Abstract:
A device for recirculating water throughout a small bore tubing of a dental unit during non-use to prevent contamination from a biofilm buildup. The device includes a pump, a reservoir, and a decontaminator positioned along a waterloop formed by a plurality of water lines, the device for recirculating water also being under microprocessor control and connected to the dental unit.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a dental unit waterline recirculator device. More particularly, it relates to a system that automatically recirculates chlorinated water through the small bore plastic tubing of the dental unit during periods of downtime such as overnight and holidays. This prevents stagnation of water in the tubing which is a major cause of bacterial growth and biofilm.  
         [0003]     2. Description of the Prior Art  
         [0004]     Most dental units operate in the same manner. Pressurized air controls the flow of water and air throughout the many handpieces and many feet of handpiece tubing. A foot pedal, operated by the dentist or technician, controls the flow of pressurized air. When not in use, the handpieces either rest in a saddle on the dental unit or, if they are detachable type handpieces, are removed for disinfection between patients. The saddles contain switches that are activated when a handpiece is resting in the saddle. Each saddle switch prevents water and air from flowing-to that particular handpiece when the foot pedal is depressed.  
         [0005]     Contamination of dental unit waterlines from biofilm buildup is a growing concern in the dental profession. Biofilm is caused by water stagnating in the plastic tubing for long periods of time. The stagnating water allows bacteria, fungi, algae and protozoa to grow on the inside surface of the plastic tubing used in dental units. Scientific evidence suggests that the presence of significant amounts of bacteria in the tubing may pose a risk of exposing patients and dental personnel to contaminated aerosol. Reports have linked two post-operative Pseudomonas infections in patients with suppressed immune systems to exposure to contaminated aerosol. In addition, altered nasal flora and exposure to Legionella bacteria has been detected in dental personnel. The suspected cause of such exposure is inhalation of the fine water mist expressed by dental handpieces. Recognizing this potential health risk, the Occupational Health and Safety Administration (OSHA) has issued warnings about exposure to pathogens from dental waterline unit contamination.  
         [0006]     The levels of colony-forming units (CFU) in dental unit waterlines have been known to exceed 1,000,000 CFU/ml. CFU are the minimum number of separable cells that can give rise to a visible colony. The Centers for Disease Control (CDC) and the American Dental Association (ADA) have published guidelines recommending that no more than 500 CFU/ml be present in the dental waterline. Because of the great difficulty and expense in maintaining this standard, this maximum has not yet been made mandatory.  
         [0007]     Most current dental units employ a closed bottle system to provide a clean water supply. These devices utilize a flush and purge mechanism using disinfectants or germicides, however, the drawback to this method is the possibility that the chemicals will not be completely removed from the waterline and will be expelled into a patient&#39;s mouth, therefore, it is still recommended that the handpiece be flushed for 20 seconds prior to performing a procedure in a patient&#39;s mouth. If these procedures are improperly performed, bacterial buildup can be worse than if not performed at all. Furthermore, it has been reported that mature biofilms may become resistant to these treatments. In addition to being time consuming to operate, these devices can be very costly.  
         [0008]     U.S. Pat. No. 5,044,952 describes a device designed to prevent stagnation in the water supply. This device utilizes a steady bleed of water through the dental waterline to a main waste outlet during periods of downtime. This is inefficient and presents the risk of a leak occurring. Additionally, the water in the line is heated slightly which has been found to increase biofilm buildup. U.S. Pat. No. 5,526,841 describes a device employing a manual flush and purge method of disinfecting. The waterline is flushed with a disinfectant solution and then purged using pressurized air. Since this process is not automatic, errors could result in germicide being expressed into a patient&#39;s mouth or bacterial buildup greater than if no disinfectant were used at all. U.S. Pat. No. 5,785,523 also describes a purge and flush system for disinfection of the dental unit tubing. This system is not automatic and the same dangers are present as with all flush and purge methods. U.S. Pat. No. 6,106,771 describes a method to descale and disinfect dental unit waterlines. This method is not automatic and it employs the use of descaling agents and antimicrobial agents retaining the risk that some of this disinfecting agents will be retained in the waterline. Furthermore, this system does not provide a simple means for preventing biofilm buildup in the individual handpiece lines.  
         [0009]     Other devices are known to prevent contamination in other fields. U.S. Pat. No. 5,032,292 describes a method for preventing biofilm buildup in spas. This method employs a bidirectional flow directing water in one way when the jet pump is on and in another way when the circulation pump is on. This method could not be applied to a dental device and its handpiece lines. U.S. Pat. No. 5,178,830 describes a method for cleaning and sterilizing hemodialysis lines. This method could not be applied to dental units as it would be cost prohibitive due a greater necessity for total sterilization. In addition this device is not designed to function automatically.  
         [0010]     There is a great need for an inexpensive device that is controlled automatically and that employs a safe and efficient method of preventing biofilm buildup.  
       SUMMARY OF THE INVENTION  
       [0011]     I have invented a dental waterline recirculator connected to a dental unit that operates automatically. The recirculator turns on at the end of each day when the air and water lines are turned off. Water is pumped out of a reservoir through a decontaminator and then through a small bore tubing of the dental unit. The decontaminator can be a chlorinator that maintains a level of chlorine equal to or just slightly above the level of municipal potable water, or it can employ other agents. The water recirculates approximately 15 minutes every hour, or one hour every four hours. When the work day begins, the air and water lines are turned back on and the reservoir drains and refills itself. High and low water sensors facilitate the automatic draining and refilling. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     The invention may be best understood by those having ordinary skill in the art by reference to the following detailed description when considered in conjunction with the accompanying drawings in which:  
         [0013]      FIG. 1  is a flow diagram of an initialization process of a preferred embodiment of the waterline recirculator of the present invention prior to daytime use;  
         [0014]      FIG. 2  is a diagram of the preferred embodiment of the waterline recirculator connected to a dental unit during daytime use;  
         [0015]      FIG. 3  is a flow diagram of an initialization process of the preferred embodiment of the waterline recirculator prior to nighttime recirculation;  
         [0016]      FIG. 4  is a diagram of the preferred embodiment of the waterline recirculator connected to a dental unit during nighttime recirculation;  
         [0017]      FIG. 5  is a flow diagram of an initialization process prior to daytime use of a first alternate embodiment of the waterline recirculator;  
         [0018]      FIG. 6  is a diagram of the first alternate embodiment of the waterline recirculator connected to a dental unit and during daytime use;  
         [0019]      FIG. 7  is a diagram of the first alternate embodiment of the waterline recirculator connected to a dental unit during nighttime recirculation; and  
         [0020]      FIG. 8  is a diagram of a third alternate embodiment of the waterline recirculator during daytime use.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]     Throughout the following detailed description, the same reference numerals refer to the same elements in all figures.  
         [0022]     A dental unit waterline recirculator of the present invention works in three cycles: 1) Initialization 2) Day Use and 3) Nighttime Recirculation. Initialization will be discussed first, followed then by Day Use and then finally Nighttime Recirculation.  
         [0023]     Initialization takes place at the beginning of the workday. Referring to  FIGS. 1 and 2 , in a preferred embodiment, dental healthcare worker first turns on a waterline B, a suction line D, and an air line C. When air line C is turned on, an air switch  14  inside a dental unit  10  turns on. Alerted by the activation of air switch  14 , a microprocessor  16 , coupled to air switch  14 , directs a pump  22  to turn off, which had previously been activated from a nighttime procedure there before. Microprocessor  16  closes a solenoid valve  18  and opens a solenoid valve  46 . A solenoid valve  44  remains open. As seen in  FIG. 2 , solenoid valve  46  is positioned intermediate a drain waterline between a water reservoir  26  and a suction canister  38  of this invention. A suction line E drains water reservoir  26  through suction canister  38  and finally through outgoing suction line D and to a waste receptacle (not shown). A low water sensor  40  located inside water reservoir  26  is coupled to microprocessor  16  by way of a unidirectional electrical connection. When the water level reaches the level of low water sensor  40 , microprocessor  16  is alerted. At this time, solenoid valve  46  is closed. A three-way solenoid valve  20  was, prior to this point, closed to waterline B and open to a dental block  12  and a decontaminator  24  as shown in  FIG. 4 . Three-way solenoid valve  20  now opens to waterline B and dental block  12  and closes to decontaminator  24  as shown in  FIG. 2 . Water flows through dental unit  10  tubing and refills water reservoir  26  by way of solenoid valve  44  and a three-way solenoid valve  48  which, at this point, is open to dental unit  10  and water reservoir  26  as shown in  FIG. 4 . A high water level sensor  42  is coupled between water reservoir  26  and microprocessor  16  by way of a unidirectional electrical connection. When the water in water reservoir  26  reaches the high level mark, high water level sensor  42  alerts microprocessor  16 . At this time, solenoid valve  44  connected to an non-detachable air water syringe  34  closes. Three-way solenoid valve  48  is positioned on a waterline between dental block  12 , a detachable handpiece  30 , and water reservoir  26  in a “T” formation. There can be a plurality of detachable type handpieces  30 .  
         [0024]     Prior to initialization, three-way solenoid valve  48  is open to dental block  12  and water reservoir  26  (see  FIG. 4 ). Upon closing of solenoid valve  44 , three-way solenoid valve  48  closes to water reservoir  26  and opens to detachable handpiece  30 . The dental unit waterline recirculator is now in position for daytime use as shown in  FIG. 2 .  
         [0025]     In a first alternate embodiment, initialization proceeds as shown in  FIG. 5 . In this first alternate embodiment, for nighttime recirculation, detachable handpiece  30  and detachable handpiece tubing  28  is inserted into an inlet  32  in water reservoir  26  as shown in  FIG. 7 . There are an equal number of inlets  32  as there are detachable handpieces  30 . Initialization begins when microprocessor  16  turns pump  22  off at a preprogrammed user definable time. A dental technician removes detachable handpiece tubing  28  from inlet  32 . Detachable handpiece  30  is reattached to its tubing  28  and returned to its holder, called a saddle, on dental unit  10 . At this time, water line B, air line C and suction line D are turned on, thereby activating air switch  14 . Activation of air switch  14  alerts microprocessor  16  whereby the initialization process of this first alternate embodiment follows the same steps from this point forward as outlined previously in  FIG. 1 . The final step however differs wherein only solenoid  44  closes at the termination of the process because solenoid  48  is not a component of this embodiment.  
         [0026]     In a second alternate embodiment of the present invention, as shown in  FIG. 8 , prior to nighttime recirculation, handpiece  30  is removably attached to its tubing  28  by a quick release mechanism (not shown). Handpiece  30  is removed and an end  54  of tubing  28  is inserted into a handpiece insert  56 , also having a quick release mechanism, located on dental unit  10 . There are as many handpiece inserts  56  as there are detachable handpieces  30 . The handpiece insert  56  connects to a waterline leading to the water reservoir  26 . In those units with multiple handpieces  30  (not shown) each waterline from the respective handpiece insert  56  would feed into a single line that would be attached to the reservoir  26 . In this second alternate embodiment, initialization would take place in the same manner as outlined previously in  FIG. 1 , although because solenoid  48  (shown in  FIG. 2 ) is not a component of this embodiment, the initialization process is complete upon the closing of solenoid  44  which is a result of the water reservoir  26  reaching its upper limit.  
         [0027]     Referring to  FIG. 2 , during daytime use, dental unit  10  contains dental block  12  and three-way solenoid valve  20 . Waterline B carries water from a municipal water supply or a closed bottle system, whichever is used in the office, into dental unit  10  and into three-way solenoid valve  20 . Three-way solenoid valve  20  diverts water from waterline B into dental block  12  which is a common component to all dental units functioning as a water and air router. Air line C delivers air from an air source, such as an air compressor or other source (neither shown), into dental unit  10  and directly into dental block  12 . Air switch  14  is connected to microprocessor  16  which controls the air flow. During daytime use, air switch  14  is in the “ON” position allowing air to be carried from the air source to dental which routes water to detachable dental handpiece  30  and air and water to a non-detachable air water syringe  34 . There can be a plurality of detachable handpieces  30  and non-detachable handpieces  34  connected to dental block  12 . Suction canister  38  is attached to dental unit  10 . Outgoing suction line D leaves suction cannister  38 , is directed through dental unit  10 , and empties into a waste receptacle (not shown). Dental suction tool  36  is connected to suction cannister  38 . Suction line E is connected to solenoid valve  46  which is closed for daytime use thereby prohibiting any water drain from reservoir  26 .  
         [0028]     Referring to  FIG. 8 , daytime use of this alternate embodiment varies only slightly. The quick release mechanism and handpiece insert  56  on dental unit  10  can be used during daytime operation as procedures are being performed. When detachable handpieces  30  are removed between patients for cleaning, quick release end  54  of handpiece tubing  28  can be inserted into handpiece insert  56 . This prevents exposure of a free end of tubing  28  to particulate and aerosol in the air. In those dental units equipped with the handpiece inserts  56 , the insert  56  would contain a switch (not shown) that is activated when the quick release end  56  inserts therein. The switch works in the same manner as the saddle switch and would prevent water and air from entering the tubing  28  when not in use. In this second alternate embodiment, the water line B is shown connected to a closed bottle  58 .  
         [0029]     As to nighttime recirculation, and referring to  FIGS. 3 and 4 , waterline B, air line C, and suction line D are all shut off. Air switch  14  detects that air line C is off and alerts microprocessor  16 . Microprocessor  16  opens solenoid valve  18  and solenoid valve  44 . Solenoid valve  48  changes state so as to block the water line coupled to the detachable handpiece  30  and open the water line coupled to water reservoir  26  and dental block  12 . Three-way solenoid valve  20  changes state so as to block waterline B and open to dental block  12  and decontaminator  24 . Thereafter, pump  22  turns on. As shown in  FIG. 4 , water from the reservoir  26  flows through solenoid valve  18 , through pump  22  and into decontaminator  24 . In the preferred embodiment, decontaminator  24  contains a sensor (not shown) coupled electrically to the microprocessor  16  that detects the level of decontaminant present in the recirculating water. Once the decontaminant sensor detects that decontaminant has fallen below a user defined threshold level, microprocessor  16  signals a dental personnel by an audio or visual alarm that more decontaminant must be added to the decontaminator  24 . Alternatively, the decontaminant can be automatically injected by decontaminator unit  24 . In yet another embodiment, decontaminator  24  can be an entirely passive unit, wherein it is periodically refilled by a dental personnel with decontaminant tablets or liquid.  
         [0030]     With continuing reference to  FIGS. 3 and 4 , water flows out of decontaminator  24  into dental unit  10  and into solenoid valve  20 . Solenoid valve  20  directs the water into dental block  12  wherein it is diverted into each detachable dental handpiece tube  28  and into each non-detachable dental handpiece  34 . The water then flows through detachable handpiece tubing  28  into three-way solenoid valve  48  and back into the water reservoir  26  where it can be recirculated.  
         [0031]     In the first alternate embodiment of  FIG. 7 , prior to turning off waterline B, airline C and suction line D, a dental worker manually detaches removable handpiece  30  from its respective tubing  28 , exposing a free end which inserts into an inlet  32  on top of water reservoir  26 . Waterline B, airline C and suction line D are then shut off. The nighttime initialization then occurs as presented in  FIG. 3  except in this first embodiment, solenoid valve  48  is not employed. During recirculation, water flows from dental block  12 , into detachable handpiece tubing  28  and directly into water reservoir  26  by way of inlet  32  on the water. Additionally, water flows through non-detachable air water syringe  34 , through solenoid valve  44  and back into dental unit  10  where it can be recirculated according to user defined parameters. The water flows into and out of non-detachable air water syringe  34  by way of specially manufactured tubing containing an incoming and outgoing waterline, in addition to the air line.  
         [0032]     In the second alternate embodiment of  FIG. 8 , recirculation occurs as illustrated in the diagram in  FIG. 3 , except that solenoid  48  is not a component of this second alternate embodiment. Prior to air, water and suction shut off, handpiece  30  is removed and the quick release end  54  of tubing  28  is inserted into handpiece insert on the dental unit  10 . The water flows through detachable handpiece tubing  28  back into dental unit  10  by way of the handpiece insert  56  and then into the waterline connected to reservoir  26 . Upon the water flow reaching reservoir  26  a complete loop is made and the water can be recirculated. In the preferred embodiment, the system would Recirculates the water for about 15 minutes every one hour, or alternatively, for one hour every four hours. In alternate embodiments, the user can set the recirculation parameters as desired.  
         [0033]     It is understood that while solenoid valves are preferred and referenced in the detailed description above, nothing herein limits these valves to only solenoid type valves.  
         [0034]     Equivalent elements can be substituted for the ones set forth above such that they perform the same function in the same way for achieving the same result.