Abstract:
An exhaust manifold for a dental handpiece system receives at an inlet thereof return air flow provided by a dental handpiece. A unidirectional valve couples the inlet to a common manifold space which in turn couples to ambient air by way of a filter. By applying filtration on the backside of the unidirectional valve, air entering the common manifold space cannot thereafter reenter the return air conduit and thereby contaminate the same handpiece or other handpieces in a multiple handpiece system. A replaceable filter unit avoids accumulated debris and promotes better sanitary conditions.

Description:
CROSS-REFERENCE TO RELATED PROVISIONAL APPLICATION 
     The present application relies for priority of filing on prior-filed provisional application No. 60/164,127 filed Nov. 8, 1999 by the inventors named herein and entitled MULTIPORT ANTIBACKFLOW MANIFOLD WITH SINGLE NOISE REDUCING INFECTION CONTROL DISPOSABLE EXHAUST. 
    
    
     BACKGROUND OF THE INVENTION 
     As in any medical procedure, dental procedures require strict sanitary conditions guarding against contamination from patient-to-patient or from patient-to-dentist. As patients come and go through a series of examinations and procedures, the dentist must present to each patient sanitary conditions with respect to the environment of the examination and with respect to the equipment used during dental exam and dental procedures. The present invention concerns presentation of both sanitary environment and sanitary equipment to each new patient. More particularly, the present invention concerns dental handpiece systems maintained in sanitary condition and operated in such manner to prevent contamination of the surrounding environment. 
     Dental handpieces are air-driven devices. A common dental handpiece is the high-speed turbine drill. A turbine drill receives a flow of air along an air supply conduit for application against a rotatable turbine. As the air hits the turbine, it rotates the turbine and thereafter exits the handpiece by way of a return air conduit. Thus, dental handpieces are relatively lightweight devices coupled to a dental handpiece system by way of a set of air conduits. When in use the tool spins at approximately 350,000 rpm and develops a vortex or suction around the tool pulling debris, i.e., blood, saliva, or tooth material, into the handpiece in the vicinity of the turbine. More particularly, typical handpiece construction leaves open the handpiece housing in the vicinity of the turbine bearings. Due to the increased air velocity, and therefore reduced air pressure, debris in the vicinity of the tool moves into the handpiece housing. Accordingly, debris moves into the return air conduit and back into the system delivery unit and eventually into the exhaust system. Because such return air has not traditionally been managed with respect to bio-contamination, such exhaust air typically enters directly back into the ambient air of the dental operating room. 
     While not well recognized as a significant hazard to patients, dentists, and staff, such untreated release of bio-contaminants represents risk to those in the dental operating room. This becomes especially hazardous where such contaminants remain in place for long periods resulting in growth of hazardous mold and fungus. Thus, contamination becomes serious when debris collected by the handpieces rests for extended periods within the handpiece system delivery unit. Occasional maintenance or repair requiring opening of the delivery unit exposes the maintenance or repair person to significant biohazard. Without strict attention to proper cleanup procedures, such contamination can spread further into the operating room environment during maintenance, repair, or cleanup. Generally, such accumulated biohazard and resulting mold and fungus represent an undesirable presence in any medical environment. 
     According to one method of treatment, the return air tubes connect together to a common discharge and the debris collects in a gauze pad. Thus, where this method does collect some of the debris carried away from the procedure site, there remains significant contamination in the form of atomized bio-contaminants not captured in the gauze trap and, therefore, entering the ambient air of the dental examination room. When the gauze impedes airflow from the common discharge, a backpressure exists at the terminal portions, i.e., at the common discharge, and, undesirably, airflow passes in the reverse direction along such return air conduits, i.e., passes in the direction of the handpiece. This represents a significant opportunity for bio-contamination of other handpieces as well as the operating room environment. 
     A second method filters directly at the handpiece, i.e., places in-line a filter along the both the supply and return air conduit at the handpiece. Unfortunately, this should require a filter change for every use. Also, it must be replaced for every patient, it adds additional weight at the handpiece, and it finds application for only a limited set of handpiece types. 
     U.S. Pat. No. 5,897,317 issued Apr. 27, 1999 and entitled Dental Handpiece With Disposable Filter Cartridge, shows placement of a filter cartridge at the handpiece for cleaning drive air, water, chip air, and exhaust passing through the handpiece. U.S. Pat. No. 5,716,210 issued Feb. 10, 1998 and entitled Disposable Filter For Dental Handpiece also illustrates an insert placed in line at the handpiece for filtering air and water. U.S. Pat. No. 5,749,726 issued May 12, 1998 and entitled Disposable Point Of Use Filtration Element For Purifying Air And Water Supplies To Dental Handpieces also illustrates an in-line proposition for filtration at a dental handpiece relative to cooling water and cooling air supplies but unrestricted turbine supply and return air. 
     U.S. Pat. No. RE30,340 reissued Jul. 22, 1980 and entitled Dental Handpiece attempts to avoid collection of bio-contaminants at the handpiece by restricting the fluid outlet from the turbine sufficiently to ensure that a portion of the fluid is exhausted through the turbine bearings and openings in the housing to prevent ergots of foreign matter into the interior. Restricting airflow at the downstream side of the turbine, however, impedes turbine performance and, therefore, impedes overall efficiency of the dental handpiece. Furthermore, this proposition undesirably blows excess air into the patient&#39;s mouth. 
     U.S. Pat. No. 5,318,443 issued Jun. 7, 1994 and entitled Method Of Flushing Disinfecting And Lubricating A Dental Turbine Handpiece illustrates a mechanism by which a handpiece may be flushed clean of contaminants while not in operation. Unfortunately, the proposed solution does not address concerns relating to the collection and discharge of bio-contaminants during operation. 
     The “saliva ejector”, i.e., a separate device pulling by vacuum material from the patient&#39;s mouth during a procedure, removes excess fluid from the operating site. This system carries the bulk of material away from the site and is well recognized as a source of potential bio-contamination. Some saliva ejector systems filter the return air and deposit the waste into the public sewer. U.S. Pat. No. 5,571,412 issued Nov. 5, 1996 and entitled Dental Filter Assembly illustrates a filter canister assembly receiving waste from a dental cuspidor. 
     Filtration systems have also been applied in-line relative to water supply lines. For example, U.S. Pat. No. 5,971,757 issued Oct. 26, 1999 and entitled In-Line Filter System For Dental Instruments illustrates a filter unit placed in-line relative to a water supply line for a dental instrument. 
     Need remains, however, to improve dental handpiece systems to manage better the relatively smaller volume, e.g., in relation to the saliva ejector system, debris inadvertently collected at the handpiece. More particularly, there remains need to reduce the risk of contamination to the doctor, patient, and staff as a result of debris carried by the dental handpiece and potentially accumulating within the dental handpiece delivery unit. 
     The present invention addresses this and other concerns with management of bio-contamination relative to dental handpieces and dental handpiece systems. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, an exhaust manifold for a dental handpiece system receives at an inlet thereof return air flow provided by a dental handpiece. A unidirectional valve couples the inlet to a common manifold space which in turn couples to ambient air by way of a filter. By applying filtration on the backside of the unidirectional valve, air entering the common manifold space cannot thereafter reenter the return air conduit and thereby contaminate the same handpiece or other handpieces in a multiple handpiece system. 
     As applied in a multiple handpiece system, the exhaust manifold under the present invention includes a plurality of inlets each corresponding to and receiving the return air from a corresponding handpiece. Each inlet in turn couples by way of a corresponding unidirectional valve to the common manifold space. The common manifold space in turn couples to ambient air via a filter. Back pressure produced at the filter relative to the common manifold space cannot reintroduce air back into any of the return air supply conduits because the corresponding unidirectional valves block such air flow. 
     The filter unit as proposed under the present invention is removeably mounted and thereby replaceable when needed. Frequent replacement of the filter unit protects against undesirable accumulation of bio-contaminants and growth of microorganisms thereupon. 
     Ambient air within the dental examination area is thereby protected against contamination as well all dental handpieces within a dental handpiece system protected against contamination relative to bio-contaminants and oil originating from a given handpiece. 
     The subject matter of the present invention is particularly pointed out and distinctly claimed in the concluding portion of this specification. However, both the organization and method of operation of the invention, together with further advantages and objects thereof, may best be understood by reference to the following description taken with the accompanying drawings wherein like reference characters refer to like elements. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which: 
     FIG. 1 illustrates schematically a dental handpiece system including a multiport antibackflow manifold according to the present invention. 
     FIG. 2 illustrates a side sectional view of a multiport antibackflow manifold applicable to a pre-existing handpiece system and according to a preferred embodiment of the present invention. 
     FIGS. 3 and 4 illustrate bottom and top views, respectively, of an upper portion of the manifold of FIG.  2 . 
     FIG. 5 illustrates a cover for the manifold of FIG.  2 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 illustrates schematically a dental handpiece system  10  according to the present invention. According to one aspect of the present invention, system  10  employs multiple dental handpieces. In the present illustration, four such handpieces will be shown, however, it will be understood that any selected number of handpieces may be utilized under the present invention. 
     In FIG. 1, system  10  includes a set of handpieces  12 , individually handpiece  12   a - 12   d . Each handpiece  12  carries a tool  14 , individually tools  14   a - 14   d . In this particular illustration, each handpiece  12  is a high-speed turbine drill rotating the corresponding tool  14  at high speeds, e.g., 350,000 rpm, for purposes of executing dental procedures. Dental handpiece systems include other, i.e., low speed or ultra sonic, handpieces which do not necessarily undesirably collect bio-contaminants during use. However, such other handpieces typically also operate in the fashion illustrated relative to handpieces  12 , i.e., receive a flow of supply air and return the supply air through an exhaust system. The present invention is well suited for operation in conjunction with such other handpieces and is especially useful for filtering oil from the return air relative to surrounding ambient air. The present disclosure focuses, however, on the undesirable collection of bio-contaminants by high-speed handpieces such as handpieces  12  illustrated in FIG.  1 . 
     Each handpiece  12  couples to the remainder of system  10  by means of a tubing set  16 , individually tubing sets  16   a - 16   d . Each tubing set  16  includes a plurality of conduits. In addition to those illustrated herein, tubing sets  16  include cooling fluid, e.g., cooling air or water, supply and return conduits and the like (not shown herein). As relevant to the present invention, each tubing set  16  includes an air supply conduit  18  and an air return conduit  20 , individually air supply conduits  18   a - 18   d  and air exhaust conduits  20   a - 20   d . Air forced down a given supply conduit  18  strikes a turbine (not shown) within the corresponding handpiece  12  causing the corresponding tool  14  to rotate at high speed. After striking the turbine, the air travels back to the dental unit (not shown in FIG. 1) along the corresponding return conduit  20 . 
     A compressed air supply  30  couples to each of the air supply conduits  18  by way of an operator foot control  32 , e.g., foot operated control. In this manner, an operator selectively introduces air from supply  30  into a selected one of air supply conduits  18  and thereby selectively operates one of handpieces  12 . 
     Each return conduit  20  terminates at a unidirectional valve  40 , individually valves  40   a - 40   d . Each valve allows a one-way flow of return air out of the corresponding return conduit  20  and into a common manifold  42 . As may be appreciated, air exiting a given return conduit  20  and passing through the corresponding valve  40  into common manifold  42  cannot thereafter reenter any one of return conduits  20  by virtue of the valves  40 . In other words, once air enters common manifold  42  it cannot thereafter reenter any conduit  20 . Common manifold  42  couples to ambient air space  44  by way of a removable filter unit  46 . Filter unit  46  includes a hepa filter element  46   a  mounted therein. It is suggested, however, that hepa-filter element  46   a  be permanently mounted within unit  46  and that unit  46  be removably mounted. 
     As will be appreciated, back-pressure created within common manifold  42  by virtue of filter unit  46  cannot cause air flow back into return conduits  20  by virtue of unidirectional valves  40 . Accordingly, once air reaches common manifold  42  it is destined to exit system  10  only by way of filter unit  46 . 
     Debris accumulates at filter element  46   a  and eventually reaches a given magnitude, filter unit  46  may be replaced, e.g. once-a-week. System  10  thereby protects ambient air space  44  against contamination from oil as originating at compressed air supply  30  or, more importantly, bio-contaminants as carried from the patient by handpieces  12 . Filter element  46   a  provided as a hepa-filter at a 0.1 micron filtration rating eliminates most contaminants, i.e., blood, saliva, bacteria, fungus, pulled into the handpiece by vacuum effect during use thereof or other contaminants passing through the handpiece, e.g. oil from the compressed air supply  30 . Filter unit  46  may be disposed of with other bio-hazardous materials from the dental office. 
     Thus, system  10  addresses contamination control issues in dental operations. By virtue of valves  40 , return air cannot pass from one handpiece back into another handpiece. Furthermore, return air must pass through filter element  46   a  before it enters ambient air space  44 . Because filter unit  46  is replaceable, accumulated microorganisms, fungus or mold growing at filter unit  46  need not accumulate at all or beyond undesirable magnitude. System  10  thereby protects doctors, patients and staff against exposure to undesirable bio-contaminants, microorganisms, fungus, and mold in the operating area. In this aspect, system  10  eliminates a source of contamination and health risk for patients, doctors, and staff. 
     While illustrated in FIG. 1 as an integral part of a dental handpiece system, the present invention may be applied to an existing dental handpiece system by adding a multiport antibackflow manifold  100  as illustrated in FIG.  2 . In FIG. 2, the manifold  100  is illustrated in partial sectioned view. Manifold  100  includes a plurality of inlets  138  each communicating with a corresponding ball-type check valve  140 . At the downstream side of each valve  140  is the common manifold space  142 . At the upstream side is the corresponding inlet  138 . FIG. 2 illustrates manifold  100  as mounted to a dental delivery unit  200 . The dental delivery unit  200  is an enclosure structure in which the terminal ends of air return conduits  120  may be found. As illustrated in partially broken away view in FIG. 2, unit  200  includes a floor  202  and surrounding wall structures  204 . Manifold  100  mounts on the upward facing surface of floor  202  in the vicinity of an opening  206  thereof. The upper portion  100   a  of manifold  100  includes an opening  208  therethrough. A mounting bolt  210  passes through aperture  208  and a second smaller opening  212  of floor  202  to engage a nut  214  therebelow. A foot  216  extending downward from upper portion  100   a  also engages in abutment the upward facing surface of floor  202 . In this manner, upper portion  100   a  of manifold  100  finds secure and stable attachment within unit  200  upon floor  202  and in the vicinity of opening  206 . 
     As illustrated in FIG. 2, a filter unit  146  includes a stem portion  146   b  and a flange portion  146   c . A filter element  146   a  rests within the flange portion  146   c  of each filter unit  146 . Stem  146   b  includes a central conduit  146   d  through which air passes and reaches filter element  146   a  for elimination into the ambient air space  144 . Stem portion  146   b  extends through opening  206  and engages upper portion  100   a . In this manner, manifold  100  mounts within unit  200  but leaves external thereof the flange portion  146   c . Filter unit  146  may be easily withdrawn from upper portion  100   a  when sufficient time has elapsed or contaminants accumulated. A replacement filter unit  146 ′ may then be mounted to upper portion  100   a  of manifold  100 . 
     Each ball-type check valve  140  includes a corresponding ball  141  resting within a conical depression  143 . Any airflow through a given valve  140  in the direction of the corresponding inlet  138  immediately drives ball  141  into the well of depression  143  thereby blocking further airflow. Thus, each valve  140  is a unidirectional valve permitting airflow only in the direction from an inlet  138  into manifold  100 . As may be appreciated, a variety of unidirectional valve devices may be used. 
     Each filter unit  146  includes at its proximal end an annular indent  147 . An O-ring  149  rests in an opening  151  of upper portion  100   a . More particularly, a sleeve  152  captures O-ring  149  within an opening  15  of upper portion  100   a . Sleeve  152  permanently attaches to portion  100  and creates in conjunction with opening  151  an annular groove holding O-ring  149 . Stem  146   a  at its proximal end passes through sleeve  152  and engages at its annular indent  147  the O-ring  149 . This secures filter unit  146  to upper portion  100   a  of manifold  100  and also establishes an air tight seal therebetween. Thus, air entering the interior or common manifold area  142  of manifold  100  passes out of upper portion  100   a  only by way of filter unit  146  and eventually out of filter unit  146  only by way of filter element  146   a  thereof. 
     FIG. 3 illustrates a bottom view of upper portion  100   a  only. FIG. 3 illustrates opening  151  in portion  100   a  without the sleeve  152  attached therein. As best seen in FIG. 3, common manifold space  142  exists at the terminal portion of opening  151  and provides fluid communication with the remainder of common manifold space  142 . FIG. 3 also illustrates each of the four inlets  138 , individually  138   a - 138   d , for manifold  100 . Each inlet  138   a  communicates with a corresponding one of the ball-type check valves  140 , individually  140   a - 140   d . FIG. 3 also illustrates opening  208  passing through upper portion  100   a  and permitting attachment to floor  202  as illustrated in FIG.  2 . 
     FIG. 4 illustrates a top view of upper portion  100   a  with a cover  500  (FIG. 5) removed from upper portion  100   a . As seen in FIG. 4, the conic depressions  143 , individually  143   a - 143   d , open at a most-deep plane  400  within portion  100   a . At the well of each conic depression  140 , a conduit  402 , individually  402   a - 402   d , fluidly couples to the corresponding one of inlets  138 , individually  138   a - 138   d , respectively. An offset shelf  406  surrounds the periphery of plane  400  and receives cover  500  (FIG. 5) thereon. Cover  500  captures balls  141  (not shown in FIG. 4) within depressions  143  as well as closes and defines a boundary of manifold space  142 . Thus, opening  151  fluidly couples by way of manifold space  142  to the conic depressions  143  and, by way of conduits  402 , to the inlets  138 . With balls  141  in place, however, fluid flow within upper portion  100   a  is unidirectional, i.e., from inlets  138  into common manifold space  142  and thereafter out through opening  151  and filter unit  146  into ambient air space  144 . 
     FIG. 5 illustrate cover  500  including an aperture  208 ′ corresponding in position to aperture  208  of upper portion  100   a . Cover  500  attaches to and seals relative to shelve  406  (FIG.  4 ). 
     FIG. 2 also illustrates placement of sound suppression element  170  within the conduit  146   d  of unit  146 . Element  170  may be provided as a piece of open-cell foam admitting passage of air therethrough and suppressing sound emanation, e.g., exhaust and ball  141  rattle, from manifold  146 . 
     Slow speed handpieces as well as ultrasonic devices all typically couple into the same exhaust system. Such slow piece devices and ultrasonic devices don&#39;t collect significant bio-contaminants but they do carry oil in the return line. These devices can operate on the same exhaust manifold of the present invention to prevent oil contamination of the environment. 
     It will be appreciated that the present invention is not restricted to the particular embodiment that has been described and illustrated, and that variations may be made therein without departing from the scope of the invention as found in the appended claims and equivalents thereof.