WO2025117859A1

WO2025117859A1 - Bone screw for dental applications

Info

Publication number: WO2025117859A1
Application number: PCT/US2024/057906
Authority: WO
Inventors: Eswar KANDASWAMY; Peter DUPREE; James Dupree
Original assignee: Louisiana State University
Current assignee: Louisiana State University
Priority date: 2023-11-28
Filing date: 2024-11-27
Publication date: 2025-06-05
Anticipated expiration: 2026-05-28

Abstract

A device is described herein comprising a dental screw configured for insertion into bone, wherein the dental screw comprises bioabsorbable material, wherein the dental screw comprises an annular head and a body, wherein the body terminates at a sharp distal point configured to pierce the bone, and wherein the bioabsorbable material comprises alloplast material.

Description

BONE SCREW FOR DENTAL APPLICATIONS

Inventor:

Eswar Kandaswamy, Peter Dupree, James Dupree

RELATED APPLICATION

This application claims the benefit of United States Patent Application No. 63/603,482, filed November 28, 2023.

TECHNICAL FIELD

Embodiments are described herein involving the development and clinical testing of a novel screw or fixation device that are made of fully resorbable material for dental bone surgery procedures related to dental implants.

INCORPORATION BY REFERENCE

Each patent, patent application, and/or publication mentioned in this specification is herein incorporated by reference in its entirety to the same extent as if each individual patent, patent application, and/or publication was specifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 shows a tack, under an embodiment.

Figure 2 shows a tack, under an embodiment.

Figure 3 show a screw, under an embodiment.

Figure 4 shows a mounted tack, under an embodiment.

Figure 5 shows a cross-sectional view of a tack (with dimensions in millimeters), under an embodiment.

Figure 6 shows a tack (with dimensions in millimeters), under an embodiment.

Figure 7 shows a cross-sectional view of a tack, under an embodiment.

Figure 8 shows a mounted tack, under an embodiment. Figure 9A and 9B shows a bone screw that can be used in maxillofacial surgery or orthopedics, under an embodiment.

Figure 10 shows a titanium screw, under an embodiment.

Figure 11 shows a titanium screw, under an embodiment.

Figure 12 shows a titanium screw, under an embodiment.

Figure 13 shows a titanium screw, under an embodiment.

Figure 14 shows delivery device for placing a dental screw in bone, under an embodiment.

Figure 15 shows delivery device (with exterior finish) for placing a dental screw in bone, under an embodiment.

Figure 16 shows a perspective view (with exterior finish) of a delivery device handle portion, under an embodiment.

Figure 17 shows a perspective view (with exterior finish) of a delivery device handle portion, under an embodiment.

Figure 18 shows a perspective view (with exterior finish) of a delivery device claw, under an embodiment.

Figure 19 shows a a perspective view (with exterior finish) of a delivery device claw, under an embodiment.

Figure 20 shows delivery device, under an embodiment.

Figure 21 shows a perspective view of a delivery device handle portion, under an embodiment.

Figure 22 shows a perspective view of a delivery device handle portion, under an embodiment.

Figure 23 shows a perspective view of a delivery device claw, under an embodiment.

Figure 24 shows a perspective view of a delivery device claw, under an embodiment.

DETAILED DESCRIPTION Bone screws are used in orthopedic procedures and dental surgeries to hold bone fragments, fractures, and bone grafts before or during dental implant installation in the proper location during healing. These screws are either left in the body (mostly in orthopedic applications) or removed after fixation. Bone screws are manufactured in various sizes, shapes, and designs to accommodate the increasing demand for dental reconstructive procedures (1, 2). By the type of material, the global market for bone screws is segmented into stainless steel, titanium, and bioabsorbable. Titanium is the most commonly used material and is forecast to continue to dominate the market for the next 5 to 7 years. Its excellent corrosion resistance properties, as well as its high strength-to- weight ratio have driven demand (2, 3, 4). The segment of the market for bioabsorbable screws is forecast to experience robust growth during the next 5 to 7 years. Polyglycolic acid, poly-L-lactic acid, and polylactic acid are the most commonly used bioabsorbable materials. The benefits of bioabsorbable materials include less interference with MRI scans, decreased graft laceration, and reduced need for implant removal; all of these features drive the demand for products made with these materials (2, 3, 5, 6). The development of innovative techniques and technical advancements create new opportunities in the global market for bone screws. The development of bio-composite materials and more affordable bone screw systems are of intense interest. Market trends forecast that an increasing number of plates, screws, pins, interface screws, and possibly joint replacements, will be made with bio-composite materials that will not be removed from the body after healing. This adds structure and stability to the repaired areas.

There is an important need for this innovation in dentistry as currently there are no fully resorbable screws made using bone like material available for use in mainstream dental practice for the current proposed application in dental bone regeneration. Currently, there are about 3 million dental implants placed in the US every year and in many instances there is a requirement for jaw bone augmentation prior to or during implant placement. During the bone augmentation procedures, stainless steel or titanium screws are used to fixate the materials that are used to regenerate the bone. Currently available fixation screws are used to fixate membranes or be used as a tenting screw scaffold to improve bone regeneration outcomes in patients who require a dental implant but do not have sufficient bone for it. Once the bone heals and the patient is ready to get an implant placed, the screws have to be retrieved (since they do not resorb) in a more invasive procedure for screw retrieval than what is needed to carry out the installation of the dental implant. Under an embodiment, options for a tack/screw for dental bone regeneration applications are made out of titanium, stainless, or Polyglycolic acid, poly-L-lactic acid, and polylactic acid and magnesium screws. Of the options only Polyglycolic acid, poly-L-lactic acid, and polylactic acid and magnesium screws are resorbable but due to the nature of the material, they have the potential to cause significant tissue reaction.

Currently, there does not exist any bio-resorbable bone type tack/screw for dental bone regeneration procedures. The orthopedic field has only recently started to introduce screws made out of allograft and xenograft but these screws are significantly larger and cannot be used for dental bone regeneration applications. There is a need for use of resorbable materials in these applications due to the fact that the material need not be retrieved and can be left in place to resorb and fully incorporate into the bone over time.

The novel screw or fixation device (called bone screw) is made of xenograft, allograft, or alloplastic bone replacement grafts. The creation of a screw out of the same bone materials (xenograft, allograft, or alloplast) similar to what is currently used for bone augmentation procedures eliminates the need for an additional retrieval step. The bone replacement material can be made in the form of a screw or in the shape of a pyramid with a sharp end that allows for piercing and fixation of the membrane or be used as a tenting screw. The screw can be self tapping or the host bone is prepared using a drill that creates a channel that is the same shape as the bone screw” and it can then be tapped or screwed into place. Milling machines may mill a screw shaped device out of the currently available bone replacement materials. The milling is performed with a design and out of target materials that can withstand the torque and force generated during installation of the screws in human bone.

Under an embodiment, the screws are created from materials including allograft cortical bone blocks, xenograft cortical bone blocks, and hydroxyapatite or resorbable ceramic blocks. These blocks are milled to the shape of a screw (or pyramid shape or others, as discussed above). Alternative embodiments cast these materials into differing desired shapes.

Under an embodiment, optionally a drill tap creates a channel in the bone to accept the bone screw. A kit may comprise a drill/tap and screw (and also, a holder for the delivery of the screw into the bone and a mallet for tapping the screw in place (if needed)). Once the prototype screw and drills are ready, strength and performance of the screws are tested relative to the performance of available titanium screws, the gold standard. Under an embodiment, testing is performed on saw-dust mandibles compared to currently available gold standard tacks and screws made out of titanium. The saw dust mandibles are commonly used for simulation exercises for dental implants and bone grafting in the dental field as they closely mimic the structure of real human bone. Once we evaluate the performance of our invention in this model, further testing is performed on cadavers or pig jaws to measure the time taken as well as the tapping ability of the prototype screw on the jaw bone.

Under an embodiment, in-vitro testing on hydroxyapatite cylinders is performed to determine if strength parameters are sufficient for screw/tack milling. 3D drawings of a tack and screw for milling/ 3D printing applications are generated. For testing purposes, one may manually mill and machine the tack out of hydroxyapatite blocks.

Under an embodiment, max load and max compressible stress of hydroxyapatite tacks versus standard titanium tacks are tested on human mandibular bone. See results below:

Under an embodiment, max load and max compressible stress of hydroxyapatite tacks versus standard titanium tacks are tested on saw dust mandible. (Note that Saw dust mandible is considered to be comparable to jaw bone). See results below:

Under an embodiment, max load and max compressible stress of hydroxyapatite tacks versus standard titanium tacks are tested on bovine rib bone. See results below:

Test results above correspond to testing performed on Figures 1, 4, 5, 6, 7, and 8, under an embodiment.

Tack compressive stress without bone Max load N

Maximum compressive stress (Mpa)

HA disc

350 120

Titanium tack 34.52 48

Test results in the table directly above correspond to test preformed on HA and Titanium raw material discs. Under an embodiment, tack compressive stress without bone is tested. This test just compresses the screw until breakage or until the screw deforms or the test is stopped. It has two plates, and one plate pushes the screw towards the other and measures the forces. Such test was performed on twelve HA and twelve titanium screws. Results are set forth in table below. HA COMPRESSIVE

TITANIUM COMPRESSIVE

A resorbable tack made of allograft or alloplastic material is generated for dental applications. Under an embodiment, pre-made hydroxyapatite blocks and cylinders are procured. Strength testing is performed on the pre-made hydroxyapatite cylinders as a starting point for manual machining. Strength testing parameters were comparable to previously published literature on similar materials.

A 3-D printing method and protocol is developed to fabricate these screws. Following that, rapid prototyping is available using either 3D printing applications or machining applications. Under an embodiment, the tacks are manually machined for testing purposes. Under an embodiment, the manually machined tacks are tested for strength parameters on dental bone models, bovine rib bone and human fresh cadaver mandibular samples with titanium tacks which are considered the gold standard. The results of the test are set forth above. To summarize the results, the manually milled hydroxyapatite tacks performed similarly in all three tests (force, compressive strength parameters) to the gold standard titanium tacks. Maximum load is the maximum force that the screw withstands during the test (this depending on the screw type and can either be in the middle or end of the test in case of screw deformation or breakage). The maximum compressive strength is the same parameter but it measures it in Mega pascal relative to the area of the screw. These parameters are important as the screw needs to be able to withstand the force without breakage or deformation when being driven into the bone. This is especially relevant if the screw is used without prior tapping (which in some cases is possible when the bone density is not too hard). All these strength tests were conducted without a drill tap prior to the screw test. Tf a drill tap is used, it is anticipated that the force required to drive the screw is a lot less.

Additionally, no pre-mature failures of the hydroxyapatite tacks are noted during the testing. The sharpness of the hydroxyapatite tacks were tested for the piercing ability of membranes, and it was able to pierce a membrane without difficulty.

Figure 1 shows an unmounted tack, under an embodiment.

Figure 2 shows an unmounted tack, under an embodiment.

Figure 3 show a screw, under an embodiment.

Figure 4 shows a mounted tack, under an embodiment.

Figure 6 shows a tack (with dimensions in millimeters), under an embodiment.

Figure 7 shows a cross-sectional view of a tack, under an embodiment.

Figure 8 shows a mounted tack, under an embodiment.

Under an embodiment, the milled (or 3D printed) tacks are approximately (with a 0.5mm dimensional tolerance) 3mm diameter at the head, 1 mm diameter of the body and 2-3 mm in length of the tack portion. These dimensions are roughly based on pre-existing screws made out of titanium.

Figure 9A and 9B show a bone screw that can be used in maxillofacial surgery or orthopedics, under an embodiment.

Figure 10 shows a titanium screw, under an embodiment. Figure 11 shows a titanium screw, under an embodiment.

Figure 12 shows a titanium screw, under an embodiment.

Figure 13 shows a titanium screw, under an embodiment.

Note that all screws shown in figures are HA bone screws except that figures 10- 13 show a titanium screw.

Figure 14 shows device 1400 for placing a dental screw in bone, under an embodiment. The device includes a handle portion 1410 comprising a proximal grip 1412 and trigger component 1414. The trigger component is rotatably coupled to a securing pin 1416 laterally disposed through a body 1418 of the device 1400. An upper end of the trigger component 1414 (housed within the body 1418) is attached to a drive component 1420 which threadably engages a drive screw 1422. The drive screw is attached to a connecting rod (not shown) which extends through a barrel portion 1430 and is itself attached to or integrally formed with a claw 1440.

As the trigger components move in a proximal direction towards the handle, the drive component moves in a distal direction. The drive screw is configured such that distal movement of the drive component retracts the drive screw which then retracts the connecting rod and claw. (The drive screw may be configured to provide motion in the opposite direction). Note that the claw features a point of attachment 1442 for securing a bone screw in place. Bone is placed between an attached bone screw and an oppositely disposed base 1444. Retraction of the claw as described above generates force to insert the screw into bone.

Figure 18 shows a perspective view (with exterior finish) of a delivery device claw, under an embodiment. Figure 19 shows a a perspective view (with exterior finish) of a delivery device claw, under an embodiment.

Figure 20 shows delivery device, under an embodiment.

REFERENCES

1. Bone Screw System Market Size, Industry Analysis Report, Regional Outlook (U.S., Canada, Germany, UK, France, Spain, Italy, Russia, Japan, China, India, Australia, Brazil, Mexico, Argentina, South Africa, Saudi Arabia, UAE), Application Potential, Price Trends, Competitive Market Share & Forecast, 2022 - 2028, Global Market Insights, 2022.

2. Global Bone Screw System Market by Type (Stainless-steel, Titanium, Bioabsorbable), By Application (Hospital, Ambulatory Surgical Centre, Clinic) And By Region (North America, Latin America, Europe, Asia Pacific and Middle East & Africa), Forecast From 2022 To 2030, Data Intelo, 2021.

3. Bone Screw System Market Snapshot, Future Market Insights, July 2022.

4. Global Bone Screw System Market Size By Type (Conventional Screws, Locking Screws, Headless Screws), By Application (Cortical, Cancellous, Malleolus), By Geographic Scope And Forecast, Verified Market Research, August 2022.

5. Bone Screw System Market: Industry Analysis and Forecast (2021-2027) by Type and Application, Maximize Market Research, 2021.

6. Bone Screw System Market Overview, Industry ARC, 2022. 7. Global Bone Screw System Market Insights and Forecast to 2028, Market Reports World, January 27, 2022.

8. Global Bone Screw System Market Growth, Share, Size, Trends and Forecast (2022-2028), Research Analysis Insights, October 2022.

Claims

CLAIMS What is claimed is

1. A device comprising, a dental screw configured for insertion into bone, wherein the dental screw comprises bioabsorbable material, wherein the dental screw comprises an annular head and a body, wherein the body terminates at a sharp distal point configured to pierce the bone, wherein the bioabsorbable material comprises alloplast material.

1 a. The device of claim 1 , wherein the alloplast comprises hydroxyapatite. lb. The device of claim la, wherein the body comprises a variable diameter. lc. The device of claim lb, wherein a first portion of the body comprises approximately 1.9 millimeters. ld. The device of claim lb, wherein a second portion of the body tapers to the sharp point. le. The device of claim Id. wherein a length of the tapered surface comprises approximately 1.92 millimeters. lf. The device of claim la, wherein a diameter of the annular head comprises approximately 2.49 millimeters. lg. The device of claim la, wherein a height of the annular head comprises approximately .6 millimeters.

2. A device comprising, a dental screw configured for insertion into bone, wherein the dental screw comprises bioabsorbable material, wherein the dental screw comprises an annular head and a body, wherein the body terminates at a sharp distal point configured to pierce the bone, wherein the bioabsorbable material comprises at least one of xenograft, allograft, and alloplastic material.

3. A delivery device for insertion of a dental screw into bone, the delivery device comprising, a proximal handle, a drive mechanism, and a securing claw; the drive mechanism comprising a securing pin, a drive component, and a drive screw, wherein the drive screw is attached to a drive rod which translates motion of the drive screw into motion of the securing claw; the proximal handle portion comprising a trigger component rotatably attached to the securing pin, wherein the drive component is threadably engaged with the drive screw, wherein proximal movement of the trigger component moves the drive component in a distal direction, wherein the threadable engagement translates the distal motion of the drive component into retraction motion of the drive screw, the drive rod, and the securing claw.