Abstract:
The present invention provides a dental prophylaxis angle that includes a housing, a rotor disposed in the housing, and a drive shaft driving the rotor. The drive shaft and the rotor operate together with a sidewall of the housing against a common surface of the rotor to prevent removal of the rotor from the housing in a direction along an axis of rotation of the rotor.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a Continuation of U.S. application Ser. No. 12/196,891, filed Aug. 22, 2008, now U.S. Pat. No. 8,360,774, which is a Continuation of U.S. application Ser. No. 11/189,193, filed Jul. 26, 2005, now U.S. Pat. No. 7,422,433, all of which are incorporated herein by reference in their entirety. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    N/A 
       FIELD OF THE INVENTION 
       [0003]    The present invention relates to dental instruments, and more particularly to dental prophylaxis devices. 
       BACKGROUND OF THE INVENTION 
       [0004]    Dental prophylaxis angles, generally referred to as “prophy angles,” are commonly used dental instruments providing rotation for dental tools such as brushes, prophy cups, or other receptacles used in polishing teeth. A prophy angle typically includes a housing having a neck and a head portion extending at approximately a 90° angle to the neck, which increases the ability of a dentist to reach various surfaces of the teeth of a patient. A drive shaft can be located within the housing and attached to a driven gear in the head of the prophy angle. Prophy angles are generally affixed to a handpiece, which connects the prophy angle to a drive source, thereby enabling a rotating motion of the drive shaft and driven gear of the prophy angle and any affixed dental tool. 
         [0005]    Prophy angles are commonly manufactured from lightweight plastic to make them disposable and thereby increasing overall sterility in the dental environment. One drawback of these current instruments is that they are often cumbersome to assemble and may contain a myriad of loosely fitting parts. For example, prior prophy angles have included a two-piece housing which must be mated together prior to use to enclose the inner components of the angle. During use of the prophy angle, the housing may experience increased strain when in contact with the teeth of a patient, and cause the seams in the housing to separate and expose the inner components of the angle. Such separation in the housing may result in a spacing apart or separation of the internal gears of the angle, potentially leading to failure of the device. 
         [0006]    In addition to concerns regarding housing integrity, the drive shaft and driven gear of an angle may experience some displacement during use of the prophy angle. As the angle is being used, the drive shaft may excessively move forward or backward due to an increase in the pressure placed on the rotating parts, and result either in an increased amount of force between the gear teeth of the drive shaft and the driven gear, or separation of engagement of the gear teeth of the shaft from those of the driven gear. Subsequently, this displacement can also lead to a premature malfunction of the prophy angle prior to completing a dental procedure. 
         [0007]    Furthermore, conventional prophy angles may have a significant amount of contact between surfaces of the housing, the drive shaft and the driven gear. Such large, often flat surfaces can generate increasing amounts of friction as the prophy angle is used at higher rates of rotation. The increased friction can prevent the prophy angle from reaching the desired rate of rotation, may cause enhanced wear and tear between the interacting components, and may generate greater heat, thus making the angle uncomfortable to use. 
         [0008]    In light of the above limitations, it would be desirable to provide a prophy angle having a singular housing, where the prophy angle limits displacement of the internal components during use, and further reduces friction between interacting surfaces. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention advantageously provides a dental prophylaxis angle having a housing, a drive shaft, and a rotor. In one embodiment, the drive shaft drives the rotor and operate together with a sidewall of the housing against a common surface of the rotor to prevent removal of the rotor from the housing in a direction along an axis of rotation of the rotor. 
         [0010]    In another embodiment, a prophy angle can include a housing defining a first bore and a second bore, a rotor disposed within the second bore and rotating about an axis parallel to an interior wall of the second bore, a multiplicity of ribs extending from the interior wall of the second bore, and a drive shaft driving the rotor disposed within the first bore. The drive shaft and the multiplicity of ribs operate together against a common surface of the rotor to prevent removal of the rotor from the second bore in a direction along the axis. 
         [0011]    In yet a different embodiment, a dental prophylaxis angle can include a housing defining a first bore and a second bore, a rotor disposed within the second bore and rotating about an axis parallel to an interior wall of the second bore; and a drive shaft driving the rotor disposed within the first bore. The drive shaft and a sidewall of the second bore operate together against a common surface of the rotor to prevent removal of the rotor from the second bore in a direction along the axis. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    A more complete understanding of the present invention, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein: 
           [0013]      FIG. 1  shows a top view of a housing in accordance with the present invention; 
           [0014]      FIG. 2  illustrates a side view of a housing in accordance with the present invention; 
           [0015]      FIG. 3  depicts a rotor in accordance with the present invention; 
           [0016]      FIG. 4  shows a side view of a drive element in accordance with the present invention; 
           [0017]      FIG. 5  illustrates an angled view of a drive element in accordance with the present invention; 
           [0018]      FIG. 6  depicts a side view of a drive element in accordance with the present invention; 
           [0019]      FIG. 7  illustrates a collar in accordance with the present invention; 
           [0020]      FIG. 8  shows an assembly view of a prophy angle in accordance with the present invention; and 
           [0021]      FIG. 9  shows an assembled prophy angle in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0022]    In an exemplary embodiment, the present invention provides a dental prophylaxis angle having a singular housing  10 , a drive shaft  12 , a rotor  14 , and a collar  16 .  FIGS. 1 and 2  illustrate the singular housing  10  as a one-piece element which defines a first bore  18  extending through a length of the housing  10 . A second bore  20  is in communication with and extends from the first bore  18  at a substantially perpendicular angle. The housing  10  further defines an annular groove  22  circumscribing a portion of the first bore  18 , and a housing shoulder  24  disposed about a portion of the first bore  18  where the first bore  18  decreases in diameter. 
         [0023]    A plurality of rotor bearing elements  26  is radially positioned within the second bore  20 . Each rotor bearing element  26  includes an upper bearing surface  28 , as well as having a spherical recess  30  on a surface of the bearing element that is substantially perpendicular to the upper bearing surface  28 . In addition, the housing  10  includes a third bore  32  that is substantially coaxial with the second bore  20 , yet having a diameter substantially less then the diameter of the second bore  20 . The housing  10  can be constructed from a variety of available plastics having sufficient rigidity to apply pressure to a patient&#39;s teeth, while remaining flexible enough to receive the internal components of the prophy angle. 
         [0024]    As shown in  FIG. 3 , the rotor  14  includes a button  34  disposed at one end, to provide, e.g., attachment of a prophy cup (not shown). The button  34  may include additional protrusions to accommodate a specific prophy cup, but is not limited to a specific shape or orientation. The rotor  14  further includes a radially-extending flange  36 , a plurality of driven gear teeth  38 , and an intermediate disc  40  radially disposed about a center axis of the rotor  14 . Moreover, a spherical bearing  42  is included along a length of the rotor  14 , in addition to a spherical tip  44  at an end of the rotor  14  opposite the button  34 . 
         [0025]    In  FIGS. 4 through 6 , the drive shaft  12  is shown as an elongate body having a plurality of drive gear teeth  46  disposed at one end. A post  48  extends shortly beyond the plurality of drive gears  46 , with the post  48  having a spherical depression  50  on an end surface. 
         [0026]    Now referring to  FIG. 7 , the present invention includes the collar  16 , where the collar  16  defines an axial bore  52  extending throughout the length of the collar  16 . The collar  16  also includes a protruding first annular wall  54  circumscribing a portion of the collar  16  proximate a first end of the collar  16 . A second annular wall  56  circles the axial bore  52  at a second end surface opposite the first end of the collar  16 . Both the first and second annular walls may include semi-circular cross sections, e.g., the protruding walls may have rounded surfaces. In addition, the collar  16  defines a collar shoulder  58  disposed about a portion of the collar  16  where the exterior diameter of the collar  16  decreases. 
         [0027]    As shown in  FIG. 8 , the prophy angle of the present invention is shown in an exploded assembly view to illustrate the placement and interaction of the components. In this embodiment, the rotor  14  is positioned within the second bore  20  of the singular housing  10  with the spherical tip  44  of the rotor  14  extending downward into the third bore  32  of the housing  10 . Because of the spherical nature of the rotor  14  tip, there is minimal contact between the rotor  14  and the lower surface of the third bore  32  as compared to a traditional tip having a flat surface. As such, friction between the spherical tip  44  and the housing  10  is reduced significantly at this contact point. Moreover, during use, the spherical tip  44  acts to transmit high thrust loads experienced by the rotor  14  to the housing  10 , thereby reducing the loads experienced between the meshed gears of the rotor  14  and the drive shaft  12 . 
         [0028]    The spherical bearing  42  of the rotor  14  is received by the spherical recess  30  of each of the plurality of rotor bearing elements  26 , with the intermediate disc  40  being located proximate to the upper bearing surface  28  of each of the plurality of rotor bearing elements  26 . Of note, it is not necessary that the curvature of the spherical bearing or the curvature of the spherical recesses are indeed substantially spherical. Rather, it is intended that the curvature of the spherical bearing is substantially similar to the curvature of the recess in the rotor bearing elements, whether the curved surfaces are precisely spherical, ovoidal, elliptical or otherwise. 
         [0029]    The flange  36  of the rotor  14  rests over the opening of the second bore  20 , effectively preventing any debris from entering the interior of the housing  10 , which could potentially interfere with the subsequent operation of the prophy angle, while the button  34  for a prophy cup (not shown) remains exposed to the exterior of the housing  10 . 
         [0030]    Subsequent to the placement of the rotor  14 , the drive shaft  12  is inserted into the first bore  18  of the housing  10  such that the plurality of drive gear teeth  46  of the drive shaft  12  engages the plurality of driven gear teeth  38  of the rotor  14 . In addition, the spherical depression  50  on the post  48  of the drive shaft  12  abuts the spherical bearing  42  of the rotor  14 . While in general operation, the contact between the spherical depression  50  of the drive shaft  12  and the spherical bearing  42  of the rotor  14  may be minimal. However, should the drive shaft  12  experience any displacement or increased pressure against the rotor  14 , the rotor  14  will transmit the additional force to the housing  10  through the spherical recesses  30  of the plurality of rotor bearing elements  26 . By transferring the force to the housing  10 , the likelihood that the increased force will cause the gears of the drive shaft  12  and the rotor  14  to seize is significantly reduced. 
         [0031]    Next, the collar  16  is positioned in the first bore  18  of the housing  10  such that a portion of the drive shaft  12  is located within the axial bore  52  of the collar  16 . The collar  16  is placed within the housing  10  and moved towards the direction of the rotor  14 . Moreover, the second annular wall  56  of the collar  16  abuts an underside of the plurality of drive gear teeth at a rear shoulder, providing a rounded bearing surface of the collar  16  in contact with the drive shaft  12 . The rounded surface of the second annular wall  56  reduces the contact area between the collar  16  and the drive shaft  12 , thereby reducing friction as compared to traditional flat contact surface areas. 
         [0032]    In this position, the first annular wall  54  of the collar  16  couples with the annular groove  22  of the housing  10 , thereby securing the collar  16  in the housing  10 . As a result, the collar  16  secures the drive shaft  12  in engagement with the rotor  14 , which is further supported and secured by the plurality of rotor bearing elements  26  in the second bore  20  of the housing  10 . These features of the prophy angle significantly reduce and may altogether prevent any displacement of the drive shaft  12  or rotor  14  while the prophy angle is being used. 
         [0033]    The prophy angle of the present invention provides an easily assembled dental device having features which secure the inner components against displacement during use, as well as providing numerous rounded surfaces which reduce friction experienced between moving parts by reducing the contacting surface areas. 
         [0034]    It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described herein above. In addition, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. A variety of modifications and variations are possible in light of the above teachings without departing from the scope and spirit of the invention, which is limited only by the following claims.