Abstract:
An ultrasonic liquefaction endodontic system having a graspable hand piece having a flow passageway therethrough. An ultrasonic energy generator is secured to the hand piece. A flexible injection tube is dimensioned for insertion into a tooth root canal. A source of flushing fluid under pulsed pressure is connected to the hand piece by which fluid pressure pulses having ultrasonic energy superimposed thereon are forced into a root canal.

Description:
REFERENCE TO PENDING APPLICATIONS  
       [0001]     This application is not based upon any pending domestic or international patent applications.  
       REFERENCE TO MICROFICHE APPENDIX  
       [0002]     This application is not referenced in any microfiche appendix.  
       FIELD OF THE INVENTION  
       [0003]     This invention relates to endodontic root canal preparation achieved by simultaneous liquefaction and acoustic debridgement.  
       BACKGROUND OF THE INVENTION  
       [0004]     This invention relates to dental instruments and particularly to endodontic instruments, systems and procedures for treating a tooth root canal in which the root canal is cleansed of bacteriological materials by physical and acoustic debridgement and flushing with an irrigation solution, particularly the apparatus and equipment for providing irrigation to remove diseased and necrotic tissue.  
         [0005]     Endodontic has become an important part of dentistry. Whereas, prior to the common use of endodontic procedures, an abscessed tooth was typically treated only by extraction of the tooth. However since the advancement of endodontics abscessed teeth can be successfully treated to permit retention by a patient for greatly increased health and physiological benefit. Endodontics has been one of the great advancements in modern medicine.  
         [0006]     The endodontic preparation of a root canal typically includes opening the root canal through the coronal area of the tooth and thereafter manipulating files and reamers within the root canal to physically remove as much as possible of the pulpal material. This pulpal material is typically infected or necrotic, that is, dead material and any such material that remains in the root canal after the procedure is completed is a source of potential infection. For this reason the proper treatment of a root canal attempts to remove as much of such necrotic pulpal material as is possible. By use of files and reamers, a substantial portion of such pulpal material can be removed however it is virtually impossible in most cases to remove all such material by physical manipulation of tools within the canal. For this reason, in recent times procedures have been developed wherein the root canal is irrigated or flushed with a fluid to remove and/or neutralize organic pulpal material that remains after files and reamers have been employed.  
         [0007]     As background information reference may be had to U.S. Pat. No. 4,330,278 that issued May 18, 1982 to Howard Martin, entitled “Endodontic Flow-Through Ultrasonic Instrument Holder Device”. This device shows a system that includes a holder for holding an instrument used for dental work that includes a passageway by which flushing fluid can be injected into a tooth during endodontic procedures. The present invention is an improvement on this basic concept as revealed in this U.S. patent.  
       BRIEF SUMMARY OF THE INVENTION  
       [0008]     The invention herein is a system and a method for simultaneous liquefaction and acoustic debridgement of a tooth root canal. The system includes a manipulatible hand piece having a flow passageway therethrough. An ultrasonic energy generator is secured to the hand piece. A flexible injection tube is dimensioned and configured for insertion into a tooth root canal. A coupler is employed for removably affixing the proximal end of the injection tube to a hand piece. A pressurized source of flushing fluid is connected to the hand piece by which fluid having ultrasonic energy imposed thereon is forced into the root canal.  
         [0009]     An important improvement in the invention herein is the provision of a system in which fluid is injected into a tooth root canal using pressure pulses that augments the dislodgement and removal of debris contained in the root canal while simultaneously the fluid pressure pulses are superimposed with ultrasonic energy.  
         [0010]     A more complete understanding of the invention will be obtained from the following detailed description of the preferred embodiments taken in conjunction with the drawings and attached claims.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is a partial cross-sectional view of a hand piece by which an irrigation fluid may be injected into a tooth root canal. The hand piece has an ultrasonic generator as a part thereof whereby the flushing fluid injected into the tooth root canal is energized with ultrasonic energy.  
         [0012]      FIG. 2  shows the hand piece as illustrated in  FIG. 1  with an ultrasonic generator having provision to accommodate the flow of flushing fluid therethrough.  
         [0013]      FIG. 3  is a diagrammatic view of a system for employing the invention. This figure shows a positive displacement pump that forces irrigation fluid under pulsed pressure for injecting into a tooth&#39;s root canal. This figure further shows electrical energy applied to the hand piece ultrasonic generator whereby ultrasonic energy is applied to the hand piece and to the flushing liquid.  
         [0014]      FIG. 4  is a chart illustrating the pressure of irrigation fluid injected into a tooth root canal by the systems and methods of this invention and shows pressure pulses having superimposed ultrasonic energy thereon.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0015]     It is to be understood that the invention that is now to be described is not limited in its application to the details of the construction and arrangement of the parts illustrated in the accompanying drawings. The invention is capable of other embodiments and of being practiced or carried out in a variety of ways. The phraseology and terminology employed herein are for purposes of description and not limitation.  
         [0016]     Elements shown by the drawings are identified by the following numbers: 
     10  Tooth      12  coronal area      14  Roots      16  open area      18  root canal      20  root canal      22  Apex      24  hand piece      26  tubular body portion      28  flow passageway      30  internal threads      32  enlarged portion      34  coupling nut      36  Passageway      38  flexible injection tube      40  enlarged end portion      42  distal end      44  ultrasonic generator      46  passageway      48  power cord      50  reservoir      52  pump      54  conduit      56  supply tube      58  power plug      60  cylinder      62  piston      64  motor      66  shaft      68  crank arm      70  piston rod      72  inlet valve      74  outlet valve      76  pressure pulses    
 
         [0051]     Referring to the drawings and first to  FIG. 1 , a typical tooth  10  is illustrated in cross-section. The tooth includes a coronal area  12  and roots  14  extending therefrom. The coronal area has an open area  16  that has been drilled to provide access to the upper end of root canals  18  and  200 . These root canals  18 ,  20  extend to the apex  22  of each of the canals.  
         [0052]     The practice of endodontic includes, as an important part thereof, preparation of root canals  18  and  20  to receive filler material. Such filler material is typical gutta percha but other comparable materials have been developed. It is important that the root canals  18  and  20  be shaped and cleaned as thoroughly as possible to remove all organic material. Such organic material is typically pulpal material that exists as a natural portion of a tooth and by which a tooth is nourished during the formation process. Such pulpal material, if left within a root canal and entrapped by filler material, can become infected and thereby cause problems to the patient. The infection that originates within a root canal can spread to other parts of the body. For this reason, it is important, as above stated, to remove as much pulpal and other necrotic material from the confines of the root canals  18  and  20  as is possible.  
         [0053]     The typical endodontic procedure requires the endodontist to scrape and shape the root canals in a way to remove as much as possible of pulpal material and to shape the root canal to receive filler material. However, though not shown in  FIG. 1 , root canals  18  and  20  typically have laterally extending fissures and other irregularities in which pulpal material can become entrapped and so that it is very difficult to remove all pulpal material by physically scraping and shaping alone.  
         [0054]     For this reason, a procedure has arisen wherein after a root canal is cleansed and shaped mechanically, the root canal is then flushed. For use in flushing a tooth root canal by the methods of this invention, a hand piece, generally indicated by the numeral  24 , is employed. Hand piece  24  includes a tubular body portion  26  that has a flow passageway  28  therethrough. The distal end of the tubular body portion is slightly enlarged and provided with internal threads  30 , the enlarged portion being indicated by the numeral  32 .  
         [0055]     Threadably received within the outer end of enlarged portion  32  is a coupling nut  34  that has passageway  36  through it. An injection tube  38  has an integral enlarged end portion  40 . The flexible injection tube extends through passageway  36  in the coupling nut which engages enlarged end portion  40  so that the flexible injection tube  38  is connected to the outer end of hand piece tubular body portion  26 . The flexible injection tube  38  is elongated and may, as indicated, be tapered towards the distal end  42  that is configured to reach as near as possible to the lower end portions of root canal  18 ,  20 .  
         [0056]     Hand piece  24  further includes, as a part of the body portion, an ultrasonic generator  44  that has the capacity to generate ultrasonic sound energy in the form of vibrations. The sound vibrations from ultrasonic generator  44  are coupled to the hand piece tubular body portion and to flexible injection tube  38 .  
         [0057]      FIG. 2  shows the hand piece  24  that has been described and shows a passageway  46  extending through ultrasonic generator  44 . Thus, passageway  46  is in communication with the tubular body portion flow passageway  28  which in turn communicates with the flexible injection tube  38 . A power cord  48  supplies electrical energy to ultrasonic generator  44   
         [0058]      FIG. 3  shows diagrammatically the method of practicing the invention. The hand piece  24  is shown diagrammatically with flexible injection tube  38  and ultrasonic generator  44 . The system is shown by which liquid may be injected through the hand piece  26  and thereby the flexible injection tube  38  for passage into the root canal of a tooth as shown in  FIG. 1  for purposes of flushing the tooth as a part of an endodontic procedure.  
         [0059]     Fluid for use in flushing a tooth is contained in a reservoir  50 . A typical fluid useable for flushing an endodontically prepared root canal is sodium hypochlorite, usually used as a diluted solution. A pump  52  is employed for moving fluid from reservoir  50  by way of a conduit  54  to a supply tube  56  whereby the fluid is conveyed to hand piece  24 , fluid passing through ultrasonic generator  44 . Supply tube  56  is shown to carry with it a conductor for electrical energy supplied by a power plug  58 . While pump  52  may be a variety of different types a preferred practice of the invention employs a positive displacement pump  52  that includes a cylinder  60  and a piston  62 . A motor  64  drives a shaft  66  that has a crank arm  68 . Extending from crank arm  68  is a piston rod  70 . Pump  52  further includes an inlet valve  72  and an outlet valve  74 .  
         [0060]     When motor  64  is energized, piston  62  is reciprocated. On each reverse stroke liquid is drawn from tank  50  through intake valve  52  and on the forward or power stroke intake valve  52  is closed and the liquid is forced from the interior of cylinder  64  through outlet valve  74 . The liquid passing through conduit  54 , supply tube  56 , ultrasonic generator  44 , tubular body portion  26  and out through the distal end  42  of flexible injection tube  38 .  
         [0061]     As previously stated, pump  52  may be a variety of pumps but a preferred practice of the invention employs a positive displacement pump to thereby cause the fluid flow through the system to be in a series of pressure pulses as contrasted with substantially constant pressure fluid flow.  FIG. 4  is a chart showing the preferred practice of the invention wherein the abscissa is time and the ordinate is pulse pressure showing that the pressure on the fluid passing into a root canal is a sequence of pulses that vary in frequency directly proportional to the rate pump  64  is rotated. Further, an important aspect of the invention is that the fluid injected into a root canal has pressure pulses having superimposed ultrasonic forces.  FIG. 4  shows the pressure relationship of the liquid passing into a root canal of the system of this invention in which the abscissa is time and the ordinate is fluid pressure. This figure illustrates the variation in fluid pressure as a consequence of the positive displacement pump showing a sequence of pulses created when piston  62  moves forward separated by periods of low or substantially zero pressure as piston  62  is moved rearwardly. The result is a series of rapid sequential pressure pulses. A unique feature of this invention is the provision of pressure pulses having ultrasonic energy imposed thereon.  
         [0062]     The use of ultrasonic energy for improving endodontic procedures is documented in U.S. Pat. No. 4,330,278. The concept herein is to provide a system of flushing or irrigating a root canal in a way to maximize removal and neutralization of organic material. Further, the solution by which the canal is washed is preferably one that removes and neutralizes necrotic tissue so as to reduce the chance that the root canal will have bacteria therein when it receives the filler material after the canal has been properly prepared. The use of sodium hypochlorite to react with necrotic tissue is well known. In addition to sodium hypochlorite other chemical solutions may be employed and sodium hypochlorite is illustrated herein as a typical solution that has the capacity to react with and neutralize necrotic material while having minimal effect on non-necrotic tissue in the body.  
         [0063]     The rate of pressure pulses employed in the practice of the invention can vary substantially from a relatively low frequency of two or three pulses per second to a high frequency such as 50 to 100 pulses per second. The ultrasonic frequency rate can also vary but typically is at a frequency above 20,000 Hz.  
         [0064]     The ultrasonic generator as indicated in  FIGS. 1 and 2  is diagrammatic only since such apparatus is known in the industry and readily commercially available. The flow of fluids through the channels provided in the system forms an effective pathway for the transmission of ultrasonic energy since ultrasonic signals flow through a liquid medium with little resistance as is readily indicated by the success of sonar and other apparatus for measuring using sound energy transmitted through water.  
         [0065]     While the invention has been described with a certain degree of particularity, it is manifest that many changes may be made in the details of construction and the arrangement of components without departing from the spirit and scope of this disclosure. It is understood that the invention is not limited to the embodiments set forth herein for purposes of exemplification, but is to be limited only by the scope of the attached claims, including the full range of equivalency to which each element thereof is entitled.