Abstract:
Apparatus and method for catheterized delivery or infusion of medication and anaesthesia are disclosed. The perforating catheter is first used to perforate the periodontal ligament and/or the cortical plate of bone tissue, and is then left in place and used as a catheter for insertion of a hypodermic needle of smaller gauge to deliver medication or anaesthesia to a target area. The perforator is a bevelled needle for drilling into the ligament or bone tissue. For drilling, the device comprises an adaptor which transmits the rotational movement from a dental hand piece or the like to the bevelled needle. A cap is also included for protecting the bevelled needle during storage of the device. The adaptor may have a rod which extends axially into the bevelled needle when the device is assembled for drilling. The rod is used to prevent the debris resulting from drilling from blocking the passage in the bevelled needle. As well, the rod reinforces the needle and maintains the alignment between the perforator and the adaptor for improved drilling efficiency.

Description:
[0001]    This invention is a continuation-in-part patent application to 09/255,442 filed Feb. 22, 1999 which is a continuation of patent application Ser. No. 09/022/314 filed Feb. 11, 1998 which is a continuation of patent application Ser. No. 08/471372, now issued as U.S. Pat. No. 5,762,639. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention provides for a simple method and device for infusing or injecting medication; it is applicable to medical or dental and the like procedures. More particularly, the invention is directed to catheterized delivery of anesthesia and other medication. More particularly still, it is directed to catheterized delivery of dental anaesthetic to a targeted nerve and to an apparatus for such delivery.  
         BACKGROUND OF THE INVENTION  
         [0003]    There are a variety of methods currently in use for providing local anaesthetic in dentistry. These methods and apparatuses however all have disadvantages, either being difficult for practitioners to perform or painful and unpleasant to the patient.  
           [0004]    An example of a method used currently in dentistry is the infiltration method, whereby a local anaesthetic solution is injected into the soft tissue of gingiva. In doing so, the solution eventually passes through the cortical plate affecting the nerve bundle entering the tooth. Disadvantages of this method include the delay of onset of anaesthesia after the injection and, in most cases, ballooning of the injected tissue. As well, there is an extended period of time for recovery of the tissue until return to normal condition.  
           [0005]    Another method which is currently used is the regional block method whereby an anaesthetic solution is injected locally in proximity to the nerve trunk as it enters the bone. Disadvantages of this procedure are that it is extremely difficult to locate the nerve trunk, there is discomfort to the patient and a delay for the anaesthetic to take effect. As in the case of the infiltration method, this method necessitates a long recovery period for tissue to return to normal.  
           [0006]    At present, two types of apparatus have been used to perform intra-osseous anaesthesia. These are surgical burs used to perforate the cortical plate and the villet injectors.  
           [0007]    The use of a surgical bur has disadvantages in that burs are expensive and they have to be sterilized between uses or a new bur used each time. In addition, the method is slow, requiring the attached gingiva and periosteum to be anaesthetized before the cortical plate is perforated. The villet injector is an apparatus that serves both as a perforator and injector. It uses specially designed needles rotated by a conventional dental motor. A disadvantage of this device is that the needle often becomes clogged with pulverized bone which obstructs the passage in the needle and prevents injection of the anaesthetic solution. It is generally difficult to remove the clogging material from the needle and often the use of a second needle is necessary. Other disadvantages of this method include the initial capital cost of the instrument purchase, and the cost of the needles which are somewhat expensive. In addition, the design of the instrument makes access to various parts of the mouth difficult and sometimes impossible.  
           [0008]    Intra-osseous and targeted root-canal nerve anaesthesia have not become popular for the reason that there has not been a practical technique of making the injections successfully. For example, there has been a general belief that this method is radical and to be restored to only if nerve block and infiltration anaesthetic do not accomplish the desired result. However, intra-osseous and targeted injections produce positive, more profound anaesthesia and could be made with less pain than either of the other types according to the present invention.  
           [0009]    Targeted anaesthesia has several advantages over prior art nerve block or infiltration methods. There is no feeling of numbness in the tongue, cheek, or lips during or after the injection and there is no after-pain. The anaesthetic is profound and acts immediately alleviating the necessity of waiting for the anaesthetic to take effect as with the nerve block and infiltration methods. Furthermore, as only a few drops of anaesthetic are injected, there is no feeling of faintness or increasing of the pulse rate.  
           [0010]    To achieve targeted anaesthesia one must gain access, if intra-osseous, to the cancellous bone by going through the cortical layer; or to the bottom of the tooth, if root-canal targeted anaesthesia is desired. Because of instant anaesthesia and profound pulpal anaesthesia, there is a much greater control over the region one wishes to anaesthetize, resulting in a much smaller dose of anaesthetic; as well as, of course, other medication, where applicable.  
           [0011]    U.S. Pat. No. 5,173,050 (Dillon) discloses a dental apparatus for perforating the cortical plate of human maxillary and mandibular bones. The apparatus of Dillon comprises a metal needle moulded into a plastic shank. The shank is being formed with means for cooperation with a dental hand piece for transmitting the rotational movement to the needle. The needle used for drilling is solid and has a sharp bevelled free end. The apparatus described by Dillon is disposable.  
           [0012]    However, the device disclosed in Dillon&#39;s patent cannot be used as a catheter for injecting anaesthetic by inserting a hypodermic needle through the drilling needle. As well, the device disclosed by Dillon is not provided with means for blocking entry of bone debris into the needle passageway. In addition, the direct connection between the hand piece and the perforator does not provide for a safe and reliable barrier against bacteria passing from the needle to the hand piece.  
           [0013]    U.S. Pat. No. 3,534,476 (Winters) discloses a drilling and filling root canal apparatus. The drilling is performed by a drill having a central bore. The depth of the root canal is determined in advance and a stop is placed on the drill to limit the depth of drilling. The device is provided with a flexible rod which is pushed into the root canal so that the drill is directed along this road to follow the contour of the canal so that resulting bore will have an uniform diameter which is free of shoulders or ledges. The apparatus disclosed by Winters is concerned with enlarging the root canal after the nerve has been extracted. This apparatus is not used for injecting medication in close proximity to a targeted area for treatment or anaesthetic.  
           [0014]    U.S. Pat. No. 4,944,677 (Alexandre) discloses a smooth hollow needle with a bevelled point for drilling a hole into the jawbone near the apex of the tooth to be anaesthetized. Thereafter, the drilling device  13  removed from the jaw, and a hypodermic needle of substantially the same gauge is inserted into the hole and anaesthesia is injected. Thus, there is no cathetized delivery of medication, with the attendant disadvantage that the pre-drilled hole may be difficult to locate when inserting the hypodermic needle.  
           [0015]    One significantly older United States patent that is discussed by Alexandre (above) is U.S. Pat. No. 2,317,648 (Siqveland) granted in 1943. In addition to the disadvantage mentioned by Alexandre, the fact that Siqveland teaches use of threaded sleeve which penetrates the bone during drilling and is left (screwed) in the bone to serve as a guide for insertion of the actual injection needle. Due to the cost of such a device, it cannot be made disposable; but more importantly, for the threaded sleeve to be securely fastened in the bone it would have to rotate at a much slower speed than the drill (as in Siqveland) or the drilling catheter (as in the present invention).  
           [0016]    Several other U.S. patents such as U.S. Pat. No. 5,332,398 in the name of Miller, and U.S. Pat. No. 4,969,870 in the name of Kramer have followed the teaching of Siqveland wherein the catheter is at least somewhere along its outer periphery threaded, or designed to implant itself fixedly within the bone it is being disposed in; Furthermore, designs of this type require slowly turning the drilling shaft (or catheter sleeve) into the bone until resistance is encountered at which point the catheter is determined to be in place.  
           [0017]    Over the past 50 year or so, and at least since the invention of Siqveland, patented in 1943, devices and processes for intraosseous anesthesia have been developed and refined. However, heretofore, no other inventors have provides a useful, workable convenient and inexpensive solution that affords all of the benefits provided by this invention. For example, non of the prior art devices allow a motorized handpiece to drive a small intraosseous catheter/drill having a rod/drill therein wherein the device can be placed by drilling at high or slower speeds and removed by simple withdrawal by pulling out the catheter. Most of the effort in this field had been directed toward longer term delivery of medication wherein the catheters have had some means of latching into the bone for more permanent placement. Furthermore, the instant invention does not suffer from may of the drawbacks of inserting the needle/drill into the bore being cut by the end tip of the drill, since the outside walls of the needle/drill are of a uniform diameter and non-varying. With the long-felt want of this device, in the past decade in view of the many publications in this field, no such optimal device has been suggested.  
           [0018]    In contrast to the prior art, the instant invention provides a dual purpose perforator which includes a needle/sleeve that serves as a relatively high-speed drill bit and which serves as a catheter that is removable by withdrawing it by pulling it out, and not by unscrewing it. The perforator has a substantially uniform outer diameter and has a smooth non-threaded outer surface; preferably, the catheter is a larger gauge needle than the removable rod contained within which may also be in the form of a beveled needle for preventing bone, skin and debris from entering the catheter during entry into the bone. A hypodermic needle of same gauge as the rod is later placed in the catheter after the rod is removed.  
           [0019]    Advantageously, the beveled end of the rod assists the cutting of the opening into the bone along with the perforator as they are both rotated by the dental hand piece they are coupled therewith.  
           [0020]    To our knowledge, there are no prior art patents, which teach the use of a perforator having a hypodermic needle-like cutting tool wherein the outer diameter is uniform allowing both precise cutting of a small hole, and allowing easy removal by simply pulling the device out without unthreading, wherein the perforator has an upper end adapted to be connected to a motorized dental hand piece; and, wherein the perforator has a rod therein which turns with the perforator needle-like cutting tool assisting in preventing debris from entering the perforator; and wherein the rod is itself a needle-like cutting tool assisting in the cutting of the opening.  
           [0021]    To our knowledge, aside from the parent patent application, now issued as U.S. Pat. No. 5,332,398, there are no prior art patents, which teach the use of a perforator having a hypodermic needle-like cutting tool wherein the outer diameter is uniform allowing both precise cutting of a small hole, and allowing easy removal by simply pulling the device out without unthreading, wherein the perforator has an upper end adapted to be connected to a motorized dental hand piece; and, wherein the perforator has a rod therein which turns with the perforator needle-like cutting tool assisting in preventing debris from entering the perforator; and wherein the perforator serves as a catheter for accommodating a hypodermic needle having a same outer diameter as the rod, after the catheter is inserted into the bone.  
           [0022]    It is the belief of the inventor, that this novel method and combination of elements will eventually change the way in which many dentists infuse medication and local anesthesia.  
           [0023]    Unlike the prior art catheters the catheter drill of the instant invention will not bind or increase its resistance against the drilling hand piece as it is drilling into the bone. The uniform outer diameter allows the drill/needle to cut without binding and acting as a self-tapping hollow screw.  
         SUMMARY OF THE INVENTION  
         [0024]    The present invention endeavours to mitigate the problems and disadvantages of delivering dental anaesthetic encountered with the prior art methods and devices.  
           [0025]    The present invention provides a perforator having a central passage, which perforator then remains in place as a catheter for allowing a hypodermic needle to be inserted through the passage to deliver the desired medication. The preferred apparatus is provided with means for obstructing the entry of debris in the perforator&#39;s passage.  
           [0026]    In accordance with the invention, there is provided a device for perforating the periodontal ligaments, cortical plate or small bones, and the like and for injecting substances at a predetermined site, comprising:  
           [0027]    perforator for drilling a hole into the ligament, bone or tissue, wherein said perforator is provided with an inner passage to form a catheter adapted to remain in the hole for directing a hypodermic needle to the predetermined site; and  
           [0028]    an adapter for coupling to an end of the perforator and for latching a latching-type powered dental handpiece thereto and for transmitting rotational movement from the powered dental handpeice to said perforator, the perforator having a drilling needle extending from an end thereof, the drilling needle having a uniform outer diameter and a smooth non-varying outer surface allowing removal once inserted into the periodontal ligaments, cortical plate or small bones and the like by withdrawing the needle by pulling backwards along a line defined by a longitudinal axis of the inserted drilling needle; the adapter for coupling with the perforator in a locking engagement such that rotational motion imparted to the adapter, rotates the perforator when the adapter is coupled with the perforator, the adapter having an upper end having a driving shank extending along a rotational axis for removably engaging the powered dental hand tool, the adapter having a rod sized to be accommodated within the perforator and sized to fit into a passage in said drilling needle at a lower end thereof.  
           [0029]    In a further aspect, the rotary drive shaft comprises an axial rod adapted to be inserted into the hollow drilling catheter when engaging it.  
           [0030]    According to another aspect of the present invention, there is provided a device for perforating the periodontal ligaments, cortical plate of small bones, and the like, for injecting substances at a predetermined site, comprising:  
           [0031]    a perforator for drilling a hole into the ligament, bone or tissue, wherein said perforator is provided with an inner passage to form a catheter adapted to remain in the hole perforated for directing a hypodermic needle to said predetermined site, and an adaptor for latching in a latching-type powered dental handpiece for transmitting rotational movement to said perforator, the adapter having a rod at an end thereof sized to be disposed within the perforator inner passage.  
           [0032]    The catheterized intra-osseous delivery system of the present invention comprises a perforator with a bevelled drilling needle that is used as a drill and a catheter. The needle is attached at one end to a plastic or metal body. For drilling, the body is attached to a matching adaptor provided with a driving shank which is rotated by a conventional contra angle or straight dental hand piece. Then, the perforator is used as a catheter, whereby a hypodermic needle is inserted through the drilling needle without losing access to the already perforated bone.  
           [0033]    In the preferred form of the invention the apparatus is disposable. Before disposal, the perforator receives a cap over the needle for protection against accidental contamination of environment.  
           [0034]    The present invention also provides a method of medical treatment, comprising the steps of: inserting a catheter, at a point in the gingival sulcus between outer tooth surface and marginal gingiva, or through gingiva and cortical plate, to a predetermined depth; and injecting medication or anaesthesia through said catheter.  
           [0035]    Advantageously, the system of the present invention provide users with a more secure and less painful method and device for direct access for injecting medication to a target area into the cortical plate of the bone.  
           [0036]    In addition, the system facilitates and adds a level of security previously unavailable for the anaesthetic in that it has a sure and immediate effect.  
           [0037]    Another advantage of this system is that it provides benefits to the dentists by facilitating the use of a low cost, disposable device.  
           [0038]    Still another advantage of this invention is that the risk of contamination is lower than with the current devices. This is because the device is disposable and because the risk of the dental equipment used with the device of the invention becoming contaminated is low. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0039]    These and other features of the invention will become more apparent from the following description of the preferred embodiments, in which reference is made to the appended drawings, wherein:  
         [0040]    [0040]FIG. 1 illustrates an exploded view of the device showing the component parts and their inter-relationship;  
         [0041]    [0041]FIG. 2A illustrates the device assembled for drilling;  
         [0042]    [0042]FIG. 2B Illustrated a longitudinal cross-section through the device illustrated in FIG. 2A, taken along line A-A of FIG. 2A;  
         [0043]    [0043]FIG. 3 shows a detailed view of the area marked on FIG. 2B;  
         [0044]    [0044]FIG. 3B shows a detailed view of the rod-needle inserted in the perforator cutting/drilling-needle inserted in a different orientation than in FIG. 3;  
         [0045]    [0045]FIG. 4 is a cross-sectional view of the body of the perforator taken along lines B-B of FIG. 2;  
         [0046]    [0046]FIG. 5 is a cross-sectional view of the adaptor body;  
         [0047]    [0047]FIG. 6 is a cross-sectional view of the cap;  
         [0048]    FIGS.  7 A- 7 C illustrate the method according to the invention, FIG. 7A shows the device drilling, in the bone tissue; FIG. 7B shows the perforator inserted into the bone tissue and the adaptor de-coupled; and FIG. 7C shows the perforator inserted into the bone tissue as a catheter and a hypodermic needle set for delivering an injection;  
         [0049]    [0049]FIG. 8 illustrates another embodiment of the invention;  
         [0050]    [0050]FIG. 9 illustrates an alternative method of delivery medication to treat a root-canal nerve;  
         [0051]    [0051]FIG. 10 illustrates from a plan view the point of catheter insertion for the alternative method shown in FIG. 9;  
         [0052]    [0052]FIG. 11 is a perspective, exploded view of the parts of an alternative embodiment of the invention wherein the catheter and adapter can be temporarily locked while drilling occurs;  
         [0053]    [0053]FIG. 12 is a sectional elevation of the same catheter assembly; and,  
         [0054]    [0054]FIG. 13 is a plane view of an additional, optional component of the assembly. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0055]    [0055]FIG. 1 illustrates an exploded view of the device showing the component parts and their inter-relationship. The device comprises a perforator  1 , an adaptor  3  and a cap  5 .  
         [0056]    The perforator  1  has a bevelled drilling needle  7  which is used both as a drill and a catheter. Needle  7  is bevelled at both ends, as better shown on FIG. 2B. The first end  9  is formed as a drilling tip in that it has cutting teeth along the edge, as shown in FIG. 3. The second end  11  is bevelled for receiving and directing the needle of a hypodermic syringe and for easy coupling with the adaptor  3 , as will be seen later.  
         [0057]    A flange  13  is fixed on the needle about the second end  11 , so that the needle passes along the geometrical axis of the flange  13 . The flange  13  is manufactured or moulded of a plastic or other material, and it has a generally cylindrical outer shape. This shape is preferred as the flange  13  rotates together with the needle  7  for drilling. Variations of the shape illustrated in the attached drawings may also be contemplated.  
         [0058]    The flange  13  is adapted for receiving cap  5  at one end and for coupling with the adaptor  3  at the other end. As an example, a collar  15  may be provided on the flange  13  so that the cap  5  holds over the collar  15  when pressed. The cap  5  is needed to protect and cover the tip  9  of the needle  7  before use and when the device is disposed of.  
         [0059]    For ease of manipulation the internal diameter of the cap  5  and the external diameter of the collar  15  should be as large as is reasonable and preferably between 10 to 20 times greater than the diameter of the needle  7 . Another advantage of the collar  15  is that it provides a stop to limit the depths of penetration of the needle  7  (the depth of penetration of the needle  7  is, therefore, termed the drilling length, as opposed to the remaining length of the needle  7 , which is termed the attachment length). The flange  13  is shaped to form an inner axial shaft  17  projecting from the centre of the collar  15 , and a female connector  19  for coupling with a corresponding male connector provided in the adaptor  3 .  
         [0060]    The coupling between the perforator and the adaptor is illustrated on FIGS. 2B, 4 and  5 . FIG. 2B shows a longitudinal section of a female connector  19  provided in the flange  13  and a male connector  21  provided in the adaptor  3 . FIG. 4 illustrates a cross-section of an exemplary female connector  19 , while FIG. 5 shows a cross-section of the corresponding male connector  21 . The male connector is provided with radial ribs  23 , extending towards the centre but not meeting to leave room for the central shaft  17 , while corresponding grooves  25  are provided in the female connector, alternating with islands  20 . The female connector is also formed with a clearance ring  22  for accommodating the thickness of the body  29  of the adaptor.  
         [0061]    The tubular shaft  17  forms a reinforced passage for drilling needle  7 . The shaft also provides enough contact surface between the drilling needle and the body to ensure that these two parts rotate together during drilling. As could be seen on FIG. 2B, end  11  of the needle is bevelled and extends a little over the shaft  17 , but there is a clearance between the tip of end  11  and the male connector when the device is assembled for drilling.  
         [0062]    When rotated, the drilling needle  7  penetrates in the bone tissue through gingiva or ligament and drills a hole with the cutting tip  9 . The perforator  1  may remain in place as a catheter, with the drilling needle inserted into the bone. Then, a hypodermic needle may be introduced through the passage of drilling needle  7  to inject a medicament directly into the bone. Therefore, the drilling needle  7  is selected to have a wide enough passage for allowing a hypodermic needle with a smaller gauge to be inserted through needle  7 .  
         [0063]    The adaptor  3  has several important functions. Firstly, the adaptor conveys the rotational movement from a dental hand piece or the like to the perforator. As well, the adaptor is provided with means for blocking bone debris for entering into the syringe passage and also aligns and reinforces the needle  7  during drilling. In the preferred embodiment of this invention is it important that the adapter be coupled with the dental hand tool which dives the adapter about its longitudinal axis. It is also important that the adapter conveys its rotational movement from the dental hand piece to the perforator 3. By providing this novel arrangement, after the perforator is inserted into the bone, where it is to remain, all that is required is that the adapter with the dental handpiece be removed from the perforator. Hence the order of dental hand piece driving the adapter including the rod  27  which in turn drives the perforator and its drilling needle is important in the preferred embodiment.  
         [0064]    The adaptor includes a rod  27 , a body  29  and a shank  31 .  
         [0065]    Body  29  includes male connector  21  which is formed, as indicated above, with longitudinal ribs  23  which couple with grooves  25  of the female connector  19  for driving needle  7 . The shank  31  extends along the axis of the adaptor and is formed with a joint  33  for attachment with a contra-angle or straight hand piece. The shank  31  has a groove  35  and a cut-out  37  to fix the shank in place in the known manner. Generally, the shank transmits to the needle  7  the rotational movement from the hand piece.  
         [0066]    The shank  31  also acts as a barrier for contamination, at it is generally thought that bacteria is reluctant to change direction, and there are a plurality of 90° angles between the tip  9  of drilling needle  7  and the joint  33 .  
         [0067]    The rod  27  has the diameter and length selected in accordance with the size of needle  7 . The rod  27  is fixed in the geometrical centre of body  29  so as to readily penetrate into the hollow passage of the needle, when the device is assembled for drilling. When the rod  27  is inserted within the needle passage, it advances through the length of the needle up to the bevelled end, as shown on FIGS. 2A and 3 and  3 B in dotted lines. In this way, the debris from drilling cannot penetrate to block the needle passage. In addition, the rod gives additional rigidity, strength and alignment to needle  7  during drilling. The rod also Advances through the a portion of the shank as is illustrated in FIG. 2B in dotted lines. Furthermore, the rod which can itself be in the form of a needle similar to the hypodermic needle for delivery of medication, wherein the rod end is sharp and pointed, to assist in the drilling process. By using standard hypodermic needle tubing for the rod, the cost of the device can be minimized while gaining the benefit of the cutting tip. In manufacture, the cutting tip of the drilling needle  7  and the rod can be cut at the same time to a desired length.  
         [0068]    [0068]FIG. 8 illustrates an alternative embodiment of the present invention. In this variant, body  13  is provided with an internal thread while body  29  is provided with a matching external thread. By threading one to the other and using the central rod  27  to align the two bodies together, the perforator could be driven by the hand piece in a similar manner as in the variant disclosed above. Of course, the thread is going in an opposite direction to the direction of rotation of the device for avoiding disconnection of the two bodies.  
         [0069]    An alternative method of targeted delivery is shown in FIGS. 9 and 10. The perforator  7  is inserted at a point  30  between teeth, parallel to the tooth  31  in treatment, and penetrates through gingival sulcus  32  and ligament  33  to a depth near the entry of the nerve, artery and vein bundle  34  through the bone  35  and into the tooth-root canal  36 . This method of targeted delivery, say, of anaesthesia is suitable, where perforating vertical to the tooth through gingiva and cortical bone is not convenient or possible; as in the case of rear molars.  
         [0070]    There are a variety of ways that this invention can be devised but the end result is to perform catheterized intra-osseous delivery system.  
         [0071]    The device of this invention operates as follows:  
         [0072]    First, a site for the injection is selected by the practitioner. The gingiva over the injection side is disinfected and topically anaesthetized. A small amount of anaesthetic solution is injected until blanching of the tissue, and this will anaesthetize the gingiva and the periosteum. The following operations are illustrated in FIGS. 7A, 7B and  7 C, and FIGS. 9 and 10.  
         [0073]    As can be seen in FIG. 7A, the bevelled end  9  of the needle  7  is placed against the gingiva and shank  31  is attached with joint  33  to a contra angle or to a straight dental hand piece. The adaptor and perforator are coupled for drilling.  
         [0074]    The perforator should be held perpendicular to the cortical plate, or if not possible or convenient, it should be held vertical and parallel to the long axis of the tooth as shown in FIG. 9, having been inserted between teeth as shown in FIG. 10. The perforator is then operated in small bursts of rotation from the hand piece until resistance is no longer felt, as is well known to dentists.  
         [0075]    Next, the adaptor  3  is removed from the engagement with perforator  1  by applying pressure to the body  13  with the fingers thus keeping the needle  7  in the perforated cortical plate. This is shown in FIG. 7B.  
         [0076]    The presence of the needle  7  in the cortical plate, or down the side of the tooth as in FIG. 9, allows an injection to be made without complicated manoeuvres to find the perforation in the case of floating gingiva or the free or marginal gingiva. FIG. 7C illustrates the next step, namely how the injection needle is inserted through the perforator  1  for delivering the anaesthetic solution required.  
         [0077]    The last step is to remove the perforator  1  from the cortical plate and reinstall the cover cap  5  over the needle  7 , then insert the adaptor to the perforator making the unit complete and disposable. The cap  5  provides a means whereby the apparatus may be removed from the dental hand piece without any risk of the user being in contact with body fluids which will be present on the needle after use. This is extremely important particularly since there may be a risk of contacting Aids or Hepatitis should the user accidentally prick a finger with the needle. It is therefore desirable that the cap should be of a hard or rigid rubber or plastic material not easily penetrated by the needle. Referring to FIG. 11 and  12 , the catheter assembly comprises a disposable contamination protective cap or housing  10  which, in the assembled state, surrounds a hollow drilling needle or catheter  11 , preferably of stainless steel, having a drilling tip  12  and a non-drilling end with an outwardly flaring end portion  13 . The end portion is fixed, and preferably molded, within a cylindrical driven flange  14  which is made of plastic material and is disposable along with the needle.  
         [0078]    The flange is adapted bo be driven by the drive means including a drive flange  16  which has a periphery matching radius of the flange  14 , and which is integrally formed with a shaft  17  suitably dimensioned to fit into the handpiece of a standard dental drill; the diameter of this shaft being preferably between 2.27 and 2.45 mm. Parts  16  and  17  may either be metal or plastic, and will also normally be considered disposable. The flange  16  and shaft  17  have an axial bore into which is secured a rod  20  having a cutting tip (not shown) which projects from the flange  17  by an amount equivalent to the main drilling length of the needle  11 , and which prevents the needle from becoming blocked with debris during operation.  
         [0079]    The driven flange  14  and the drive flange  16  each have a longitudinal groove, indicated respectively at  14   a,    16   a.  When all the parts are assembled, these grooves are occupied by a longitudinal internal rib  21  in the cylindrical wall of the a locking sleeve  22 . This is a thin-walled, disposable cap-type part, the cylindrical wall of which is capable of substantially enclosing the two flanges  14  and  16 , and having an upper end flange  22   a  which, when the sleeve is fully engaged with the two flanges  14  and  16 , rests against the upper surface of the flange  16 . The sleeve  22  serves to hold the flanges together, as well as transmitting rotary motion from the drive to the driven flange. The sleeve is a push fit within the housing  10 .  
         [0080]    The parts are sold in the assembled condition as shown in FIG. 12. For use the housing  10  is removed, the shaft  17  is fitted into a drilling machine, and a drilling proceeds in the normal way. After drilling, the shaft  17  with flange  16 , and rod  20  and sleeve  22 , are removed from the flange  14 , and anaesthetic is then introduced through the needle  11  which then acts as a catheter.  
         [0081]    All parts of the assembly are disposable after use.  
         [0082]    [0082]FIG. 13 shows a further feature of this embodiment, namely a holder  30  which comprises a rod  30   a  fixed at one end to part circular clip portion  30   b  which is formed to encircle a circumferentially grooved central area  14   b  of the flange  14 . This holder may be placed in position to hold the flange  14  after drilling has taken place, with its rod  30   a  lying along side of the patients mouth and preventing undesirable movement of the flange  14  during the injection step.  
         [0083]    In summary, this invention provides particular advantages not suggested in prior art devices. The provision of an adapter piece having a rod at a lower end, a shaft at an upper end for coupling with a motorized dental handpeice, and an intermediate hub disposed between the rod and the shaft wherein the hub has means for locking with a catheter having a drilling needle provides numerous advantages. The drilling needle has a uniform outer diameter and can be withdrawn by simply pulling it out. The adapter is designed to prevent the drilling needle from becoming blocked during drilling and is designed to turn the drilling needle when powered by the handpeice. More importantly, when the catheter has drilled the hole in the bone, the adapter can be removed with the handtool leaving the catheter in place.  
         [0084]    Numerous other embodiments can be envisaged without departing from the spirit and scope of the invention. For example, the end of the rod can be provided with a cutting tip assisting the cutting needle in drilling the hole. Furthermore, the rod itself can be a square rod for engaging a complementary recess in the catheter opening. This embodiment would allow the device to function even if the rod was partially extracted during the drilling of the hole as any portion of the square rod could be used to drive the cutting needle.  
         [0085]    Another embodiment this invention provides an automatic delivery of fluid or medication to the catheter. Here, a medication injection device comprises a housing for grasping by an operator, wherein the housing has a distal end; a rotatable hollow drill bit mounted to the distal end of the housing, wherein the drill bit includes a bore therethrough, and wherein the drill bit is suitable for intraosseous drilling; means disposed in the housing for rotating the drill bit; and fluid dispensing means including a fluid reservoir stationarily mounted in the housing and means for supplying a controlled dose of medication fluid for intraossaous injection through the bore of the drill bit. Yet still further, a removable rod is inserted into the drill bit for preventing material from blocking the catheter. In order to prevent debris from entering the drilling needle, a solid or hollow rod is disposed within the drill bit which is spring loaded in the head of the housing opposite the drill bit. The rod under spring tension is removed by removing a cap on the head of the handpiece.