SPEED REDUCING DENTAL HANDPIECE

Abstract: This invention is a disposable prophylaxis tool used in dentistry that includes an integrally formed gear reduction mechanism (60) within the housing (20) to allow a high powered drill output to drive the tool through the reducing gears in a slow reliable manner. The disposable prophylaxis cup is formed from inexpensive plastic and lends itself to mass production and assembly to be economically discarded after a single use thereby promulgating hygiene.

Description: Speed Reducing Dental Hand Piece Technical Field The following invention relates generally to instrumentalities used in the dental environment. More specifically, the instant invention is directed to a hand piece which reduces a high speed air motor which typically runs up to 500,000 rpm to a low speed hand piece, whose operating speed is in the order of 5,000 to 20,000 rpm for use in low speed dental operations, such as when polishing teeth. Background Art It is known to use gears in order to reduce speeds in many environments. Commonly, the smooth meshing of gears entails lubrication. If the device is to work in an aeseptic environment, seals must isolate the lubricated areas from an output shaft to prevent the migration of lubrication therebeyond. In the dental environment, however, it is more than just objectionable to allow the migration of lubricating oil outside a gear casing. A health issue arises. Further, the problem associated with the lubrication migrating beyond the seal is exacerbated in the dental environment where saliva, blood and debris from a patient's mouth is likely to contact the dental instrument. Heretofore, dental instruments have been made from metal which allow them to be autoclaved for sterilization prior to subsequent reuse. However, for rotating machinery that is provided with seals and lubrication, a high temperature autoclave using volatile solvents can reduce the life of the tool. More importantly, debris generated from the patient's mouth may provide an ongoing hazard particularly now with the awareness of communicable diseases having reached an acute level. Accordingly, a need exists for a disposable device which allows reliable single use, but which can be affordably discarded after a single use due to manufacturing economics. The following prior art reflects the state of the art of which applicant is aware and is included herewith to discharge applicant's acknowledged duty to disclose relevant prior art. It is stipulated, however, that none of these references teach singly nor render obvious when considered in any conceivable combination the nexus of the instant invention as disclosed in greater detail hereinafter and as particularly claimed. U.S. PATENT DOCUMENTS PATENT NO. ISSUE DATE INVENTOR 263,814 September 5, 1882 Schmitz 969,378 September 6, 1910 Krause 1,343,115 June 8, 1920 Current 1,601,397 September 28, 1926 Kochendarfer 1,999,488 April 30, 1935 Swisher, et al. 2,017,881 October 22, 1935 Wiseman 2,025,779 December 31, 1935 Roelke 2,033,662 March 10, 1936 Witt 2,128,157 August 23, 1938 Monnier, et al. 2,135,933 November 8, 1938 Blair 2,203,974 June 11, 1940 Weinhardt 2,226,145 December 24, 1940 Smith 2,300,828 November 3, 1942 Goldenberg 2,315,016 March 30, 1943 Shotton 2,328,270 August 31, 1943 Greenberg 2,463,118 March 1, 1949 Moore 2,586,968 February 26, 1952 Maclay 2,684,035 July 20, 1954 Kemp 2,789,352 April 23, 1957 Wiseman Re. 24,391 November 12, 1957 McFadden 2,836,877 June 3, 1958 Hannahan 2,933,046 April 19, 1960 McCray 2,937,444 May 24, 1960 Kern 3,043,274 July 10, 1962 Quackenbush 3,054,355 September 18, 1962 Neely 3,163,934 January 5, 1965 Wiseman 3,192,922 July 6, 1965 Winkler 3,229,369 January 18, 1966 Hoffmeister, et al. 3,309,965 March 21, 1967 Weickgenannt 3,376,825 April 9, 1968 Burnett 3,421,224 January 14, 1969 Brehm, et al. 3,477,793 November 11, 1969 Kitagawa 3,510,229 May 5, 1970 Smith 3,719,440 March 6, 1973 Snider 3,727,313 April 17, 1973 Graham 3,740,853 June 26, 1973 Brahler 3,856,432 December 24, 1974 Campagnuolo, et al. 3,855,704 December 24, 1974 Booth 3,877,574 April 15, 1975 Killick 3,942,392 March 9, 1976 Page, Jr., et al. 3,955,284 May 11, 1976 Balson 3,987,550 October 26, 1976 Danne, et al. 4,040,311 August 9, 1977 Page, Jr., et al. 4,053,983 October 18, 1977 Flatland 4,171,571 October 23, 1979 Gritter 4,182,041 January 8, 1980 Girard 4,185,386 January 29, 1980 Nordin, et al. ,248,589 February 3, 1981 Lewis ,259,071 March 31, 1981 Warden, et al. ,261,536 April 14, 1981 Melcher, et al. ,266,933 May 12, 1981 Warden, et al. ,365,956 December 28, 1982 Bailey ,392,779 July 12, 1983 Bloemers, et al. ,465,443 August 14, 1984 Karden ,540,337 September 10, 1985 Olsen ,693,871 September 15, 1987 Geller ,767,277 August 30, 1988 Buse 4,795,343 January 3, 1989 Choisser 4,842,516 June 27, 1989 Choisser 4,846,638 July 11, 1989 Pahl, et al. 4,863,344 September 5, 1989 Stefanini 4,929,180 May 29, 1990 Moreschini 4,941,828 July 17, 1990 Kimura 5,020,994 June 4, 1991 Huang 5,028,233 July 2, 1991 Witherby 5,040,978 August 20, 1991 Falcon, et al. 5,062,796 November 5, 1991 Rosenburg 5,094,615 March 10, 1992 Bailey 5,120,220 June 9, 1992 Butler 5,156,547 October 20, 1992 Bailey 5,163,825 November 17, 1992 Oetting 5,423,679 June 13, 1995 Bailey 5,425,634 June 20, 1995 Brockway 5,425,638 June 20, 1995 Abbott 5,484,284 January 16, 1996 Bailey 5,503,555 April 2, 1996 Bailey FOREIGN PATENT DOCUMENTS PATENT NO. ISSUE DATE INVENTOR DE 12,584 March 17, 1903 Bryn DE 646,193 June 9, 1937 Dϋrhager NZ 102,378 October 27, 1949 Walsh DE 803,306 April 2, 1951 Hollmann GB 2,154,283 September 4, 1985 Collier GB 2,209,284 May 7, 1988 Kimura OTHER PRIOR ART On cludine Author, Title, Date, Pertinent Pa lees. Etc. ) Oralsafe, Advertisement for Oralsafe Disposable Handpiece, Dentistry Today Trade Journal, August, 1992, entire advertisement. Denticator, Product Brochure, 1990, entire brochure. SmartPractice, Advertisement for a Smart Angle™ prophy angle, entire advertisement. Dental Products Report, "Disposable Handpiece", November, 1992, page 96. Diversified Dental Supply, Inc., Advertisement for Disposable High Speed Hand Pieces, entire advertisement. The National Magazine for Dental Hygiene Professionals, Product Report, "Prophy Cups", January, 1992, page 38. Dental Products Report, New Products, "Prophy Cups", January, 1992, page 30. Oralsafe, Advertisement for Oralsafe disposable handpieces, Impact,The Newsmagazine of the Acadamy of General Dentistry, December, 1992, entire advertisement. Young Dental, advertisement for Turbo™ Cup prophy cup, 1991, entire advertisement. Disclosure of Invention Accordingly, the instant invention addresses these problems by providing a device which is tailored for the specific purpose and for a single use. In this way, maximum hygiene will have been afforded and the safety of the patient will receive paramount import. The air turbine on a dental drill has a drive speed well above that which is needed for the prophylaxis that normally occurs when one goes to a dentist for teeth cleaning. In fact high speed cleaning is contraindicated. The instant invention resolves this problem by providing a housing in which a drive shaft is coupled to the high speed output of the air motor. The drive shaft includes a drive gear which is surrounded by idler gears which in turn rotates a driven gear with sufficient speed reduction so that a shaft driven by the driven gear communicates with an output gear at a desired slow speed for dental prophylaxis. Industrial Applicability The industrial applicability of this invention shall be demonstrated through discussion of the following objects of the invention. Accordingly, it is an object of the present invention to provide a unitary disposable prophy angle which reduces the high speed from a conventional dental motor to one sufficient to promulgate dental prophylaxis by polishing. A further object of the present invention is to provide a device as characterized above which avoids the problems of contamination from one patient to the next by being economically formed to allow disposal after a single use. A further object of the present invention is to provide a device as characterized above which is durable in construction, safe to use and lends itself to the economies of mass production. A further object of the present invention is to provide a device as characterized above which reliably drives an output at a constant, slow speed. Viewed from a first vantage point, it is object of the present invention to provide a speed reducing dental hand piece, comprising, in combination: a housing having an input end and an output end, a drive shaft including a coupling means at one end and a drive gear at another end, the drive shaft coupling means located at the input end of the housing and the drive shaft extending into the housing, a driven gear operatively coupled to the drive gear in the housing and having an output means, the driven gear having more teeth than the drive gear whereby the drive gear and driven gear cooperate to reduce rotational speed of the output means compared to the coupling means. Viewed from a second vantage point, it is an object of the invention to provide a method for reducing a high speed source of power to a lower speed for use in dental prophylaxis, the steps including: providing a housing with a cylindrical bore and an offset bore in communication therewith, providing a prophy drive in the offset bore, providing a speed reducing drive in the cylindrical bore coupled to the prophy drive, and driving the speed reducing drive. These and other objects will be made manifest when considering the following detailed specification when taken in conjunction with the appended drawing figures. Brief Description of Drawings Figure 1 is a perspective view of the apparatus according to the present invention. Figure 2 is a sectional view taken along lines 2-2 of figure 1. Figure 2A is a detail of figure 2. Figure 3 is a sectional view taken along lines 3-3 of figure 2. Figure 4 is an exploded parts perspective of the apparatus according to the present invention. Figures 5A, 5B and 5C reflect alternative prophy devices. Best Mode(s) for Carrying Out the Invention Considering the drawings, wherein like reference numerals denote like parts throughout the various drawing figures, reference numeral 10 is directed to the disposable speed reducing hand piece for dental prophylaxis according to the present invention. In its essence, the hand piece 10 (shown in figure 4) includes a housing 20, a tail piece 40 at an end of the housing remote from a prophylaxis cup drive 80, a drive shaft 50 nested within the housing and oriented adjacent the tail piece 40, the drive shaft 50 having a slotted drive head 54 for receiving input from a high speed dental motor and a drive gear 56 associated therewith. A plurality of idler gears 68 circumscribe the drive gear 56 and are fixed into position on posts 64 contained within a cup 62 which has an interior back wall 63 and an interior side wall defines a driven gear 66 in communication with the idler gears 68. The driven gear 66 moves a driven shaft 70 and thence to an output gear 76 that couples with a short gear 82 in communication with the prophy cup drive 80. More particularly, the speed reducing hand piece 10 (figures 1 and 4) details a housing 20 which includes a central cylindrical portion 22 having a plurality of longitudinally extending ribs 24 disposed around the outer periphery of the cylindrical section 22. This central section communicates with an input end on the left-hand side characterized in a second cylindrical section 34 having a cross- sectional area greater than the central section 22 with an area of transition therebetween including an integral conical transition 32. An end 26 opposite the input end 34 defines an output end 26. The output end 26 is of a lesser cross- sectional area, but is also cylindrically shaped and includes a necked-down portion 27 at an area of transition between the central section 22 and the output end 26. The output end 26 further communicates with an orthogonally offset terminus 28 having a central bore 30 disposed with a central axis transverse to the long axis of the housing's main body. The tail piece 40 completes the housing 20. In essence, the tail piece has a central section 42 of substantially the same cylindrical diameter as the input end 34, and the tail piece 40 is fixed to the housing main body 20 by means of a stepped down sleeve 44 which frictionally resides within an interior bore 36 of the input end 34. The friction fit may be enhanced by an annular groove 35 disposed on the interior bore 36. The groove 35 receives projections 37 located on sleeve 44. Front face 37a of the projection is curved to ease locking in the tail piece 40. Rear face 37b is vertical and flat. The projection 37 defines a one-way barb which resists removal. Bore 36 may also receive a trackway 31 to align with a key 29 formed on sleeve 44 which assists with alignment. An outwardly diverging (with respect to the major housing 20) section 46 completes the tail piece 40 and constitutes a truncated cone having a greater cross- sectional opening area remote from the housing 20 than closer. This tail piece 40 mates with a source of power. Prior to installing the tail piece 40 on the housing 20, however, drive elements are first placed within the housing. More specifically, the output end 26 of the housing 20 receives a driven gear assembly 60. The driven gear assembly includes a driven shaft 70 having at the output end, that is, an output gear 76 fortified by a cylindrical support 74. The shaft 70 is thinner than the support 74 and includes a disc 72 integrally formed on the shaft 70 to minimize shaft flexing because the disc 72 fits with close tolerance into the interior bore 21 of the housing 20. The driven shaft 70 then extends to the input end (rearwardly) to form a driven gear cup 62 defined as a blind bore with an open end facing the input end of the housing. An interior side wall of the blind bore is provided with a plurality of gear teeth 66. The interior back wall 63 (figure 2) of the gear cup 62 supports a plurality of idler gear support posts 64. A plurality of idler gears 68 are supported on these posts 64 and are in meshing engagement with the interior teeth 66 of the gear cup 62. Preferably, three idler gears 68 are included as shown in figure 3 spaced from a central point of the gear cup at about 120° intervals. The idler gears 68 are of a substantially lesser dimension than the available interior bore space to provide a central clearance for a drive gear 56 placed centrally with respect to the three idler gears 68 of the gear cup 62. The drive gear 56 drives the idler gears 68 which thereafter rotate the drive cup 62 via teeth 66. Note in figure 2 that the transition between the back wall 63 of the drive cup and its outer peripheral side wall 62 nests adjacent a portion of the housing where the input end 34 transitions at 32. This positively locates the driven elements 60 in conjunction with projection 37 and groove 35. The drive gear 56 is integrally formed on a drive shaft 52 having a slotted head 54 at one end for receiving input from a source. The area between the drive shaft 52 and the drive gear 56 includes a locating disc 58 fixed on the drive shaft 52. In conjunction with groove 35 and projections 37, this allows the drive shaft assembly 50 to be fixed and located within the housing by virtue of the tail piece 40 and its necked-down portion 44 abutting against one face of the disc 58 assuring that the drive shaft neither wanders axially nor flexes. In use and operation, because the drive gear 56 has substantially fewer teeth than the drive cup teeth 66, one rotation of the drive gear 56 results only in a partial rotation of the drive cup. This reduces the speed appreciably and allows the device to be used in dental applications that benefit from a slower rotation. For example, a polishing compound can be applied to a prophy cup fitted on drive 80 which is driven by the short gear 82 that is fitted into the housing 20 by first placing the short gear 82 into the bore 30 of the offset terminus 28 and then allowing the output gear 76 to mesh with gear 82. Figures 5 A, 5B and 5C show variations of the prophy cup drive: a friction fit, a screw thread and a latch coupling, respectively. Moreover, having thus described the invention, it should be apparent that numerous structural modifications and adaptations may be resorted to without departing from the scope and fair meaning of the instant invention as set forth hereinabove and as described hereinbelow by the claims.

Claims: Claims I Claim: Claim 1 - A speed reducing dental hand piece, comprising, in combination: a housing having an input end and an output end, a drive shaft including a coupling means at one end and a drive gear at another end, said drive shaft coupling means located at said input end of said housing with said drive shaft and drive gear extending into said housing, a driven gear operatively coupled to said drive gear in said housing and having an output means, said driven gear having more teeth than said drive gear whereby said drive gear and driven gear cooperate to reduce rotational speed of said output means compared to said coupling means. Claim 2 - The dental hand piece of claim 1 including a plurality of idler gears circumscribing said driven gear and oriented in meshing engagement with said drive gear and said driven gear whereby when said drive gear rotates said idler gears, said idler gears rotate said driven gear. Claim 3 - The dental hand piece of claim 2 wherein said driven gear is disposed within a driven cup, and said driven gear is integrally formed on an interior surface of said cup, said idler gears in meshing engagement therewith. Claim 4 - The dental hand piece of claim 3 wherein said cup includes a back wall with a plurality of posts which project into said cup and support said idler gears in said cup. Claim 5 - The dental hand piece of claim 4 wherein said idler gears are three in number. Claim 6 - The dental hand piece of claim 5 wherein said output means includes an output gear connected to said cup by means of a driven shaft integrally formed with said cup. Claim 7 - The dental hand piece of claim 6 including a prophy cup drive means having a short gear in meshing engagement with said output gear, said prophy cup drive means disposed within said housing. Claim 8 - The dental hand piece of claim 7 wherein said housing has a longitudinally extending substantially cylindrical portion and said output end includes a bore which is orthogonally offset from said cylindrical portion and integrally formed therewith. Claim 9 - The dental hand piece of claim 8 wherein said central cylindrical portion has a plurality of longitudinally extending ribs disposed around the outer periphery, said input end characterized by a second cylindrical section having a cross-sectional area greater than said central section, an area of transition therebetween including a conical transition section. Claim 10 - The dental hand piece of claim 9 wherein an end opposite said input end defines said output end having a lesser circular cross-sectional area than said cylindrical portion including a necked-down portion of an area of transition from said central portion, said output end in operative communication with an orthogonally offset terminus having a central bore disposed therewithin. Claim 11 - The dental hand piece of claim 10 including a disposable prophy cup drive disposed within said central bore of said orthogonally offset terminus in operative communication with said output gear mounted on said driven shaft. Claim 12 - The dental hand piece of claim 11 including a tail piece having a stepped-down sleeve frictionally residing within an interior bore of said input end. Claim 13 - The dental hand piece of claim 12 wherein said tail piece supports said drive shaft by having a terminus of said stepped-down sleeve adjacent a locating disc on said drive shaft, said drive shaft having a slotted end opposite said drive gear to be driven by a dental tool. Claim 14 - The dental hand piece of claim 13 wherein said tail piece includes a central section of substantially the same cylindrical diameter as said input end of said housing and said tail piece includes an outwardly diverging section adjacent its said slotted end. Claim 15 - The dental hand piece of claim 14 wherein said stepped-down sleeve includes means for interlocking engagement with an interior bore of said housing. Claim 16 - The dental hand piece of claim 15 wherein said interlocking means includes a plurality of outwardly extending projections adapted to coact with an annular groove. Claim 17 - The dental hand piece of claim 16 wherein said projections are disposed upon said stepped-down sleeve and said annular groove resides within said interior bore of said housing. Claim 18 - The dental hand piece of claim 17 wherein said projections have an arcuate first face to allow axial insertion into said annular groove and a steep vertically disposed back face to serve as a barb retarding retraction therefrom. Claim 19 - The dental hand piece of claim 18 including a keyway at the juncture between said stepped-down sleeve and said interior bore of said housing for alignment. Claim 20 - The dental hand piece of claim 19 wherein said keyway is disposed on said stepped-down sleeve and a corresponding trackway is located on said interior bore of said housing. Claim 21 - A method for reducing a high speed source of power to a lower speed for use in dental prophylaxis, the steps including: providing a housing with a cylindrical bore and an offset bore in communication therewith, providing a prophy drive in the offset bore, providing a speed reducing drive in the cylindrical bore coupled to the prophy drive, and driving the speed reducing drive.

Inventors: MENDOZA JOSE L, MENDOZA, JOSE, L.
Applicants: DENTICATOR INT INC, MENDOZA JOSE L, DENTICATOR INTERNATIONAL, INC., MENDOZA, JOSE, L.
Application year: 1998
Main classification: A61C1
IPC codes: A61C17