched first jaw support  126  and an arched second jaw support bite pad  148   b  may be used on the arched second jaw support  113 . In addition, an extended arched jaw support bite pad  147   a  may be used on the extended arched first jaw support  126   b  and an extended arched second jaw support bite pad  147   b  may be used on the extended arched second jaw support  113   b . According to an embodiment, the bite pads  146 ,  147 , and  148  may be installed onto the jaw supports by snapping them in through placing a protrusion, such as rear stoppers  153  and  154 , through an opening in the bite pad  148 , such as opening  158 . According to an embodiment, a tab  159  may be provided on the bite pad  148  to visually indicate which side of the bite pad  148  should face inward towards to other bite pad in the pair. According to an embodiment, rear stoppers  153  and  154  may also make it easier for the user to retain the jaw exerciser in their mouth during stretches and therefore may allow for substantial hands-free operation of the jaw exerciser. 
     As shown in  FIGS. 14, 15 and 16 , the manner in which the upper and lower teeth come together may differ for users with an underbite (where the user&#39;s lower jaw protrudes) or an overbite (where the user&#39;s upper jaw and teeth significantly extend past their bottom jaw and teeth), in comparison to a normal bite. An embodiment for a normal bite is shown in  FIG. 14 , in which the first jaw support frame  120  extends just a bit less than the second jaw support frame  112  to suitably position first jaw support  113  relative to second jaw support  113  to accommodate a normal bite. According to an embodiment as shown in  FIG. 15 , the first jaw support frame  120   c  including first jaw support  126   c  may extend a shorter distance than in the embodiment shown in  FIG. 14  in order to accommodate users with an overbite. As shown in  FIG. 16 , the first jaw support frame  120   d  including first jaw support  126   d  may extend a greater distance than in the embodiment shown in  FIG. 14  in order to accommodate users with an underbite. 
     The shaft  116 , the first jaw support frame  120 , the second jaw support frame  112 , the distance adjuster such as jack screw  130 , and the retaining screw  140  may be constructed from materials which provide sufficient mechanical strength and rigidity for use in holding the jaw of a user open when the device is used as a jaw exerciser. According to an embodiment, the aforementioned components may be made of plastic, such as injection molded plastic. In other embodiments, the aforementioned components may include plastics such as polypropylene or polystyrene, composites, or a combination of suitable materials. According to an embodiment, the aforementioned components may be made from plastic using a 3D printer. 
     The bite pads  146 ,  147  and  148  may be constructed from materials which may enhance comfort for the teeth of a user when the device is used as a jaw exerciser. According to an embodiment, the bite pads  146 ,  147 , and  148  may be made of foam, rubber or any other suitable material known to a skilled person that would provide increased comfort to the teeth of the user. 
     According to an embodiment as shown in  FIG. 1 , the jaw exerciser  100  may be assembled and disassembled by a user with relative ease. According to an embodiment, to assemble the jaw exerciser  100 , the user places the open end of shaft  116  through hole  124  of the first jaw support frame  120  and then through hole  125  of the second jaw support frame  112 . The user may then insert the retaining screw  140  into the complementary receiving recess such as a threaded hole  119  in the open end of the shaft  116 . The user may then slide the second jaw support frame  112  up the shaft  116  thereby moving the first and second jaw supports  126  and  113  to the closed position where they are adjacent to each other. 
     The distance adjuster, such as jack screw  130 , is then inserted through a hole which may be threaded such as threaded hole  118  in the second jaw support frame  112  and turned using a knob  135  at the top of the jack screw  130  until it engages a complementary recess such as recess  122  for receiving the jack screw  130  in the first jaw support frame  120 . The jack screw  130  may then be further turned to lower the second jaw support frame  112  including the second jaw support  113  by the jack screw  130  pushing the second jaw support frame  112  away from the first jaw support frame  120  including the first jaw support  126 . While in use in a user&#39;s mouth, the distance between the first jaw support  126  and the second jaw support  113  may be further adjusted using only one hand by turning the jack screw  130  clockwise or counterclockwise using the knob  135  and, if reducing the distance between the jaw supports, pushing upwards on the adjustable second jaw support frame  112 . 
     According to an embodiment, disassembly of the jaw exerciser  100  may be accomplished by unscrewing the jack screw  130  and disengaging it from the first jaw support frame  120  and then from the second jaw support frame  112 , unscrewing the retaining screw  140 , and sliding the second jaw support frame  112  and then the first jaw support frame  120  off the open end of the shaft  116  so as to disengage it. Shaft  116 , first jaw support frame  120 , second jaw support frame  113 , jack screw  130  and retaining screw  140  of the jaw exerciser  100  may then be transported and reassembled as desired by the user. 
     According to an embodiment, in use, the jaw exerciser  100  may be inserted into the user&#39;s mouth where the first jaw support  126  and second jaw support  113  are at a distance between each other where the user&#39;s mouth opens to a comfortable level. The user may then hold that stretch for a first period of time, such as 20 seconds, and then reduce the distance between the first jaw support  126  and the second jaw support  113  for a second period of time, such as 20 seconds, as a rest period, and then repeat the process by increasing the distance between the first jaw support  126  and the second jaw support  113  to the original distance, for a session of alternating stretches and rest periods for an appropriate duration, for example, 15 minutes. 
     A further exercise regimen, which may be more appropriate for experienced users, may involve inserting the jaw exerciser  100  into the user&#39;s mouth where the first jaw support  126  and second jaw support  113  are at a distance between each other where the user&#39;s mouth opens to a comfortable level and holding that stretch for a longer duration, such as 5 minutes. After 5 minutes, the distance between the first jaw support  126  and second jaw support  113  may be increased and the stretch held for another 5 minutes. This process may then repeat twice more for a total exercise time of 20 minutes. Other jaw exercise regimens may be designed and used as appropriate for the particular user or as may be recommended for rehabilitation by a healthcare professional. 
     It is recommended that the user wash the jaw exerciser  100  with soap, such as dish soap, and water prior to first use, and after subsequent uses. 
     The present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Certain adaptations and modifications of the invention will be obvious to those skilled in the art. Therefore, the presently discussed embodiments are considered to be illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than the foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.