Patent Application
20170028143
The invention relates to a device for the practice of oral medicine, including dentistry. Particularly, the invention relates to a guiding device for administering an injection of anesthesia in the vicinity of an inferior alveolar nerve. More particularly, the invention relates to a guiding device that helps to prevent injecting beyond the pterygomandibular space during inferior alveolar nerve block.
The inferior alveolar nerve is unusual in having a passage inside the mandibular bone, protected by a cortical layer. Inferior alveolar nerve block (IANB) is the preferred anesthetic technique for dental and oral surgery procedures, involving the infiltration of the nerve before its entry into the mandibular canal.
In spite of certain complications and a failure rate varying from 5 to 20%, IANB remains the technique most frequently used for dental or oral surgery procedures involving the mandible. To be effective, the projection point of the needle must be in contact with the medial surface of the mandibular ramus, above and posterior to the lingula of the mandible. To achieve this, some authors have described intra-oral landmarks, which may vary depending on individual morphology. According to the anatomical technique in the art, the body of the syringe is oriented toward the contralateral molars or premolars, depending on the orientation of the mandibular ramus. The needle penetration point is at the center of an inverted mucosal triangle formed by the projection of the anterior edge of the mandibular ramus (outside), the medial pterygoid muscle (inside), and the bottom of the vestibule (above).
Numerous techniques exist for analgesia of the inferior alveolar nerve in a limited area of the pterygomandibular space, which reflects the difficulties encountered by practitioners.
For guide devices used in existing syringe analgesia mandibular foramen (EP 2009/2429618), the locking of the syringe and the injection are when the tip of the needle comes into abutment against the medial side of the ramus (i.e., at the bone contact). However, upon its penetration into the soft tissue, the needle may bend, deflect, or slide along the pterygomandibular fascia thereby changing the trajectory imposed by the device. The tip can then be found beyond the pterygomandibular space (in parotid space). An injection into the parotid space may result in a temporary paralysis of the facial nerve.
Accordingly, there exists a need for a guiding device that does not inject beyond the pterygomandibular space during inferior alveolar nerve block.
In one embodiment, the invention relates to a guiding device for administering an injection of anesthesia in the vicinity of an inferior alveolar nerve, in a subject, the device comprising: a retro-mandibular tip operably linked to a guide unit, said guide unit adopted to receive a syringe, wherein said guide unit comprises a mechanism adopted to hold said syringe such that its needle is located at a predetermined distance from the posterior edge of the mandibular ramus.
In another embodiment, the invention relates to a guiding device for administering an injection of anesthesia in the vicinity of an inferior alveolar nerve, in a subject, the device comprising: a retro-mandibular tip operably linked to a guide tube, said guide tube adopted to receive a syringe, wherein said guide tube comprises a stopper mechanism adopted to stop the advancement of said syringe, passing through said guide tube, at a predetermined point in said syringe. In a particular embodiment, the stopper mechanism is adopted to stop the advancement of said syringe when its needle is located at a distance, ranging between about 7 mm and about 25 mm, from the posterior edge of the mandibular ramus.
In another embodiment, the invention relates to a method of administering an injection of anesthesia in the vicinity of an inferior alveolar nerve of a subject, the method comprising the steps of: a) providing a guiding device, the device comprising a retro-mandibular tip operably linked to a guide unit, said guide unit adopted to receive a syringe, wherein said guide unit comprises a mechanism adopted to hold said syringe such that its needle is located at a distance, ranging between about 7 mm and about 25 mm, from the posterior edge of the mandibular ramus; b) holding said device in place in contact with a facial region relating to a mandible; c) inserting a syringe through said guide tube of said device; and d) administering the injectable medium at a location immediately before the inferior alveolar enters the mandibular foramen.
In another embodiment, the invention relates to a method of administering an injection of anesthesia in the vicinity of an inferior alveolar nerve of a subject, the method comprising the steps of: a) providing a guiding device, the device comprising a retro-mandibular tip operably linked to a guide tube, said guide tube adopted to receive a syringe, wherein said guide tube comprises a stopper mechanism adopted to stop the advancement of said syringe, passing through said guide tube, at a predetermined point in said syringe; b) holding said device in place in contact with a facial region relating to a mandible; c) inserting a syringe through said guide tube of said device; and d) administering the injectable medium at a location immediately before the inferior alveolar enters the mandibular foramen.
Other features and advantages of the present invention will become apparent from the following detailed description examples and figures. It should be understood, however, that the detailed description and the specific examples while indicating preferred embodiments of the invention are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
The invention provides a guiding device for administering an injection of anesthesia in the vicinity of an inferior alveolar nerve. Specifically, the invention provides a guiding device that helps to prevent injecting beyond the pterygomandibular space during inferior alveolar nerve block.
In one embodiment, provided herein is a guiding device for administering an injection of anesthesia in the vicinity of an inferior alveolar nerve, in a subject, the device comprising: a retro-mandibular tip operably linked to a guide unit, said guide unit adopted to receive a syringe, wherein said guide unit comprises a mechanism adopted to hold said syringe such that its needle is located at a predetermined distance from the posterior edge of the mandibular ramus.
In another embodiment, provided herein is a guiding device for administering an injection of anesthesia in the vicinity of an inferior alveolar nerve, in a subject, the device comprising: a retro-mandibular tip operably linked to a guide tube, said guide tube adopted to receive a syringe, wherein said guide tube comprises a stopper mechanism adopted to stop the advancement of said syringe, passing through said guide tube, at a predetermined point in said syringe.
In another embodiment, provided herein is a method of administering an injection of anesthesia in the vicinity of an inferior alveolar nerve of a subject, the method comprising the steps of: a) providing a guiding device, the device comprising a retro-mandibular tip operably linked to a guide unit, said guide unit adopted to receive a syringe, wherein said guide unit comprises a mechanism adopted to hold said syringe such that its needle is located at a predetermined distance from the posterior edge of the mandibular ramus; b) holding said device in place in contact with a facial region relating to a mandible; c) inserting a syringe through said guide tube; and d) administering the injectable medium at a location immediately before the inferior alveolar enters the mandibular foramen.
In another embodiment, provided herein is a method of administering an injection of anesthesia in the vicinity of an inferior alveolar nerve of a subject, the method comprising the steps of: a) providing a guiding device, the device comprising a retro-mandibular tip operably linked to a guide tube, said guide tube adopted to receive a syringe, wherein said guide tube comprises a stopper mechanism adopted to stop the advancement of said syringe, passing through said guide tube, at a predetermined point in said syringe; b) holding said device in place in contact with a facial region relating to a mandible; c) inserting a syringe through said guide tube; and d) administering the injectable medium at a location immediately before the inferior alveolar enters the mandibular foramen.
Human mandible and inferior alveolar nerve block are fully described in U.S. Pat. Nos. 6,139,529 and 8,257,341; U.S. Patent Application Publication 20110236866; and PCT International Patent Application Publication WO2010/097520, all of which are incorporated herein in their entirety.
Mandibular foramen 5 on the internal surface of ramus 2 provides an ideal location for administering anesthesia to a patient. Generally, the anesthesia is administered near the mandible foramen 5 to cause blockage of the nerve and the nearby lingual nerve for subsequent dental procedures.
However, this process has proven difficult because of the existence of soft tissue as well as small space to work, combined with various anatomical variations. As discussed above, for guide devices used in existing syringe, the tip of the needle comes into abutment against the medial side of the ramus 2. Upon its penetration into the soft tissue, the needle may bend, deflect, or slide along the pterygomandibular fascia thereby changing the trajectory imposed by the device. The tip can then be found beyond the pterygomandibular space (in parotid space), resulting in a temporary paralysis of the facial nerve.
The inventor of the instant patent application developed a device that overcomes the aforementioned problems. Specifically, the inventor of the instant application developed a guiding device that helps to prevent injecting beyond the pterygomandibular space during inferior alveolar nerve block.
As shown in
Guide tube 14 is adopted to receive and hold a syringe 30, as shown in
In a particular embodiment, guide tube 14 includes mechanism adopted to hold syringe 30 such that, during dental anesthesia, its needle 34 is located at a predetermined distance, for example, ranging between about 7 mm and about 25 mm, from the posterior edge of the mandibular ramus 2. In one example, the mechanism is a stopper mechanism 19 adopted to stop the advancement of said syringe 30, passing through said guide tube 14, at a predetermined point in syringe 30. In some embodiments, outlet port 18 has a reduced diameter relative to the diameter of inlet port 16 such that the guide tube 14 abuts against the end of the syringe body 32.
Any stop or lock mechanism, known to one of skilled in the art, capable of stopping the advancement of syringe 30 passing through said guide tube 14 can be used. Examples of such mechanisms, include, but are not limited to hinge and knob.
Stopper mechanism 19 holds syringe 30 or stops advancement of syringe 30 at a predetermined point such that its needle 34 is located at a predetermined distance from the posterior edge of the mandibular ramus 2. The predetermined distance may range between about 7 mm and about 25 mm, preferably 15 mm. In a particular embodiment, the predetermined distance is about 15 mm. In some embodiments, the predetermined distance may range between about 7 mm and about 15 mm, and preferably between about 9 mm and 12 mm.
Retro-mandibular tip 12 is operably linked to guide tube 14 by any suitable connecting mechanisms known to one of skilled in the art. In some embodiments, connecting mechanism includes one or more connecting arms (e.g., items 20, 22, and 24 shown in
In some embodiments, as shown in
In one embodiment, as shown in
ER=EP+PR,
wherein ER refers to the distance between the edge of the inlet port 16 and the retro-mandibular tip 12 edge, EP refers to the distance between the edge of the inlet port 16 and the point of needle 34, and PR refers to the distance between and the point of needle 34 and the retro-mandibular tip 12 edge.
As shown in
In some embodiments, as shown in
In one embodiment, as shown in
SR=PF+PR,
wherein SR refers to the distance between the edge of the outlet port 18 and the retro-mandibular tip 12 edge, PF refers to the needle 34 length, and PR refers to the distance between and the point of needle 34 and the retro-mandibular tip 12 edge, and wherein said PR ranges, for example, from about 7 mm to about 25 mm.
As shown in
Guiding device 10 can be made of any suitable material, known to one of skilled in the art. Examples of such materials include, but are not limited to, polymers, plastics, thermoplastics, metals, alloys and combinations thereof. In a particular embodiment, guiding device 10 is made of a polymer.
The invention also provides methods for administering an injection of anesthesia in the vicinity of an inferior alveolar nerve of a subject. As shown in
The guiding device 10 of the invention can also be used in conjunction with one or more complementary injection techniques, such as, for example, but not limited to, the Gow-Gates mandibular nerve block, Akinosi-Vazirani closed-mouth mandibular nerve block, intra-osseous anesthetic injection, periodontal ligament anesthetic injection, and retromolar technique.
The term “subject,” as used herein, may refer to both human and non-human subjects.
Any patent or patent application publication cited herein is incorporated by reference herein in its entirety.
The following examples are presented in order to more fully illustrate the preferred embodiments of the invention. They should in no way be construed, however, as limiting the broad scope of the invention.
The availability of several techniques for inferior alveolar nerve analgesia in a targeted area of the pterygomandibular space reflects the difficulties faced by practitioners. The objective of this study was to design a guiding device for inferior alveolar nerve block. An analysis of 40 CT scans of facial masses aided in the determination of the most appropriate configuration of the guiding device. Depending on individual morphological characteristics, the projection point of the device was situated on the medial surface of the mandibular ramus, between 7.0 mm and 14.0 mm anterior to the posterior edge of the ramus.
The design of the device was conducted with CT scans made in the Medical Imaging Service at the Hospital of Troyes (France), on 40 consecutive patients aged 12 to 71 years (21 men, 19 women) with no exclusion criteria. These patients had undergone one of the following interventions: extraction of impacted third molars near the inferior alveolar nerve, treatment of impacted canines, pre-implant assessment, or excision of a cyst close to the inferior alveolar nerve.
The tomodensitometric sections were obtained with the aid of a Toshiba AQUILON 64 scanner (Nasu, Japan) with the following parameters: section thickness, 0.5 mm; pitch, 1.0 mm; and field size, 30.0 mm. The axial cuts studied (scale 1:1) were slices that passed the mandibular ramus, parallel to the inferior border of the body of the bone.
For Inferior Alveolar Nerve Block (IANB) to be successful, the tip of the needle must be in contact with the medial surface of the mandibular ramus, above and behind the lingula of the mandible, which marks the anterior edge of the mandibular foramen. This site favors the diffusion of the solution toward the foramen.
A projection plane precisely defined the orientation of the syringe at the moment of injection. This projection plane is passed by two axes (
The first axis was situated at the medial surface of the mandibular ramus, 14.0 mm anterior to its posterior edge. This axis was determined in such a way that it was always situated behind the lingula of the mandible and considered individual variations in the position of the lingula. Previously, it was reported that the position of the lingula can vary from one mandible to another by a distance of 14.0-23.0 mm anterior to the posterior edge of the mandibular ramus.
The second axis passed by the mesiobuccal cusp of the first mandibular molar opposite the side designated for analgesia, and by the contact point between the second premolar and the first maxillary molar opposite the side designated for analgesia. This axis was determined so that it would be situated sufficiently laterally in the oral cavity to avoid an anatomical obstacle: the temporal crest.
The orientation of the body of the syringe in the projection plane and according to the highest axis in the oral cavity is compatible with successful analgesia. Because the projection plane cannot be visualized in the mouth, this study was undertaken with axial CT sections.
The projection angle between the projection plane and the sagittal plane passing by the posterior edge of the mandibular ramus varies among individuals and depends on the shape of the dental arches and the orientation of the mandibular ramus. To evaluate the amount of variation in this projection angle, the inventor selected three reference points on each tomodensitometric section (
Two axes corresponded to these three points, the ramus axis (R, P) and the projection axis (P, D). These axes formed two respective angles with the sagittal plane passing by point R: the ramus angle and the projection angle, which inspired the design of the guiding device.
As shown in
As shown in
The results of the CT scans are presented in Table 1 below.
53°
22°
42°
62°
The projection angle varied from 53° to 62°, with an average of 56°. The ramus angle varied from 22° to 42°, with an average of 32°.
Taking into account the variability among individuals, the inventor of the instant application configured the device so that its guiding axis would project against the medial surface of the mandibular ramus no more than 14.0 mm anterior to the posterior edge of the mandibular ramus for all patients (that is, always behind the mandibular foramen).
It was possible to record the orientation of the projection axis in relation to point R chosen on one of the tomodensitometric sections on the guiding device, such that the point of projection indicated by the device would contact bone 14.0 mm anterior to the posterior edge of the mandibular ramus. Because the projection angle varies among individuals, it was necessary to verify whether the position of the projection point indicated by the device is compatible with analgesia by superimposing the device at points R and D of other tomodensitometric sections. For this reason, sections from patients presenting the most extreme projection angles were analyzed, that from patient 1 presented the most closed projection angle (
When the orientation of the projection axis in relation to point R in patient 23 was recorded, and this point and the axis were superimposed on points R and D, respectively, in patient 1, the projection point P′ indicated by the device was in bone contact 24.0 mm anterior to point R (
Conversely, when the orientation of the projection axis in relation to point R in patient 1 was recorded and this point and this axis were superimposed on points R and D, respectively, in patient 23, the projection point P″ indicated by the device was in bone contact 7.0 mm anterior to point R (
Thus, the position of point R in relation to the projection axis established for patient 1 was used to configure the device, such that the projection axis protruded onto the medial surface of the mandibular ramus for all patients, at a distance of 7.0-14.0 mm anterior to the posterior edge of the mandibular ramus.
CT scans with the projection angles are shown in
As shown in
As shown in
The causes of failure of anesthesia in current practice are varied. These causes may be due to a lack of knowledge of anatomical structures or to a lack of experience of the practitioner. One of the advantages of the device 10 of the invention described herein is to indicate the axis at which the needle must be applied to put its tip in contact with the bone above and posterior to the lingula. The device 10 applied against the occlusal surfaces of the maxillary teeth improves the practitioner's gestural precision by stabilizing the point of needle penetration. The device 10 of the invention can inject an analgesic solution above and behind the mandibular foramen in a reliable and reproducible manner.
It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications that are within the spirit and scope of the invention, as defined by the appended claims.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2015/000699 | 2/27/2015 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 61945499 | Feb 2014 | US |
