TARGETED CATHETER DRUG ADMINISTRATION

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 adpator for improved drilling efficiency.

Description: TARGETED CATHETER DRUD AD IN I STATION BACKGROUND OF THE INVENΗON 1. Field of d e invention 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 anaesthesia 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. 2. Related Art 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. 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. 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. 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. 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. Odier 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. 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 me 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. 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. 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. United States Patent 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. However, the device disclosed in Dillon'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 wid 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. United States Patent 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. United States Patent 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. One significantly older United States patent that is discussed by Alexandre (above) is United States Patent 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). SUMMARY OF THE INVENTION The present invention endeavours to mitigate the problems and disadvantages of delivering dental anaesthetic encountered with die prior art methods and devices. 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 d e passage to deliver d e desired medication. The preferred apparatus is provided widi means for obstructing the entry of debris in die perforator's passage. According to an apparatus aspect of the present invention, a device for cadietized delivery of medication comprises: a hollow drilling catheter means for penetrating ligament, tissue or bone and adapted to remain in place after drilling; and means for engaging and disengaging die drilling cadieter to and from a rotary drive shaft. In a further aspect, the rotary drive shaft comprises an axial rod adapted to be inserted into the hollow drilling cadieter when engaging it. According to anodier aspect of the present invention, there is provided a device for perforating the periodontal ligaments, cortical plate of small bones, and die like, for injecting substances at a predetermined site, comprising: a perforator for drilling a hole into d e 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 cadieterized intra-osseous delivery system of the present invention comprises a perforator witii a bevelled drilling needle that is used as a drill and a cadieter. The needle is attached at one end to a plastic or metal body. For drilling, the body is attached to a matching adaptor provided widi 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 widiout losing access to the already perforated bone. In die preferred form of die invention the apparatus is disposable. Before disposal, die perforator receives a cap over the needle for protection against accidental contamination of environment. 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 deptii; and injecting medication or anaestiiesia through said cadieter. Advantageously, die system of the present invention provide users widi a more secure and less painful memod and device for direct access for injecting medication to a target area into die cortical plate of die bone. In addition, die system facilitates and adds a level of security previously unavailable for the anaesthetic in that it has a sure and immediate effect. Another advantage of tiiis system is that it provides benefits to die dentists by facilitating the use of a low cost, disposable device. Still anodier advantage of tins invention is tiiat the risk of contamination is lower than with d e current devices. This is because the device is disposable and because die risk of die dental equipment used wid die device of die invention becoming contaminated is low. BRIEF DESCRIPΗON OF THE DRAWINGS These and other features of the invention will become more apparent from die following description of die preferred embodiments, in which reference is made to d e appended drawings, wherein: Figure 1 illustrates an exploded view of die device showing the component parts and tiieir inter-relationship; Figure 2 A illustrates die device assembled for drilling; Figure 2B Illustrated a longitudinal cross-section dirough the device illustrated in Figure 2A, taken along line A-A of Figure 2A; Figure 3 shows a detailed view of die area marked on Figure 2B; Figure 4 is a cross-sectional view of die body of die perforator taken along lines B-B of Figure 2; Figure 5 is a cross-sectional view of the adaptor body; Figure 6 is a cross-sectional view of d e cap; Figure 7A - 7C illustrate the metiiod according to die invention, Figure 7A shows die device drilling in d e bone tissue; Figure 7B shows the perforator inserted into the bone tissue and die adaptor de-coupled; and Figure 7C shows die perforator inserted into die bone tissue as a catheter and a hypodermic needle set for delivering an injection; Figure 8 illustrates anotiier embodiment of die invention; Figure 9 illustrates an alternative method of delivery medication to treat a root-canal nerve; and Figure 10 illustrates from a plan view the point of catheter insertion for die alternative metiiod shown in Figure 9. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Figure 1 illustrates an exploded view of die device showing die component parts and their inter-relationship. The device comprises a perforator 1, an adaptor 3 and a cap 5. The perforator 1 has a bevelled drilling needle 7 which is used botii as a drill and a cadieter. Needle 7 is bevelled at both ends, as better shown on Figure 2B. The first end 9 is formed as a drilling tip in that it has cutting teetii along the edge, as shown in Figure 3. The second end 11 is bevelled for receiving and directing d e needle of a hypodermic syringe and for easy coupling with die adaptor 3, as will be seen later. A flange 13 is fixed on die needle about d e second end 11, so tiiat die needle passes along die 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 die flange 13 rotates together widi d e needle 7 for drilling. Variations of die shape illustrated in the attached drawings may also be contemplated. The flange 13 is adapted for receiving cap 5 at one end and for coupling widi d e adaptor 3 at die otiier end. As an example, a collar 15 may be provided on die flange 13 so that the cap 5 holds over die collar 15 when pressed. The cap 5 is needed to protect and cover die tip 9 of the needle 7 before use and when die device is disposed of. For ease of manipulation die internal diameter of die cap 5 and die external diameter of d e collar 15 should be as large as is reasonable and preferably between 10 to 20 times greater than the diameter of d e needle 7. Another advantage of d e collar 15 is tiiat it provides a stop to limit die deptiis of penetration of die needle 7. 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 widi a corresponding male connector provided in the adaptor 3. The coupling between die perforator and die adaptor is illustrated on Figures 2B, 4 and 5. Figure 2B shows a longitudinal section of a female connector 19 provided in die flange 13 and a male connector 21 provided in die adaptor 3. Figure 4 illustrates a cross-section of an exemplary female connector 19, while Figure 5 shows a cross- section of die corresponding male connector 21. The male connector is provided widi radial ribs 23, extending towards die centre but not meeting to leave room for the central shaft 17, while corresponding grooves 25 are provided in the female connector, alternating widi islands 20. The female connector is also formed widi a clearance ring 22 for accommodating die tiiickness of the body 29 of die adaptor. The tubular shaft 17 forms a reinforced passage for drilling needle 7. The shaft also provides enough contact surface between the drilling needle and die body to ensure that these two parts rotate togetiier during drilling. As could be seen on Figure 2B, end 11 of die needle is bevelled and extends a little over the shaft 17, but there is a clearance between die tip of end 11 and die male connector when the device is assembled for drilling. When rotated, the drilling needle 7 penetrates in die bone tissue dirough gingiva or ligament and drills a hole widi die cutting tip 9. The perforator 1 may remain in place as a catheter, with die drilling needle inserted into die bone. Then, a hypodermic needle may be introduced dirough die passage of drilling needle 7 to inject a medicament direcdy into the bone. Therefore, the drilling needle 7 is selected to have a wide enough passage for allowing a hypodermic needle widi a smaller gauge to be inserted through needle 7. The adaptor 3 has tiiree functions. Firstiy, the adaptor conveys die rotational movement from a dental hand piece or the like to the perforator. As well, the adaptor is provided widi means for blocking bone debris for entering into die syringe passage and also aligns and reinforces the needle 7 during drilling. The adaptor includes a rod 27, a body 29 and a shank 31. Body 29 includes male connector 21 which is formed, as indicated above, widi longitudinal ribs 23 which couple widi grooves 25 of die female connector 19 for driving needle 7. The shank 31 extends along die axis of the adaptor and is formed wid a joint 33 for attachment widi 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 die needle 7 d e rotational movement from the hand piece. The shank 31 also acts as a barrier for contamination, at it is generally thought diat bacteria is reluctant to change direction, and tiiere are a plurality of 90° angles between die tip 9 of drilling needle 7 and die joint 33. The rod 27 has the diameter and length selected in accordance widi d e size of needle 7. The rod 27 is fixed in die geometrical centre of body 29 so as to readily penetrate into the hollow passage of me needle, when die device is assembled for drilling. When die rod 27 is inserted witiiin the needle passage, it advances dirough die length of die needle up to die bevelled end, as shown on Figures 2A and 3 in dotted lines. In tiiis way, die debris from drilling cannot penetrate to block die needle passage. In addition, die rod gives additional rigidity, strengtii and alignment to needle 7 during drilling. The rod also advances dirough die a portion of die shank as is illustrated in Figure 2B in dotted lines. Figure 8 illustrates an alternative embodiment of die present invention. In tiiis variant, body 13 is provided widi an internal tiiread while body 29 is provided widi a matching external thread. By tiireading one to die other and using the central rod 27 to align die two bodies togetiier, the perforator could be driven by die hand piece in a similar manner as in die variant disclosed above. Of course, die tiiread is going in an opposite direction to die direction of rotation of die device for avoiding disconnection of the two bodies. An alternative method of targeted delivery is shown in Figures 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 deptii near die entry of die nerve, artery and vein bundle 34 dirough die bone 35 and into d e tooth-root canal 36. This method of targeted delivery, say, of anaesthesia is suitable, where perforating vertical to me tooth dirough gingiva and cortical bone is not convenient or possible; as in die case of rear molars. There are a variety of ways that this invention can be devised but die end result is to perform catiieterized intra-osseous delivery system. The device of tiiis invention operates as follows: First, a site for the injection is selected by die practitioner. The gingiva over die injection side is disinfected and topically anaesthetized. A small amount of anaesthetic solution is injected until blanching of die tissue, and tiiis will anaesthetize the gingiva and die periosteum. The following operations are illustrated in Figures 7 A, 7B and 7C, and Figures 9 and 10. As can be seen in Figure 7 A, die bevelled end 9 of die needle 7 is placed against die gingiva and shank 31 is attached widi joint 33 to a contra angle or to a straight dental hand piece. The adaptor and perforator are coupled for drilling. The perforator should be held perpendicular to die cortical plate, or if not possible or convenient, it should be held vertical and parallel to the long axis of the tootii as shown in Figure 9, having been inserted between teetii as shown in Figure 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. Next, die adaptor 3 is removed from the engagement with perforator 1 by applying pressure to the body 13 widi die fingers tiius keeping the needle 7 in die perforated cortical plate. This is shown in Figure 7B. The presence of die needle 7 in the cortical plate, or down die side of die toodi as in Figure 9, allows an injection to be made witiiout complicated manoeuvres to find the perforation in me case of floating gingiva or the free or marginal gingiva. Figure 7C illustrates the next step, namely how the injection needle is inserted dirough die perforator 1 for delivering die anaestiietic solution required. The last step is to remove the perforator 1 from the cortical plate and reinstall the cover cap 5 over the needle 7, tiien insert the adaptor to die perforator making d e unit complete and disposable. The cap 5 provides a means whereby the apparatus may be removed from die dental hand piece without any risk of die 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 die user accidentally prick a finger widi die needle. It is tiierefore desirable tiiat die cap should be of a hard or rigid rubber or plastic material not easily penetrated by die needle.

Claims: WHAT IS CLAIMED IS: 1. A device for catiietized delivery of medication comprises: a hollow drilling cadieter means for penetrating ligament, tissue or bone and adapted to remain in place after drilling; and means for engaging and disengaging die drilling cadieter to and from a rotary drive shaft. 2. A device as claimed in claim 1, wherein die rotary drive shaft comprises: an axial rod adapted to be inserted into d e hollow drilling cadieter when engaging it. 3. A device for perforating the periodontal ligaments, cortical plate or small bones, and die like, for injecting substances at a predetermined site, comprising: a perforator for drilling a hole into the ligament, bone or tissue, wherein said perforator is provided widi 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. 4. A catiieterized intra-osseous delivery system comprising: a perforator with a bevelled drilling needle tiiat is used as a drill and a cadieter; said needle attached at one end to a plastic or metal flange, which is attached to a matching adaptor provided widi a driving shank to be rotated by a conventional contra angle or straight dental hand piece; whereby die perforator is used as a cadieter for a hypodermic needle to be inserted dirough die drilling needle widiout losing access to die already perforated bone. 5. An apparatus as claimed in claim 4, wherein the apparatus is disposable, and die perforator receives a cap over the needle for protection against accidental contamination of environment. 6. A method of medical treatment, comprising the steps of: inserting a catheter, at a point in die gingival sulcus between outer tooth surface and marginal gingiva, or through gingiva and cortical plate, to a predetermined deptii; and injecting medication of anaesthesia through said cadieter. 7. A device as claimed in claim 1, wherein said perforator comprises: a first connector formed inside a first body of a generally cylindrical outer shape, for cooperation widi said adaptor; a drilling needle extending from said first body along die rotational axis of said first body and opposed to said first connector, said needle being fixed to said first body. 8. A device as claimed in claim 1, wherein said adaptor comprises: a second connector formed inside a second body of a generally cylindrical outer shape; a driving shank extending along d e rotational axis of said second body, said shank having an end fixed to said second body opposite to said second connector, and a free end adapted to receive a rotational movement; and a rod extending along die rotational axis of said second body in an opposite direction to said driving shank, said rod sized to fit into the passage of said needle. 9. A device as claimed in claim 3, wherein said first and said second connectors are provided widi complementary configurations for engagement to each other when moved along die rotational axis towards each otiier. 10. A device as claimed in claim 2, wherein said needle has a drilling lengtii and a attachment length, and a passage sized to accommodate a hypodermic needle of a smaller gauge. 11. A device as claimed in claim 8, wherein said drilling lengtii ends widi a cutting edge. 12. A device as claimed in claim 9 wherein said cutting edge is bevelled. 13. A device as claimed in claim 10 wherein said cutting edge is provided wid cutting teeth along die circumference. 14. A device as claimed in claim 8, wherein said attachment length ends widi a catheter end. 15. A device as claimed in claim 12, wherein said cadieter end is bevelled. 16. A device as claimed in claim 8, wherein said attachment length is received in a central shaft provided in said first body for increasing die surface of attachment between said needle and said first body. 17. A device as claimed in claim 16, wherein said rod comprises: a anchoring part incorporated and fixed into said shank, for driving said rod to rotate with said shank; and a free part of a length selected to extend up to die beginning of the bevelled tip of said needle when d e rod is inserted into said needle, for blocking entrance of debris resulting during bone perforation. 18. A device as claimed in claim 1, further comprising a protection cap for shielding said drilling tip during storage. 19. A device as claimed in claim 2, wherein said first body is provided widi means for receiving and securing a protective cap over said needle. 20. A device as claimed in claim 17, wherein said means for securing comprises a disc centred about said needle and fixed on said first body for receiving said protection cap.

Inventors: GIBBS DAVID E, GIBBS, DAVID, E.
Applicants: GIBBS DAVID E, GIBBS, DAVID, E.
Application year: 1996
Main classification: A61B17
IPC codes: A61B17, A61M25