Abstract
A multi-unit abutment aligning a dental implant and a screw-attached prosthesis with copings is disclosed. The multi-unit abutment has a threaded base post for attachment to the implant and a ball portion. A swivel shell surrounds the ball and may be fixed in position with a lock screw. A drive feature on the ball allows a tool passing through the lock screw to drive the base post into the implant with the multi-unit assembly in a linear configuration. The swivel shell is then positioned and fixed at a desired tilt and azimuthal angle. The swivel shell has a mating surface for a coping. The lock screw remains accessible through an aperture in the coping when the prosthesis is positioned on the implant abutments. Different embodiments are disclosed for capturing the swivel shell on the ball. Methods for improving passive alignment of the prosthesis to the implants are described.
Claims
1. A system for alignment and attachment of a dental prosthesis to an implant with a prosthetic screw, wherein the prosthetic screw comprises a head and a threaded shaft, the system comprising: an abutment base having a longitudinal axis, the abutment base comprising a proximal end comprising a ball portion and an abutment base drive interface; and a distal end comprising screw threads for attachment to the implant; and a swivel shell having an inner surface and an outer surface, wherein the swivel shell includes a swivel aperture proximate the distal end and a threaded aperture at the proximal end; and a lock screw having a longitudinal axis, wherein the lock screw comprises a portion with external threads compatible with the threaded aperture of the swivel shell; and a portion with internal threads sized to engage the prosthetic screw shaft; and a lock screw drive interface; and wherein rotating the lock screw is capable of fixing the orientation of the longitudinal axis of the lock screw in an orientation that is not parallel to the longitudinal axis of the abutment base.
2. The system of claim 1 wherein the ball portion of the abutment base is compressed between a portion of the inner surface of the swivel shell and the lock screw.
3. The system of claim 1 wherein the swivel shell comprises a swivel base and a swivel mount that are mechanically assembled to capture the ball portion of the abutment base.
4. The system of claim 1 further comprising a Ti base wherein the Ti base has an aperture on the proximal end that is larger than the prosthetic screw threaded shaft and smaller than the prosthetic screw head and a distal end that is shaped to be supported by the swivel shell in a known orientation.
5. The system of claim 1 wherein the abutment base drive interface is a socket for receiving an abutment base drive tool and wherein the abutment base drive tool has a longitudinal axis and an abutment base drive tip shaped to engage the abutment base drive interface.
6. The system of claim 1 wherein the lock screw drive interface is a through socket for receiving a lock screw drive tool, and wherein the lock screw drive tool has a longitudinal axis and a maximum width that is less than the maximum width of the threaded shaft of the prosthetic screw.
7. The system of claim 6 wherein the lock screw drive tool is sized to pass through the aperture of the Ti base without interference.
8. The system of claim 6 wherein the abutment drive tool tip is sized to pass through the lock screw.
9. The system of claim 8 wherein the abutment drive tool tip is designed to tighten the abutment base into the implant to a first torque without simultaneously tightening the lock screw to fix the orientation of the swivel shell.
10. The system of claim 7 wherein the orientation of the swivel shell is selected by tilting the lock screw drive tool away from the linear axis of the abutment base and tightening the lock screw to a second torque.
11. The system of claim 10 wherein the abutment drive tool tip is used to tighten the lock screw.
12. A method for aligning and attaching a dental prosthesis to an implant with a prosthetic screw using the system of claim 1, the method comprising: attaching the lock screw to the swivel shell around the abutment base with the ball portion loosely constrained inside the swivel shell with the abutment base screw threads extending through the swivel aperture to form a multi-unit abutment assembly; inserting the abutment drive tool tip through the lock screw to engage the abutment base drive interface; presenting the abutment base drive tool and multi-unit abutment assembly to the implant; rotating the abutment base drive tool to attach the abutment base to the implant to a first torque; disengaging the abutment base drive tool from the abutment base drive interface; moving the swivel shell to a different orientation; rotating the lock screw drive tool to fix the orientation of the swivel shell axis relative to the implant axis to a second torque; presenting a prosthesis comprising a Ti base to the implant abutment system; and attaching the prosthesis to the implant abutment with a prosthetic screw.
13. The method of claim 12 further comprising applying force to the prosthesis to move the swivel shell into alignment with the Ti base.
14. The method of claim 12 wherein the Ti base is incorporated into the prosthesis using a lift off process with a temporary fastener, the temporary fastener comprising: a post having an axis, a first post end and second post end, wherein the first post end is threaded for screw attachment to the lock screw; and a cap, wherein the cap is attached to the second post end; and wherein the temporary alignment fastener is configured to hold the Ti base against the swivel shell by applying a rotary force to the cap to screw the first post end into the lock screw and wherein the cap is separable from the post through a release force directed away from the first post end.
15. A system for alignment and attachment of a dental prosthesis to an implant using a multi-unit implant abutment, the multi-unit implant abutment comprising: a ball and shell assembly comprising: a base comprising an abutment drive interface for screw attachment to the implant; the base comprising a first end having a ball and a second end with a threaded post with a longitudinal axis; and wherein the threaded post is designed to screw into a dental implant to a predetermined torque; a shell portion having an interior surface and an exterior surface; wherein the shell portion has a first end with an aperture and a second end has a lock screw; and wherein the ball is captured inside the shell portion with the threaded portion of the base post extending through the aperture; a Ti base, the Ti base comprising an aperture on the proximal end and an interface on the distal end designed to mount on the exterior of the shell portion in a known position; and one or more drive tools designed to engage the abutment drive interface and the lock screw; wherein at least one drive tool is capable of being inserted through the Ti base aperture to engage the lock screw; and wherein tightening the lock screw applies pressure on the ball to fix the orientation of the shell.
16. A system for alignment and attachment of a dental prosthesis to an implant using a multi-unit implant abutment of claim 15 wherein the Ti base is incorporated into a prosthesis and wherein a force is applied to the prosthesis to align the multi-unit abutment with the Ti base when the lock screw is tightened.
17. The system for alignment and attachment of a dental prosthesis to an implant using a multi-unit implant abutment of claim 15 further comprising a prosthetic screw, wherein the prosthetic screw comprises: a head portion with a width larger than the Ti base aperture; and a threaded shaft portion with a width smaller than the Ti base aperture; and wherein the lock screw includes threads for receiving the threads of the prosthetic screw.
18. The system for alignment and attachment of a dental prosthesis to an implant using a multi-unit implant abutment of claim 17 wherein the lock screw comprises a longitudinal aperture that comprises internal threads for engaging the prosthetic screw shaft; and a drive interface for receiving a tool for tightening the lock screw.
19. The system for alignment and attachment of a dental prosthesis to an implant using a multi-unit implant abutment of claim 15 wherein the base is comprised of two components, and wherein the two pieces are joined with the shell aperture captured between the two components.
20. The system for alignment and attachment of a dental prosthesis to an implant using a multi-unit implant abutment of claim 15 wherein the lock screw has a longitudinal aperture and wherein the aperture is sized to allow the abutment drive tool to extend through the lock screw.
Description
BRIEF DESCRIPTION OF THE FIGURES
[0044] FIG. 1 is a bottom exploded isometric view of a first embodiment of an omnidirectional multi-unit abutment assembly with Ti base and prosthetic screw.
[0045] FIG. 2 is a top exploded isometric view of a first embodiment of an omnidirectional multi-unit abutment assembly with Ti base and prosthetic screw.
[0046] FIG. 3 is a side plan view of the assembled system of FIGS. 1 and 2 without the prosthetic screw with longitudinal axes of components aligned.
[0047] FIG. 4 is a side cross-sectional view of the assembled system of FIG. 3 taken through the longitudinal axis.
[0048] FIG. 5 is a side plan view of the assembly of FIG. 4 after reorienting the swivel shell and Ti base.
[0049] FIG. 6 is a top isometric assembled view of the omnidirectional multi-unit abutment of FIGS. 1 and 2.
[0050] FIG. 7 is a side cross-sectional view of the assembly of FIGS. 3 and 4 during the attachment to the implant. Inset FIG. 7A includes a relative scaling of the implant drive tool.
[0051] FIG. 8 is a side cross-sectional view of the assembly of FIGS. 3 and 4 after reorienting the swivel shell and Ti base as in FIG. 5 showing the fixing of the orientation with the lock screw. Inset FIG. 8A includes a relative scaling of the lock screw drive tool.
[0052] FIG. 9 is a side cross-sectional view of the assembly of FIG. 8 after fixing the Ti base with the prosthetic screw.
[0053] FIG. 10 is a bottom assembled isometric view of a second embodiment of an omnidirectional multi-unit abutment and Ti base in a linear configuration.
[0054] FIG. 11 is a side plan view of the embodiment of FIG. 10.
[0055] FIG. 12 is a cross-sectional view of the embodiment of FIG. 11 along the longitudinal axis.
[0056] FIG. 13 is a cross-sectional view of the embodiment of FIG. 11 after the prosthetic screw is added.
[0057] FIG. 14 is a top exploded isometric view of a third embodiment of an omni-directional multi-unit abutment with Ti base and prosthetic screw.
[0058] FIG. 15 is a top isometric view of the embodiment of FIG. 14 in a linear assembled configuration.
[0059] FIG. 16 is a cross-sectional view of the embodiment of FIG. 14 along the longitudinal axis.
[0060] FIG. 17 is a top schematic plan view of a lock screw for the embodiment of FIG. 14 with a hexalobular internal (Torx) drive feature.
[0061] FIG. 18 is a top schematic plan view of the lock screw for the embodiment of FIG. 14 with a four-lobe internal drive feature.
[0062] FIG. 19 is a top exploded isometric view of a four-lobe driver tip with lock screw and abutment base for the embodiment of FIG. 14.
[0063] FIG. 20 is an exploded top isometric view of a two-part abutment base stem with sleeve and swivel mount for a fourth embodiment of an omni-directional abutment.
[0064] FIG. 21 is a top isometric view of the assembled two-part abutment base stem with sleeve and swivel mount of FIG. 20.
[0065] FIG. 22 is a cross-sectional view of the assembled two-part abutment base stem with sleeve and swivel mount of FIG. 21 along the longitudinal axis.
[0066] FIG. 23 is a cross-sectional view of the application environment of a representative embodiment of an omnidirectional multi-unit abutment including prosthesis and implant.
DETAILED DESCRIPTION OF THE INVENTION
[0067] There are multiple embodiments included in this disclosure to illustrate options for providing the benefits of a screw-attached omni-directional multi-unit abutment. FIG. 1 and FIG. 2 illustrate an exploded view of one embodiment of an omnidirectional multi-unit abutment 100 comprising four parts: an abutment base 1, swivel mount 2, swivel base 3, and lock screw 4. A representative Ti base 5 and prosthetic screw 6 are also shown in the exploded drawings of FIG. 1 and FIG. 2. This omnidirectional multi-unit abutment assembly 100 may be made of titanium or any other suitable material for implant abutment systems including precious and non-precious metals and alloys, ceramics, and high-strength engineering polymers (e.g. PEEK, PEI), or combinations of the aforementioned materials. Treatments, coatings or gels may be added to surfaces or in spaces between parts to prevent undesired biological growth or advance healing. FIG. 3. shows the elements of FIGS. 1 and 2 except for the prosthetic screw 6 in a linear orientation. FIG. 4. illustrates internal features of the assembly of FIG. 3 along the longitudinal cross-section designator A-A of FIG. 3. Note that the presence of the Ti base 5 is shown for illustration purposes in FIG. 4. Ti base 5 is ultimately retained in the prosthesis (not shown) and attached to the omnidirectional multi-unit abutment using prosthetic screw 6 as shown in FIG. 6. Prosthetic screw 6 may be a permanent screw or may be a provisional fastener of the type described in co-owned U.S. Pat. No. 11,311,354 and other applications related by continuity. FIG. 6 is a perspective view of the assembly of FIGS. 1 and 2 in a linear configuration. FIG. 5 is a side view of the embodiment tilted at about 30 degrees. FIGS. 7-9 show different stages in the installation of this embodiment into an implant and adjustment.
[0068] The abutment base 1 includes a ball or spherical portion 13 which may be approximately 3.25 mm in diameter with an abutment base drive feature 10 on the proximal end. As illustrated, this drive feature may be a hexalobular internal (Torx) drive feature socket of T5 size centered on the longitudinal axis at the top of ball portion 13. Other types of drive tools may be used. At the distal end of the abutment base 1 is a threaded portion 14 for attachment to female threads of an implant 16 that is secured into the patient's jaw bone. The implant 16 and its attachment to the mandible or maxilla bones are described schematically in this disclosure since the inventive concepts of the omnidirectional multi-unit abutment can be adapted to interface with different abutments. The generic implant 16 illustrated in FIG. 7 with female threading is a very common design, but the abutment base attachment 14 and seating 21 may be adapted to conform to other implants.
[0069] The swivel base 3 includes an aperture 19 and an interior curvature portion 15 which is sized and shaped to essentially match the curvature of the ball portion 13 of the abutment base 1. The swivel mount 2 illustrated includes internal threading 20 for attaching to the external threads 9 of the lock screw 4. It also includes a Ti base seating feature 22 for supporting and orienting the Ti base 5 when it is mounted with the prosthetic screw to the omnidirectional multi-unit abutment 100. The swivel mount may optionally include engagement features 11 that may be used to attach a tool such as a wrench to aid assembly or to restrict the azimuthal orientation (not illustrated) of the Ti base 5. Restricting the orientation of a Ti base with matching engagement features of a Ti base and implant abutment is a common technique which is useful for single tooth crowns. The omnidirectional multi-unit abutment 100 embodiments herein can be readily adapted to single tooth prostheses by fixing the azimuthal orientation of a non-cylindrically symmetrical Ti base with a matching abutment mounting surface which will not be described in detail.
[0070] The ball portion 13 of the abutment base 1 may be captured between the swivel base 3 and the swivel mount 2 which comprise a swivel shell around the ball portion 13 with the abutment base screw thread portion 14 extending through swivel base aperture 19. For this insertion process, the aperture 19 must be larger than the abutment seat projection 21. The swivel base 3 and swivel mount 2 are preferentially joined at interface joint 12 by continuous welding or spot welding, for example, with a laser after positioning around ball 13 to form base assembly 101. This joining technique provides a strong assembly of a thinner shell over a shorter distance, but other joining techniques may be used to capture the ball portion 13 within a shell. As shown in the cross-sectional view of FIG. 4, after joining, the mechanical design of the internal curvature 15 and aperture 19 of the assembled swivel base 3 and swivel mount 2 may be designed to prevent the ball portion 13 of the abutment base from escaping the swivel shell. The relative sizes and shapes of the aperture 19 and the size and shape of the abutment base 1 at the abutment seat projection 21 determine the range of tilt possible. In general, if the swivel base aperture 19 and the minor diameter or width of the internal threads 20 of the swivel mount are both less than the width of the ball 13, then the ball 13 is captured within a shell absent the lock screw 4.
[0071] The lock screw 4 illustrated has external threads 9 to engage the internal threads 20 of the swivel mount 2. These threads may be, for example, m3×0.35 size. Lock screw 4 also has internal threading 7 for attaching the prosthetic screw 6 and an internal drive feature 8 for tool attachment to tighten the lock screw 4 in the swivel mount 2. Representative prosthetic screw sizes include m1.4×0.3 threads, m1.6×0.35, UNF 1-72, etc. Drive feature 8 may be a socket accommodating common dental drivers including Torx T5 or T6, 0.035″ to 0.050″ hex or square drivers, or similarly sized straight and star drivers. As illustrated, the internal threading 7 and drive feature 8 have a partial overlap along the longitudinal axis of the lock screw. This is a design choice. Complete axial overlap or no axial overlap are other design options.
[0072] The swivel base 3 is configured to engage a segment of the spherical ball feature 13 when lock screw 4 is tightened. The figures and cross-sections shown illustrate an embodiment where the swivel base and mount may be positioned and rotated anywhere within a 30-degree cone as shown in FIG. 5 and FIG. 8. The tilt magnitude and orientations of adjustment allowed are a design choice, although 30 degrees of tilt is generally sufficient for most clinical applications. As shown in this embodiment, the swivel base aperture 19 and the aperture with threading 20 in the swivel mount 2 are smaller than the diameter of the ball portion 13. In this case, the ball portion of the abutment base 13 may be loosely captured by the swivel base 3 and swivel mount 2 when these two parts are mutually attached. That is, the lock screw 4 does not have to be attached to the swivel mount 2 to have a shell that captures the ball portion 13 with the illustrated embodiment. This is a design option, not a requirement for benefitting from the inventive concepts of this disclosure.
[0073] The cross-sectional view in FIG. 4 of this omnidirectional multi-unit abutment embodiment with Ti base 5 may be used to illustrate some of the advantages of the preferred geometric relationships between elements. As shown, the ball portion 13 is spherical throughout the range of motion of the shell formed by the swivel base 3, swivel mount 2 and lock screw 4. The tilt range limitation due to interference of the swivel base 3 proximate the aperture and the abutment base 1 surface 61 near the abutment seat 21 has been labeled as angle b in FIG. 5 and FIG. 9. The interior curvature of the swivel mount 2 is essentially the same as that of the ball portion 13. The lock screw 4 also has essentially the same curvature as the ball 13 in the area of contact. The interior curvature 15 of the swivel mount 2 is preferentially slightly larger than the curvature of the ball 13. As a result, when the lock screw 4 is tightened, the ball portion 13 is contacting the interior curvature 15 of the swivel base 3 and a corresponding interior curvature of the lock screw 4. Since the interior curvature of the swivel mount 2 is larger, it does not contact the ball when the lock screw 4 is fully tightened. This provides a more consistent continuous circular seal of the swivel base to the ball to help block the ingress of biological contamination into the interior of the omnidirectional multi-unit abutment assembly. In the linear configuration of FIG. 4, the lock screw 4 also provides an equivalent circular seal with the ball portion 13. As illustrated in the maximum tilt condition of FIG. 9, the continuous seal of the swivel base 3 to the ball is maintained. However, the seal of the lock screw 4 to the ball 13 is not continuous due to the abutment drive feature 10. However, when the Ti base 5 and prosthetic screw 6 are applied to the omnidirectional multi-unit abutment, the abutment drive feature 10 is effectively sealed.
[0074] The relatively large ring contact of the hollow lock screw 4 to the ball 13 distributes the clamping force over a larger area than the concentrated contact of a solid set screw. The extended contact and matching curvature 15 of the swivel base to the ball 13 has been determined to have sufficient frictional grab to allow tightening the lock screw 4 in excess of 25 Ncm without holding the swivel base 3 or swivel mount 4 when parts are made of titanium. The relatively large contact area also minimizes distortion of the ball 13 from clamping compared to a concentrated sold set screw, which eases repositioning of the tilt or azimuthal angles without interference from distortions of the ball 13 geometry. The relatively large outer diameter of the locking screw 4 also provides sufficient wall thickness between internal threading 7 and external threading 9 for mechanical strength for applying torque to the lock screw 4 with drive tool sizes comparable to the width of the threads of the prosthetic screw 6.
[0075] A relatively large lock screw 4 provides a sufficient number of engaged external lock screw threads 8 with the internal threads 20 of the swivel mount to provide stable clamping forces on the ball 13. Although threads (not illustrated) can also be used at the joint 12 between the swivel mount 2 and swivel base 3, the omnidirectional multi-unit abutment diameter would need to be increased to have sufficient wall thickness and engaging thread depth to have equivalent strength to the relative sizes shown in FIG. 4. However, if it is desirable to prevent over-torquing of the lock screw 4, limited engagement of screw threads between the swivel mount 2 and swivel base 3 could be used to cause separation when a threshold torque is reached. Other options for torque limiting include tailoring the preferred welded joint strength described above, increasing the aperture 19 size in the swivel mount, and/or introducing intentionally thinner wall sections in the swivel base proximate the aperture 19 that have lower torque resistance. Although intentional failure by design will likely result in loss of the omnidirectional multi-unit abutment, this may be preferable to excess stress that could result in a future failure of the prosthesis or implant retention.
[0076] The hollow style lock screw 4 and drive geometries illustrated in FIG. 4 provide benefits in dental system installation and maintenance. After the swivel base 3 is attached to the swivel mount 2 to form base assembly 101, the ball portion 13 of the implant base is captured by the shell portion formed by the swivel mount 2 and swivel base 3. The lock screw 4 may be started into the swivel mount 2 and rotated enough to secure it but without contacting the ball portion 13 to form the omnidirectional multi-unit abutment assembly 100. The Ti base 5 may be optionally placed on top of the omnidirectional multi-unit abutment assembly and parts aligned along a common axis as shown in FIGS. 3 and 4. Ti base 5 is not required to be in place during installation and orientation of the abutment base 1, swivel base 3, swivel mount 2 and lock screw 4. Thus aligned, a drive tool 17 may be inserted through the Ti base 5 and the lock screw 4 to engage the drive feature 10 of the abutment base 1 as illustrated in FIG. 7. Note that it may be necessary to slightly rotate drive tool 17 after passing through the lock screw 4 in order to engage the abutment base drive interface 10. Preferably the engagement fit of the drive tool 17 and abutment base drive feature 10 has sufficient friction to cause the omnidirectional multi-unit abutment 100 to remain on the drive tool 17 to present the omnidirectional multi-unit abutment assembly to the implant 16 as shown in FIG. 7. A slight torquing of the lock screw 4 in the unwind direction may help in this retention. As the drive tool 17 is rotated, the abutment base threads 14 engage the implant 16 and the omnidirectional multi-unit abutment assembly may be screwed down to attain the desired seating of the abutment seat 21 to the implant 16. Since the drive tool engages both the abutment base 1 and lock screw 4, these parts rotate simultaneously. Since the lock screw 4 position is not changing with respect to the abutment base 1, the ball portion 13 is not being gripped between the swivel base 3 and the lock screw 4. The rotational force from the drive tool 17 is drives the abutment base threads 14 deeper into the implant 16.
[0077] The seating portion 21 of the abutment base that contacts the implant can be modified to match the seating geometry of fixed angle abutments. The drive feature 10 allows for securing the abutment base 1 threaded portion 14 to the implant 16. The tightening of the abutment base 1 to the implant may proceed until the desired seating pressure at the abutment seat 21 is obtained. A representative torque value is about 30 Ncm, although the value will depend upon the implant system employed and may be higher or lower than this. For immediate loading of a prosthesis, the torque value should be less than the torque value used to install the implant into the jaw bone.
[0078] As shown in FIG. 8, once the abutment base 1 is secured to the implant 16, the linear configuration of FIG. 7 is no longer needed. The tilt and azimuth angle of the swivel mount 2 to receive Ti base 5 desired for prosthesis attachment can be selected by movement of drive tool 18 which is inserted into lock screw 4. Rotating drive tool 18 causes the lock screw 4 and swivel base 3 to clamp ball portion 13 and lock the angulation of the omnidirectional multi-unit abutment 100. Engagement features 11 may be included to prevent the lock-screw and swivel base from rotating while the lock screw 4 is tightened. Other engaging features such as small holes or splines may also be used as anti-rotation or azimuthal selection features for this purpose. In the case of a single tooth prosthesis, a selection feature on the swivel mount 2 engaging a rotational fixing feature on a Ti base allows the azimuthal angle of the Ti base to be selected and held while tightening the lock screw 4. A coaxial two-piece tool that engages the anti-rotation features and includes a drive tool similar to 18 may be used to orient and tighten the swivel mount 2 and lock screw 4 in position on the ball portion 13 of the abutment base 1. Having the Ti base 5 included in the arrangement of FIG. 5 may be convenient for azimuthal selection.
[0079] The drive feature 7 of the lock screw 4 is preferably accessible through the Ti base 5 in both a provisional and the final prostheses. This allows moving and re-torquing the lock screw 4 in the proper orientation should it loosen over time, making minor adjustments to improve passive fit, and replacing and realigning one omnidirectional multi-unit abutment 100 within a plurality of omnidirectional multi-unit abutments 100. From a comparison of the drive tool dimension d1 shown in the inset FIG. 7a to the drive tool dimension d2 shown in the inset FIG. 8a, the drive tool 18 shown in FIG. 8 is larger than the drive tool 17 in FIG. 7. This is not required. A benefit of using two different sizes, for example, a T5 driver 17 to drive the abutment base 1 and a T6 driver 18 for securing the lock screw 4 provides extra clearance in the lock screw 4 while driving the abutment base. Since the torque used for driving the abutment base 1 may be chosen to be higher than the torque used for the lock screw 4, a first torque wrench with drive tool 17 and a second torque wrench with drive tool 18 may help ensure the desired torques are obtained. Of course, in order to allow the assembled omnidirectional multi-unit abutment 100 to be installed into the implant 16 as shown in FIG. 7, the size and shape of the drive tool 17 must pass through the lock screw 4. The drive tool 18 in FIG. 8 is prevented from passing completely through the lock screw 4 since the lock screw internal drive interface 8 shown does not extend all the way to the distal side of the lock screw 4. This is a design choice.
[0080] Some practitioners may choose to use their muscle memory experience instead of a calibrated objective tool to determine when a predetermined desired torque is applied to the implant base 1 and the lock screw 4. If the abutment base drive interface 10 and lock screw drive interface 8 are the same size and shape, then one tool can be used for drive tool 17 and 18. In this case, after driving the abutment base 1 into the implant 16 as in FIG. 7, drive tool 17 would only need to be extracted just enough to disengage with the abutment base drive interface 10 before repositioning it to lock the omnidirectional multi-unit abutment 100 position by rotating lock screw 4. If different calibrated torques are desired, two different wrenches could be used with the same drive tool tip size. Some practitioners may prefer to leave the drive tip inserted in the omnidirectional multi-unit abutment for both torquing process steps and switch torque wrenches set to different values. Since the rotational axis of drive tool 17 is generally different than drive tool 18, using the same torque magnitude for the abutment base 1 and lock screw 4 may be acceptable. A torque wrench that has a push button or other selector to switch between two different torque settings may be useful. Automatic selection could be based on the difference between the deeper drive tool depth required to engage the abutment base drive interface 10 compared to the lock screw drive interface 8, for example, by requiring a force along the axis of the drive tool tip to cause a spring loaded sheath to engage the higher torque mechanism. In this case, the lower torque setting could remain engaged, if desired, although it would slip.
[0081] FIG. 9 shows is a cross-sectional view of the omnidirectional multi-unit abutment assembly 100 including prosthetic screw 6 that retains Ti base 5. Prosthetic screw 6 may be replaced with a separable fastener (not shown) as described in the referenced U.S. Pat. No. 11,311,354 to facilitate positioning of the Ti base 5 into the prosthesis with a lift off process. Note that even after the Ti base 5 is incorporated into the prosthesis, it is possible to access the lock screw drive interface 8 by removing the prosthetic screw 6. This is essentially changing the configuration from FIG. 9 to FIG. 8. This benefit will be described in more detail after other embodiments are presented.
[0082] A variation of the embodiment shown in FIG. 1 through FIG. 9, is illustrated in FIG. 10 through FIG. 13. From a practical design standpoint, given constraints of conventional abutment diameters, seating heights (the distance between the seating surface 22 for the Ti base 5 and implant seating surface 21 in the first embodiment) and other dimensional constraints, omnidirectional multi-unit abutment designs may also include embodiments in which the abutment base 30 and ball or spherical feature 31 are initially separate components. In the embodiment of FIGS. 1-9 the ball is approximately 3 mm diameter. A nominal seating height of approximately 2.5 mm is illustrated in the figures.
[0083] The second embodiment illustrated in FIGS. 10-13 is shown with about the same dimensions to work with the same implant 16 and Ti bases 5 as the omnidirectional multi-unit abutment assembly 100 shown in FIGS. 1-9. The seating height between the abutment seat 42 and Ti base seat 41 is also comparable. The major difference is that the swivel 32 is captured between portions of a two-part abutment base 30. The abutment base 30 in FIG. 12 comprises a separate ball portion 31 attached to a stem portion 34. A discrete 31 may be useful, for example, in case a swivel base will not fit through the required abutment diameter without interference. Consequently, the embodiment in FIG. 10 through FIG. 13 includes a ball 31 with drive interface 45 with distal mounting hole 46 that is attached to a mating post feature 35 of the abutment base stem portion 34. After inserting ball 31 into swivel 32, ball 31 is assembled to base stem portion 34 by any form of mechanical engagement such as press-fitting, heat-shrinking, laser-welding, adhesives, or combinations thereof. For example, ball 31 may have a light press-fit onto post 34 and a small radial laser-weld at interface 35. This method reliably joins the ball to the base, while minimizing mechanical precision, providing a fillet at the mating joint 35, and sealing this joint from liquid ingress.
[0084] In the embodiment illustrated, the minor diameter of the internal threading 38 of the swivel 32 is large enough to allow ball 31 to be inserted through the internal threads 40 of the swivel mount 32. The drive interface 45 may be used to orient the ball for assembly. After capturing the swivel 32 and installing and tightening the lock screw 33, the ball 31 contacts the swivel 32 along a seating surface 47. Approximately 17.5 degrees of seating/interference surface is illustrated in FIGS. 12-13. The lock screw 33 also makes contact with the ball 31 along interface 48. Various surface finishes and mechanical features may be employed to enhance the locking ability of mating surfaces 48 and 47 to ball 31, such as surface texture, ridges, or ribs. Note that this approach of capturing the swivel 32 to the ball prevents the swivel 32 from falling off the ball 31. The swivel 32 contacts the distal surface of the ball similar to the swivel base 3 of the first embodiment of FIGS. 1-9, but also provides the Ti base seat 41 to support the Ti base 5 in a known orientation analogous to that provided by of the previous Ti base seat 22 of swivel mount 2.
[0085] The lock screw 33 is similar to the lock screw 4 in the first embodiment. It contains prosthetic screw threads 36, drive socket feature 37, seating surface 48 and external threads 39. The proximal end of the ball portion 31 includes drive socket feature 45 that may be accessed through the lock screw 33 similar to lock screw 4 described above. When lock screw 33 is tightened using drive feature 37, the swivel 32 engages a seating surface 47 of the ball 31 which allows for the lock screw 33 to fix the swivel 32 in the ideal omnidirectional orientation up to thirty degrees off the implant axis and at the desired azimuthal angle. Again, Ti base 5 is does not need to be present during installation and orientation of the omnidirectional multi-unit abutment. Through proper selection of the sizes of prosthetic screw threading 36 and drive features 45 and 37 and 44, it is possible to utilize a single drive tool for the three steps of tightening the abutment base 30 into the implant (not shown), locking the orientation of the swivel 32 with lock screw 33, and tightening the prosthetic screw 44. For example, a single T5 drive tool typical of an M1.6×0.35 prosthetic screw 43 with threading 36 can be used if the drive interfaces 37, 44 and 45 also have T5 socket characteristics. Of course, in this case, the lock screw drive interface 37 would need to extend through the lock screw 33 (not shown) in order to engage the abutment base drive socket feature 45. The portion of the M1.6 prosthetic screw threads removed for the T5 driver has been determined to provide adequate thread integrity to properly retain the prosthetic screw. Other standard and custom threads and drive geometry combinations may also be used to allow the use of a single drive tool.
[0086] By assembling the ball 31 to the abutment base 30, the width of the abutment base 30 at the implant seating location 42 may be larger than in the first embodiment. In the first embodiment, the threaded end 14 of the abutment base 1 was inserted into the swivel base aperture 19 to contact the ball portion 13. The ball portion 13 was captured by joining the swivel mount 2 to the swivel base 3. By merging the characteristics of the swivel base 3 and swivel mount 2 into a one-piece swivel 32 in this embodiment, the size of the distal end of the abutment base is not constrained by the aperture at the distal end of the swivel 32 aperture. In the embodiment of FIGS. 10-13, the minor diameter of the lock screw external threads 39 must be larger than the diameter of the ball 31 to allow the ball to be inserted through the swivel 32 to be joined to the abutment base 30. A comparison of FIG. 12 with FIG. 4 shows that this results in a shorter depth for engaging threading between the swivel 32 and lock screw 33.
[0087] Another approach for capturing a swivel shell component to an abutment base with a ball feature is shown in FIGS. 14-16. In this embodiment, the abutment base assembly 101 is fabricated from swivel 32 and a ball with taper stem 50 that has a ball feature 13 with drive feature 45 at the proximal end and tapered stem 51 at the distal end. The tapered stem 51 is joined to a base 52 having a tapered socket 53 at the proximal end and an abutment base screw thread 14 at the distal end. The widest part of the ball with taper stem 50 is the diameter of the ball 13. Swivel 32 is captured by inserting the tapered stem 51 into the proximal side of the swivel 32 before inserting the tapered stem 51 into the tapered socket 53.
[0088] FIGS. 15 and 16 show the abutment base assembly 101. As before, the tapered stem 51 and base 52 may be joined with different techniques. However, including welding at interface 63 is preferred. A comparison of FIG. 16 to FIG. 14 shows that the ball portion 13 of the ball with tapered stem 50 may have improved structural stability compared to abutment base ball 31. This may be important considering the small size of the parts and the desire to have smooth swiveling action and tight sealing of the parts when locked in position.
[0089] The lock screw 49 illustrated in FIG. 14 differs from the lock screws 4 and 33 in previous embodiments by including a hex drive feature 64 on its exterior surface near the proximal end. This hex drive feature 64 is provided to aid removal of a failed installation. For example, if the prosthetic screw stem 25 breaks off in the lock screw 4, the lock screw drive interface 8 may be plugged so that the drive tool 18 used for installing the omnidirectional multi-unit abutment cannot be inserted. As an alternative to removing the broken stem 25, a wrench (not shown) could be applied to the hex feature 64 to remove the lock screw 49. Of course, these hex features 64 would generally not be accessible with the Ti base 5 in position on the omnidirectional multi-unit abutment. As a result, the lock screw drive interface 37 is preferred for using the Ti base embedded in the prothesis to help align and lock the omnidirectional multi-unit abutment orientation to improve passive fit. If necessary, a wrench could also be applied to the flat 11 on the side of swivel 32 to help with removal of the plugged lock nut 49 since the Ti base 5 would not be covering it.
[0090] FIG. 17 is a top plan view of the lock screw 49. At the outer edge is the lock screw exterior threading 39 and at the center is the lock screw internal drive interface 8 which is shown as a Torx style. The major diameter 66 (dotted line) and minor diameter arc 65 of the lock screw internal threads 7 are shown. The minor diameter 65 is not a continuous circle but a series of discontinuous arc segments due to the lock screw internal drive interface 8 that is axially overlapping the lock screw internal threading 7. Note that the lock screw 49 has the lock screw internal drive interface 8 and the internal threading 7 extending all the way through the lock screw 49. In other words, there is essentially complete axial overlap of them through the thickness of the lock screw 49 so that a sufficiently long prosthetic screw thread 25 and a drive tool 18 can both pass through the thickness of the lock screw 49. The amount of material in the lock screw 49 that is available for the drive tool 18 to apply torque to lock the orientation of the omnidirectional multi-unit abutment 100 corresponds to the volume bounded by the major diameter 66 and minor diameter 65 of the internal screw threads 7 minus the material removed to provide the lock screw drive interface 8 socket for the drive tool 18 (not illustrated). The size and shape of the drive tool interface 8 can be modified to change the strength of the remaining internal threads 7 for holding the prosthetic screw 6 and maximum torque application to the lock screw 49 to fix orientation before damaging the internal threads 7.
[0091] FIG. 18 is a top plan view of the lock screw 49 with an alternate lock screw internal drive interface 54. This drive tool interface 49 has 4-lobes instead of the 6 lobes of the Torx drive tool interface illustrated previously. As a result of having fewer lobes and more pronounced lobe transitions, a visual comparison to FIG. 17 is sufficient to show that more of the internal threading is retained compared to FIG. 17. As a result, there are material and geometric trade-off options that are available to compensate for any mechanical strength degradation resulting from the axial overlap of the internal threading 7 and lock screw drive interface 54 that allows the final alignment and locking of the omnidirectional multi-unit abutment 100 to be done with the prosthesis in place.
[0092] FIG. 19 illustrates a 4-lobe drive tip 62 with the lock screw 49 of FIG. 18 and an abutment base 59 with a matching 4-lobe drive interface 60. The other parts of the omnidirectional multi-unit abutment 100 are not shown for clarity. Since drive tip 62 is sized to pass through the lock screw 49, it can be used to drive abutment base 59 into the implant 16 (not shown). Since the drive tip is sized to pass through the Ti base aperture 23 (not shown), it can also rotate the lock screw 49 to fix the position of the omnidirectional multi-unit abutment through the prosthesis (not shown) in which the Ti base 5 (not shown) is embedded.
[0093] FIG. 20 illustrates another embodiment of a two-part abutment base 55 that is assembled to capture a swivel 32. In this embodiment, the ball portion 13 and the abutment base screw threads 14 are included in an abutment base stem 56. The distal end of the abutment ball base stem is inserted into the swivel 32 and then into a hollow sleeve 57 matching the interface requirements of the abutment 16 that will be used. The sleeve 57 has a maximum width that is larger than the diameter of the ball portion 13. As a result, when sleeve 57 is joined to abutment base stem 56, swivel 32 is captured. Any of the various joining operations mentioned above may be used, although including welding at interface 58 as shown on FIG. 22 is preferred. Also shown in FIG. 22 are two critical dimensions for the assembly process above. The minimum diameter “d” of the through aperture of the swivel 32 must be larger than the maximum width “c” of the abutment base stem 56 below the ball portion. Due to the similarities of this embodiment to previous ones, the other parts and characteristics will not be described.
[0094] Many other methods of capturing swivels on a ball with attached abutment connection assembly are possible such as different forms of male pins on the ball, female sockets on the abutment base, a threaded post on the ball or abutment. Although essentially spherical balls have been illustrated to demonstrate inventive concepts and provide maximum orientational flexibility, other shapes may be used to intentionally restrict orientation. Mating interfaces may be tailored to meet objectives in embodiments that have not been presented that still use one or more of the inventive concepts illustrated.
[0095] FIG. 23 shows a cross-section of the application environment of an installed omnidirectional multi-unit abutment 100 of the first embodiment. The implant 16 has been installed in the patient's bone and soft tissue shown schematically as 70. The abutment base 1 has been screwed into the implant 16 to a desired torque level. In this case, the swivel mount 4 has been tilted to essentially its maximum capability comparable to FIG. 8. The Ti base 5 is embedded in the prosthesis 68. The occlusal surface 72 of the prosthesis is shown schematically as 72. The Ti base 5 is seated on the swivel mount 4, but the prosthetic screw 6 has been removed to allow the lock screw interface 8 to be accessible to a drive tool 71 through prosthetic screw access hole 69. Note that while a 4-lobe drive tool 71 is illustrated, a smaller drive tool (not shown) would be required to drive the abutment base 1 into the implant 16 as described previously for the first embodiment. As mentioned with the first embodiment, it may be beneficial to be able to make changes in omnidirectional multi-unit abutment orientation while the prosthesis is in position. FIG. 23 will be used to describe this in more detail.
[0096] Although only one implant is shown in FIG. 23, benefits of in situ adjustment are magnified when the prosthesis includes multiple Ti bases mating to multiple implants. During the fabrication or modification of the prosthesis for implant mounting, uncertainties in Ti base position may be accumulated. Due to the random nature of these shifts, the orientation and position of the Ti bases may drift from each other and from the position of the set of abutments initially used to orient the Ti bases with the prosthesis. Even if the Ti bases are positioned perfectly initially, the shape of the patient's jaw or the prosthesis may change over time. As shown in FIG. 23, removing the prosthetic screws 6 allow the lock screws 4 to be accessed and loosened with drive tool 71. Applying a re-seating force to the prosthesis 68 from the occlusal side 72 will push the embedded Ti bases 5 against the Ti base seats 22 thereby redirecting the orientation of the omnidirectional multi-unit abutment. Tightening the lock screws 4 with the drive tool 71 while maintaining the reseating force on the prosthesis 68 will lock this orientation. The prosthetic screws 6 can then be reinserted and torqued to secure the Ti bases 5 and prosthesis 68 in position. If it is desirable to check the torque on the lock screws 4 to see if they have loosened over time, this can also be done through the Ti bases 5 embedded in the prosthesis 68.
[0097] Similarly, if one omnidirectional multi-unit abutment 100 of a set fails and needs to be replaced, the prosthesis 68 with its embedded Ti bases 5 can be removed after removing all of the prosthetic screws 6. Reversing the angle setting and implant attachment processes shown in FIG. 8 and FIG. 7 will remove the failed omnidirectional multi-unit abutment assembly 100. Repeating the process of FIG. 7 to attach the new omnidirectional multi-unit abutment 100 to the implant 16 will result in the abutment base 1 being secured into the implant 16, but the shell consisting of the swivel base 3, swivel mount 2 and lock screw 4 will be loose. Minimal pressure on the lock screw 4 is sufficient to hold the orientation of the omnidirectional multi-unit abutment so that gravity doesn't cause it to move, but only require a minimal force application to change its orientation. Rough positioning of the swivel mount 4 sufficient to engage the Ti base 5 in the prosthesis 68 and manually applying pressure to the prosthesis from the occlusal side 72 will reorient the newly installed omnidirectional multi-unit abutment to align with the Ti base 5 already installed in the prosthesis. The lock screw 4 can then be tightened through the aperture 23 in the Ti base 5 in proper position as shown in FIG. 23. Whether the prosthetic screws 6 from the original omnidirectional multi-unit abutments 100 are used to maintain the alignment pressure on the newly installed omnidirectional multi-unit abutment 100 before tightening the lock screw 6 is optional.
[0098] Since the lock screw drive interface 8 is accessible through the Ti base 5 and prosthesis 68, a variation of the one-screw passive fit testing protocol may be used to make minor adjustments to the orientation of the omnidirectional multi-unit abutment to improve passive fit at the time of original installation. There are different options for exploiting the ability to reorient the omnidirectional multi-unit abutment 100 through the apertures 23 of the Ti bases 5 installed in the prosthesis 68. In one approach, all of the prosthetic screws 6 are removed. While the prosthesis 68 remains in place, all of the omnidirectional multi-unit abutment lock screws 4 are loosened and then made finger tight to provide some friction resisting, but not preventing swiveling slip. The actual torque value for being appropriately finger tight will depend upon the construction and surface finish of the omnidirectional multi-unit abutment, but will generally less than a few Ncm. Next, all of the prosthetic screws 6 are reinstalled and torqued to the recommended value. In this manner, the orientation of each of the omnidirectional multi-unit abutments will be more closely matched to the prosthesis 68. Next, a single prosthetic screw 6 is removed to provide access to the lock screw 4 of the omnidirectional multi-unit abutment in that position. The lock screw 4 is torqued to its predetermined value. The prosthetic screw 6 is reinserted and torqued to the predetermined value. This is repeated until all of the omnidirectional multi-unit abutment lock screws 4 have been tightened and all prosthetic screws 6 are tightened.
[0099] The fine adjustment process above may be modified depending upon the particulars of the initial level of passive fit. For example, it may be desirable to only loosen some of the omnidirectional multi-unit abutment lock screws 4 while leaving others fixed as anchor points from the original prosthesis fitting. This may result from a requirement to compromise passive fit somewhat for better occlusion or other reasons. Or the results of the traditional one screw or screw resistance tests may suggest orientational adjustment of only a subset of the omnidirectional multi-unit abutments or a different order of adjustment. In any case, these passive fit improvements follow directly from the capability of orienting and fixing the omnidirectional multi-unit abutment while the prosthesis is in place.
[0100] It is preferred that the omnidirectional multi-unit abutment 100 embodiments above be adapted to be compatible with Ti bases 5 and threaded implants 16 that have already been qualified and commercially successful. The threading and seating to widely available implants improves the inventory equation since the same implants may be used with conventional straight abutments as well as the embodiments above in the same patient. While less critical, the compatibility with widely available screw-attached Ti bases 5 is also seen as an advantage However, inventive features of the described embodiments can be integrated into or adapted to work with newly designed implants that adopt inventive concepts for passive fit improvement or installation efficiency and repair described above. These inventive concepts can also be adapted to work with prostheses that are not attached with screws. These adaptations are not excluded and are considered to be disclosed herein and within the scope of claims that may be broadly interpreted to apply to them. U.S. Pat. No. 11,311,354 includes different approaches for aligning Ti bases with abutments for incorporation into a prosthesis using a temporary fastener in a lift-off process. The basic design of the temporary fasteners illustrated in that co-owned patent can be employed with the omnidirectional multi-unit abutments and Ti bases described above.
[0101] Various embodiments have been described to illustrate the disclosed inventive concepts, not to limit the invention. Combining inventive elements of one or more of the embodiments with known materials, components and techniques in dental science to create further embodiments using the inventive concepts is considered to be part of this disclosure.
