The present invention relates to the field of oral surgery tools. More particularly, the invention relates to oral surgery tools needed for performing a closed sinus lift procedure and a method therefor.

Background of the Invention

A sinus lift procedure needs to be performed prior to implantation within an excessively thin upper jaw bone, generally thinner than 8 mm, in the vicinity of the premolar and molar teeth which border the maxillary sinus cavities. During the sinus lift procedure, a sufficient amount of bone is grafted to the upper jaw bone to be able to anchor a dental implant.

One known method, often referred to as an "open sinus lift procedure" is performed from inside the intraoral cavity. A lateral incision is made into the gum and gum tissue is pulled back, and an opening is cut in the exposed lateral bony wall of the sinus cavity. A membrane covering the sinus cavity, often referred to as the Schneiderian membrane (hereinafter "sinus membrane" or "membrane"), is carefully repositioned, and bone graft material is placed into the newly created space. In this procedure, however, the sinus membrane is susceptible to being detached, torn or punctured. In another method, an implant hole is drilled within the jawbone, while being spaced approximately 1 mm below the sinus, and then an osteotome is used for tapping the remaining shell of bone with a mallet or small hammer towards the sinus cavity, causing bone tissue to be compacted for receiving the dental implant. The tapped shell displaces the membrane into the sinus cavity, making room for the grafted material which is then inserted via the implant hole. The implant is then introduced into the inserted grafted material, allowing the latter to become osseointegrated while the implant becomes anchored. The amount of bone augmentation achieved with the osteotome technique is usually less than what can be achieved with the first technique. Also, the osteotome technique is traumatic, and may cause the jawbone to become fragmented if a force is not properly applied to the osteotome, and the osteotome may even penetrate the sinus cavity if an excessive force is applied.

Recently another prior art method has been adopted whereby sinus lifting is performed hydraulically. For example disclosed in "Sinus Lift Drill" [www.ssimplant.com], the sinus lift drill (SLD) procedure includes nine basic steps^ (l) high speed drilling, (2) low speed drilling with a reamer until reaching the maxillary sinus floor to form a protrusion in the cortical bone of the maxillary sinus floor, (3) removal of the protrusion using another drill, (4) penetrating the sinus floor with a retractable safety rod to smoothly contact the sinus membrane, (5) infusing saline solution to elevate the sinus membrane, (6) extending the hole in the sinus floor by an additional drilling step, (7) infusing grafting materials by a syringe, (8) final drilling step and rinsing hole, and (9 ) anchoring implant.

The membrane is liable to be damaged in any of the various drilling steps if an excessive amount of force is applied, necessitating the membrane to be repaired and the bone augmentation procedure to be delayed, and often leading to infections. The duration of this procedure is relatively long, often taking as much as 25 minutes or more, due to the large number of steps involved, increasing the risk of infection.

It is an object of the present invention to provide a closed sinus lift procedure which is considerably quicker than a prior art procedure and is less risky to the sinus membrane.

It is an object of the present invention to provide apparatus for facilitating a speedy closed sinus lift procedure.

Other objects and advantages of the invention will become apparent as the description proceeds.

Summary of the Invention

The present invention provides a kit of surgical tools for performing a closed sinus lift procedure, comprising a multi-stepped drill for selectively drilling the maxilla to a desired depth, a shaping cutter for manually shaping a bore formed by said drill, a finger manipulatable bone condensing unit with a rounded distal tip for penetrating a bone surface adjoining a sinus membrane, and an injection tube adaptor with a rounded distal tip for positioning within said bore upon removal of said bone condensing unit, bone graft material being injectable through an injection tube coupled to said adaptor and dischargeable into a volume between the maxilla and the sinus membrane for purposes of bone augmentation.

A "closed sinus lift procedure" is one that does not involve incising the gum or the sinus cavity wall.

The present invention is also directed to a conical cutter for use in performing a sinus lift procedure, comprising a proximal finger manipulatable holder, a shank extending distally from said holder, and a conical cutting section protruding distally from said shank, wherein said cutting section is configured to facilitate a manual cutting operation within cancellous bone of the maxilla which sufficiently shapes a previously drilled bore to ensure a subsequent bone condensing operation with a sinus lifting osteotome.

The present invention is also directed to a method for performing a sinus lift procedure, comprising the steps of drilling the maxilla to a desired depth, manually shaping a bore formed by said drill, inserting a bone condensing unit within said bore and finger manipulating the same until its rounded distal tip penetrates a bone surface adjoining a sinus membrane, removing said bone condensing unit from said bore, positioning an injection tube adaptor with a rounded distal tip within said bore, and injecting bone graft material through an injection tube coupled to said adaptor and to a syringe in order to be discharged into a volume between the maxilla and the sinus membrane for purposes of bone augmentation.

Brief Description of the Drawings

In the drawings :

Fig. 1 is a schematic illustration of a drilling operation in the maxilla performed by a multi-stepped surface cutter;

Fig. 2 is a schematic illustration of a bore shaping operation performed by a manual conical cutter in the maxilla!

Fig. 3 is a schematic illustration of the conical cutter of Fig. 2 after being removed from the bore, showing bone chips from the maxilla that have been collected on its blades;

Fig. 4 is a schematic illustration of a bone compaction operation performed by a bone condensing unit inserted within the bore, following removal of the conical cutter of Fig. 3 therefrom;

Fig. 5 is a schematic illustration of a saline solution injection operation into the volume between the sinus membrane and the maxilla following removal of the bone condensing unit of Fig. 4 therefrom, for investigating membrane integrity;

Fig. 6 is a schematic illustration of a bone grafting material injection operation into the volume between the sinus membrane and the maxilla following drainage of the saline solution of Fig. 5 therefrom;

Fig. 7 is a schematic illustration of the introduction of the autologous bone chips of Fig. 3 into the bore, following the injection operation of Fig. 6;

■ Fig. 8 is a schematic illustration of an implantation operation during which an implant is introduced into the maxilla and the injected bone grafting material of Fig. 6;

- Fig. 9 is a perspective view of a multi-stepped surface cutter;

- Fig. 10 is a perspective view of a conical cutter;

- Fig. 11 is a front view of a bone condensing unit;

- Fig. 12 is a perspective view of an osteotome used in conjunction with the bone condensing unit of Fig. 11;

- Fig. 13 is a perspective view of a stopper used in conjunction with the bone condensing unit of Fig. 11; and

- Fig. 14 is a perspective view of an injection tube adaptor. Detailed Description of Preferred Embodiments

The present invention is a novel sinus lift apparatus and method for manually enlarging the hole drilled in the upper jawbone and achieving speedy bone compaction while preventing injury to the sinus membrane. Reference is first made to Figs. 1-8, which broadly illustrate a sinus augmentation method, according to one embodiment of the present invention.

As shown in Fig. 1, a multi-stepped surface cutter 10 operated at a speed of 500- 800 rpm is first used to drill a hole by a motorized drilling machine 5 in the maxilla 7 prior to a sinus augmentation procedure and the subsequent dental implant procedure. Cutter 10 penetrates the cortical bone of the alveolar crest and then cancellous bone within the maxilla. Rather than having to employ various drill bits and accessories including the replacement of different stoppers to achieve the drilling of a specific bone thickness, as practiced in the prior art, the surface cutter is configured with a plurality of steps to allow the dental practitioner to receive tactile feedback, often in the form of a temporary increase in bone resistance when a predetermined bone thickness less than the thickness of the maxilla and corresponding to a specific step thickness has been drilled.

After the surface cutter has been removed, a manual conical cutter 15 is inserted within the bore formed by the surface cutter, as shown in Fig. 2, to enlarge and shape the drilled bore, in preparation for the subsequent bone compaction and to enhance primary implant stability. Conical cutter 15 is manually rotatable at a rate of approximately 10 rpm, at a sufficiently slow speed that prevents excessive bone heating which is able to lead to thermal bone necrosis. When conical cutter 15 is removed from the bore, bone chips 16 from the maxilla 7 are collected on its blades, as shown in Fig. 3, to be used for an autologous bone graft.

Bone condensing unit 25 is inserted in the conically shaped bore and is finger manipulated, while being forcefully and controllably displaced, such as in a rotational direction, in order to further enlarge the bore, allowing its distal tip 21 to completely penetrate the maxilla 7 and to smoothly contact and slightly elevate the sinus membrane 8, as shown in Fig. 4. Stress lines 24 that distally and laterally induce bone compaction are schematically illustrated.

If the physician has difficulty in penetrating the maxilla, a bone condensing unit 25 with a longer handle may be first used. For example, tip 21 of the first unit 25 may have a diameter of 2.5 cm, and then tip 21 of a second unit 25 having a diameter of 3.44 cm and a shorter handle may then be used.

In Fig. 5, adaptor 38 of injection tube 30 connected to syringe 35 replaces the osteotome. A dose of 1-1.5 cc of saline solution 36 is injected by syringe 35 into the volume between membrane 8 and maxilla 7, to atraumatically elevate the membrane and to determine whether the latter is intact and not injured or pierced.

After the saline solution is drained, bone graft material 39 in the form of a gel is injected by syringe 35 into the volume between membrane 8 and maxilla 7, as shown in Fig. 6. After injection tube 30 is removed, bone graft material 39 is retained within said volume as a result of the viscosity of the gel and unobstructed bore 33 appears within maxilla 7, as shown in Fig. 7. Bone chips 16 previously collected by the conical cutter are introduced into bore 33, and serve as a type of catalyst for reducing the time of osseointegration of the injected bone graft material 39.

Implant 40, e.g. having a base with a diameter of 4.2 mm, is then implanted within maxilla 7 and the newly introduced bone graft material 39, as shown in Fig. 8, to produce stress lines 41 which further induce bone compaction. Implant 40 is quickly implanted after being removed from its packaging material to avoid oxidation of its titanium body. The distal end 44 of implant 40 is rounded, as an additional feature for avoiding any injury to membrane 8.

By virtue of the aforementioned method, the implant many be implanted in a short time of approximately 5 minutes after starting to drill the maxilla, considerably shorter than the 25 minute period of the prior art SLD method.

Multi-stepped surface cutter 10 is illustrated in more detail in Fig. 9. Surface cutter 10 has a cylindrical shank 3, from which distally protrudes a first cylindrical extension 4. A second cylindrical extension 9 distally protrudes from first extension 4, and includes head 11 that slopes distally to cutting edge 13. Cutter 10 also has a fitting 2 separated distally from shank 3, to assist in releasably coupling the cutter to the drill.

The first extension 4 has a smaller diameter than shank 3, to produce an annular shoulder 17 therebetween for indicating to the dental practitioner that a predetermined depth within the maxilla has been drilled. Likewise the second extension 9 has a smaller diameter than the first extension 4, to produce an annular shoulder 18 therebetween. For example, extension 9 has a length of 3 mm and a diameter of 1.90 mm, extension 4 has a length of 2 mm and a diameter of 2.50 mm, and shank 3 has a diameter of 3.10 mm.

Conical cutter 15 illustrated in Fig. 10 has a circular, proximal holder 46 to be finger manipulated by the practitioner. A cylindrical shank 47 extends distally from holder 46, and a conical cutting section 50 protrudes distally from shank 47.

Cutting section 50 comprises a central rod 52 coaxial with shank 47 and holder 46, and three, or any other desired number, of equally circumferentially spaced blades 54 that extend radially from rod 52. Each blade 54 is thin and subtends a discrete circumferential angle ranging from 7- 10 degrees, e.g. 8 degrees, to define a volume between adjacent blades for collecting bone chips that have been removed from the maxilla. A blade 54 is configured with a proximal, triangularly shaped cutting portion 55 which is slightly spaced from shank 47 and whose pointed edge 57 extends radially outwardly, and with a distal tapered portion 56 whose radial dimension is significantly less than that of portion 55 and which extends to the tip of rod 52. Blade 54 has two opposed planar lateral surfaces 61, each of which is coincident with both portions 55 and 56, to define a corresponding cutting edge 65 with the interface with portion 55 and a cutting edge 66 with the interface with portion 56. Thus each blade 54 has five cutting edges: pointed edge 57 at the center of portion 55, two edges 65 at each lateral end of portion 55, and two edges 66 at each lateral end of portion 56.

The configuration of cutting section 50 is designed to facihtate a manual cutting operation within relatively soft cancellous bone of the maxilla, and at times even within the relatively high rigidity cortical bone of the sinus floor which is adjacent to the sinus membrane. Edges 65 serve to shape the bore to a conical form, and edges 57 and 66 serve to increase the diameter of the bore. The tip of rod 52, which is slightly rounded to prevent inadvertent damage to the sinus membrane or to the surrounding maxilla structure, is first inserted into the bore formed by the surface cutter. While the conical cutter 15 is rotated by holder 46, edges 65 both widen and shape the bore.

For example, when the surface cutter produced a bore having a depth of 3 mm and a diameter of 1.90 mm, due to the excessively thin maxilla of the subject who requires a sinus lift procedure, only tapered portion 56 which is dimensioned with a length of 5.30 mm and a maximum diameter of 2.44 mm is used to widen and shape the bore. Tapered portion 56 is able to be seated within the bore, to assist the practitioner while manually manipulating the conical cutter 15.

When the maxilla is thicker, the practitioner is able to rely on proximal portion 55 to provide a tactile indication of the increased depth and width of the conically formed bore. For example, when the surface cutter produced a bore having a depth of 5 mm and a diameter of 2.50 mm, proximal portion 55 is used to increase the depth of the bore to 7.80 mm and its diameter to 3.40 mm. The practitioner is able to reliably limit the cutting depth of the conical cutter so as to be spaced from the sinus membrane.

Fig. 11 illustrates finger manipulatable, bone condensing unit 25, which comprises osteotome 20 and displaceable stopper 70.

Osteotome 20, as also shown in Fig. 12, has a circular, proximal holder 22, and a cylindrical shank 23 coaxial with holder 22 which terminates with a rounded tip 21 for smooth contact with the sinus membrane. Shank 23 is formed with threading 27 at the proximal end thereof.

Cooperating with osteotome 20 is stopper 70, which is also illustrated in Fig. 13. Annular stopper 70 has a proximal flange 72 and a tube 75 distally extending from the proximal face 73 of flange 72. The inner diameter of flange 72 and tube 75 is greater than the outer diameter of osteotome shank 23, allowing stopper 70 to be fitted over shank 23. The inner surface 77 of tube 75 is formed with threading which is engageable with threading 27 of osteotome shank 23, allowing stopper 70 to be selectively displaced along osteotome shank 23 upon manipulation of flange 72, in order to define a desired length of shank 23 to be exposed to the surrounding maxilla.

Indicia 29 may be applied, such as by engraving, to osteotome shank 23, for assisting the practitioner in accurately selecting the desired exposed shank length. Indicia 29, which are applied to shank 23 between threading 27 and distal tip 21, may be in the form of a plurality of distally separated circular graduations or markings, e.g. separated by increments of 1 mm. The proximal end of tube may be aligned with one of the indicia 29.

While the length of prior art osteotomes is relatively large, on the order of 25 cm with a holder diameter on the order of 10 cm in order to withstand the relatively high tapping forces applied by a mallet needed to cause displacement of the sinus membrane, the osteotome of the present invention is considerably smaller, for example having a finger manipulatable length of 26 mm and a holder diameter of 10 mm. Since only finger applied forces are transmitted to osteotome 20, rather than elbow bending and mallet initiated high magnitude forces as practiced in the prior art which can lead to injurious and infection causing sinus penetration, the practitioner can carefully control movement of the osteotome. That is, the diameter of shank 23, e.g. 3.44 mm, is greater than the diameter of the bore formed by the proximal portion of the conical cutter. Thus distal displacement of bone condensing unit 25 will widen the bore and induce lateral bone compaction to a greater degree, as illustrated by stress lines 24 of Fig. 4. During additional finger manipulation, bone condensing unit 25 is distally displaced and the finger applied force is sufficient to penetrate the remaining shell of the sinus floor. Injury to the sinus membrane is prevented by virtue of the rounded tip 21, which is adapted to softy contact the membrane.

Fig. 14 illustrates injection tube adaptor 38 through which the bone graft material is discharged into the volume between the sinus membrane and maxilla. Injection tube 30 shown in Fig. 5 is coupled to proximal nipple 31 of adaptor 38. An intermediate tube 32 extends from nipple 31 to cylindrical holder 34, from which distally extends an annular discharge tube 37 of varying diameter to assist in discharge of the bone graft material. Adaptor 38 is also formed with an annular and rounded distal tip 43 having a smaller diameter than discharge tube 37. Distal tip 43 is shaped similarly to distal tip 21 of bone condensing unit 25, to avoid injury to the sinus membrane while positioning the distal tip.

While some embodiments of the invention have been described by way of illustration, it will be apparent that the invention can be carried out with many modifications, variations and adaptations, and with the use of numerous equivalents or alternative solutions that are within the scope of persons skilled in the art, without exceeding the scope of the claims.