Dental handpiece

Abstract

.Iadd.A dental handpiece comprises an air driven turbine rotor provided with a chuck to removably hold a dental bur and rotate it at extremely high speed. The rotor is mounted on anti-friction bearings within a capsule which is removably received within a housing to permit replacement of the capsule and turbine as a unit. The fluid outlet from the turbine is restricted sufficiently to ensure that a portion of the fluid is exhausted through the bearings and openings in the housing to prevent egress of foreign matter into the interior. .Iaddend.

I claim: 
     
       1. A high speed dental handpiece comprising a housing having opposite ends provided with fluid discharge means therein, a shaft within said housing extending between said opposite ends thereof, means on one end of said shaft to connect a dental tool thereto, a rotor carried by said shaft between the opposite ends thereof, bearings having anti-friction members movable therein and supported within said housing to support rotatably said shaft respectively adjacent opposite ends of said rotor, each of said bearings having an opening therethrough, impeller means on said rotor extending generally axially of said rotor and terminating adjacent the opposite ends thereof, means to direct gaseous fluid under pressure against said impeller means to rotate said rotor, and means on said rotor operable to discharge driving gaseous fluid in opposite directions directly from said impeller means and through said openings in each of said bearings for exhaust from said housing through said discharge means in said opposite ends thereof. 
     
     
       2. A high speed gaseous fluid operated turbine dental handpiece comprising a housing, a rotor mounted within said housing and having fluid engageable impeller means therein, said rotor having means to connect a tool thereto, radial anti-friction bearings having annular spaces therethrough and having anti-friction bearing members movable therein, said bearings being mounted within said housing adjacent opposite ends thereof and supporting said rotor with said impeller means thereof disposed between said bearings and said impeller means discharging gaseous fluid directly and axially through said annular spaces of said bearings, the outer diameter of said rotor being greater than that of the annular spaces in said radial bearings and said housing having inlet means positioned to direct gaseous fluid against the impeller means of said rotor, and discharge means in said housing communicating with said annular spaces in said bearings and positioned to receive gaseous fluid discharged from said rotor through said bearing spaces, whereby said rotor rotates within an annular pocket within said housing. 
     
     
       3. The high speed dental handpiece set forth in claim 2 further characterized by said impeller means of said rotor extending radially therefrom and said rotor being provided with spaces between said impeller means and the opposite ends of said spaces being open and positioned opposite the said annular spaces in said bearings to discharge gaseous fluid from said spaces directly through the annular spaces of said bearings. 
     
     
       4. A high speed rotary dental handpiece comprising a housing, a rotor mounted within said housing and having fluid engageable impeller means therein comprising radial vanes spaced circumferentially around said rotor and extending substantially axially thereof, the opposite faces of each vane being at an acute angle to each other at the tips of said vanes and one face of each vane being substantially planar and the opposite face being convex, said rotor having means to connect a tool thereto, radial anti-friction cageless bearings having annular spaces therethrough and anti-friction bearing members movable therein, said bearings being mounted within said housing adjacent the opposite ends thereof and supporting said rotor therein with said impeller means thereon disposed between said bearings and said impeller means discharging gaseous fluid directly axially through said annular spaces of said bearings and the apex formed by the intersection of the planar surface of one vane and the convex surface of an adjacent vane lying immediately adjacent to and in axial alignment with the balls of said bearings, the outer diameter of said rotor being greater than that of the annular spaces in said bearings and said housing having inlet means positioned to direct gaseous fluid against the impeller means of said rotor, and discharge means in said housing communicating with said annular spaces in said bearings and positioned to receive gaseous fluid discharged from said rotor through said bearing spaces, whereby said rotor rotates within an annular pocket within said housing. 
     
     
       5. A high speed dental handpiece operated by a fluid driven rotary motor comprising, a housing having a cylindrical bore, a rotor concentrically mounted in said bore, bearings at opposite ends of said rotor supporting said rotor in said bore and having passages therethrough in an axial direction, said housing being mounted on one end of a handle, a fluid inlet passageway in said handle for directing a jet of fluid against said rotor to drive the same, an exhaust passageway in said handle, and means constricting said exhaust passageway to create a pressure in excess of atmospheric within said housing, the cross-sectional area of the inlet passageway relative to the summation of the cross-sectional areas of all exhaust passages being such that at operative inlet pressures the pressure at the exhaust passages is greater than that which will permit suction into said housing. 
     
     
       6. A high speed gaseous fluid driven turbine type dental handpiece comprising in combination, a housing having a cylindrical inner surface, a turbine rotor and concentric shaft supported for rotation within said housing, impeller means on said rotor comprising axially extending vanes substantially co-extensive in length with said rotor, annular means adjacent opposite ends of said rotor and adjoining and extending radially inwardly from said inner surface adjacent the opposite ends of the vanes of said rotor to form with said inner surface an annular pocket within which the outer ends of said vanes rotate, the opposite ends of said rotor shaft extending through the central openings of said annular means and being radially spaced therefrom to provide annular exhaust openings extending around said shaft, means to direct gaseous fluid under pressure into said housing and against the vanes of said rotor to rotate the same, said gaseous fluid being exhausted at least partially from the opposite ends of said impeller means through said annular exhaust openings and the diameters of said central openings of said annular means being greater than the root diameter of said rotor vanes, whereby fluid discharges from the apexes of the spaces between adjacent vanes through said annular exhaust openings. 
     
     
       7. A high speed dental handpiece comprising an elongated handle having fluid inlet and exhaust conduit means extending longitudinally thereof, a housing connected to one end of said handle and the interior thereof communicating with said conduit means of said handle, said housing having opposite ends provided with fluid discharge means therein, a shaft in said housing extending axially between said opposite ends thereof, means on one end of said shaft to connect a dental tool thereto, a rotor carried by said shaft between the opposite ends thereof and provided with impeller means, bearings supported within said housing and rotatably supporting said shaft respectively adjacent opposite ends of said rotor, said fluid inlet means of said handle being arranged to direct gaseous fluid under pressure against said rotor impeller means to rotate the same, means on said rotor operable to discharge a portion of the driving gaseous fluid from said impeller means past at least one of said bearings for exhaust through the discharge means at the adjacent end of said housing, another portion of said driving gaseous fluid being discharged through said exhaust conduit means of said handle, and exhaust constricting means in said exhaust conduit means operable to control the amount of gaseous fluid discharged therethrough relative to that exhausted through said discharge means in the ends of said head to insure discharge through the latter means adequate to prevent suction into said head. 
     
     
       8. A high speed dental handpiece comprising an elongated handle having fluid inlet and exhaust conduit means extending longitudinally thereof, a housing connected to one end of said handle and the interior thereof communicating with said conduit means of said handle, said housing having opposite ends provided with constricted fluid discharge means therein, a shaft in said housing extending axially between said opposite ends thereof, means on one end of said shaft to connect a dental tool thereto, a rotor carried by said shaft between the opposite ends thereof and provided with impeller means, bearings supported within said housing and rotatably supporting said shaft respectively adjacent opposite ends of said rotor, said fluid inlet means of said handle being arranged to direct gaseous fluid under pressure against said rotor impeller means to rotate the same, means on said rotor operable to discharge a portion of the driving gaseous fluid in opposite directions from said impeller means through both of said bearings for exhaust through the discharge means in the adjacent ends of said housing, another portion of said driving gaseous fluid being discharged through said exhaust conduit means of said handle, and exhaust constricting means in said exhaust conduit means operable to control the amount of gaseous fluid discharged therethrough relative to that exhausted through said constricted discharge means in the ends of said housing to insure discharge through the latter means adequate to prevent suction into said housing. 
     
     
       9. A high speed gaseous fluid driven turbine type dental handpiece comprising a housing, a rotor mounted for rotation within said housing and having fluid engageable impeller means thereon, said rotor having means to connect a tool thereto, a pair of bearings mounted within said housing and spaced axially of said rotor and supporting said rotor with said impeller means thereof disposed between said bearings, means to direct gaseous fluid under pressure against said impeller means to rotate said rotor, means on said rotor operable to discharge driving gaseous fluid in opposite and axial directions directly from said impeller means, gaseous driving fluid discharge means in said housing extending therefrom to a position remote from said housing to discharge a portion of said driving fluid directly from the rotor-containing portion of said housing to atmosphere, and additional gaseous driving fluid discharge means in said housing positioned to communicate respectively and axially with the ends of said impeller means beyond both of said bearings to discharge other portions of said driving gaseous fluid from said housing directly to exterior atmosphere. 
     
     
       10. The dental handpiece assembly according to claim 6 further including radial anti-friction bearings concentric with said annular exhaust openings and supporting the opposite ends of said rotor shaft adjacent said annular means, whereby fluid discharging through said annular exhaust openings passes directly and axially through said anti-friction bearings under pressure greater than atmospheric. 
     
     
       11. A high speed dental handpiece utilizing a high speed fluid driven motor comprising a rotor shaft supported at opposite ends by radial bearings in a housing, a threaded bore extending inwardly from one end of said shaft and concentric with the axis thereof, a tubular insert of deformable resilient material in said bore and having an outside diameter less than the root diameter of said threads, the outer surface of said insert being substantially conformable to the contour of said threads upon insertion into said insert of a tool shank having a diameter greater than the inside diameter of said insert, an opening formed in the top of said rotor shaft communicating with said bore, said opening permitting the escape of air to facilitate the insertion of said tool shank, and means for passing fluid over the upper end of said shaft to aspirate particulate material from the interior of said insert. 
     
     
       12. A chuck for a dental handpiece comprising, a tube, a tubular insert of deformable resilient material in said tube and having an outside diameter approximately the same as the inside diameter of said tube, said insert having an inside diameter slightly less than the outside diameter of a tool shank to be received therein, and means on said tube and insert operable upon insertion of said tool to interlock against axial movement whereby said insert fits tightly about said tool and is forced into firm frictional engagement with the internal walls of said tube. 
     
     
       13. A chuck according to claim 12 further comprising internal threads on said tube to receive a cold flow of said deformable material in at least partial conformity to said threads upon insertion of said tool. 
     
     
       14. A chuck for a dental handpiece comprising an internally threaded tube, a tubular elastic synthetic resin insert having an outside diameter smaller than the root diameter of said threads, the outside surface of said insert being substantially conformable to the contour of said thread upon being stretched radially outwardly by insertion of the shank of a tool to be received therein. .[.15. A dental instrument having a rotor, said rotor having a hole extending inwardly from one end thereof and concentric with the axis thereof, the outer end of said hole being adapted to receive a tool shank in frictional sliding engagement therewith and the other end of said rotor having an opening communicating with said hole to permit escape of air to facilitate the insertion of said tool shank within 
     
     
        said hole..]. 16. .[.A dental handpiece chuck according to claim 15.]. .Iadd.A dental instrument having a rotor, said rotor having a hole extending inwardly from one end thereof and concentric with the axis thereof, the outer end of said hole being adapted to receive a tool shank in frictional sliding engagement therewith and the other end of said rotor having an opening communicating with said hole to permit escape of air to facilitate the insertion of said tool shank within said hole, .Iaddend.further comprising means for passing a fluid over said other end of said rotor to aspirate particulate material from the interior thereof. 
     
     
         7. A high speed rotary dental handpiece operated by a fluid driven rotary motor comprising, a housing, a rotor concentrically mounted within said housing and having a shaft provided with a bore extending inward from one end thereof to engagingly receive the shank of a dental tool, the other end of said shaft having a hole extending thereinto and communicating with the inner end of said bore and operable to expel air from said bore upon the insertion of the shank of a dental tool therein, bearings at opposite ends of said rotor rotatably supporting said rotor in said housing and said bearings having passages therethrough in an axial direction, means to introduce fluid into said housing and direct it against said rotor to drive the same, and exhaust means to discharge said fluid from said housing, said exhaust means comprising said passages through said bearings and other exhaust passage means from said housing, said other exhaust passage mean comprising means for passing a fluid over the outer end of 
     
     
        the hole in said shaft to aspirate particulate material therefrom. 18. A high speed fluid driven dental handpiece comprising a housing having a substantially cylindrical recess therein, a lower radial bearing seated in the bottom of said recess, locking means detachably secured in said recess immediately above said bearing and locking the outer race of said bearing against the bottom of said recess, a vaned rotor having a spindle at one end frictionally and slidably engaging the inner race of said lower bearing for rotation therewith, an upper radial bearing having its inner race fixed to the other end of said rotor and the outer race thereof interengaging a seat in said recess, and a cap detachably secured to the upper end of said recess and interengaging said outer race to hold the 
     
     
        same fixed relative to said seat. 19. A high speed fluid driven dental handpiece comprising, a housing having a substantially cylindrical recess therein, a lower radial bearing seated in the bottom of said recess, a washer secured in said recess immediately above said bearing and locking the outer race of said bearing against the bottom of said recess, a vaned rotor having a spindle at one end frictionally and slidably engaging the inner race of said lower bearing for rotation therewith, an upper radial bearing having its inner race fixed to the other end of said rotor, a cylindrical spacer ring fixed to the outer cylindrical surface of said outer race and resting against a shoulder in said recess, and a cap detachably secured in said recess for holding said cylindrical spacer ring 
     
     
        against said seat. 20. A high speed fluid driven dental handpiece comprising, a housing having a substantially cylindrical recess therein, a lower radial bearing seated in the bottom of said recess, a washer secured in said recess immediately above said bearing and locking the outer race of said bearing against the bottom of said recess, a rotor having axially aligned vanes and a spindle at one end frictionally and slidably engaging the inner race of said lower bearing for rotation therewith, an upper radial bearing having its inner race fixed to the other end of said rotor and the outer race thereof interengaging a seat in said recess, and a cap detachably secured in said recess and interengaging said outer race to hold the same fixed relative to said seat, the upper and lower ends of said vanes being spaced respectively from said upper bearing and washer 
     
     
        respectively a distance in the range of between 0.005-0.025 inch. 21. A high speed fluid driven dental handpiece comprising, a housing having a substantially cylindrical recess therein, a lower radial bearing seated in the bottom of said recess, a washer secured in said recess immediately above said bearing and locking the outer race of said bearing against the bottom of said recess, a rotor having a spindle at one end frictionally and slidably engaging the inner race of said lower bearing for rotation therewith, an upper radial bearing having its inner race fixed to the other end of said rotor and the outer race thereof interengaging a seat in said recess, and a cap detachably connected to the upper end of said housing and interengaging said outer race of said upper bearing to hold the same fixed relative to said seat, said rotor having axially aligned vanes projecting radially outwardly into an annular pocket formed by the surface of said recess, the upper bearing outer race and said washer, approximately one-half the radial projection of said vanes being enclosed 
     
     
        by said pocket. 22. A high speed fluid driven dental handpiece comprising, a housing having a substantially cylindrical recess therein, a lower radial bearing seated in the bottom of said recess, a washer secured in said recess immediately above said bearing and locking the outer race of said bearing against the bottom of said recess, a vaned rotor having a spindle at one end frictionally and slidably engaging the inner race of said lower bearing for rotation therewith, an upper radial bearing having its inner race fixed to the other end of said rotor and the outer race thereof interengaging a seat in said recess, a cap detachably secured in said recess and interengaging said outer race to hold the fixed relation to said seat, a handle extending radially away from said housing, and a fluid inlet passageway in said handle communicating with the interior of said housing to direct a jet of fluid tangentially against said rotor. 
     
     
            A dental handpiece according to claim 22 further comprising a fluid exhaust passage means in said handle communicating with the interior of said housing at a location adjacent said inlet for discharging fluid after 
     
     
        it has traveled from said inlet and around said housing. 24. A dental handpiece according to claim 23 further comprising means forming fluid outlets in said cap and in the end of said housing opposite said cap for 
     
     
        exhausting fluid through said bearings. 25. A high speed fluid driven dental handpiece comprising, a housing having a substantially cylindrical recess therein, a lower radial bearing seated in the bottom of said recess, a washer secured in said recess immediately above said bearing and locking the outer race of said bearing against the bottom of said recess, a vaned rotor having a spindle at one end frictionally and slidably engaging the inner race of said lower bearing for rotation therewith, an upper radial bearing having its inner race fixed to the other end of said rotor and the outer race thereof interengaging a seat in said recess, a cap detachably secured in said recess and interengaging said outer race to hold the same in fixed relation to said seat, and means forming exhaust outlets in said cap and in said housing opposite said cap for exhausting 
     
     
        fluid through said bearings. 26. A high speed driven dental handpiece comprising, a housing having a substantially cylindrical recess therein, a lower radial bearing seated in the bottom of said recess, a washer secured in said recess immediately above said bearing and locking the outer race of said bearing against the bottom of said recess, a vaned rotor having a spindle at one end frictionally and slidably engaging the inner race of said lower bearing for rotation therewith, an upper radial having its inner race fixed to the other end of said rotor and the outer race thereof interengaging a seat in said recess, a cap detachably secured in said recess and interengaging said outer race to hold the same fixed relative to said seat, a hollow handle extending radially away from said housing, a fluid inlet tube in said handle communicating with the interior of said housing to direct a jet of fluid tangentially against said rotor, said housing having an outlet adjacent said inlet and communicating with the interior of said handle, and means located in said handle, remote from said outlet, restricting the flow of fluid out of said handle to create 
     
     
        positive internal pressure in said housing. 27. A high speed dental handpiece operated by a fluid driven rotary motor comprising, a housing having a cylinrical bore, a rotor concentrically mounted in said bore, bearings at opposite ends of said rotor supporting said rotor in said bore and having passages therethrough in an axial direction, said housing being mounted on one end of a handle, a fluid inlet passageway in said handle for directing a jet of fluid against said rotor to drive the same, an exhaust passageway in said handle, and means constricting said exhaust passageway to create a pressure in excess of atmospheric within said housing, said constricting means comprising a block in said exhaust passageway, said block having a hole therethrough, and a spring biased check ball in said hole to form automatic regulation of said pressure 
     
     
        within said housing. 28. A dental handpiece according to claim 27 further comprising means for varying the pressure of said spring against said ball. .[.29. A dental handpiece having a handle provided with fluid inlet conduit means carried thereby so as to be movable therewith at all times and extending longitudinally thereof and connectable at one end to a source of fluid under pressure, said handle also having fluid exhaust conduit means extending therealong and carried thereby so as to be movable therewith at all times; a turbine unit assembly having, a rotor and shaft arranged to be driven by fluid under pressure, bearing means for said rotor spaced longitudinally thereof, and means surrounding said rotor and having fluid inlet and outlet means therein providing communication with said rotor, said shaft having means to which a tool may be attached; and means detachably securing said turbine unit relative to one end of said handle to maintain said fluid inlet and outlet means of said rotor surrounding means of said turbine unit in registering communication respectively with said fluid inlet and exhaust conduit means of said handle to receive fluid therefrom to drive said rotor and exhaust fluid from said unit, whereby when said handle is detached from said turbine unit assembly, said fluid inlet and exhaust conduit means will be simultaneously detached from said fluid inlet and outlet means..]. .[.30. A dental handpiece having a handle provided with fluid inlet and outlet conduit means extending therethrough and said inlet conduit means being connectable at one end to a source of fluid under pressure and the other end thereof being fixedly connected to said handle adjacent one end thereof for movement with said handle at all times; a turbine unit assembly having a combination, a rotor having impeller means in the outer periphery thereof and a shaft arranged to be driven by fluid under pressure, bearing means for said rotor shaft spaced longitudinally of said shaft, and means positioned exteriorly of said impeller means of said rotor and extending longitudinally between said bearings to space the same and having fluid inlet and outlet means extending transversely therethrough and providing communication with the impeller means of said rotor, said shaft having means to which a tool may be attached; and means detachably securing said turbine unit assembly relative to said one end of said handle to maintain said fluid inlet and outlet means of said exteriorly positioned means of said turbine unit in registering communication respectively with said fluid inlet and outlet conduit means of said handle to transmit fluid to and from said rotor to drive the same, whereby when said handle is detached from said turbine unit assembly said fluid inlet and exhaust conduit means will be simultaneously detached from said fluid inlet and outlet means..]. .[.31. A dental handpiece having a handle provided with fluid exhaust conduit means and rigid fluid inlet conduit means, both of said means extending therealong and fixed thereto so as to be movable therewith at all times, said fluid inlet conduit means being connectable to a source of fluid under pressure; a turbine unit comprising in combination a rotor having impeller means on the outer periphery thereof and a shaft arranged to be driven by fluid under pressure, bearing means for said rotor shaft spaced longitudinally therealong, and means surrounding said rotor and having fluid inlet and outlet means extending transversely therethrough and communicating with said rotor, said shaft having means to which a tool may be attached; and means detachably securing said turbine unit relative to one end of said handle to maintain the fluid inlet and outlet means of said rotor surrounding means of said turbine unit in registering communication respectively with said fluid inlet and exhaust conduit means of said handle to receive fluid therefrom to drive said rotor and exhaust fluid from said turbine unit, whereby when said handle is detached from said turbine unit assembly said fluid inlet and exhaust conduit means to be simultaneously detached from said fluid inlet and outlet means..]. .[.32. A dental handpiece having a handle provided with conduit means extending longitudinally thereof and connectable at one end to a source of fluid under pressure, a housing head connected to the other end of said handle and having an opening therein, a cartridge comprising; a turbine rotor and shaft, bearings spaced axially of said shaft and supporting the same for rotation, and means surrounding said shaft and extending between said bearings to space the same in an axial direction, said last mentioned means having fluid inlet means communicating with said rotor and said rotor also having means to which a tool may be attached, said cartridge being inserted through said opening in said head into operative position therein; and means detachably connected to said head and engaging said cartridge to secure the same within said head with said fluid inlet means in said cartridge in communication with said fluid conduit means of said 
     
     
        handle..]. 33. A dental handpiece having a handle provided with conduit means extending longitudinally thereof and connectable at one end to a source of fluid under pressure, a housing head connected to the other end of said handle and having an opening at the upper end thereof and an aperture on the lower end thereof, a cartridge comprising a casing surrounding a turbine rotor arranged to be driven by fluid under pressure and having one end projecting axially beyond one end of said casing to engage a dental tool, said cartridge casing having fluid inlet means communicating with said rotor, said cartridge being inserted through said opening in the upper end of said head into operative position therein wherein the projecting end of said rotor extends through said aperture in said head, and means detachably connected to the upper end of said head to engage and secure said cartridge within said head with fluid inlet means in the casing thereof in communication with said fluid conduit means of said handle to receive fluid therefrom to drive said rotor. .[.34. A dental handpiece having a handle provided with conduit means extending longitudinally thereof and connectable at one end to a source of fluid under pressure, a housing head connected to the other end of said handle and having an opening therein, a cartridge comprising a casing surrounding a turbine rotor arranged to be driven by fluid under pressure and bearings adjacent opposite ends of said casing supporting said rotor, said cartridge casing having fluid inlet means communicating with said rotor and said rotor also having means to which a tool may be attached, said cartridge being inserted through said opening in said head into operative position therein, and securing means detachably connected to said head relative to said opening therein and engaging said cartridge within said head to hold the same therein with the fluid inlet means therein in communication with said fluid conduit means of said handle to receive fluid therefrom to drive said rotor..]. .[.35. A dental handpiece having a handle provided with conduit means extending longitudinally thereof and connectable at one end to a source of fluid under pressure, a housing head connected to the other end of said handle and having an opening at the upper end thereof, a cartridge comprising a casing surrounding a turbine rotor arranged to be driven by fluid under pressure and bearings seated relative to opposite ends of said casing and, supporting said rotor, said cartridge having fluid inlet means communicating with said rotor and said rotor also having means to which a tool may be attached, said cartridge being inserted through said opening in the upper end of said head into operative position therein, and a cap detachably connected to the upper end of said head to close said opening therein and secure said cartridge within said head with the fluid inlet therein in communication with said fluid conduit means of said handle to receive fluid therefrom to drive said rotor and also maintain said bearings seated relative to said casing 
     
     
        of said cartridge..]. 36. A dental handpiece having a handle provided with conduit means extending longitudinally thereof and connectable at one end to a source of fluid under pressure, a housing head connected to the other end of said handle and having an opening therein, a cartridge comprising a turbine rotor and shaft arranged to be driven by fluid under pressure, said cartridge having fluid inlet means communicating with said rotor and said rotor also having means to which a tool may be attached, said cartridge being inserted through said opening into operative position therein, and co-engaging indexing means on said cartridge and head operable to align the fluid inlet means of said cartridge in communication with said fluid conduit means of said handle to receive fluid therefrom to drive said rotor. .[.37. A dental handpiece having a hollow handle provided with conduit means extending longitudinally thereof and connectable at one end to a source of fluid under pressure, a housing head connected to the other end of said handle and having an opening therein, and a cartridge comprising a turbine rotor arranged to be driven by fluid under pressure, said cartridge having fluid inlet means and outlet means communicating with said rotor and said rotor also having means to which a tool may be attached, said cartridge being inserted through said opening into operative position with said head with the fluid inlet means therein in communication with said fluid conduit means of said handle to receive fluid therefrom to drive said rotor and the fluid outlet means of said cartridge in communication with the hollow handle to permit discharge of fluid from said cartridge through said handle..]..[.38. A dental handpiece having a hollow handle provided with conduit means extending longitudinally thereof and connectable at one end to a source of fluid under pressure, a housing having an opening at the upper end thereof and connected to the other end of said handle, a cartridge comprising a casing surrounding a turbine rotor arranged to be driven by fluid under pressure and having one end arranged to engage a dental tool, said cartridge casing having fluid inlet and outlet means therein communicating with said rotor, said cartridge being inserted through said opening in the upper end of said head into operative position therein, and means detachably connected to the upper end of said head to secure said cartridge within said head with the fluid inlet means in the casing thereof in communication with said fluid conduit means of said handle to receive fluid therefrom to drive said rotor and the fluid outlet means of said casing in communication with the hollow handle to permit discharge of fluid from 
     
     
        said cartridge through said handle..]. 39. A dental handpiece comprising a head, a turbine rotor and shaft supported for rotation within said head, means to rotate said rotor, said shaft having an opening extending axially therethrough to receive in one end of said opening the shank of a dental tool for rotation by said rotor, and means on one end of said head extending over the other end of shaft, said means having a hole therein in axial alignment with the opening in said shaft, whereby an elongated member may be inserted through said hole and opening in said shaft from the end thereof opposite that into which a shank of a bur is inserted, 
     
     
        thereby to push a bur or broken part thereof from said shaft. 40. A dental handpiece comprising, in combination, a handle provided on one end with a housing connected thereto and having an opening therein, said handle having fluid passage means therethrough communicating with the interior of said housing; and a fluid operated rotor cartridge assembly comprising a turbine rotor having vanes intermediate of the ends thereof, antifriction bearings having inner and outer races, said inner races receiving respectively the opposite ends of said rotor, and means extending between said outer races of said bearings and engaging the same to maintain said outer races spaced axially a precise predetermined distance, said cartridge assembly being removably positioned within said housing as a 
     
     
        unit by insertion thereof through said opening. 41. A dental handpiece comprising in combination, a handle provided on one end with a housing connected thereto and having an opening therein, said handle having fluid passage means therein communicating with the interior of said housing; and a fluid operated rotor cartridge assembly comprising a turbine rotor having vanes intermediate of the ends thereof, anti-friction bearings having inner and outer races, said inner races receiving respectively the opposite ends of said rotor, and means surrounding said rotor and extending axially between the outer races of said bearings and engaging the same to maintain said outer races spaced axially a precise predetermined distance, said surrounding means having ports communicating with the fluid passage means of said handle and said rotor cartridge assembly being removably positioned within said housing as a unit by 
     
     
        insertion thereof through said opening. 42. The dental handpiece according to claim 41 further including interengageable indexing means on said rotor cartridge unit and housing operable to maintain the ports in said surrounding means aligned with the fluid passage means of said handle, whereby fluid from said passage means is directed against the vanes of 
     
     
        said rotor to actuate it. 43. A dental handpiece comprising in combination, a handle having a housing on one end thereof connected thereto and provided with an opening therein; a fluid operated turbine motor cartridge assembly comprising a fluid operated turbine rotor having vanes intermediate the ends thereof, anti-friction bearings having inner and outer races, the inner races thereof receiving said rotor adjacent the opposite ends thereof, a casing surrounding the vanes of said rotor and the opposite ends of said casing interengaging the outer races of said bearings to position them axially spaced precisely a predetermined distance, said cartridge assembly being removably positioned within said housing as a unit and said casing preventing abnormal loading of said bearings when said cartridge assembly is so mounted; and means connectable with said housing and engaging said cartridge assembly to retain the same 
     
     
        therein. 44. A dental handpiece comprising in combination, a handle having a housing on one end thereof connected thereto and provided with an opening therein, said housing having a seat in one end; a fluid operated turbine rotor cartridge assembly comprising a fluid operated turbine having vanes intermediate the ends thereof, anti-friction bearings comprising inner and outer races mounted at opposite ends of said rotor, the inner races of said bearings receiving said rotor, means extending between the outer races of said bearings and operable to maintain the same in precise spaced position axially, the outer race of the lower bearing being received within said seat in said housing unit when said rotor assembly is inserted into said housing through said opening therein; and cap means connectable with said housing over said opening therein and engageable with said outer cartridge assembly to hold the outer races of said bearings stationary relative to said housing and said assembly seated 
     
     
        therein. 45. A dental handpiece comprising in combination, a handle having a housing on one end thereof connected thereto and provided with an opening therein; a fluid operated turbine rotor cartridge assembly comprising a fluid operated turbine having vanes intermediate of the ends thereof, anti-friction bearing units having inner and outer races and anti-friction members therebetween, the outer races of said bearing units having radial flanges projecting outwardly from the inner ends of said races and the inner races of said units respectively receiving concentrically the opposite ends of said rotor, a casing complementary to the interior of said housing and surrounding the vanes of said rotor, the opposite ends of said casing respectively abutting radial faces of said flanges of said outer races of said bearing units to space said outer races a precise predetermined distance axially and said cartridge assembly being removably mounted operatively within said housing and positionable therein as a unit by insertion thereof through said opening; and cap means for the opening of said housing releasably secured thereto and having a portion engaging the outer race of the upper bearing unit of said cartridge assembly to secure said outer races of said bearings against said ends of said casing and said cartridge assembly in operative position 
     
     
        within said housing when said cap is secured to said housing. 46. The dental handpiece set forth in claim 45 further characterized by the diameter of the periphery of said flanges and exterior of said casing being substantially even and only slightly less than the diameter of the interior of said housing which receives said turbine cartridge assembly, whereby the inner wall of said housing maintains said outer races of said bearing units and casing substantially in axial alignment when said turbine cartridge assembly is mounted within said housing. .[.47. A dental handpiece having a handle provided with conduit means extending longitudinally thereof and connectable at one end to a source of fluid under pressure, a substantially cylindrical housing head connected to the outer end of said handle with the axis of the head substantially vertical to said handle and said head having an opening in one end thereof, a cartridge comprising a turbine rotor and shaft, bearings spaced axially of said shaft and supporting the same for rotation, and means surrounding said shaft and extending between said bearings to space the same in an axial direction, said rotor having means to which a tool may be attached and said cartridge having fluid inlet means and being removably inserted into said opening in said head to operatively position the same therein; and means detachably connecting said cartridge to said head to secure at least a portion of said cartridge within said head with said fluid inlet means of said cartridge in communication with said fluid conduit means of 
     
     
        said handle..]. 48. A dental handpiece comprising in combination, a handle having fluid passage means therein and a housing on one end thereof connected thereto and provided with an opening therein, said housing having a seat in one end thereof; a fluid operated turbine rotor cartridge assembly comprising a fluid operated turbine having vanes intermediate the ends thereof; anti-friction bearings comprising inner and outer races mounted at opposite ends of said rotor, the inner races of said bearings receiving said rotor adjacent opposite ends thereof, means extending between the outer races of said bearings and surrounding said rotor vanes, said means being operable to maintain said outer races in precise spaced position axially and having fluid ports therein aligned with the passage means in said handle, the outer race of the lower bearing being received within said seat in said housing when said rotor cartridge assembly is inserted into said housing through said opening therein; interengaging means on said rotor cartridge assembly and housing and operable to prevent relative rotary movement therebetween and maintain the ports therein aligned with the passage means in said handle; and means connectable with said housing relative to said opening therein and engageable with said rotor cartridge assembly and operable to hold the outer races of said bearings stationary relative to said housing and said cartridge assembly 
     
     
        seated therein. 49. A dental handpiece comprising in combination, a handle having a housing on one end thereof connected thereto and provided with an opening; a fluid operated turbine rotor cartridge assembly comprising a fluid operated turbine having shaft ends and vanes intermediate the ends thereof, anti-friction bearing units each comprising concentric inner and outer races having radially opposed raceways and anti-friction bearing members positioned with limited clearance between said raceways to afford corresponding radial movement between said races of each bearing unit, a casing surrounding the vanes of said rotor and the opposite ends of said casing interengaging in an axial direction the outer races of said bearing units in operative position to space the same axially precisely, the inner races of said bearing units being connected frictionally to the opposite shaft ends of said rotor and thereby maintained spaced axially a predetermined amount whereby when said opposite ends of said casing interengage said outer races said raceways in said bearing units will be in precise radial opposition and thereby permit the aforementioned limited radial movement between the races of each bearing unit to be effective, said cartridge assembly being removably positioned within said housing as a unit by insertion thereof through said openin therein; and means in opposite ends of said housing interengageable with said outer races of said bearing units to hold the same in operative position relative to the opposite ends of said casing, whereby said inner and outer races of said bearing units are positioned in use respectively spaced precise predetermined distances axially to prevent abnormal loading of said 
     
     
        bearing units. 50. A dental handpiece comprising in combination, a handle having a housing on one end thereof connected thereto and provided with an opening; a fluid operated turbine rotor cartridge assembly comprising a fluid operated turbine having shaft ends and vanes intermediate thereof, anti-friction bearing units each comprising concentric inner and outer races having radially opposed raceways and anti-friction bearing members positioned with limited clearance between said raceways to afford corresponding radial movement between said races of each bearing unit, a casing surrounding the vanes of said rotor and the opposite ends of said casing interengaging respectively the opposed inner faces on the outer races of said bearing units in operative position to space the same precisely a predetermined distance axially, the inner races of said bearing units being connected frictionally to the opposite shaft ends of said rotor and thereby maintained spaced axially a predetermined amount whereby when said opposite ends of said casing engage the inner end faces of said outer races said raceways in said bearing units will be in precise opposition and thereby permit the aforementioned limited radial movement between the races of each bearing unit to be effective, said cartridge assembly being removably positioned within said housing as a unit by insertion thereof through said opening; and means in opposite ends of said housing interengageable with said outer races of said bearings to hold the same in operative position relative to the opposite ends of said casing, whereby said inner and outer races of said bearing units are positioned in use respectively spaced precise predetermined distances axially to prevent 
     
     
        abnormal loading of said bearing units. 51. A dental handpiece comprising in combination, a handle having a housing on one end thereof connected thereto and provided with an opening therein, said housing having a seat in one end thereof; a fluid operated turbine rotor cartridge assembly comprising a fluid operated turbine having vanes intermediate the ends thereof, anti-friction bearings comprising inner and outer races mounted at opposite ends of said rotor, the inner races of said bearings receiving said rotor, a clamping ring surrounding and positioning the outer race of the normally upper bearing in use, means extending between said clamping ring and outer race of the normally lower bearing in use and operable to space the outer races of said bearings a precise distance axially, the outer race of the lower bearing also being received within said seat in said housing, and cap means connectable to said housing over said opening therein and engageable with the upper end of said clamping ring to hold the outer races of said bearings firmly positioned and stationary relative 
     
     
        to the opposite ends of said casing and the seat within said housing. 52. A dental handpiece comprising in combination, a handle having a housing on one end thereof connected thereto and provided with an opening therein, said housing having a seat in one end thereof, a fluid operated turbine rotor cartridge assembly comprising a fluid operated turbine having vanes intermediate the ends thereof, anti-friction bearings comprising inner and outer races mounted at opposite ends of said rotor, the inner races of said bearings being fixed to said rotor, a clamping ring surrounding and positioning the outer race of the normally upper bearing in use, means extending between and abutting the outer race of the normally lower bearing in use and the lower surface of said clamping ring and operable to space the outer races of said bearings a precise distance axially, the outer race of the lower bearing being received within said seat in said housing; and cap means connectable to said housing over said opening therein and engageable with the upper end of said clamping ring to hold the outer races of said bearings stationary relative to said housing 
     
     
        and said cartridge assembly seated therein. 53. The dental handpiece according to claim 52 further characterized by said spacing means comprising a casing having an inwardly extending flange on the lower end thereof engageable with the upper surface of the outer race of the lower bearing, whereby said cap forces said clamping ring against the upper end of said casing and the flange on said casing forces the outer race of the lower bearing against the seat therefor in said housing when said cap is 
     
     
        connected to said housing. 54. The dental handpiece according to claim 51 further characterized by said spacing means comprising a casing surrounding the vanes of said rotor and having port means therein in alignment with the fluid passage means in the handle of said handpiece, whereby fluid is directed to said rotor to actuate it, and interengaging indexing means on said casing and housing operable to establish alignment of said ports in said casing with the fluid passage means of said handle 
     
     
        when said rotor assembly is inserted within said housing. 55. A dental handpiece comprising in combination, a handle having a housing on one end thereof connected thereto and provided with an opening therein; a fluid operated turbine rotor cartridge assembly comprising a fluid operated turbine having vanes intermediate the ends thereof; anti-friction bearings comprising inner and outer races mounted at opposite ends of said rotor, the inner races of said bearings receiving said rotor, clamping rings respectively surrounding and positioning the outer races of said bearings relative to said housing, and means extending between said clamping rings and operable to space the same and the outer races of said bearings a precise distance axially, said cartridge assembly being removably positioned with said housing as a unit by insertion thereof through said 
     
     
        opening. 56. A dental handpiece comprising in combination, a handle having a housing on one end thereof connected thereto and provided with an opening therein, said housing having a seat in one end thereof; a fluid operated turbine rotor cartridge assembly comprising a fluid operated turbine having vanes intermediate the ends thereof, anti-friction bearings comprising inner and outer races mounted at opposite ends of said rotor, the inner races of said bearings receiving said rotor, clamping rings respectively surrounding and positioning the outer races of said bearings relative to said housing, means extending between said clamping rings and operable to space the same and the outer races of said bearings a precise distance axially, the clamping ring on the outer race of the normally lower bearing in use being received within said seat in said housing; and cap means connectable to said housing relative to said opening and engageable with the clamping ring on the normally upper race in use to hold said assembly pressed against said seat in the housing and the outer 
     
     
        races of said bearing stationary relative to said housing. 57. A dental handpiece comprising in combination, a handle having a housing on one end thereof connected thereto and having a cylindrical interior wall and an opening therein, said housing having a seat in one end; a fluid operated turbine rotor cartridge assembly comprising a fluid operated turbine having vanes intemediate the ends thereof, anti-friction bearings comprising inner and outer races mounted at opposite ends of said rotor, the inner races of said bearings being fixed to said rotor, clamping rings respectively surrounding and fixed to the outer races of said bearings, a cylindrical casing extending between and abutting the inner end faces of said clamping rings and operable to space the same and the outer races of said bearings a precise distance axially, the outer diameters of the clamping rings on the outer races of the bearings being substantially the same as the outer diameter of said casing and said diameters being slightly less than the diameter of the cylindrical interior of said housing, whereby said turbine rotor cartridge assembly may be inserted into said housing through said opening to be positioned operatively therein, whereby said clamping rings and bearings are held coaxially aligned with said casing and said rotor cartridge assembly is centered relative to said housing; and locking means engageable with the clamping ring on the normally upper race in use to hold said cartridge assembly pressed against said seat in the housing and the outer races of said 
     
     
        bearings stationary relative to said housing. 58. A dental handpiece comprising in combination, a handle having a housing on one end thereof connected thereto and provided with an opening therein; a fluid operated turbine rotor cartridge assembly comprising a fluid operated turbine having vanes intermediately of the ends thereof, anti-friction bearings having inner and outer races, the inner races thereof receiving respectively the said rotor adjacent the outer ends thereof, means extending between said bearings and the opposite end portions of said means directly and respectively engaging the outer races of said bearings to space the same axially a predetermined precise distance, said cartridge assembly being removably positioned within said housing as a unit by insertion thereof through said opening; and means operable to secure said 
     
     
        assembly in operative position within said housing. 59. A dental handpiece comprising in combination, a handle having a housing on one end thereof connected thereto and provided with an opening therein; a fluid operated turbine rotor cartridge assembly comprising a fluid operated turbine having vanes intermediately of the ends thereof, anti-friction bearings having inner and outer races, the inner races thereof receiving respectively the opposite ends of said rotor, a casing surrounding the vanes of said rotor, the opposite end portions of said casing being substantially identical and directly respectively engaging the outer races of said bearings to space the same axially a predetermined precise distance, said cartridge assembly being removably positioned within said housing as a unit by insertion thereof through said opening; and means operable to secure said assembly in operative position within said 
     
     
        housing. 60. A dental handpiece comprising in combination, a handle having a housing on one end thereof connected thereto and provided with an opening therein; a fluid operated turbine rotor cartridge assembly comprising a fluid operated turbine having vanes intermediately of the ends thereof, anti-friction bearings having inner and outer races, the inner races thereof being connected respectively to the opposite ends of said rotor, a casing surrounding the vanes of said rotor and extending between said bearings, the opposite end portions of said casing respectively directly abutting the opposed faces of the outer races of said bearings to space the same axially a predetermined precise distance, said cartridge assembly being removably positioned within said housing as a unit by insertion thereof through said opening; and means operable to 
     
     
        secure said assembly in operative position within said housing. 61. A dental handpiece comprising a hollow handle having a rotor housing at one end and connected thereto, a gaseous fluid operated rotor supported for rotation within said housing, gaseous fluid conducting means within said handle operable to direct gaseous fluid to said rotor to rotate the same, means to discharge gaseous fluid from said housing into said handle, and filter means within said handle to filter said exhausting gaseous fluid 
     
     
        discharged from said handle. 62. A high speed fluid operated rotary unit comprising supporting means, conduit means connectable to a source of fluid under pressure, a housing head connected to said supporting means and having an opening, a cartridge comprising a turbine rotor arranged to be driven by fluid under pressure and having fluid inlet means communicating with said rotor and said rotor also having means engageable with material to be worked thereby, said cartridge being insertable through said opening into operative position within said head, and co-engaging indexing means on said cartridge and conduit means operable to align the fluid inlet means of said cartridge in communication with said 
     
     
        fluid conduit means to receive fluid therefrom to drive said rotor. 63. A high speed fluid operated rotary unit comprising supporting means provided with conduit means connectable to a source of fluid under pressure, a housing head connected to said supporting means and having an opening, a cartridge comprising a turbine rotor arranged to be driven by fluid under pressure, said cartridge having fluid inlet means communicating with said rotor and said rotor also having means engageable with material to be worked, said cartridge being insertable through said opening into operative position within said head, and co-engaging indexing means on said cartridge and head operable to align the fluid inlet means of said cartridge in communication with said fluid conduit means of said supporting means to receive fluid therefrom to drive said rotor. .[.64. A high speed rotary tool comprising a supporting member provided with conduit means connectable to a source of fluid under pressure, a housing connected to said supporting means and having an opening therein, a cartridge unit comprising; a turbine rotor and shaft to be driven by fluid under pressure, bearings spaced axially of said shaft and supporting the same for rotation, and means surrounding said shaft and extending between said bearings to space the same in an axial direction, said last mentioned means having fluid inlet means communicating with said rotor and said rotor also having means to which a tool may be attached, said cartridge being insertable through said opening in said housing into operative position therein; and means detachably connected to said head and engaging said cartridge to secure said cartridge within said housing with the fluid inlet means therein in communication with said fluid conduit means of said 
     
     
        supporting member to receive fluid therefrom to drive said rotor..]. 65. A high speed rotary tool comprising a supporting member provided with conduit means connectable to a source of fluid under pressure, a housing having an opening therein, a cartridge comprising; a turbine rotor and shaft to be driven by fluid under pressure, bearings spaced axially of said shaft and supporting the same for rotation, and means surrounding said shaft and extending between said bearings to space the same in an axial direction, said last mentioned means having fluid inlet means communicating with said rotor and said rotor also having means to which a tool may be attached, said cartridge being insertable through said opening of said housing into operative position therein, co-engaging indexing means on said cartridge and housing operable to align the fluid inlet means of said cartridge in communication with said fluid conduit means of said supporting member to receive fluid therefrom to drive said rotor; and means detachably connected to said housing and engaging said cartridge to 
     
     
        secure said cartridge therein. 66. A high speed dental handpiece comprising a housing having opposite ends and a chamber therein, a shaft within said housing, a rotor having impeller means carried by said shaft and positioned within said chamber with its ends in spaced relationship to the opposite ends of said chamber to provide annular expansion and distribution pockets in the opposite ends of said chamber, bearings supported by said housing for rotatable supporting said shaft outwardly from opposite ends of said rotor, means on one end of said shaft to connect a dental tool thereto, said impeller means on said rotor including means adjacent the ends thereof operable to discharge gas freely from said impeller means axially in opposite directions substantially from locations beteen the periphery and axis of said rotor for expansion and circulation into said pockets, said opposite ends of the housing being provided with gas discharge means positioned axially past said bearings and communicating with said pockets for exhausting a portion of said driving gas from said chamber, and an additional gas discharge means communicating at one end with said chamber and at the other end being directed to the 
     
     
        atmosphere at a position remote from said housing. 67.  A high speed dental handpiece comprising a housing having opposite ends and a chamber therein intermediate the ends thereof, a shaft within said housing, a rotor having impeller means carried by said shaft and positioned within said chamber, bearings supported by said housing for rotatably supporting said shaft outwardly from opposite ends of said rotor, means on one end of said shaft to connect a dental tool thereto, means to direct gas under pressure against said impeller means to rotate said rotor, said impeller means on said rotor including means adjacent the ends thereof operable to discharge gas from said impeller means axially in opposite directions into said chamber, said housing having annular spaces respectively adjacent said opposite ends of said housing and communicating with said intermediate chamber, said opposite ends of the housing also being provided with gas discharge means positioned axially past said bearings and communicating with said annular spaces to exhaust therefrom a portion of said driving gas, and an additional gas discharge means communicating at one end with said intermediate chamber and at the other end being directed to the atmosphere at a position remote from said housing.