Abstract:
This invention relates to an apparatus for dispensing a cord and comprises a housing having a cavity arranged to hold the cord. The housing also has a top cover and a bottom cover to enclose the cord. The dispenser further comprises a knob, handle or button on the dispenser, for example on the top cover or side for use in feeding the cord from the dispenser, an aperture that provides an outlet for the retraction cord to exit the housing, and a cutter near the aperture to cut the dispensed cord.

Description:
[0001]    This application claims the benefit of priority to U.S. Provisional Application No. 61/378,104, filed on Aug. 30, 2010. 
     
    
     BACKGROUND 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates to dental devices, and more particular to an apparatus for dispensing dental cords, such as but not limited to, gingival retraction cords. 
         [0004]    2. Description of the Related Art 
         [0005]    In dental treatment, it is often necessary to retract gingival tissue from a tooth in order to prepare the patient for taking impressions, setting crowns, or effecting restorations. It is important to make an accurate impression of the tooth when constructing artificial crowns to ensure that the crown remains properly secured to the tooth for an extended period of time. It is particularly important to make an accurate impression of the tooth in the area at or below the gingival margin. Failure to take an accurate impression can result in a poorly-formed or deficient prosthesis, particularly at the gingival margin. Premature failure of a crown is often due to poor marginal detail in the impression used to fabricate the crown. Retractions of the gingival tissue are typically performed using gingival retraction cords, for example, cords fabricated of cotton which may be impregnated with a therapeutic preparation. 
         [0006]    A commonly employed conventional method of using retraction cord comprises removing the retraction cord from a bulk container, cutting the retraction cord to an appropriate length, wrapping the length of retraction cord around the base of the tooth several times, and then manually forcing the retraction cord into the sulcus. The manual force will cause the gingival tissue to separate from the tooth and the presence of the cord will prevent the tissue from returning to its original state. In other known methods, two or more separate cords are often required to effect the tissue retraction. 
         [0007]    However, known gingival retraction materials and methods are not without their drawbacks. For example, known cords are typically sold in bulk within a dispensing container. Removing the cord from the containers and judging and cutting appropriate lengths can be time-consuming and laborious. To use the cord, the dental practitioner must estimate the amount required for the particular application. This requires the dental practitioner to use both hands, one to dispense the retraction cord from within the dispenser, which is a bulk length cord, and the other to cut the dispensed retraction cord with scissors that are separate from the dispenser. During this process, the dental practitioner must stop working on the patient and is not able to hold other dental instruments; nor is the dental practitioner able to position instruments in the mouth of the patient. The retraction cord must be wrapped around the tooth while the ends are held in one hand by the practitioner; as such, a significant amount of cord is wasted in the process. If the retraction cord is not cut to the appropriate length the retraction cord will not properly retract the gingival tissue and another piece of retraction cord cut to the appropriate length would be needed, further contributing wasted retraction cord to the process. Also, the cord often becomes entangled with itself within the container making removal difficult or even impossible. 
         [0008]    If an assistant is assisting the dental practitioner, the dental practitioner will have full use of their hands to continue to work on the patient, but then the dental assistant would not be able to assist the dental practitioner while the dental practitioner is working on the patient. For example, while the dental assistant is using both hands to prepare the retraction cord for the dental practitioner, the dental assistant would not be able to place and hold a saliva ejector, or other instrument, in the patient&#39;s mouth. Excess saliva in the mouth of the patient can lead the patient to experience an uncomfortable sensation which could cause the patient to gag, cough or attempt to swallow the saliva. 
         [0009]    Thus, a need exists for an improved apparatus for the dispensing of a retraction cord. 
       SUMMARY 
       [0010]    Disclosed herein is an improved apparatus for dispensing a retraction cord. 
         [0011]    In one embodiment, as embodied and broadly described herein, a device is disclosed for dispensing a retraction cord and comprises a housing having a cavity arranged to hold the retraction cord. The dispenser further comprises a knob, handle or button on the dispenser, for example on the top cover or side for use in feeding the cord from the dispenser, an aperture that provides an outlet for the retraction cord to exit the housing, and a cutter near the aperture to cut the dispensed retraction cord. 
         [0012]    When the cord feeder is a knob on the top cover it is adapted to rotate about an axis, such that rotation of the knob drives the retraction cord through the aperture and out the housing. After a desired length has been dispensed, the dispensed cord can be cut by operating the cutter. 
         [0013]    These and other aspects and advantages of the invention will become apparent from the following detailed description and the accompanying drawings which illustrate by way of example the features of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a perspective view of an embodiment of the dispenser according to the invention. 
           [0015]      FIG. 2  is a first (right) end view of the dispenser of  FIG. 1 . 
           [0016]      FIG. 3  is a first (front) side view of the dispenser of  FIG. 1 . 
           [0017]      FIG. 4  is top view of the internal components of the dispenser of  FIG. 1 . 
           [0018]      FIG. 5  is a perspective view of the knob showing portions which extend into the internal portion of the dispenser. 
           [0019]      FIG. 6  is a view of the lower surface of the top cover. 
           [0020]      FIG. 7  is a top view of the dispenser of  FIG. 1 . 
           [0021]      FIG. 8  is a bottom view of the dispenser of  FIG. 1   
           [0022]      FIG. 9  is a second (left) end view of the dispenser of  FIG. 1   
           [0023]      FIG. 10  is a second (back) side view of the dispenser of  FIG. 1   
       
    
    
     DETAILED DESCRIPTION 
       [0024]    An embodiment described below comprises a device for dispensing a string-like material, referred to herein as a dental cord for use, for example, for gingival retraction. It is understood, however, that the present invention can be used for dispensing many different string like materials, as well as other materials. The term cord is selected for description purposes but also includes a braid, twist, knit, crochet or other similar string-like structures. Referring to  FIGS. 1-4  a dispenser  10  incorporating features of the invention includes a housing  12 , a knob  18 , a cutter  20  and an aperture  24 . The housing  12  further comprises a bottom cover  14 , a top cover  16  and a cavity  26 . The cavity  26  is arranged to house the internal components of the dispenser  10 , which are discussed below.  FIGS. 7-10  are additional views of  FIG. 1 . 
         [0025]    It is to be understood that when an element or component is referred to as being “on” another element or component, it can be directly on the other element or intervening elements may also be present. Furthermore, relative terms such as “between”, “within”, “adjacent” and “below”, and similar terms, may be used herein to describe a relationship of one element or component to another. It is understood that these terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures. 
         [0026]    Although the terms first, second, etc. may be used herein to describe various elements or components, these elements or components should not be limited by these terms. These terms are only used to distinguish one element or component from another. Thus, a first element discussed below could be termed a second element without departing from the teachings of the present invention. It is understood that actual systems or fixtures embodying the invention can be arranged in many different ways with many more features and elements beyond what is shown in the figures. 
         [0027]      FIG. 1  discloses an embodiment of the invention wherein the knob  18  is rotatably mounted on the housing  12 . The knob  18  has a central axis  25  and is adapted to rotate about the central axis  25 . Rotation of the knob  18  about its central axis  25  dispenses an amount of dental cord  30  through the aperture  24  and in proximity to the cutter  20 . Cutter  20  is adapted to cut the dental cord  30  that has been dispensed through aperture  24 . 
         [0028]    In an embodiment incorporating features of the invention, the knob  18  is adapted to rotate in only one direction and does not rotate in the opposite direction. In such an embodiment, retraction of the dispensed dental cord  30  back into the housing  12  is precluded. Prohibiting the knob  18  from rotating in the opposite direction prevents the dispensed dental cord from being retracted back into the housing  12 . It is important to prevent the retraction of the dental cord, such as but not limited to gingival retraction cord, back into the housing  12  because the uncut dispensed dental cord may have become contaminated by contact with bodily fluids of a patient or dental practitioner, or might have been exposed to chemicals or agents used in conjunction with the dental cord. Precluding the retraction of the uncut dispensed dental cord back into the housing  12  reduces the probability of the dental cord within the housing  12  from being contaminated, which, in turn, requires the entire bulk dental cord be discarded. 
         [0029]    In a second embodiment, the knob  18  is adapted to rotate in either direction. In this second embodiment, if too much dental cord, such as dental floss, is dispensed by the dispenser  10 , then rotation of the knob  18  in the opposite direction will allow the excess dental cord to be retracted back into the housing. However, care must be taken so that the exposed end of the cord is not withdrawn into the dispenser so that a subsequent length cannot be fed therefrom. In a further embodiment, for example, for feeding long lengths of the cord, such as may be desired for delivering dental floss, the device will allow feeding a length of floss which can be grasped by the user so that additional floss can be manually pulled from the dispenser without manually turning the knob  18 . In yet other embodiments of the invention, the knob  18  has limited ability to rotate in the opposite direction, and cannot freely rotate in the opposite direction. 
         [0030]    Referring to  FIGS. 4 and 5 , the knob  18  further comprises a shaft  38 , having a first end  42  integral with the knob  18  and a second end  44  which is configured to extend into the housing  12  of the dispenser  10 . The shaft  38  extends through an opening  40  of the top cover  16  of the housing  12  and is received by a drive wheel  32  located within the housing  12 , such that the knob  18  is rotatably mounted to the housing  12 . The drive wheel  32  is positioned on the shaft  38  between the first end  42  and the second end  44 , wherein the second end  44  has an attachment device  46 , such as finger extensions, which couples the second end  44  of the shaft  38  to mating structure on the drive wheel  32 . The first end  42  of the shaft  38  is positioned adjacent to the opening  40  of the top cover  16 . Included in the first end  42  of the shaft  38  is at least one structure, such as but not limited to slots or holes  48 , the at least one structure preferably having a vertical edge  47  and a sloped edge  49 . However, in other embodiments the at least one structure can have many different shapes and/or edges. 
         [0031]    Referring to  FIG. 6 , the top cover  16  of housing  12  comprises a plurality of extensions  50  adjacent the opening  40  and the first end  42  of the shaft  38 . In other embodiments, the housing has at least one extension  50 . Each of the plurality of extensions  50  is adapted to engage a structure  48  to allow or prevent rotational movement of the knob  18 . In an embodiment where the knob  18  can rotate in only one direction, the knob  18  is maintained in a static position when the extensions  50  contact the sloped edge  49  and the vertical edge  47  of the structure  48 . The extensions  50  contacting the vertical edge  47  of the structure  48  prevent rotation of the knob  18  in the opposite direction. When the knob  18  is rotated in the proper direction, the sloped edge  49  of the structure  48  imparts a force on the extensions  50 , causing the extensions to become slightly displaced such that the extensions  50  glide along the sloped edge  49  of the structure  48  until the extensions  50  reach the surface of the first end  42  of the shaft  38  not having a structure  48 . At this point, the surface of the first end  42  imparts a force on the extensions  50  causing the extensions  50  to maintain their displacement and glide along the surface of the first end  42  of the shaft  38 . The extensions  50  remain displaced until the extensions  50  pass the vertical edge  47  of a structure  48 . The extensions  50  are then able to return to their non-displaced position and can contact the sloped edge  49  and the vertical edge  47  of the structure  48 . In other words, as the knob  18  is turned to dispense the cord the extensions  50  ride along the rotating surface of the first end  42 , sliding over the structure  48 . However, if the knob  18  is rotated in the opposite direction (i.e., backward) at least one extension will slide into a structure  48  and will contact the vertical edge  47  preventing further backward rotation. 
         [0032]    In some embodiments of the invention, there is at least one extension  50 , while in other embodiments there is a plurality of extensions  50 . Additionally, in some embodiments there is at least one structure  48 , while in other embodiments, there are a plurality of structures  48 . Furthermore, the structures  48  can be evenly spaced apart or the separation between structures  48  can be varied. When the extensions  50  are gliding on the surface of the first end  42 , in between structures  48 , or on the sloped edge of the structure  48 , the knob  18  has the limited ability to rotate in the opposite direction. Further rotation in the opposite direction is precluded upon the extensions  50  contacting the vertical edge of the structure  48 . 
         [0033]    As shown in  FIG. 4 , the housing  12  has a cavity  26  which is arranged to house the internal components of the dispenser  10 . The internal components housed within the cavity comprise a spool  28  of bulk dental cord  30 , a drive wheel  32 , a second wheel  34  and a bracket  52 . The bracket  52  has a spool extension  54  upon which the spool  28  is rotatably mounted and a conduit  36 . The spool extension  54  is adapted to receive the spool  28  of bulk dental cord  30 . The conduit  36  provides a pathway between the spool  28  and the aperture  24  for the dental cord  30 . The dental cord travels along the conduit  36  as it is being fed from the dispenser  10  by rotation of the knob  18 . The dental cord which has been unwound from the spool  28 , prior to delivery through the aperture  24  is housed within conduit  36  when the dispenser  10  is not in use. 
         [0034]    The drive wheel  32  is in frictional contact with the second wheel  34  and the dental cord  30  so that the dental cord  30  positioned therebetween is fed in response to rotation of the drive wheel  32 . The drive wheel  32 , which rotates about the same central axis as the knob  18 , is attached to the shaft  38  so that the drive wheel  32  rotates in the same direction as the knob  18 . The dental cord from the spool  28  is positioned within the conduit  36  and is in contact with both the drive wheel  32  and the second wheel  34 . When the knob  18  is rotated in the direction to dispense the dental cord, the rotation of the drive wheel  32  causes the dental cord to be driven towards the aperture  24 . Interposing the dental cord between the drive wheel  32  and the second wheel  34  allows the drive wheel  32  to impart a force on the dental cord such that the dental cord is driven in relation to the rotation of the knob  18 . In the embodiments where the knob  18  can rotate in the opposite direction, such rotation causes the drive wheel  32  to impart a force on the dental cord in the opposite direction to retract the dental cord into the housing  12 . The second wheel  34  is positioned adjacent the drive wheel  32  to provide a surface opposite the drive wheel  32 . This configuration ensures that the dental cord remains interposed between the drive wheel  32  and the second wheel  34 , and allows the drive wheel  32  to impart a force on the dental cord to drive the dental cord towards the aperture  24 , or to retract the dental cord in such embodiments where the knob  18  is configured to rotate in the opposite direction. 
         [0035]    One skilled in the art will recognize based on the teachings herein that means other than the drive or second wheels can be used to advance the cord. For example, the cord in the channel can be grasped by an internal clamping means which is then moved linearly forward to feed a length of cord out the aperture, this grasp and feed procedure repeated to provide additional lengths. 
         [0036]    The cutter  20  comprises a cutter body  56  having a cutter first end  58  and a cutter second end  60 , the cutter body  56  being preferentially attached to the bracket  52  at the cutter second end  60 . In the embodiment shown in the figures, the cutter body  56  has a curved shape between the cutter first end  58  and the cutter second end  60 . In other embodiments, the cutter body  56  can have different shapes and is not limited to a curved shape. The cutter first end  58  terminates adjacent the aperture  24  and has a cutting edge  62  attached to the end thereof. The bottom cover  14  of the housing  12  has a cut-out portion (not shown) which is adapted to receive the cutter  20 . 
         [0037]    The cutter  20  is adapted to cut the dispensed dental cord  30  at the aperture  24  in order to separate the dental cord from the dispenser  10 . To operate the cutter  20 , pressure is applied to the cutter body  56  to cause the cutting edge  62  to contact the dispensed dental cord  30  at the aperture  24 . Prior to operating the cutter  20 , the dispensed dental cord is interposed between the cutting edge  62  and a vertical edge  66  of the bottom cover  14  of the housing  12 . When pressure is applied to the cutter  20  the cutter body  56  slides along the outer surface of the cover  14 , the cutting edge  62  contacts the dental cord  30  positioned in the aperture  24  and presses the dental cord against the vertical edge  66  of the bottom cover  14  by the cutting edge  62 . The pressure applied to the cutter body  56  is sufficient to cause the cutting edge  62  to cut the dental cord when pressed up against the vertical edge  66  of the bottom cover  14 . 
         [0038]    Based on the teachings herein, one skilled in the art will recognize that the described device provides to the user the ability to dispense a desired length of cord. 
         [0039]    The dispenser  10  is configured such that it can be operated by a user using a single hand. For example, the user can hold the dispenser  10  in their hand and rotate the knob  18  using a finger, for example the thumb. The knob  18  is rotated using the finger until the desired amount of dental cord is dispensed. The user may than use the same finger used to rotate the knob  18  to operate the cutter  20 . The user, while applying constant pressure to the cutter  20 , can then position the dispenser  10  in proximity to their other hand or another person such that the dispensed dental cord is grasped and separated from the dispenser  10 . The dispenser  10  is configured to ease the process of removing bulk dental cord from its container. Additionally, the knob  18  is configured such that a rotation between structures  48  dispenses a predetermined amount of dental cord. This eliminates the guesswork needed in dispensing dental cord from bulk containers. Different embodiments can dispense different lengths of cord per rotation of the knob  18 , with some embodiments dispensing cord in the range ½ to 3 inches of cord per knob rotation, while other embodiments can dispense cord in the range of 1 to 2 inches of cord per knob rotation. In still other embodiments, approximately 1½ inches of cord can be dispensed per knob rotation. The dispenser can also comprise notch or detent arrangement that the knob  18  interacts with as it rotates, with the user being able to feel the notch interaction as the knob  18  is rotated. This interaction allows the user to feel the amount of rotation by feeling the interaction with the notches, with different notches in different embodiments arranged to allow the user to feel a full rotation, half rotation, quarter rotation, or even smaller amounts of rotation. The dispenser  10  having an integrated cutter  20  also eliminates the need to have to use both hands in order to dispense the dental cord because the same hand can be used to dispense and cut the dental cord; whereas in current practice, one hand is needed to hold the dental cord dispensed from its container and another hand to operate the scissors to cut the dispensed dental cord. 
         [0040]    The dispenser shown in the figures can be made of plastic, but is not intended to be limited to plastic. The dispenser can also be made of various different materials such as, but not limited to, wood, paper, metal, or combinations thereof. In some embodiments of the invention, the cutting edge  62 , such as but not limited to a blade, of cutter  20  is not replaceable; whereas in other embodiments, the cutting edge  62  is disposable and can be replaced with a new cutting edge. The cutting edge  62  is fabricated from materials typically used for knives, scalpels, i.e., carbon steel, stainless steel, ceramics, etc., corrosion resistant materials being preferred for cords which include various medicaments. In some embodiments of the invention, the dispenser  10  is configured such that the housing  12  cannot be opened in order to place a replacement spool  28  of dental cord when all the dental cord has been dispensed. In other embodiments, the housing  12  can be opened and refilled with a replacement spool  28  in order to reuse the dispenser  10 . 
         [0041]    The present invention is described herein with reference to certain embodiments, but it is understood that the invention can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. For example, the embodiments herein show a manually rotated knob. However, alternate cord advancing mechanisms can be used such as a lever or a push button operated spring driven arrangement. Still further, dispensing from the spool can be accomplished by a battery or gas powered drive actuated by a button or lever, the drive rotating the drive wheel  32  or the drive wheel  34 . Still further, it is not required that the cord be on a spool. In an alternate embodiment, the cord is wound on a rod which is placed in the dispenser, or the cord can be loosely placed in a chamber located within the dispenser, no spool or rod being present. In a like manner the cutting function can also utilize a battery, spring or gas driven cutting blade. While the primary purpose of the dispenser is to dispense a retraction cord, one skilled in the art will recognize it has utility as a dispenser for other cords or string-like materials, such as dental floss, or in non-dental applications as a dispenser and cutter for packaging string or twist ties for plastic bags.