referring first to fig1 for a perspective view of a prophy angle 10 as a preferred embodiment of present invention . the prophy angle includes a driving shaft 30 that engages and driving a driven rotor 40 . the prophy angle includes a long leg and a short leg wherein the driving shaft 30 extends along a longitudinal direction inside the long leg of the housing 20 and the rotator 40 extends along a perpendicular direction inside the short leg of the prophy housing 20 . a powered dental handpiece ( not shown ) is provided to couple to the tail of the driving shaft 30 to rotate the shaft 30 and a snap - on rubber prophy cup with prophy paste ( not shown ) is provided to connect to the cup holder head of the driven rotor for rotate with the rotator 40 when driven by the rotating shaft 30 . fig2 a is a cross - sectional view of the prophy angle shown in fig1 , where a driving rotating shaft 30 is enclosed in the housing 20 . fig2 a represents the paw - like driving shaft positioner structure while fig2 b represents the horse - shoe - like driving shaft positioner structure . the prophy angle 20 further includes a driving shaft locking means 60 to retain the driving shaft at a fixed horizontal location . the driving shaft 30 is engages a driven rotator 40 to translate first rotation of the driving shaft 30 along a horizontal rotational axis to a second rotation of the driven rotor along a vertical rotational axis . the driven rotator 40 is maintained in a vertical position by a driven rotor retainer 50 . at the lower end of the driven rotator 40 , a pair of splinter is further provided to more securely attached to a disposable prophy cup ( not shown ) that is snapped onto the lower end of the rotor 40 . the details structure of the driving shaft locking means 60 and the driven rotator retainer 50 will be further described below . fig3 a and 3b are a perspective views of the parts assembled inside housing for a paw - like driving shaft positioner structure and a horse - shoe - like driving shaft positioner structure respectively . in order to enclose the driving shaft 30 and the driven rotor inside the housing 20 , the housing 20 has a hollow space as that shown in fig2 a or 2 b . the housing 20 is hollow to provide a longitudinal passageway 21 and a transverse passageway 22 inside the short and long legs of the housing such that the driving shaft 30 and the driven rotor can be placed therein to engage each other for generating a gear - driving mechanism . the driving shaft 30 is placed along the longitudinal passageway 21 with a locking system 60 are preferably perpendicular to the transverse passageway 22 for placing the driven rotor 40 with the vertical position fixed by a driven rotor retainer 50 along the transverse passage 22 . it is desirable to fix driven rotor 40 with respect to driving shaft 30 to ensure constant gearing action during operation . at the near end of transverse passageway 22 of housing 20 , there exists a driven rotor - positioning hole 23 centered on the axis of transverse passageway 22 . the diameter of driven rotor positioning hole 23 is loosely fit to the diameter of rotor head 41 as shown in fig4 and 5 below of driven rotor 40 to ensure the concentricity of rotation of driven rotor 40 . the depth of driven rotor positioning hole 23 is designed such that the gearing action between gear head 31 of driving shaft 30 and gear shoulder 43 of driven rotor 40 stays constant during rotation , and such that cup flange 44 stays slightly in contact with open end 29 of housing 20 . in order to prevent axial movement of driving shaft 30 from its position relative to driven rotor 40 within longitudinal passageway 21 of housing 20 , there exist two longitudinal positioning steps 25 , 26 on the wall of longitudinal passageway 21 of housing 20 . the longitudinal positioning step 25 controls the axially forward position of driving shaft 30 by blocking the head side of shaft shoulder 33 in position when axially forward directed forces are exerted on driving shaft 30 . longitudinal positioning step two 26 positions driving shaft locking means 60 which controls the axially backward position of driving shaft 30 by blocking the tail side of shaft shoulder 33 in position when axially backward directed forces are exerted on driving shaft 30 . there are slots 27 and 28 provided on the housing 20 for adapting the driving shaft locking means 60 as will be further described below . fig4 and 5 are perspective views of the parts of fig3 a and 3b respectively before these parts are assembled for showing the details of paw - like and horse - shoe - like positioners , respectively , e . g ., the structural details of the driving shaft locking means 60 and the driven rotor retainer 50 . two kinds of retaining mechanism are presented for this invention to achieve the retaining function of driving shaft locking means 60 : the paw - like mechanism as shown in fig3 a and fig5 , and the horse - shoe - like mechanism as shown in fig3 b and fig6 . referring to fig4 , the driving shaft locking means 60 includes a washer 61 and paw - like positioner 62 . the head side of washer 61 is blocked by longitudinal positioning step 26 of longitudinal passageway 21 of housing 20 after final assembly . the diameter of washer 61 is slightly greater than the diameter of longitudinal positioning step 26 of longitudinal passageway 21 of housing 20 so that , after assembly , washer 61 provides an axially forward directed retaining force to driving shaft 30 . paw - like positioner 62 tightly presses the tail side of washer 61 after final assembly . the diameter of paw - like positioner is slightly greater than the diameter of longitudinal positioning step 26 of longitudinal passageway 21 of housing 20 so that , after assembly , paw - like retainer 62 provides an extra axially forward directed retaining force to driving shaft 30 . paw - like positioner 62 may be made of a metal material , retainer toes 63 are bent backwards and splintered into the wall of housing 20 to provide a strong axially backward directed retaining force during operation of prophy angle 10 . referring to fig5 for an alternate driving shaft locking means 60 that is simply made up by a horse - shoe - like locker 64 . the detail structural features of the horseshoe locker 84 is further illustrated in fig6 b . the horse - shoe - like locker 64 is inserted through horse - shoe - like locker head slot 27 on the wall of longitudinal passageway 21 of housing 20 and reaches to horse - shoe - like locker tail slot 28 on the other side of the wall of longitudinal passageway 21 of housing 20 . the front side of horse - shoe - like locker 64 is located at longitudinal positioning step 26 of longitudinal passageway 21 of housing 20 after assembly , and the horse - shoe - like locking means provides a strong longitudinal backward directed retaining force during operation of prophy angle 10 . transverse locking is achieved by a special structure on the locker legs 65 . there exists a step 66 near the end of both locker legs , which ensures the transverse positioning of the horse - shoe - like locker 64 . the step depth is equal to the wall thickness of the housing so that when assembled , the edge of step 66 will stay against the inner wall of the housing . on the other side , two elastically bendable arms 67 and 69 are formed near the other ends of the legs 65 which ensure transverse positioning of the horse - shoe - like locker 64 on that side . the tip 68 of the locking means 60 is constructed such that , when assembled , the edge of tip 68 will stay against the other side of the inner wall of the housing . that transverse locking mechanism ensures horse - shoe - like locker 64 will not drop out as a result of any accidental forces exerted on it . the dimensions of horse - shoe - like locker 64 are such that horse - shoe - like locker 64 is positioned accurately to avoid any contact with shaft tail 34 . details of how the parts of this locking means are related to the housing can further be referenced to fig7 a to 7c referring to fig7 a to 7c for details of the driven rotor retainer 50 to maintain the driven rotor 40 stays in position under any conditions which would tend to pull it out of open end 29 of transverse passageway 22 of housing 20 . the driven rotor 40 is provided with a horse - shoe - like driven rotor retainer 50 that is firmly positioned next to rotor neck 42 of driven rotor 40 by two driven rotor retainer forks 51 through driven rotor retainer slot 24 on the wall of transverse passageway 21 of housing 20 . thus , driven rotor retainer 50 is able to retain rotor head 41 without it dropping out during operation . in addition , there exists a retaining tongue 52 that can be elastically bent between the two retaining forks 51 in driven rotor retainer 50 . a retaining hook 53 exists at the tip of retaining tongue 52 that further ensures driven rotor 50 is not dropped out by any accidental forces exerted on it . two retaining shoulders 54 extends out at the curve side of driven rotor retainer 50 that match the shape of driven rotor retainer slot 24 on the wall of transverse passageway 21 of housing 20 . these ensure that driven rotor retainer 50 cannot touch any parts of driven rotor 40 other than rotor head 41 . in order to prevent possible rotational slipping between the prophy cup and the driven rotor during operation , a pair of sharp pointed splinters 46 is arranged circumferentially on the neck of the cup end of the driven gear rotor , upon which the snap - on prophy cup sits . refer fig2 . the splinters 46 pierce into the rubber base of the snap - on prophy cup and force it to rotate with the driven gear rotator without the possible free spinning of the rotor within the prophy cup . according to above descriptions , a dental prophylaxis angle enclosing in a housing is disclosed . the dental prophylaxis angle comprises a driving shaft engaging and translating a rotational movement to a driven rotor wherein a constant engagement is maintained between the driving shaft and the driven rotor by a first and second position retainers for retaining the driving shaft and the driven rotor at fixed positions respectively . in a preferred embodiment , the first and second position retainers are securely attached to the housing each at a fixed position . in another preferred embodiment , the first position retainer keeping the driving shaft from a horizontal shift and the second position retainers keeping the rotor from a vertical shift . in another preferred embodiment , the housing further having slits for adapting a part of the first and second position retainers for securely keeping the first and second position retainers at fixed positions . in another preferred embodiment , the housing further includes inner steps for mechanically retaining the first and second position retainers for restricting the first and second position retainers from a lateral movement inside the housing . in another preferred embodiment , the housing further includes inner space for adapting a portion of the driven rotor therein for mechanically retaining the rotor from tilting beyond a certain incline angle . although the present invention has been described in terms of the presently preferred embodiment , it is to be understood that such disclosure is not to be interpreted as exhaustive or limiting . various alternations and modifications will no doubt become apparent to those skilled in the art after reading the above disclosure . accordingly , it is intended that the appended claims be interpreted as covering all alternations and modifications as fall within the true spirit and scope of the invention .
a disposable , securely retained dental angle is provided . the angle includes a one - piece hollow housing having a short leg at its front end , which is angled with respect to the long leg . both the short and long legs have a through bore . the short leg has an aperture , which is connected to the bore of the long leg to allow insertion of a driving shaft through the short leg of the angle . a driven rotor is inserted in the short leg . a horse - shoe - like snap rotor retainer fits within the short leg over the driven rotor to retain the driven rotor in the angle . a paw - like or , alternately , a horse - shoe - like locking means fits within the long leg over the driving shaft to lock the driving shaft in the angle and to retain the angle together . in one embodiment , a pair of splinters on the driven rotor provides the function to retain the rubber prophy cup firmly while the driven rotor is in operation .