Abstract:
A dental prophylaxis angle is provided having a body having a sleeve sized for fitting the nose of a dental handpiece, a drive part comprising a drive shaft extending into the sleeve and a drive member on the drive shaft. A driven part comprising a driven part shaft. The drive and driven parts has axes of rotation which are at substantial angles to each other. The drive part shaft is sized for gripping by a gripping mechanism in the handpiece. The drive member has a forward surface and a post extending from its forward surface. The drive part post is sized to limit end play of the drive part. Additionally, the drive part post has a shallow cavity formed in a forward surface thereof to reduce the contact area of the post with the driven part shaft, and to provide a reservoir for lubricant in the angle.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0001]    Not Applicable  
         STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    Not Applicable.  
         BACKGROUND OF THE INVENTION  
         [0003]    This invention relates to dental prophylaxis angles. It has particular, although not exclusive, application to disposable dental prophylaxis angles.  
           [0004]    Commercial embodiments of the disposable dental prophylaxis angles disclosed in Bailey, U.S. Pat. No. 5,328,369, which is incorporated herein by reference, and particularly the embodiments of FIGS.  1 - 5  and  7 - 8  of the noted Bailey patent, have been successfully sold by Young Dental Manufacturing Company of Earth City, Mo. for several years. Until the present invention, these angles have included the finger  53  on the cap and the groove  55  in the drive gear shaft for the purpose of controlling end play (excessive forward movement) of the drive shaft.  
           [0005]    Other approaches to controlling end play of the drive shaft have been used. Thiedemann et al., U.S. Pat. No. 1,534,817, Graham, U.S. Pat. No. 3,727,313, and Warden et al., U.S. Pat. No. 4,266,933 have allowed the forward end of the drive gear to abut the shaft of the driven gear in order to limit end play. Kraenzle, U.S. Pat. No. 6,203,322, sizes a portion of the shaft of his driven gear for continuous engagement by a flat surface at the forward end of the drive shaft over a substantial area of the flat surface to limit the forward movement of the drive shaft. Commercial devices made in accordance with Graham, U.S. Pat. No. 3,727,313 include a short post, with a central opening extending deeply into the drive shaft, at the forward end of the drive gear.  
           [0006]    All of these modified angles suffer from requiring a large area of contact between the drive gear or extension post and the shaft of the driven gear. This large contact area increases friction and makes lubricating the moving parts more difficult.  
         BRIEF SUMMARY OF THE INVENTION  
         [0007]    Briefly stated, a dental prophylaxis angle of the present invention includes a body having a sleeve, a neck at the end of the sleeve, and a head formation at the end of the neck. A chamber in the head formation and a passage extends through the neck and sleeve and is in communication with the head formation chamber. The sleeve sized to fit the nose of a dental handpiece.  
           [0008]    The dental angle includes a drive part having a drive shaft which extends through the neck and sleeve passage, a drive member near the forward end of the drive shaft, and a post extending from the forward surface of the drive member. The drive part shaft has an axis of rotation and is sized for gripping by a gripping mechanism in the handpiece  
           [0009]    The post has a cavity formed in a forward surface thereof. The cavity can be filled with a lubricant. The drive part post cavity is defined in part by a peripheral wall of the post. The cavity can have a generally concave surface. Alternatively, the cavity can be defined by a generally cylindrical wall and a bottom surface. Preferably, the drive part post has a height approximately equal about 5% to about 30% of the height of the drive gear (from the back surface of the drive gear to the forward surface of the drive gear).  
           [0010]    The dental angle also includes a driven part which is received in the head formation chamber. The driven part includes a driven part shaft, a driven member, and a post to which a dental tool can be mounted. The driven member engages the drive member, such that the driven part is rotated by rotation of the drive part. The driven part has an axis of rotation at a substantial angle to the axis of rotation of the drive part  
           [0011]    The neck ends in a shoulder, and the drive member is sized to limit rearward movement of the drive shaft. Additionally, the drive part post is sized to limit end play of the drive part.  
           [0012]    The driven part post has a length such that thrust loads are passed through the driven part shaft and borne by the angle body, rather than by the angle gears. To accomplish this, the length of the driven part shaft is about 11% to about 15% greater than the drive gear diameter.  
           [0013]    Preferably, the drive part and the driven part are molded of plastic. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0014]    [0014]FIG. 1 is a cross-sectional view of a prophylaxis angle of the present invention;  
         [0015]    [0015]FIG. 2 is a side elevational view of a drive part having a drive shaft and drive member or gear;  
         [0016]    [0016]FIG. 3 is a view of the drive part rotated 90° relative to the view of FIG. 2;  
         [0017]    [0017]FIG. 4 is an end view of the drive member;  
         [0018]    [0018]FIG. 5 is an enlarged cross-sectional view of the drive part taken along line  5 - 5  of FIG. 4 showing the cavity in the end post of the drive part;  
         [0019]    [0019]FIG. 6 is a cross-sectional view of an alternative embodiment of the post of the drive part;  
         [0020]    [0020]FIG. 7 is a side elevational view of a driven part of the prophylaxis angle;  
         [0021]    [0021]FIG. 8 is an end view of the driven part;  
         [0022]    [0022]FIG. 9 is a cross-sectional view of the driven part;  
         [0023]    [0023]FIG. 10 is a cross-sectional view of another alternative embodiment for the drive and driven parts. 
     
    
       [0024]    Corresponding reference numerals will be used throughout the several figures of the drawings.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0025]    The following detailed description illustrates the invention by way of example and not by way of limitation. This description will clearly enable one skilled in the art to make and use the invention, and describes several embodiments, adaptations, variations, alternatives and uses of the invention, including what I presently believe is the best mode of carrying out the invention.  
         [0026]    A prophylaxis (or dental) angle  1  of the present invention is shown generally in FIG. 1. The angle  1  includes a body  3  having a sleeve  5 , a neck  7 , and a head formation  9 . The sleeve  5  is sized to be fit the nose of a dental handpiece, such as a Doriot. A passage  11  extends through the sleeve  5  and neck  7  and is in communication with a chamber  13  formed in the head formation  9 . As seen in FIG. 1, a shoulder  15  is formed at the front of the neck  7  where the passage  11  intersects with the chamber  13 .  
         [0027]    The angle  1  is preferably formed as described in the above noted U.S. Pat. No. 5,328,369, which is incorporated herein by reference. Namely, the head formation  9  is formed essentially of two parts, a first part, which is formed integrally with the sleeve and neck, and a cap which closes the head first part. However, the head formation could be formed in many other ways as well, and the construction of the head formation does not constitute a part of the present invention. For example, the head formation could be formed in a clam shell formation, as shown and described in Kraenzle, U.S. Pat. No. 6,203,322. Alternatively, the head formation could be formed as a one-piece element which is secured to the neck.  
         [0028]    A one-piece molded drive part  21  is received in the angle. The drive part includes a drive gear  23  near one end of a drive gear shaft  25 . The shaft  25  is sized to be gripped by the gripping mechanism of a handpiece. The drive gear  23  is larger in diameter than the drive shaft  25  at the junction between the two, and hence, the drive part  21  includes a shoulder  27  at the back surface of the drive gear  23 . The angle  1  is preferably formed such that the drive part is inserted into the passage  11  rear end first. The drive part  21  is inserted into the passage  11  until the shoulder or back surface  27  of the gear  23  abuts the neck shoulder  15 . Hence, the drive gear  23  extends into the chamber  13  of the head formation  9 . Drive gear teeth  29  are formed at the forward end of the drive gear  23 , and a post  31  extends from the forward surface  33  of the drive gear  23 . As seen in FIG. 5, the post  31  has a cavity  35  in the front surface of the post, the front surface of the post defining, in this embodiment, the front surface of the drive part. The cavity  35  is a shallow cavity; that is, the cavity is wider than it is deep. Preferably, the cavity is bounded by the outer wall  34  of the post and is concave. The concavity of the front surface of the post may be of any shape, although a particularly convenient shape is for it to be sloped inward from the outer wall. Preferably, the diameter of the cavity at the forward end of the post is greater than 50% of the diameter of the post.  
         [0029]    An alternate embodiment of the drive part post  31 ′ is shown in FIG. 6. In this embodiment, the cavity  35 ′ is deeper, forming more of a bowl. Rather than being defined by a sloped or concave surfaces, the cavity  35 ′ is defined by a generally cylindrical side wall  35   a  and a generally flat bottom  35   b.    
         [0030]    A one-piece molded driven part  41  (shown in detail in FIGS.  7 - 9 ) is received in the head formation chamber  13 . The driven part  41  includes a shaft  43 , a driven gear  45  at the end of the shaft  43 , and a post  47 . The drive gear has teeth  48 . The post  47  is adapted to receive a tool, such as a prophylaxis cup, brush, etc. Illustratively, the driven part post  47  includes a bore  49  with splines  51 . The tool includes a threaded shaft, and the splines  51  and shaft are sized so that the shaft threadedly engages the splines  51  when the tool is secured to the post  47 .  
         [0031]    When the drive and driven assemblies are placed in the angle  1 , the drive gear teeth and driven gear teeth are in meshing contact, such that the driven gear  45 , and hence the post  47  and tool will rotate as the drive gear  23  rotates.  
         [0032]    The driven gear shaft  43  is preferably sized such that thrust loads applied to the angle during use will pass through to the bottom of the head formation. Thus, the thrust loads will be borne by the angle body, rather than the gears. Hence, high thrust loads will not cause the gears to “bottom out” or “over-mesh,” that is, the drive and driven gears will not be forced to mesh such an extent that the teeth of the respective gears are urged into the clearance of the opposing gear, which would potentially result in seizing-up of the gears.  
         [0033]    The drive part post  31  (or  31 ′) is sized to reduce end play in the drive part, again, to reduce the possibility of the drive and driven gears from bottoming out should the drive part be pushed forward against the driven part. Thus, the drive part post  31  (or  31 ′) is sized slightly less than the distance between the end surface  33  of the drive gear  23  and the driven gear shaft  43 . It has been found that in normal testing conditions, the drive part post  31  (or  31 ′) is sized such that, during operation of the angle, the drive part post  31  (or  31 ′) does not generally contact the driven gear shaft  43 . Contact between the drive part post and the drive part shaft will occur, however, when the angle is subject to extreme loading conditions.  
         [0034]    The end surface of the post (or the drive part) is shown, for example, in FIG. 6 to be flat. However, this end surface, which defines a contact surface if and when drive part contacts the driven part shaft, can be any desired shape. For example, the end surface can be curved convexly or concavely. Additionally, the surface can slope or curve radially inwardly or outwardly.  
         [0035]    In a preferred construction of the angle  1 , and the drive and driven assemblies  21  and  41 , the drive gear has a diameter of about 0.19″ and a length between its back surface  27  and the forward surface of the post  31  (or  31 ′) of about 0.185″; the drive part post  31  (or  31 ′) has a height from the drive gear surface  33  to the forward end of the post  31  (or  31 ′) of about 0.018″ and a diameter of about 0.1″; the drive gear teeth  29  have an axial depth of about 0.043″. The post cavity  35  has a depth of about 0.003″. The second embodiment of post cavity  35 ′ has a depth of about 0.02″. On the driven part  41 , the shaft  43  has a length of about 0.215″ and a diameter of about 0.1″; the driven gear has a diameter of about 0.2″; and the drive teeth have an axial height of about 0.043″.  
         [0036]    The construction of the drive part post  31  (or  31 ′) reduces contact of the post  31  with the driven part shaft  43  if (or when) pressures are exerted on the angle during use, which would cause the drive part post  31  to engage the driven part shaft  43 . As can be appreciated, if the drive part post were solid (or had a flat end surface) there would be a substantial amount of surface engagement of the drive part post with the driven part shaft. It has been found that such engagement hinders operation of the angle  1 . The cavity  35  (or  35 ′) reduces the contact between the drive part post  31  (or  31 ′) and the driven part shaft  43  to two points or small areas of contact. Thus, the upstanding periphery of the cavity is preferably relatively narrow to form an insubstantial contact surface with the driven part shaft. That is, in cross-section the potentially contacting surface of the drive part post is preferably less than twenty percent of the total width of the post, and more preferably, the width of the potentially contacting surface is less than ten percent of the total width of the post.  
         [0037]    The cavity  35  (or  35 ′) also provides a small reservoir which can receive lubricant. A preferred lubricant is a semi-solid gel, calcium soap type grease available from Century Lubricants—FUCHS of Kansas City, Kans. under the product code FMG 387. Other lubricants could be used. Hence, the angle can be easily lubricated during assembly of the angle and a controlled quantity of lubricant can be stored in the cavity for release onto the driven gear as the angle  1  is used. The cavity  35  (or  35 ′) is simply filled with lubricant prior to insertion of the drive part  21  into the angle body  3 . During operation of the angle, the lubricant will lubricate the points of contact between the drive part post  31  and the driven part shaft  43  (if and when contact occurs). Additionally, lubricant will, to some degree, will be distributed throughout the chamber  13 , thereby providing lubrication for the teeth of the drive and driven gears. This lubrication will facilitate smoother operation of the angle.  
         [0038]    Another embodiment of the drive part  21 ″ and the driven part  41 ″ is shown in FIG. 10. In this embodiment, the drive part  21 ″ includes a drive member  23 ″ near the end of a drive shaft  25 ″. A cavity  35 ″ is defined by an annular wall  35   a ″ extending from the end of the drive member. As shown, the cavity  35 ″ is deeper than the wall  35   a ″. The driven part  41 ″ includes a driven member  45 ″ at an end of a driven shaft  43 ″. The driven shaft  43 ″ has a pair of circumferential grooves  53  formed therein. The grooves  53  are spaced apart a distance equal to the diameter of the cavity  35 ″, and are positioned on the shaft  43 ″ to be aligned with the drive part wall  35   a ″ when the drive member and driven member are in meshing contact. Thus, if and when the drive part contacts the driven part, the annular wall  35   a ″ will engage the groove  53  of the driven part  41 . When the driven part wall  35   a ″ does engage the groove  53 , the wall  51   a ″ will reduce the play of the drive part  41 ″ in the chamber  13 , and help distribute the thrust loads rearwardly into the body neck, where the thrust loads can be absorbed by the neck structure.  
         [0039]    As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. The size and shape of the cavity may be varied, although it is preferred that the cavity be relatively shallow, that is wider than it is deep. Although the post and cavity have particular utility in a disposable prophylaxis angle in which the drive part is inserted from the front, it can be used in other types of prophylaxis angles, for example, metal prophylaxis angles. Depending on the shape of the drive gear or member, the post can be eliminated, and the cavity can be formed in the forward surface of the drive member. In the embodiment of FIG. 10, if the drive part shaft were to be tapered, such that its diameter is greater near the driven member than at the bottom of the driven shaft, the groove spaced farthest from the driven part shaft could be eliminated. These examples are merely illustrative.