Patent Publication Number: US-2015068041-A1

Title: Disposable prophylaxis angle with improved gear retainer

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a divisional of U.S. patent application Ser. No. 13/682,862, filed on Nov. 21, 2012. 
    
    
     FIELD OF THE INVENTION 
     The present technology generally relates to dental or prophylaxis angles and, more specifically, to disposable prophylaxis angles and methods of use. 
     BACKGROUND 
     Prophylaxis angles (aka “prophy” angles or dental angles) are used by dental personnel to clean and/or polish teeth. Prophy angles generally include a body having a head, where the head has a central axis angled relative to a central axis of the body. The structural angle between the two central axes is normally 90°. However, other types of prophy angles, known as contra-angles, include a head angled from the body at an angle greater than 90°. Typically, the head of a contra-angle may be angled between about 10° to about 30° greater than 90° from the axis of the body. Contra-angles can be used by dental personnel for reaching difficult spots within the mouth of a patient. Prophy angles will usually have a dental bit, such as a prophy cup, a brush, and/or a bur, coupled at the end of the head that allows the dentist to clean and polish a patient&#39;s teeth. 
     Drive and driven gears are arranged within the body of the prophy angle in a meshing relationship in order to rotate the dental bit. In some devices, a cap slips over the driven gear and attaches to the body in order to secure the gears within the body. A portion of the driven gear usually extends out of an opening in the cap and provides a location where the dental bit can be attached. Once entirely assembled, the prophy angle can be coupled to a handpiece, such as a Doriot-type handpiece. Specifically, the body is slipped over the nose of the handpiece which has a collet adapted to receive the shaft of the driving gear. The collet holds the drive shaft against axial movement and connects the shaft to a motor adapted to rotate the driving gear which, in turn, rotates the driven gear and the dental bit. 
     In the past, dentists used non-disposable, metal prophy angles. While sturdy, metal prophy angles required extensive care to ensure against transferring disease and germs from one patient to another. If the metal prophy angle is not properly sealed, bodily fluids from a patient, such as saliva and/or blood, can penetrate the prophy angle. Simply wiping down the metal prophy angle between uses is not adequate sterilization. Rather, to achieve proper sterilization, the metal prophy angles must be autoclaved after each use and periodically disassembled and thoroughly cleaned in order to remove contamination. Cleaning the metal prophy angles also removes any grit which may have penetrated the housing which, if not properly removed, might interfere with the gears and thereby reduce the operating life of the metal prophy angle or otherwise make it difficult to operate. Metal prophy angles also require periodic lubrication to ensure that the gears run smoothly, quietly, and efficiently to reduce heat build-up. Thus, the care required for metal prophy angles is quite extensive. 
     Due to the extensive care required by non-disposable prophy angles, plastic disposable prophy angles are desired by dentists. Disposable prophy angles are much more sanitary than non-disposable ones, and therefore more useful in preventing cross-contamination between patients. Moreover, their disposable nature eliminates the need to thoroughly sanitize, clean, and lubricate them between each use. While various types and configurations of disposable prophy angles have been made, it nonetheless remains beneficial to find improved disposable prophy angles that offer advantages over prior models. 
     SUMMARY OF THE INVENTION 
     In some embodiments, a dental prophylaxis angle is disclosed and may include a body having a neck that defines a first axial bore and a head that defines a second axial bore, the first and second axial bores communicating at an intersection and being angularly-offset from each other, and the body defining an opening that spans contiguous portions of both the neck and the head. A drive gear may be rotatably mounted in the first axial bore and having a drive gear head and a locking flange axially-offset from the drive gear head, an annular locking groove being defined between the drive gear head and the locking flange. A driven gear may be rotatably mounted in the second axial bore and operatively coupled to the drive gear. A gear retainer may be included and have an annular body configured to extend about an outer surface of the head, a heel extending from the annular body, an arm extending from the heel, and a wedge extending from the arm, wherein the heel and the arm are cooperatively configured to cover the opening and the wedge is configured to be received in the annular locking groove. 
     In other embodiments, a method of assembling a prophylaxis angle is disclosed. The method may include inserting a drive gear into a first axial bore defined within a neck of an angle body, the drive gear having a drive gear head and a locking flange axially-offset from the drive gear head, and inserting a driven gear into a second axial bore defined within a head of the angle body, the first and second axial bores being angularly-offset from each other and communicating at an intersection in the angle body, the body defining an opening that spans contiguous portions of both the neck and the head. The method may also include operatively coupling the drive gear to the driven gear such that rotation of one rotates the other, and installing a gear retainer on the head, the gear retainer having an annular body that extends about an outer surface of the head, a heel extending from the annular body, an arm extending from the heel, and a wedge extending from the arm. 
     In yet other embodiments, a gear retainer for securing a drive gear and a driven gear within a prophylaxis angle housing may be disclosed. The gear retainer may include an annular body configured to extend about an outer surface of a head of the prophylaxis angle housing when installed, a heel extending from the annular body, an arm extending from the heel at an angle, and a wedge extending orthogonally from the arm. 
     The features and advantages of the present invention will be readily apparent to those skilled in the art upon a reading of the description of the preferred embodiments that follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following figures are included to illustrate certain aspects of the present disclosure, and should not be viewed as exclusive embodiments. The subject matter disclosed is capable of considerable modification, alteration, and equivalents in form and function, as will occur to those skilled in the art and having the benefit of this disclosure. Moreover, while the subject technology is susceptible of many different embodiments, there is shown in the drawings and will herein be described in detail various embodiments of the disclosure with the understanding that the embodiments are to be considered an exemplification of the principles of the subject technology and are not intended to limit the broad aspect of the disclosure to the specific embodiments illustrated. 
         FIG. 1  illustrates an exemplary prophy angle, according to one or more embodiments disclosed. 
         FIGS. 2   a  and  2   b  illustrate front and side views, respectively, of an exemplary drive gear, according to one or more embodiments disclosed. 
         FIGS. 3   a - 3   c  illustrate front, side, and end views, respectively, of an exemplary driven gear, according to one or more embodiments disclosed. 
         FIGS. 4   a - 4   c  illustrate isometric, side, and interior views, respectively, of an exemplary gear retainer, according to one or more embodiments disclosed. 
         FIG. 5  illustrates another exemplary prophy angle, according to one or more embodiments disclosed. 
         FIGS. 6   a  and  6   b  illustrate isometric and side views of another exemplary gear retainer, according to one or more embodiments disclosed. 
         FIG. 7  illustrates another exemplary prophy angle, according to one or more embodiments disclosed. 
         FIGS. 8   a  and  8   b  illustrate isometric and side views of another exemplary gear retainer, according to one or more embodiments disclosed. 
         FIG. 9  illustrates another exemplary prophy angle, according to one or more embodiments disclosed. 
         FIGS. 10   a  and  10   b  illustrate isometric and side views of another exemplary gear retainer, according to one or more embodiments disclosed. 
     
    
    
     DETAILED DESCRIPTION 
     While the present invention is susceptible of many different embodiments, there is shown in the drawings and will herein be described in detail one or more exemplary embodiments of the invention with the understanding that the present disclosure is to be considered an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiments illustrated. 
     Referring to  FIG. 1 , illustrated is an exemplary prophylaxis angle (“prophy” angle)  10 , according to one or more embodiments disclosed. The prophy angle  10  includes a body  12  having a sleeve  14 , a neck  16 , and a head  18 . In one embodiment, the sleeve  14 , neck  16 , and head  18  may be formed as a single, integral piece. In other embodiments, however, the sleeve  14 , neck  16 , and head  18  may be individual components coupled together by various means, including, but not limited to, mechanical fasteners, structural threading, adhesives, ultrasonic welding, combinations thereof, or the like. As illustrated, the sleeve  14  may be formed as an elongate cylinder, having a generally circular cross-section, but may equally be formed using other hollow, accommodating shapes, without departing from the scope of the disclosure. A slot  20  may be defined at the distal end  22  of the sleeve  14  and configured to receive a positioning pin or finger from a handpiece (not shown), such as a standard Doriot-type handpiece. In one embodiment, the slot  20  is longer than necessary to accommodate the positioning pin from the handpiece, and the thinness of the walls of the sleeve  14  permits the sleeve  14  to expand slightly when it is forced onto the corresponding handpiece for operation. 
     The proximal end of the sleeve  14  tapers to the neck  16 , which exhibits a smaller outside and inside diameter than the sleeve  14  but is nonetheless coaxial with the sleeve  14 . The sleeve  14  and the neck  16  cooperatively define a first axial bore  24  having a first central axis  26 . The head  18  is generally formed as a cylinder extending from the neck  16  and defining a second axial bore  28  that has a second central axis  30 . The first and second axial bores  24 ,  28  are in communication with each other at an intersection  29  of the neck  16  and the head  18 . 
     In one embodiment, an annular or generally arcuate groove  23  is defined about at least a portion of the distal end  25  of the head  18 . An opening  27  may be defined in the neck  16  behind the head  18 , and may span contiguous portions of both the neck  16  and the head  18 . In one embodiment, the opening  27  may be generally rectangular in shape. In other embodiments, however, the opening  27  may take the form of other shapes without departing from the scope of the disclosure. 
     The interior of the head  18  may further define an axial protrusion  31 , an annular channel  33 , and an interior biasing surface  35 . The axial protrusion  31  extends axially into the second axial bore  28  and provides a mounting location for a driven gear  38 , as will be described below. The annular channel  33  may be defined in the head  18  about the base of the axial protrusion  31 , and may also facilitate a portion of the mounting location for the driven gear  38 . The interior biasing surface  35  is generally orthogonal to the first central axis and is exposed to the first axial bore  24 . 
     As illustrated, the head  18  may be disposed at an angle with respect to the neck  16 , with the first central axis  26  intersecting the second central axis  30  at point A. Other prophy angles, such as the prophy angle  100  described below with reference to  FIG. 5 , have the second central axis  30  disposed at a right angle  32  (i.e., 90° from the first central axis  26 ) with respect to first central axis  26 . The prophy angle  10  illustrated in  FIG. 1  may be characterized as a contra-angle, where the second central axis  30  is angularly-offset from the right angle  32  by a first angle  34 . In one or more embodiments, the first angle  34  ranges between about 10° to about 30°. In at least one embodiment, however, the first angle  34  may be about 15° to about 22°. 
     The prophy angle  10  further includes a drive gear  36 , a driven gear  38 , and a gear retainer  40  to secure the drive and driven gears  36 ,  38  within the body  12 . Referring to  FIGS. 2   a  and  2   b , illustrated are front and side views, respectively, of the drive gear  36 , according to one or more embodiments. The drive gear  36  includes a drive gear head  43 , an elongate, rotatable shaft  44  extending from the drive gear head  43 , a locking flange  46 , an intermediate flange  48 , and a plurality of angularly-spaced driving teeth  50  extending axially from the proximal end of the drive gear head  43 . The driving teeth  50  extend about a rotational axis  52  of the drive gear  36 . As can be appreciated, the rotational axis  52  of the drive gear  36  may be substantially co-axial with the first central axis  26  ( FIG. 1 ) when the prophy angle  10  is fully assembled. In one embodiment, a drive gear protrusion  51  may be defined on the end of the shaft  44  and extend axially from the driving teeth  50  a short distance. 
     The drive gear head  43  includes a drive bearing surface  54  and a tapered trailing edge  56 . In one embodiment, the drive bearing surface  54  is the outer circumferential surface of the drive gear head  43  and extends axially from the plurality of driving teeth  50 . The tapered trailing edge  56  provides a structural transition from the drive bearing surface  54  to the shaft  44 . The locking flange  46  is axially-spaced from the drive gear head  43  and, in particular, from the tapered trailing edge  56 , thereby defining an annular locking groove  58  therebetween. In one embodiment, the locking groove  58  may have an outside diameter that is substantially the same as the diameter of the shaft  44 . In other embodiments, the outside diameter of the locking groove  58  may be more or less than the outside diameter of the shaft  44 , without departing from the scope of the disclosure. In some embodiments, the locking groove  58  may be configured to receive a portion of the gear retainer  40  in order to secure the drive gear  36  within the body  12  ( FIG. 1 ), as will be described in more detail below. 
     The intermediate flange  48  may be axially-spaced from the locking flange  46  along the length of the shaft  44 . In one embodiment, the intermediate flange  48  forms an integral part of the shaft  44  and is molded or otherwise constructed therewith as a single structural element. In other embodiments, however, the intermediate flange  48  is coupled to the shaft  44  using various means known in the art, such as, but not limited to, mechanically-fastening, ultrasound welding, adhesives, combinations thereof, or the like. In one embodiment, the intermediate flange  48  has a tapered leading edge  60  to allow for easier assembly of the prophy angle  10 . 
     Both the drive bearing surface  54  and the intermediate flange  48  may have respective outside diameters that are larger than that of the shaft  44  but slightly less than the inside diameter of the first axial bore  24  defined in the neck  16  ( FIG. 1 ). Accordingly, during operation the drive bearing surface  54  and the intermediate flange  48  may each be configured to bias the inside surface of the first axial bore  24  or otherwise help maintain the drive gear  36  substantially centered therein. In one or more embodiments, the locking flange  46  may also have a similarly-sized outside diameter so as to help maintain the drive gear  36  substantially centered within the first axial bore  24 . 
     Referring now to  FIGS. 3   a ,  3   b , and  3   c , illustrated are front, side, and end views, respectively, of the driven gear  38 , according to one or more embodiments disclosed. The driven gear  38  may be a generally-cylindrical structure having a rotational axis  78  that may be substantially co-axial with the second central axis  30  ( FIG. 1 ) when the driven gear  38  is fully assembled within the prophy angle  10 . The driven gear  38  includes a first end  62 , a second end  64 , and a driven bearing surface  66  extending between the first and second ends  62 ,  64 . The first end  62  may include a boss  68  that defines a bit cavity  70  therein. The bit cavity  70  may extend axially into the driven gear  38  and define a plurality of axially-extending splines  72  therein. The splines  72  may be configured to engage or otherwise secure a dental bit to the driven gear  38 , as will be described below. In other embodiments, the splines  72  may be substituted for other engagement means such as, screw threadings, without departing from the scope of the disclosure. 
     The boss  68  may be a tapered, annular structure, but in other embodiments, the boss  68  may be a substantially-cylindrical structure, without departing from the scope of the disclosure. The first end  62  may further define a shoulder  67  adjacent the driven bearing surface  66  and substantially orthogonal to the rotational axis  78 . The shoulder  67  may provide a structural transition from the driven bearing surface  66  to a radial surface  69  substantially parallel to the rotational axis  78 , but orthogonal to the shoulder  67 . The shoulder  67  and the radial surface  69  may each be configured to bias corresponding portions of the gear retainer  40  in order to maintain the driven gear  38  in its assembled configuration and centered within the second axial bore  28  ( FIG. 1 ) during operation. 
     The second end  64  of the driven gear  38  may define a mounting pedestal  74  and a plurality of angularly-spaced driven teeth  76 . The driven teeth  76  may extend about the rotational axis  78  and also about the outer circumferential surface of the mounting pedestal  74 . The driven teeth  76  may be configured to engage the drive teeth  50  ( FIGS. 2   a  and  2   b ) in a generally meshing relationship. In one embodiment, the drive and driven teeth  50 ,  76  are characterized as corresponding spur gears with straight teeth  50 ,  76  parallel to their respective axes of rotation  52 ,  78 . In other embodiments, however, the drive and driven teeth  50 ,  76  may be corresponding bevel gears, where the axes of rotation  52 ,  78  intersect but the gears  36 ,  38  are conically-shaped such that the axes  52 ,  78  are not orthogonal, but angularly-offset. 
     A mounting cavity  80  may be defined within the mounting pedestal  74 . The mounting cavity  80  may be configured to receive the axial protrusion  31  ( FIG. 1 ) defined in the head  18  when the driven gear  38  is inserted into the second axial bore  28 , thereby mounting the driven gear  38  for rotation therein. In one embodiment, the mounting pedestal  74  is a tapered, annular structure. In other embodiments, however, the mounting pedestal  74  may be substantially cylindrical. In either case, a mounting surface  75  of the mounting pedestal  74  may be received within or otherwise come into close proximity with the annular channel  33  ( FIG. 1 ) defined in the head  18 . 
     The driven bearing surface  66  may have an outside diameter that is slightly less than that of the inside diameter of the second axial bore  28  ( FIG. 1 ). Accordingly, the driven bearing surface  66  may be configured to bias the inner surface of the second axial bore  28  and thereby maintain the driven gear  38  substantially centered therein during use. 
     Referring now to  FIGS. 4   a ,  4   b , and  4   c , illustrated are isometric, side, and interior views, respectively, of an exemplary gear retainer  40 , according to one or more embodiments disclosed. The gear retainer  40  may have a generally annular body  82  defining a central opening  83  and an inner circumferential surface  84  that transitions orthogonally into a generally planar, first retaining surface  85 . The central opening  83  provides a second retaining surface  87 , substantially orthogonal to the first retaining surface  85 . The first and second retaining surfaces  85 ,  87  may be configured to engage or otherwise bias the shoulder  67  and the radial surface  69 , respectively, of the driven gear  38  ( FIGS. 3   a  and  3   b ) when the prophy angle  10  is in its assembled configuration. 
     One or more retainer protrusions  86  may be arranged or otherwise formed about the inner circumferential surface  84  of the gear retainer  40 . The retainer protrusions  86  may be equidistantly-spaced about the inner circumferential surface  84 , or they may be randomly-spaced, without departing from the scope of the disclosure. The retainer protrusions  86  may be configured to be received into (e.g., snapped into) and/or generally mate with the arcuate groove  23  ( FIG. 1 ) defined about the distal end  25  of the head  18 . In at least one embodiment, the retainer protrusions  86  are omitted from the gear retainer  40 , and the gear retainer  40  is otherwise secured to the head  18  by other means of attachment such as, but not limited to, ultrasonic welding, mechanical attachments, adhesives, combinations thereof, and the like. 
     The gear retainer  40  may also include an arcuate heel  88  that extends from the annular body  82 , an arcuate arm  90  that extends from the heel  88 , and an arcuate wedge  92  that extends from the arm  90 . As illustrated in  FIG. 4   b , the heel  88  extends substantially perpendicular from the annular body  92 , forming a right angle  93  therebetween. The arm  90  extends from the heel  88  at an angle  94  offset from the right angle  93 . The angle  94  is configured to generally correspond to the first angle  34  ( FIG. 1 ) and thereby accommodate the angular offset between the first and second central axes  28 ,  30  ( FIG. 1 ). Accordingly, the angular disposition between the heel  88  and the arm  90  allows the gear retainer  40  to properly cover the opening  27  ( FIG. 1 ) that extends across portions of both the neck  16  and the head  18 . Specifically, the arcuate heel  88  may cover the opening  27  spanning the portion of the head  18 , and the arcuate arm  90  may cover the opening  27  spanning the portion of the neck  16 . 
     Referring again to  FIG. 1 , with continued reference to  FIGS. 2   a - b,    3   a - c,  and  4   a - c,  the prophy angle  10  may be assembled by inserting the drive gear  36  axially into the first axial bore  24  through the opening at the distal end  22  of the body  12 . The drive gear  36  is advanced until the drive gear protrusion  51  ( FIG. 2 ) comes into contact with the interior biasing surface  35  of the head  18 , or otherwise comes substantially close thereto. As can be appreciated, the drive gear protrusion  51  may serve to axially-offset the drive gear  36  from the head  18  so that the driving teeth  50  may rotate unobstructed from the head  18  during operation. 
     The driven gear  38  may then be inserted axially into the second axial bore  28 , leading with its second end  64  ( FIGS. 3   b  and  3   c ). The driven gear  38  is advanced until the axial protrusion  31  defined in the head  18  is received into the mounting cavity  80  defined in the mounting pedestal  74  ( FIGS. 3   b  and  3   c ) and the mounting surface  75  of the mounting pedestal  74  is received into the annular channel  33 . Inserting the driven gear  38  into the second axial bore  28  also places the driven teeth  76  in meshing engagement with the driving teeth  50  ( FIGS. 2   a - b ), such that rotation of one causes rotation of the other. 
     Once the teeth  50 ,  76  are engaged for mutual operation, the gear retainer  40  may be installed on the head  18  to prevent the drive and driven gears  36 ,  38  from being removed from the body  12 . To install the gear retainer  40 , the central opening  83  ( FIGS. 4   a  and  4   c ) is aligned with the first end  62  ( FIG. 3   b ) of the driven gear  36  and the boss  68  ( FIGS. 3   a  and  3   b ) is extended therethrough. The inner circumferential surface  84  ( FIGS. 4   a  and  4   c ) of the gear retainer  40  has a slightly larger diameter than the outer circumferential surface of the head  18  such that the inner circumferential surface  84  can be extended over the outer circumferential surface of the head  18 . As the gear retainer  40  is advanced onto the head  18 , the radial disposition of the heel  88  and arm  90  ( FIGS. 4   a - 4   c ) is adjusted so as to generally align with the opening  27 . In one embodiment, the gear retainer  40  is advanced until the retainer protrusion(s)  86  ( FIGS. 4   a  and  4   c ) snaps into the arcuate groove  23  defined about the distal end  25  of the head  18 . In other embodiments, the gear retainer  40  may be formed such that it can be attached to the head  18  in other ways, such as via a threaded screw connection or adhesives. Once properly coupled, the gear retainer  40  may be ultrasonically-welded to the head  18  such that separation of the two components is prevented. 
     In this coupled and assembled configuration, the first retaining surface  85  ( FIGS. 4   a  and  4   c ) of the gear retainer  40  engages or is otherwise substantially adjacent to the shoulder  67  of the driven gear  38  ( FIGS. 3   a  and  3   b ). As illustrated in  FIG. 1 , the first retaining surface  85  also engages or is otherwise substantially adjacent to the distal end  25  of the head  18 . The second retaining surface  87  ( FIGS. 4   a  and  4 C) of the gear retainer  40  engages or is otherwise substantially adjacent to the radial surface  69  of the driven gear  38  ( FIGS. 3   a  and  3   b ). Moreover, the arcuate wedge  92  ( FIGS. 4   a - 4   c ) is disposed or otherwise received within the locking groove  58  ( FIG. 2   b ) to lock the drive gear  36  within the body  12  and prevent its axial displacement. By biasing against the tapered trailing edge  56  ( FIG. 2   b ) on one side and against the axial face of the locking flange  46  ( FIG. 2   b ) on the other side, the wedge  92  maintains the drive gear  36  in a position that allows for a proper meshing relationship between the drive and driven teeth  50 ,  76 . Accordingly, the wedge  92  prevents the drive gear  36  from becoming displaced within the body  12  due to the rotation of the shaft  44 . It will be appreciated that the tapered trailing edge  56  may facilitate easier installation of the wedge  92  within the locking groove  58 . 
     During operation of the prophy angle  10 , when the drive and driven gears  36 ,  38  are mutually rotating, the arcuate inner surfaces of the heel  88 , the arm  90 , and the wedge  92  may be configured to help maintain the drive and driven gears  36 ,  38  in co-axial relation with the first and second central axes  26 ,  30 , respectively. Specifically, the arcuate inner surface of the heel  88  may be arranged adjacent to or otherwise in communication with the driven bearing surface  66  of the driven gear  38  ( FIG. 3   b ); the arcuate inner surface of the arm  90  may be arranged adjacent to or otherwise in communication with the drive bearing surface  54  of the drive gear  36  ( FIG. 2   b ); and the arcuate inner surface of the wedge  92  may be arranged adjacent to or otherwise in communication with the outer circumferential surface of the locking groove  58  of the drive gear  36  ( FIG. 2   b ). 
     Still referring to  FIG. 1 , a dental bit  96  may be attached to the driven gear  38  via the bit cavity  70 . In one embodiment, the dental bit  96  is screwed into the driven gear  38 . In other embodiments, however, other means of attachment may be utilized, without departing from the scope of the disclosure. The dental bit  96  is used to clean or polish a patient&#39;s teeth. In addition to the dental bit  96 , other dental instruments can be attached to the drive gear  38  as is well-known to those skilled in the art. 
     Referring now to  FIG. 5 , illustrated is another exemplary prophy angle  100  according to one or more embodiments of the disclosure. The prophy angle  100  may be substantially similar to the prophy angle  10  described above and therefore may be best understood with reference thereto, where like numerals correspond to like elements that will not be described again in detail. Unlike the prophy angle  10  described above, the first and second central axes  26 ,  30  of the prophy angle  100  may be arranged substantially perpendicular to each other, such that the head  18  is disposed at a right angle to the neck  16 . 
     Referring to  FIGS. 6   a  and  6   b , illustrated are isometric and side views, respectively, of an exemplary gear retainer  140 , according to one or more embodiments disclosed. The gear retainer  140  may be substantially similar to the gear retainer  40  described above and therefore may be best understood with reference to  FIGS. 1 and 4   a - 4   c,  where like numerals correspond to like components that will not be described again. Similar to the gear retainer  40  described above, the arcuate heel  88  of the gear retainer  140  extends substantially perpendicular  102  from the annular body  82 . Unlike the gear retainer  40 , however, the arcuate arm  90  extends from the heel  88  at a generally orthogonal angle  104  with respect to the heel  88 . The angle  104  corresponds to the angular offset between the first central axis  26  and the second central axis  30  ( FIG. 5 ). Accordingly, since the first and second central axes  26 ,  30  in the prophy angle  100  are substantially perpendicular, the angle  104  between the heel  88  and the arm  90  will correspondingly be about 90°. 
     When properly installed, the heel  88  and the arm  90  of the gear retainer  140  cover the opening  27  ( FIG. 5 ) that extends across portions of both the neck  16  and the head  18 . Specifically, the arcuate heel  88  covers the opening  27  spanning the portion of the head  18 , and the arcuate arm  90  covers the opening  27  spanning the portion of the neck  16 . Moreover, the wedge  92  is received in the locking groove  58  defined between the trailing edge  56  of the drive gear  36  and the locking flange  46  (see  FIG. 2   b ) and thereby locks the drive gear  36  within the body  12 . 
     Referring now to  FIG. 7 , illustrated is another exemplary prophy angle  700 , according to one or more embodiments. The prophy angle  700  may be substantially similar to the prophy angle  10  of  FIG. 1  and therefore may be best understood with reference thereto, where like numerals will correspond to like elements not described again in detail. As illustrated, the drive gear  36  and driven gear  38  are arranged within the first and second axial bores  24 ,  28 , respectively, as generally described above. The drive gear  36  and driven gear  38  are installed such that the driving and driven teeth  50 ,  76  are arranged in meshing engagement such that rotation of one causes rotation of the other. Once the teeth  50 ,  76  are engaged for mutual operation, a gear retainer  702  may be installed on the head  18  to prevent the drive and driven gears  36 ,  38  from accidentally being removed from the body  12 . 
     Referring to  FIGS. 8   a  and  8   b , with continued reference to  FIG. 7 , illustrated are isometric and side views, respectively, of the gear retainer  702 , according to one or more embodiments disclosed. The gear retainer  702  may be substantially similar to the gear retainer  40  of  FIGS. 4   a - 4   c  and therefore may be best understood with reference thereto. As illustrated, the gear retainer  702  may have a body  704  that defines a central aperture  714  configured to receive a portion of the driven gear  38  when properly installed on the head  18  of the prophy angle  700 . The body  704  may define an outer circumferential surface  708   a  and an inner circumferential surface  708   b,  and the inner circumferential surface  708   b  may transition orthogonally into a retaining surface  710  similar to the retaining surface  85  of  FIGS. 4   a - 4   c.    
     The gear retainer  702  may also include an arcuate flange  712  that extends from or otherwise forms part of the body  704  such that the inner circumferential surface  708   b  may extend into or otherwise merge with the inner surface of the arcuate flange  712 . An aperture  714  may be defined in the body  704 . In some embodiments, the aperture  714  may be defined entirely by or within the arcuate flange  704 . In other embodiments, the aperture  714  may be defined entirely by or within the body  704 . In yet other embodiments, the aperture  714  may be defined by a combination of both the arcuate flange  704  and the body  704 , without departing from the scope of the disclosure. In operation, the aperture  714  may be configured to receive at least one protrusion  716  ( FIG. 7 ) defined on the outer surface of the head  18  and thereby at least partially secure the gear retainer  702  to the body  12 . Those skilled in the art will readily recognize that more than one aperture  714  may be defined in the body  704  and configured to receive a corresponding more than one protrusion  716  defined on the outer surface of the head  18 , without departing from the scope of the disclosure. 
     Similar to the gear retainer  40  of  FIGS. 4   a - 4   c,  the gear retainer  702  may also include an arcuate heel  718  that extends from the body  704  and an arcuate arm  720  that extends from the heel  718 . As illustrated in  FIG. 8   b , the heel  718  extends substantially perpendicular from the body  704 , thereby forming a right angle  722  therebetween, and the arm  720  extends from the heel  718  at an angle  724  offset from the right angle  722 . The angle  724  may be configured to generally correspond with the first angle  34  ( FIG. 7 ) and thereby accommodate the angular offset between the first and second central axes  28 ,  30 . Accordingly, the angular disposition between the heel  718  and the arm  720  allows the gear retainer  700  to properly occlude the opening  27  ( FIG. 7 ) defined across portions of both the neck  16  and the head  18  of the prophy angle  700 . Specifically, the arcuate heel  718  may be configured to cover the opening  27  spanning the portion of the head  18 , and the arcuate arm  720  may be configured to cover the opening  27  spanning the portion of the neck  16 . 
     The gear retainer  702  may further include an arcuate wedge  726  and a locking mechanism  728  that extend orthogonally from the arm  720 . As illustrated, the locking mechanism  728  may be offset a short distance from the arcuate wedge  726  on the arm  720 . The locking mechanism  728  may include or otherwise define a beveled surface  730  and a locking surface  732 . 
     Referring again to  FIG. 7 , to install the gear retainer  702  on the prophy angle  700 , and thereby secure the drive and driven gears  36 ,  38  within the body  12 , the gear retainer  702  may be extended over the head  18  such that the central opening  706  ( FIGS. 8   a  and  8   b ) is aligned with and receives the driven gear  36  therethrough. The gear retainer  702  may be advanced until the aperture  714  defined in the body  704  receives the protrusion  716  defined on the head  18 . In at least one embodiment, the protrusion  716  may define or otherwise provide a beveled surface  734  configured to engage and cause the arcuate flange  712  to flex until the protrusion  716  is received within the aperture  714  and the arcuate flange  712  is able to snap into place. 
     As the gear retainer  702  is advanced onto the head  18 , the radial disposition of the heel  718  and the arm  720  may concurrently be adjusted so as to generally align with the corresponding portions of the opening  27 . Once aligned with the opening  27 , the arcuate wedge  726  and the locking mechanism  728  may be configured to receive the locking flange  46  therebetween as the arm  720  is secured into the opening  27 , and thereby lock the drive gear  36  within the body  12  and prevent its axial displacement. The beveled surface  730  of the locking mechanism  728  may be configured to engage the neck  16  at the opening  27  and cause the locking mechanism  728  to flex and snap into place. Once snapped into place at the opening  27 , the locking surface  732  may be configured to engage the inner surface of the first axial bore  24 . Accordingly, the locking mechanism  728  and the arcuate flange  712  may cooperatively secure the gear retainer  702  to the prophy angle  700 . In some embodiments, once properly secured to the prophy angle  700 , the gear retainer  702  may be ultrasonically-welded to the head  18  such that separation of the two components is substantially prevented. 
     Referring now to  FIG. 9 , illustrated is another exemplary prophy angle  900  according to one or more embodiments of the disclosure. The prophy angle  900  may be substantially similar to the prophy angle  700  of  FIG. 7  and therefore may be best understood with reference thereto, where like numerals will correspond to like elements not described again in detail. Unlike the prophy angle  700  described above, the first and second central axes  26 ,  30  of the prophy angle  900  may be arranged substantially perpendicular to each other, such that the head  18  is disposed at a right angle to the neck  16 . 
     Referring to  FIGS. 10   a  and  10   b , illustrated are isometric and side views, respectively, of an exemplary gear retainer  902 , according to one or more embodiments. The gear retainer  902  may be substantially similar to the gear retainer  702  of  FIG. 7  and therefore may be best understood with reference thereto. Similar to the gear retainer  702  described above, the arcuate heel  718  of the gear retainer  902  extends substantially perpendicular from the body  704 . Unlike the gear retainer  702 , however, the arcuate arm  720  may extend from the heel  718  at a generally orthogonal angle  904  with respect to the heel  718 . The angle  904  corresponds to the angular offset between the first central axis  26  and the second central axis  30  ( FIG. 9 ). Accordingly, since the first and second central axes  26 ,  30  in the prophy angle  900  are substantially perpendicular, the angle  904  between the heel  718  and the arm  720  will correspondingly be about 90°. Installing the gear retainer  902  on the prophy angle  900  may be accomplished in a manner that is substantially similar to how the gear retainer  702  of  FIG. 7  is installed, and therefore will not be described again in detail. 
     Once the prophy angles  10 ,  100 ,  700 ,  900  are assembled, they can be used by a hygienist or other dental professional to clean or polish teeth. The shaft  44  ( FIG. 2   b ) of the drive gear  36  extends through the open distal end  22  of the body  12  so that it can be attached to a dental handpiece (not shown). In use, the dental handpiece provides rotary motion to the shaft  44 , and rotation of the shaft  44  rotates the drive gear  36 . Due to the meshing configuration between the drive gear  36  and the driven gear  38 , rotation of the drive gear  36  causes rotation of the driven gear  38  which, in turn, rotates the dental bit  96 . The compact design of the prophy angles  10 ,  100 ,  700 ,  900  provide increased visibility and maneuverability within a patient&#39;s mouth. When the hygienist is finished, the prophy angle  10 ,  100 ,  700 ,  900  may be disengaged from the dental handpiece and properly disposed of. 
     In one or more embodiments, some or all of the various components of the prophy angles  10 ,  100 ,  700 ,  900  described above may be made of plastic and manufactured, for example, by injection molding techniques. This provides for an inexpensive, disposable dental hand tool. As discussed earlier, disposable prophy angles are beneficial because they eliminate the need to sterilize the prophy angle between each patient. Thus, there is no risk of cross-contaminating patients. Moreover, the prophy angles  10 ,  100  generally described herein may exhibit a reduced overall size when compared to previous models. For example, the design of the disclosed prophy angles  10 ,  100  may allow for a significant reduction in the diameter and length of the body  12 , especially the respective diameters and lengths of the neck  16  and the head  18 . Those skilled in the art will readily appreciate that this reduces the overall surface area of the prophy angles  10 ,  100 , thereby allowing the hygienist greater visibility of the teeth/mouth area as well as increase maneuverability while still providing the same cleaning method. 
     Therefore, the present invention is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the present invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative embodiments disclosed above may be altered, combined, or modified and all such variations are considered within the scope and spirit of the present invention. The invention illustratively disclosed herein suitably may be practiced in the absence of any element that is not specifically disclosed herein and/or any optional element disclosed herein. While compositions and methods are described in terms of “comprising,” “containing,” or “including” various components or steps, the compositions and methods can also “consist essentially of” or “consist of” the various components and steps. All numbers and ranges disclosed above may vary by some amount. Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range is specifically disclosed. In particular, every range of values (of the form, “from about a to about b,” or, equivalently, “from approximately a to b,” or, equivalently, “from approximately a-b”) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. Moreover, the indefinite articles “a” or “an,” as used in the claims, are defined herein to mean one or more than one of the element that it introduces. If there is any conflict in the usages of a word or term in this specification and one or more patent or other documents that may be incorporated herein by reference, the definitions that are consistent with this specification should be adopted.