Patent Description:
The simplicity of screw-attached systems provides some benefits over snap-on systems beyond fabrication cost. The mounting pressure between the coping and abutment is readily controlled through the torque applied to the screw to tighten it. This axial tension control and the self-aligning characteristics of engaged screw threads provides more certainty in the engagement force and relative orientation of the components. Even if a screw breaks, techniques are known for removing the pieces without damage to surrounding components. Screws also have a benefit of independence for removal since each coping can be loosened individually. Tilting the prosthesis after screw removal to disengage one coping cannot cause reengagement of another coping.

In the case of a single-tooth crown attachment, the Ti base and abutment surfaces preferably include features to remove rotational symmetry about the azimuthal axis in the mating of the abutment and coping surfaces. Rotational locking features may also be included in these single mount systems. When the prosthesis contains multiple copings for attachment to multiple abutments, this rotational fixation is not generally required. For example, <NUM> degree tapered mating surfaces for multiple interface locations are sufficient to provide complete registration. This form is illustrated in the drawings of this disclosure for convenience, but is not meant to be limiting.

The goal for all implant attached prostheses is to have a passive fit of the prosthesis superstructure to the implants to avoid stress on the prosthesis or on the osseointegration process of the implants. These stresses may cause problems during the initial loading or crop up much later. Misfit can lead to both mechanical and biological problems in single implant and multiple implant treatments. The mechanical problems may include loosening of prosthesis retaining and abutment screws and fracture of components including screws. Biological issues may include discomfort, progressive marginal bone loss, bacterial infection, microbial plaque buildup and implant loosening.

Having a passive fit initially or being able to readjust or rework components later to adapt to changes are important for successful prosthesis functionality and survival. Due to the build-up of tolerances and introduction of misalignments and distortions in producing a prosthesis, attaining a passive fit remains a challenge. The use of direct pick-up impression procedures is beneficial, but improvements are still needed. A review of passive fit challenges has been provided by<NPL>).

A treatment option for edentulous patients that is gaining popularity involves the placement of four to eight implants in the edentulous jaw and the mounting of a prothesis arch. A transmucosal abutment is fastened to the implant and intended to remain in place indefinitely. While it would be desirable to have the axes of all of the implants located parallel to one another, underlying bone structure often results in installing implants at an angle from this ideal mutual orientation. "Multi-unit abutment" is a popular descriptor for a specific type of transmucosal abutment used for the restoration of the edentulous jaw with a single prosthesis, that is a full arch prosthesis.

The multi-unit abutment (commonly referred to as an "MUA") is a fairly easy way to improve divergent angulations of implants with options of <NUM> degree, <NUM> degrees, and <NUM> degrees angulation corrections. Generally, <NUM> degree MUAs are easier to position because the abutment is positioned in line with the linear axis of the implant. The <NUM> and <NUM> degree MUAs typically include a "screw access" indicator that is relatively long and difficult to work around in tight spaces, such as the posterior of the jaw where these abutments are commonly positioned to compensate for the disto-angulation of the posterior implants popularized by Dr Paolo Maolo in <NUM>.

There have been several alternative abutment designs for the restoration of the edentulous arch. Although most implant companies have settled on the MUA geometry adopted by Nobel Biocare, there have been some attempts to improve on the weaknesses of that geometry. For example, Dentsply Implants Astra EV system uses a "mulTi base" abutment that improves on the lack of coverage of the prosthetic screw in the multi-unit abutment. Neoss uses a version of the MUA that "reduces the height of the abutment" by using a female connection as opposed to the standard male connection of the MUA. Regardless of the benefits of these improved designs, each design requires the clinician to order a specific stock of specific angulation corrections and heights. An example of the complexity of the inventory management is when the implant system offers multiple implant/abutment connections (e.g., narrow platform and regular platform) and multiple heights to the MUAs (e.g., <NUM>, <NUM>, <NUM>, <NUM>, etc.) as well as different angulations or tilt angles (e.g., <NUM> degree, <NUM> degrees, and <NUM> degrees). To maintain sufficient stock to be well-prepared for a full arch implant fixed immediate load procedure could require having the three tilt angle options multiplied by the number of platform options multiplied by the number of reasonable tissue heights for the amount of implants expected to be placed (a minimum of four according to Paolo Maolo's protocol).

The resulting inventory equation follows: <MAT>.

This inventory problem is increased when multi-unit abutment systems also require unique implants, Ti bases and prosthetic fasteners. This inventory management complexity is further exacerbated when practitioners prefer different vendor systems under different patient circumstances, or when different practitioners in a practice prefer different vendor offerings.

In addition to the complexity of the inventory management, there is also a limitation to the discrete nature of the "angulation correction" (for example, limited to three specific angles <NUM>, <NUM> and <NUM>) and the internal connection of the implant about its longitudinal axis that may be referred to as an azimuthal angle. In many cases an internal hex limits the possibilities to <NUM> azimuth positions with <NUM> degrees of variation from one position to the next. In some cases, <NUM> degrees would be too little tilt angle correction, but <NUM> degrees is excessive. The same would hold true for <NUM> to <NUM>. Or <NUM> degrees may be an appropriate tilt correction, but due to the limitation of the <NUM> positions in the internal hex, the <NUM> degrees of correction required cannot be applied in the ideal azimuthal direction of correction needed. The same holds true for <NUM>-degree correction. Novice clinicians to full arch implant treatment struggle with the selection and positioning of multi-unit abutments. Procedure times are extended which can cause increased morbidity to the patient.

Although there is uncertainty over whether angled implants are more susceptible to loss of osseointegration than straight abutments, all implants do impart higher mechanical stress and strain on bone structures than natural teeth. Natural teeth can move an order of magnitude more in their sockets than an implant embedded in bone. This natural shock absorber helps cushion the range of force magnitudes and directions applied to the teeth from the bone. Screw loosening has been associated with bending of the screw joint and settling effects in which initial surface microroughness keeps joined parts initially separated, but high spots are gradually worn down. Microgaps from initial mechanical misfit between elements in the prosthesis superstructure may be too small for detecting with an explorer, yet large enough to concentrate mechanical forces coming from different directions at different magnitudes in the process of mastication. These microgaps may still be large compared to bacteria that can penetrate and grow in internal cavities of the overall dental prosthesis superstructure installation.

Due to the large range of variables, application specifics and difficulty of in situ measurements, there is not an accepted passive fit threshold for long-term success. The quality of fit may be tested in the dental laboratory with analogs and at installation in the patient, but this is not an exacting science. For example, a "one screw test" for fit involves tightening only one screw at one end of the prosthesis and then looking for lift at the opposing end. A "screw resistance test" variant of this involves inserting and seating screws in sequence and then seeing if any needs to be turned more than <NUM> degrees to achieve say <NUM> Ncm of torque. Failure of the prescribed go-no go test criterion means that the prosthesis needs to be reworked or replaced. Since the same process will be used to fabricate the replacement, there is not certainty that this replacement will be properly aligned.

Even if all of the multi-unit abutments are perfectly aligned and secured initially with the implants and prosthesis, changes may occur over time. For example, the prothesis may deform, or the bone structure may change, or perhaps more likely a fastener becomes loose or breaks. In many prior art systems, the prosthesis must be completely removed to try to adjust the orientation, retighten a multi-unit abutment fastener, replace a component or perhaps even fabricate and fit a whole new prosthesis. Inefficient trial and error fitting cycles to improve alignment are frustrating to both the patient and dental practitioner. Replacing a single failed multi-unit abutment out of several and properly aligning it with an existing prosthesis may be even more difficult than the initial installation alignment. There is a need for a way to provide adjustments to the orientation of a multi-unit abutment orientation while the prosthesis is in place.

Some commercial systems require the sequential assembly of the multi-unit abutment elements in situ during their installation in the patient's mouth. This increases the chance of the patient accidentally swallowing components. Some systems require multiple tools to be employed which can also extend procedure complexity and times.

To address one or more of the above challenges and limitations of the current multi-unit abutments available on the market, new multi-unit abutment embodiments are disclosed herein. These units are designated as omnidirectional in the sense of being able to be positioned over a continuous range of orientations sufficient for correcting implant angulation differences typically found in general practice. Although the discussion above was based on structural reasons, angled implants may also be preferred simply for aesthetic reasons, for example, to reorient screw access holes in single tooth crowns. Embodiments of omnidirectional multi-unit abutments are offered that have advantages in inventory management, placement procedures, options for angulation correction and flexibility, improving passive fit and to remove limitations to angle corrections or other issues with existing multi-unit abutment systems for single implant crowns and multiple implant prostheses.

<CIT> discloses a submergible screw-type implant including a longitudinal channel which directs bone chips towards the base of a bore in the patient's bone in which the implant is installed. These bone chips promote autogenous rapid regrowth of new bone to securely anchor the implant in place. In order to be able to position the implant at the most advantageous angle at the edentulous sight, angled abutments for supporting an artificial tooth structure or angularly adjustable abutments are provided. The angularly adjustable abutments may be in the form of a ball and socket joint in which the socket includes an inner casing having a peripheral extension that acts to lock the joint at the desired angle. Also, the support for an artificial tooth may include a shock-absorbing cushion to prevent some of the forces of mastication from disturbing the implant.

<CIT> discloses a dental jaw implant with a base part implanted in the bone substance of the human jaw.

The invention is defined by the independent claim. Preferred embodiments of the invention are defined by the dependent claims. The invention relates to a multi-unit abutment for screw attachment to a dental implant which allows seating of Ti bases at a user-selected rotation and tilt angle relative to the implant. This seating orientation can be fixed prior to bonding the Ti base to the prosthesis, and in some embodiments can be adjusted or tightened by removing the prothesis retention screw while the Ti base is otherwise held onto the abutment. In this manner, the final relative orientation of the adjustable abutment can be directly influenced by the fixed position of the Ti bases in the prosthesis. This can correct or reduce misalignments resulting from the accumulation of positioning errors in steps of the fabrication of the prosthesis relative to the initial position of the abutments.

For the purposes of this disclosure, a dental prosthesis is defined broadly to be anything that incorporates one or more dental copings or Ti bases that can be mounted and removed from one or more implant abutments. Different Ti base designs are known in the dental industry, and the systems and methods disclosed here can be adapted to work with many commercially available types of Ti bases including pick-up copings, temporary cylinders, inserts and impression copings. Implant abutments are known in the dental industry having compatible interfaces to these Ti bases. Since the mechanical interface is the same, for the purposes of this disclosure, implant abutment is considered a generic term that includes abutment analogs. Description of abutment alignment systems and process methods with Ti bases and implants that are installed in a patient's jaw should be considered to also describe equivalent inventive concepts that may be used with Ti bases and implant analogs in a dental lab. A common geometry comprises a conical Ti base seated to a conical implant abutment. Although this form of system is used in the figures and discussion below, the inventive concepts may also be applied to other types of Ti bases and abutments.

The inventive concepts disclosed herein can be used with different types of dental prostheses. The dental prosthesis can be any form of impression used in a dental lab to assist in creating and testing dental prostheses. A dental prosthesis can also be one fabricated in the dental lab using a physical model made from the impression, a dental prosthesis newly fabricated, or an existing prosthesis being converted for screw attachment. A dental prosthesis is defined to include a single-tooth appliance such as a crown, or any multiple-tooth bridge or denture. These prostheses may incorporate Ti bases to provide a separable interface to provide orientation with an appropriate abutment attached to a patient's jaw or gingiva. Although the name implies applications with multiple implants, multi-unit abutments may also be used individually to provide mounting to an implant for single tooth prostheses. As a result, the term multi-unit abutment will be used herein whether for single implant or multiple implant applications and for any form of dental prosthesis. The multi-unit abutments for use with the inventive concepts disclosed herein include screw threads to mount the prosthesis with Ti bases onto the abutments and the abutments into the implants. While the concepts describe the typical male threads in the multi-unit abutment mating with female threads on the implant, this is for convenience in disclosure. Unless explicitly stated or restricted by functional necessity, some inventive concepts may be applied with systems having female threads in the multi-unit abutment engaging a screw with male threads in an implant. These are considered to be straightforward variations of the inventive concepts. One benefit of preferring the typical female threading of the implant for abutment attachment is standardization and implementation flexibility. For the same reasons, prosthetic screws with male threads and commercially available Ti bases are preferred, but may not be required to gain some benefit from inventive concepts disclosed. These types of variations are considered to be within the scope of this disclosure.

The systems and methods disclosed herein can be used with prostheses for attachment to implants in both the upper and lower jaw. As a result, portions of the system that are oriented downward for the lower jaw will be oriented upward for the upper jaw and vice versa. For convenience, a disclosure of an embodiment of inventive concepts that is limited to a single jaw orientation, is considered to disclose an embodiment for the opposite jaw orientation. When referring to the perspective of a clinician, proximal portions are nearer to the clinician than distal portions. While a term such as top is the opposite of the term bottom, and proximal is the opposite of distal, their actual relative orientation will be determined by the context of their use. The term tissue-side is used interchangeably with intaglio to indicate the side of a prosthesis that is opposite the occlusal or cameo surface.

The inventive systems disclosed are beneficially applicable to screw-attached prostheses and abutments. Key benefits of screw-attachment are variable tightening torques and reversibility. The terms permanent, semi-permanent, definitive and final when referring to screw-attachment are used interchangeably in this disclosure. A conventional screw that is definitively attached can still be removed by accessing the screw and rotating it in the opposite direction that was used for attachment. For the purposes of screw-attached prostheses for this disclosure, the attachment is semi-permanent, permanent or definitive in the sense that frequent attachment and removal is not anticipated for normal use. In contrast, a temporary screw attachment is applied for a planned process duration or other anticipated interval. The positioning of the Ti bases in the dental prosthesis may be effectively performed with a lift-off process using the temporary screws disclosed in co-owned <CIT>. However, the utility of inventive concepts in this disclosure are not dependent upon using the system or methods disclosed in the referenced patent.

Screw attachment of an abutment to an implant is also described in the embodiments. However, some of the disclosed concepts may readily be adapted to other systems that do not utilize screw attachment of dental components to an implant such as snap-on or magnetic systems. These modifications are considered to be obvious variations of the inventive concepts described in the current disclosure.

Removal of a semi-permanent or definitive screw is generally motivated by a problem or an opportunity for an improvement. Access to the screw to apply a tool for removal may require removal of material covering the screw that was added for aesthetic reasons. Some embodiments provide for adjusting the orientation of the multi-unit abutment when the prosthesis is positioned on the multi-unit abutment without a semi-permanent or definitive screw in place. This may to improve passive fit of the prosthesis to implants when initially installed or after the system has been used for an extended period of time. While the implant abutments are generally used initially to position the Ti bases in the prosthesis, individual alignment errors will necessarily accumulate during subsequent processing or over time. The apparatus and methods disclosed below allow the set of Ti bases in the prosthesis to be used for fine tuning the alignment of the multi-unit abutments to the set of Ti bases improve the overall passive fit.

Elements disclosed herein may be characterized as having an axis or a longitudinal axis. In the case of a long cylindrical object like a pencil, the longitudinal axis is unambiguously through the center of the cylinder from the writing end to the eraser end of the pencil. The longitudinal axis is traditionally considered to be along the length or longest dimension of an object characterized by length, width and thickness in descending dimensional magnitude. If instead of a pencil, a threaded bolt is considered, the axis or even longitudinal axis may be considered to be through the center from the engaging end of the threads through the center of the head of the bolt. The rotational axis in this case and the longitudinal axis are the same even for stubby bolts. In this disclosure, the axis or longitudinal axis of an object with screw threads will be the same as the rotational axis of the threading. Widths will be measured perpendicular to this rotational axis. Thus, a traditional nut with interior threads would be considered to have a longitudinal axis through the middle of the central aperture, i.e., where the matching bolt's axis would be located when engaged. By extension, a washer without threads captured between a bolt and a nut would also be considered to have a longitudinal axis or simply an axis centered in the aperture and perpendicular to the plane of the washer. For the purposes of this disclosure, a linear assembly of components results from having the component axes of the assembly in a roughly colinear arrangement. Thus, an assembly comprising a bolt with a washer and nut would be a linear assembly even if the axis of the washer can move around the shared axes of the bolt and nut due to the washer aperture being larger than the width of the threaded section of the bolt. External threading is generally characterized as having a minor diameter measured at the root of the threads and a major diameter measured at the crest of the threads. Internal threading is generally characterized as having a minor diameter at the crests and a major diameter at the roots. Unless otherwise specified, the width of the external threads on a bolt stem is defined to be the major diameter or maximum deviation from the bolt's axis, that is, what would be measured with calipers. The width of the internal threads of a nut is defined to be the minor diameter of the internal threads or minimum deviation from axis of the nut, that is, what could be measured with a pin or plug gauge.

In this disclosure some threaded elements that tighten by relative rotation may have some characteristics that could be considered nut-like and others that are screw-like, such as elements having both female and male threading. The term screw will be used generically in this disclosure for these threaded elements in discussing the inventive concepts. However, external threading on a screw will be considered to be male and internal threading will be considered to be female.

For the purposes of this disclosure, the term ball means a mechanical structure that includes some geometric attributes of a sphere. It is a more generic term that allows for only some portions of the surface of the ball having essentially spherical surfaces while other portions can deviate significantly from having spherical surfaces. Spherical surfaces are preferred for some of the orientational flexibility and sealing of the contact surfaces between a ball and a structure that can be repositioned and locked in position relative to the ball perhaps by swiveling. A shell is something that at least partially surrounds a ball. Contacting surfaces between the exterior of a ball and the interior of a shell are preferably spherical surface segments of about the same diameter for increased frictional grip when starting the fixing process or for providing a sealing surface to block the interior of the assembly from biological contamination. While having the flexibility to position the axis of a prosthetic screw and Ti base without restriction at an angle of <NUM> degrees with respect to the axis of an implant and at any rotation angle around either axis may be preferred, mating elements of the implant, ball, shell or Ti base may be designed to restrict this omnidirectional angular flexibility. Such restrictive modifications are known in the art and may be used with some inventive concepts disclosed here.

It is common in prosthodontics to secure threaded elements to a desired torque or to have some elements fastened to a higher or lower torque than some other combination of elements. For example, if three elements are screwed together in sequence, it is common to prefer that the first two are assembled with a higher torque so that the third element can be attached or removed without affecting the attachment of the first two. In some cases, torques are quantified with torque wrenches and sometimes the experience of the practitioner is used to determine when the torque is sufficient for functioning as desired. For the purposes of this disclosure, these torques will be considered to be predefined whether assessed in a quantitative or a qualitative manner. If a quantitative minimum torque value or acceptable range is specified to be essential, measurement with a tool or with some indication structure built into the parts is expected. In some embodiments, it may be desirable to prevent excessive torquing that could cause structural or biological stress on the implant seating or prosthesis through controlled failure of sacrificial elements. This controlled mechanical failure may result from both intentionally weakened structures or characterization of inherent failure characteristics of uniform structures.

Other terms in the specification and claims of this application should be interpreted using generally accepted, common meanings qualified by any contextual language where they are used. The terms "a" or "an", as used herein, are defined as one or as more than one. The term "plurality", as used herein, is defined as two or as more than two. The term "another", as used herein, is defined as at least a second or more. The terms "including" and/or "having", as used herein, are defined as comprising (i.e., open language). The term "coupled", as used herein, is defined as connected, although not necessarily directly, and not necessarily mechanically. The terms "about" and "essentially" mean ±<NUM> percent. Reference throughout this document to "one embodiment", "certain embodiments", and "an embodiment" or similar terms means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of such phrases or in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments without limitation. The term "or" as used herein is to be interpreted as an inclusive or meaning any one or any combination. Therefore, "A, B or C" means any of the following: "A; B; C; A and B; A and C; B and C; A, B and C". An exception to this definition will occur only when a combination of elements, functions, steps or acts are in some way inherently mutually exclusive.

The drawings featured in the figures are for the purpose of illustrating certain convenient embodiments of the present invention and are not to be considered as limitation thereto. The term "means" preceding a present participle of an operation indicates a desired function for which there is one or more embodiments, i.e., one or more methods, devices, or apparatuses for achieving the desired function and that one skilled in the art could select from these or their equivalent in view of the disclosure herein and use of the term "means" is not intended to be limiting. Other objects, features, embodiments and/or advantages of the invention will be apparent from the following specification taken in conjunction with the following drawings.

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> illustrate an exploded view of one embodiment of an omnidirectional multi-unit abutment <NUM> comprising four parts: an abutment base <NUM>, swivel mount <NUM>, swivel base <NUM>, and lock screw <NUM>. A representative Ti base <NUM> and prosthetic screw <NUM> are also shown in the exploded drawings of <FIG>. This omnidirectional multi-unit abutment assembly <NUM> 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, PE!), 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. shows the elements of <FIG> except for the prosthetic screw <NUM> in a linear orientation. illustrates internal features of the assembly of <FIG> along the longitudinal cross-section designator A-A of <FIG>. Note that the presence of the Ti base <NUM> is shown for illustration purposes in <FIG>. Ti base <NUM> is ultimately retained in the prosthesis (not shown) and attached to the omnidirectional multi-unit abutment using prosthetic screw <NUM> as shown in <FIG>. Prosthetic screw <NUM> may be a permanent screw or may be a provisional fastener of the type described in co-owned <CIT> and other applications related by continuity. <FIG> is a perspective view of the assembly of <FIG> in a linear configuration. <FIG> is a side view of the embodiment tilted at about <NUM> degrees. <FIG> show different stages in the installation of this embodiment into an implant and adjustment.

The abutment base <NUM> includes a ball or spherical portion <NUM> which may be approximately <NUM> in diameter with an abutment base drive feature <NUM> 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 <NUM>. Other types of drive tools may be used. At the distal end of the abutment base <NUM> is a threaded portion <NUM> for attachment to female threads of an implant <NUM> that is secured into the patient's jaw bone. The implant <NUM> 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 <NUM> illustrated in <FIG> with female threading is a very common design, but the abutment base attachment <NUM> and seating <NUM> may be adapted to conform to other implants.

The swivel base <NUM> includes an aperture <NUM> and an interior curvature portion <NUM> which is sized and shaped to essentially match the curvature of the ball portion <NUM> of the abutment base <NUM>. The swivel mount <NUM> illustrated includes internal threading <NUM> for attaching to the external threads <NUM> of the lock screw <NUM>. It also includes a Ti base seating feature <NUM> for supporting and orienting the Ti base <NUM> when it is mounted with the prosthetic screw to the omnidirectional multi-unit abutment <NUM>. The swivel mount may optionally include engagement features <NUM> 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 <NUM>. 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 <NUM> 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.

The ball portion <NUM> of the abutment base <NUM> may be captured between the swivel base <NUM> and the swivel mount <NUM> which comprise a swivel shell around the ball portion <NUM> with the abutment base screw thread portion <NUM> extending through swivel base aperture <NUM>. For this insertion process, the aperture <NUM> must be larger than the abutment seat projection <NUM>. The swivel base <NUM> and swivel mount <NUM> are preferentially joined at interface joint <NUM> by continuous welding or spot welding, for example, with a laser after positioning around ball <NUM> to form base assembly <NUM>. 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 <NUM> within a shell. As shown in the cross-sectional view of <FIG>, after joining, the mechanical design of the internal curvature <NUM> and aperture <NUM> of the assembled swivel base <NUM> and swivel mount <NUM> may be designed to prevent the ball portion <NUM> of the abutment base from escaping the swivel shell. The relative sizes and shapes of the aperture <NUM> and the size and shape of the abutment base <NUM> at the abutment seat projection <NUM> determine the range of tilt possible. In general, if the swivel base aperture <NUM> and the minor diameter or width of the internal threads <NUM> of the swivel mount are both less than the width of the ball <NUM>, then the ball <NUM> is captured within a shell absent the lock screw <NUM>.

The lock screw <NUM> illustrated has external threads <NUM> to engage the internal threads <NUM> of the swivel mount <NUM>. These threads may be, for example, m3x0. <NUM> size. Lock screw <NUM> also has internal threading <NUM> for attaching the prosthetic screw <NUM> and an internal drive feature <NUM> for tool attachment to tighten the lock screw <NUM> in the swivel mount <NUM>. Representative prosthetic screw sizes include m1. <NUM>×<NUM> threads, m1.6x0. <NUM>, UNF <NUM>-<NUM>, etc. Drive feature <NUM> may be a socket accommodating common dental drivers including Torx T5 or T6, <NUM>" to <NUM>" hex or square drivers, or similarly sized straight and star drivers. As illustrated, the internal threading <NUM> and drive feature <NUM> 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.

The swivel base <NUM> is configured to engage a segment of the spherical ball feature <NUM> when lock screw <NUM> 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 <NUM>-degree cone as shown in <FIG> and <FIG>. The tilt magnitude and orientations of adjustment allowed are a design choice, although <NUM> degrees of tilt is generally sufficient for most clinical applications. As shown in this embodiment, the swivel base aperture <NUM> and the aperture with threading <NUM> in the swivel mount <NUM> are smaller than the diameter of the ball portion <NUM>. In this case, the ball portion of the abutment base <NUM> may be loosely captured by the swivel base <NUM> and swivel mount <NUM> when these two parts are mutually attached. That is, the lock screw <NUM> does not have to be attached to the swivel mount <NUM> to have a shell that captures the ball portion <NUM> with the illustrated embodiment. This is a design option, not a requirement for benefitting from the inventive concepts of this disclosure.

The cross-sectional view in <FIG> of this omnidirectional multi-unit abutment embodiment with Ti base <NUM> may be used to illustrate some of the advantages of the preferred geometric relationships between elements. As shown, the ball portion <NUM> is spherical throughout the range of motion of the shell formed by the swivel base <NUM>, swivel mount <NUM> and lock screw <NUM>. The tilt range limitation due to interference of the swivel base <NUM> proximate the aperture and the abutment base <NUM> surface <NUM> near the abutment seat <NUM> has been labeled as angle b in <FIG> and <FIG>. The interior curvature of the swivel mount <NUM> is essentially the same as that of the ball portion <NUM>. The lock screw <NUM> also has essentially the same curvature as the ball <NUM> in the area of contact. The interior curvature <NUM> of the swivel mount <NUM> is preferentially slightly larger than the curvature of the ball <NUM>. As a result, when the lock screw <NUM> is tightened, the ball portion <NUM> is contacting the interior curvature <NUM> of the swivel base <NUM> and a corresponding interior curvature of the lock screw <NUM>. Since the interior curvature of the swivel mount <NUM> is larger, it does not contact the ball when the lock screw <NUM> 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>, the lock screw <NUM> also provides an equivalent circular seal with the ball portion <NUM>. As illustrated in the maximum tilt condition of <FIG>, the continuous seal of the swivel base <NUM> to the ball is maintained. However, the seal of the lock screw <NUM> to the ball <NUM> is not continuous due to the abutment drive feature <NUM>. However, when the Ti base <NUM> and prosthetic screw <NUM> are applied to the omnidirectional multi-unit abutment, the abutment drive feature <NUM> is effectively sealed.

The relatively large ring contact of the hollow lock screw <NUM> to the ball <NUM> distributes the clamping force over a larger area than the concentrated contact of a solid set screw. The extended contact and matching curvature <NUM> of the swivel base to the ball <NUM> has been determined to have sufficient frictional grab to allow tightening the lock screw <NUM> in excess of <NUM> Ncm without holding the swivel base <NUM> or swivel mount <NUM> when parts are made of titanium. The relatively large contact area also minimizes distortion of the ball <NUM> 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 <NUM> geometry. The relatively large outer diameter of the locking screw <NUM> also provides sufficient wall thickness between internal threading <NUM> and external threading <NUM> for mechanical strength for applying torque to the lock screw <NUM> with drive tool sizes comparable to the width of the threads of the prosthetic screw <NUM>.

A relatively large lock screw <NUM> provides a sufficient number of engaged external lock screw threads <NUM> with the internal threads <NUM> of the swivel mount to provide stable clamping forces on the ball <NUM>. Although threads (not illustrated) can also be used at the joint <NUM> between the swivel mount <NUM> and swivel base <NUM>, 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>. However, if it is desirable to prevent over-torquing of the lock screw <NUM>, limited engagement of screw threads between the swivel mount <NUM> and swivel base <NUM> 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 <NUM> size in the swivel mount, and/or introducing intentionally thinner wall sections in the swivel base proximate the aperture <NUM> 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.

The hollow style lock screw <NUM> and drive geometries illustrated in <FIG> provide benefits in dental system installation and maintenance. After the swivel base <NUM> is attached to the swivel mount <NUM> to form base assembly <NUM>, the ball portion <NUM> of the implant base is captured by the shell portion formed by the swivel mount <NUM> and swivel base <NUM>. The lock screw <NUM> may be started into the swivel mount <NUM> and rotated enough to secure it but without contacting the ball portion <NUM> to form the omnidirectional multi-unit abutment assembly <NUM>. The Ti base <NUM> may be optionally placed on top of the omnidirectional multi-unit abutment assembly and parts aligned along a common axis as shown in <FIG>. Ti base <NUM> is not required to be in place during installation and orientation of the abutment base <NUM>, swivel base <NUM>, swivel mount <NUM> and lock screw <NUM>. Thus aligned, a drive tool <NUM> may be inserted through the Ti base <NUM> and the lock screw <NUM> to engage the drive feature <NUM> of the abutment base <NUM> as illustrated in <FIG>. Note that it may be necessary to slightly rotate drive tool <NUM> after passing through the lock screw <NUM> in order to engage the abutment base drive interface <NUM>. Preferably the engagement fit of the drive tool <NUM> and abutment base drive feature <NUM> has sufficient friction to cause the omnidirectional multi-unit abutment <NUM> to remain on the drive tool <NUM> to present the omnidirectional multi-unit abutment assembly to the implant <NUM> as shown in <FIG>. A slight torquing of the lock screw <NUM> in the unwind direction may help in this retention. As the drive tool <NUM> is rotated, the abutment base threads <NUM> engage the implant <NUM> and the omnidirectional multi-unit abutment assembly may be screwed down to attain the desired seating of the abutment seat <NUM> to the implant <NUM>. Since the drive tool engages both the abutment base <NUM> and lock screw <NUM>, these parts rotate simultaneously. Since the lock screw <NUM> position is not changing with respect to the abutment base <NUM>, the ball portion <NUM> is not being gripped between the swivel base <NUM> and the lock screw <NUM>. The rotational force from the drive tool <NUM> is drives the abutment base threads <NUM> deeper into the implant <NUM>.

The seating portion <NUM> of the abutment base that contacts the implant can be modified to match the seating geometry of fixed angle abutments. The drive feature <NUM> allows for securing the abutment base <NUM> threaded portion <NUM> to the implant <NUM>. The tightening of the abutment base <NUM> to the implant may proceed until the desired seating pressure at the abutment seat <NUM> is obtained. A representative torque value is about <NUM> 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.

As shown in <FIG>, once the abutment base <NUM> is secured to the implant <NUM>, the linear configuration of <FIG> is no longer needed. The tilt and azimuth angle of the swivel mount <NUM> to receive Ti base <NUM> desired for prosthesis attachment can be selected by movement of drive tool <NUM> which is inserted into lock screw <NUM>. Rotating drive tool <NUM> causes the lock screw <NUM> and swivel base <NUM> to clamp ball portion <NUM> and lock the angulation of the omnidirectional multi-unit abutment <NUM>. Engagement features <NUM> may be included to prevent the lock-screw and swivel base from rotating while the lock screw <NUM> 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 <NUM> 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 <NUM>. A coaxial two-piece tool that engages the anti-rotation features and includes a drive tool similar to <NUM> may be used to orient and tighten the swivel mount <NUM> and lock screw <NUM> in position on the ball portion <NUM> of the abutment base <NUM>. Having the Ti base <NUM> included in the arrangement of <FIG> may be convenient for azimuthal selection.

The drive feature <NUM> of the lock screw <NUM> is preferably accessible through the Ti base <NUM> in both a provisional and the final prostheses. This allows moving and retorquing the lock screw <NUM> 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 <NUM> within a plurality of omnidirectional multi-unit abutments <NUM>. From a comparison of the drive tool dimension d1 shown in the inset <FIG> to the drive tool dimension d2 shown in the inset <FIG>, the drive tool <NUM> shown in <FIG> is larger than the drive tool <NUM> in <FIG>. This is not required. A benefit of using two different sizes, for example, a T5 driver <NUM> to drive the abutment base <NUM> and a T6 driver <NUM> for securing the lock screw <NUM> provides extra clearance in the lock screw <NUM> while driving the abutment base. Since the torque used for driving the abutment base <NUM> may be chosen to be higher than the torque used for the lock screw <NUM>, a first torque wrench with drive tool <NUM> and a second torque wrench with drive tool <NUM> may help ensure the desired torques are obtained. Of course, in order to allow the assembled omnidirectional multi-unit abutment <NUM> to be installed into the implant <NUM> as shown in <FIG>, the size and shape of the drive tool <NUM> must pass through the lock screw <NUM>. The drive tool <NUM> in <FIG> is prevented from passing completely through the lock screw <NUM> since the lock screw internal drive interface <NUM> shown does not extend all the way to the distal side of the lock screw <NUM>. This is a design choice.

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 <NUM> and the lock screw <NUM>. If the abutment base drive interface <NUM> and lock screw drive interface <NUM> are the same size and shape, then one tool can be used for drive tool <NUM> and <NUM>. In this case, after driving the abutment base <NUM> into the implant <NUM> as in <FIG>, drive tool <NUM> would only need to be extracted just enough to disengage with the abutment base drive interface <NUM> before repositioning it to lock the omnidirectional multi-unit abutment <NUM> position by rotating lock screw <NUM>. 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 <NUM> is generally different than drive tool <NUM>, using the same torque magnitude for the abutment base <NUM> and lock screw <NUM> 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 <NUM> compared to the lock screw drive interface <NUM>, 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.

<FIG> shows is a cross-sectional view of the omnidirectional multi-unit abutment assembly <NUM> including prosthetic screw <NUM> that retains Ti base <NUM>. Prosthetic screw <NUM> may be replaced with a separable fastener (not shown) as described in the referenced <CIT> to facilitate positioning of the Ti base <NUM> into the prosthesis with a lift off process. Note that even after the Ti base <NUM> is incorporated into the prosthesis, it is possible to access the lock screw drive interface <NUM> by removing the prosthetic screw <NUM>. This is essentially changing the configuration from <FIG>. This benefit will be described in more detail after other embodiments are presented.

A variation of the embodiment shown in <FIG>, is illustrated in <FIG>. From a practical design standpoint, given constraints of conventional abutment diameters, seating heights (the distance between the seating surface <NUM> for the Ti base <NUM> and implant seating surface <NUM> in the first embodiment) and other dimensional constraints, omnidirectional multi-unit abutment designs may also include embodiments in which the abutment base <NUM> and ball or spherical feature <NUM> are initially separate components. In the embodiment of <FIG> the ball is approximately <NUM> diameter. A nominal seating height of approximately <NUM> is illustrated in the figures.

The second embodiment illustrated in <FIG> is shown with about the same dimensions to work with the same implant <NUM> and Ti bases <NUM> as the omnidirectional multi-unit abutment assembly <NUM> shown in <FIG>. The seating height between the abutment seat <NUM> and Ti base seat <NUM> is also comparable. The major difference is that the swivel <NUM> is captured between portions of a two-part abutment base <NUM>. The abutment base <NUM> in <FIG> comprises a separate ball portion <NUM> attached to a stem portion <NUM>. A discrete <NUM> 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> includes a ball <NUM> with drive interface <NUM> with distal mounting hole <NUM> that is attached to a mating post feature <NUM> of the abutment base stem portion <NUM>. After inserting ball <NUM> into swivel <NUM>, ball <NUM> is assembled to base stem portion <NUM> by any form of mechanical engagement such as press-fitting, heat-shrinking, laser-welding, adhesives, or combinations thereof. For example, ball <NUM> may have a light press-fit onto post <NUM> and a small radial laser-weld at interface <NUM>. This method reliably joins the ball to the base, while minimizing mechanical precision, providing a fillet at the mating joint <NUM>, and sealing this joint from liquid ingress.

In the embodiment illustrated, the minor diameter of the internal threading <NUM> of the swivel <NUM> is large enough to allow ball <NUM> to be inserted through the internal threads <NUM> of the swivel mount <NUM>. The drive interface <NUM> may be used to orient the ball for assembly. After capturing the swivel <NUM> and installing and tightening the lock screw <NUM>, the ball <NUM> contacts the swivel <NUM> along a seating surface <NUM>. Approximately <NUM> degrees of seating/interference surface is illustrated in <FIG>. The lock screw <NUM> also makes contact with the ball <NUM> along interface <NUM>. Various surface finishes and mechanical features may be employed to enhance the locking ability of mating surfaces <NUM> and <NUM> to ball <NUM>, such as surface texture, ridges, or ribs. Note that this approach of capturing the swivel <NUM> to the ball prevents the swivel <NUM> from falling off the ball <NUM>. The swivel <NUM> contacts the distal surface of the ball similar to the swivel base <NUM> of the first embodiment of <FIG>, but also provides the Ti base seat <NUM> to support the Ti base <NUM> in a known orientation analogous to that provided by of the previous Ti base seat <NUM> of swivel mount <NUM>.

The lock screw <NUM> is similar to the lock screw <NUM> in the first embodiment. It contains prosthetic screw threads <NUM>, drive socket feature <NUM>, seating surface <NUM> and external threads <NUM>. The proximal end of the ball portion <NUM> includes drive socket feature <NUM> that may be accessed through the lock screw <NUM> similar to lock screw <NUM> described above. When lock screw <NUM> is tightened using drive feature <NUM>, the swivel <NUM> engages a seating surface <NUM> of the ball <NUM> which allows for the lock screw <NUM> to fix the swivel <NUM> in the ideal omnidirectional orientation up to thirty degrees off the implant axis and at the desired azimuthal angle. Again, Ti base <NUM> 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 <NUM> and drive features <NUM> and <NUM> and <NUM>, it is possible to utilize a single drive tool for the three steps of tightening the abutment base <NUM> into the implant (not shown), locking the orientation of the swivel <NUM> with lock screw <NUM>, and tightening the prosthetic screw <NUM>. For example, a single T5 drive tool typical of an M1. <NUM> × <NUM> prosthetic screw <NUM> with threading <NUM> can be used if the drive interfaces <NUM> , <NUM> and <NUM> also have T5 socket characteristics. Of course, in this case, the lock screw drive interface <NUM> would need to extend through the lock screw <NUM> (not shown) in order to engage the abutment base drive socket feature <NUM>. The portion of the M1. <NUM> 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.

By assembling the ball <NUM> to the abutment base <NUM>, the width of the abutment base <NUM> at the implant seating location <NUM> may be larger than in the first embodiment. In the first embodiment, the threaded end <NUM> of the abutment base <NUM> was inserted into the swivel base aperture <NUM> to contact the ball portion <NUM>. The ball portion <NUM> was captured by joining the swivel mount <NUM> to the swivel base <NUM>. By merging the characteristics of the swivel base <NUM> and swivel mount <NUM> into a one-piece swivel <NUM> 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 <NUM> aperture. In the embodiment of <FIG>, the minor diameter of the lock screw external threads <NUM> must be larger than the diameter of the ball <NUM> to allow the ball to be inserted through the swivel <NUM> to be joined to the abutment base <NUM>. A comparison of <FIG> with <FIG> shows that this results in a shorter depth for engaging threading between the swivel <NUM> and lock screw <NUM>.

Another approach for capturing a swivel shell component to an abutment base with a ball feature is shown in <FIG>. In this embodiment, the abutment base assembly <NUM> is fabricated from swivel <NUM> and a ball with taper stem <NUM> that has a ball feature <NUM> with drive feature <NUM> at the proximal end and tapered stem <NUM> at the distal end. The tapered stem <NUM> is joined to a base <NUM> having a tapered socket <NUM> at the proximal end and an abutment base screw thread <NUM> at the distal end. The widest part of the ball with taper stem <NUM> is the diameter of the ball <NUM>. Swivel <NUM> is captured by inserting the tapered stem <NUM> into the proximal side of the swivel <NUM> before inserting the tapered stem <NUM> into the tapered socket <NUM>.

<FIG> show the abutment base assembly <NUM>. As before, the tapered stem <NUM> and base <NUM> may be joined with different techniques. However, including welding at interface <NUM> is preferred. A comparison of <FIG> shows that the ball portion <NUM> of the ball with tapered stem <NUM> may have improved structural stability compared to abutment base ball <NUM>. 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.

The lock screw <NUM> illustrated in <FIG> differs from the lock screws <NUM> and <NUM> in previous embodiments by including a hex drive feature <NUM> on its exterior surface near the proximal end. This hex drive feature <NUM> is provided to aid removal of a failed installation. For example, if the prosthetic screw stem <NUM> breaks off in the lock screw <NUM>, the lock screw drive interface <NUM> may be plugged so that the drive tool <NUM> used for installing the omnidirectional multi-unit abutment cannot be inserted. As an alternative to removing the broken stem <NUM>, a wrench (not shown) could be applied to the hex feature <NUM> to remove the lock screw <NUM>. Of course, these hex features <NUM> would generally not be accessible with the Ti base <NUM> in position on the omnidirectional multi-unit abutment. As a result, the lock screw drive interface <NUM> 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 <NUM> on the side of swivel <NUM> to help with removal of the plugged lock nut <NUM> since the Ti base <NUM> would not be covering it.

<FIG> is a top plan view of the lock screw <NUM>. At the outer edge is the lock screw exterior threading <NUM> and at the center is the lock screw internal drive interface <NUM> which is shown as a Torx style. The major diameter <NUM> (dotted line) and minor diameter arc <NUM> of the lock screw internal threads <NUM> are shown. The minor diameter <NUM> is not a continuous circle but a series of discontinuous arc segments due to the lock screw internal drive interface <NUM> that is axially overlapping the lock screw internal threading <NUM>. Note that the lock screw <NUM> has the lock screw internal drive interface <NUM> and the internal threading <NUM> extending all the way through the lock screw <NUM>. In other words, there is essentially complete axial overlap of them through the thickness of the lock screw <NUM> so that a sufficiently long prosthetic screw thread <NUM> and a drive tool <NUM> can both pass through the thickness of the lock screw <NUM>. The amount of material in the lock screw <NUM> that is available for the drive tool <NUM> to apply torque to lock the orientation of the omnidirectional multi-unit abutment <NUM> corresponds to the volume bounded by the major diameter <NUM> and minor diameter <NUM> of the internal screw threads <NUM> minus the material removed to provide the lock screw drive interface <NUM> socket for the drive tool <NUM> (not illustrated). The size and shape of the drive tool interface <NUM> can be modified to change the strength of the remaining internal threads <NUM> for holding the prosthetic screw <NUM> and maximum torque application to the lock screw <NUM> to fix orientation before damaging the internal threads <NUM>.

<FIG> is a top plan view of the lock screw <NUM> with an alternate lock screw internal drive interface <NUM>. This drive tool interface <NUM> has <NUM>-lobes instead of the <NUM> 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> is sufficient to show that more of the internal threading is retained compared to <FIG>. 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 <NUM> and lock screw drive interface <NUM> that allows the final alignment and locking of the omnidirectional multi-unit abutment <NUM> to be done with the prosthesis in place.

<FIG> illustrates a <NUM>-lobe drive tip <NUM> with the lock screw <NUM> of <FIG> and an abutment base <NUM> with a matching <NUM>-lobe drive interface <NUM>. The other parts of the omnidirectional multi-unit abutment <NUM> are not shown for clarity. Since drive tip <NUM> is sized to pass through the lock screw <NUM>, it can be used to drive abutment base <NUM> into the implant <NUM> (not shown). Since the drive tip is sized to pass through the Ti base aperture <NUM> (not shown), it can also rotate the lock screw <NUM> to fix the position of the omnidirectional multi-unit abutment through the prosthesis (not shown) in which the Ti base <NUM> (not shown) is embedded.

<FIG> illustrates another embodiment of a two-part abutment base <NUM> that is assembled to capture a swivel <NUM>. In this embodiment, the ball portion <NUM> and the abutment base screw threads <NUM> are included in an abutment base stem <NUM>. The distal end of the abutment ball base stem is inserted into the swivel <NUM> and then into a hollow sleeve <NUM> matching the interface requirements of the abutment <NUM> that will be used. The sleeve <NUM> has a maximum width that is larger than the diameter of the ball portion <NUM>. As a result, when sleeve <NUM> is joined to abutment base stem <NUM>, swivel <NUM> is captured. Any of the various joining operations mentioned above may be used, although including welding at interface <NUM> as shown on <FIG> is preferred. Also shown in <FIG> are two critical dimensions for the assembly process above. The minimum diameter "d" of the through aperture of the swivel <NUM> must be larger than the maximum width "c" of the abutment base stem <NUM> below the ball portion. Due to the similarities of this embodiment to previous ones, the other parts and characteristics will not be described.

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.

<FIG> shows a cross-section of the application environment of an installed omnidirectional multi-unit abutment <NUM> of the first embodiment. The implant <NUM> has been installed in the patient's bone and soft tissue shown schematically as <NUM>. The abutment base <NUM> has been screwed into the implant <NUM> to a desired torque level. In this case, the swivel mount <NUM> has been tilted to essentially its maximum capability comparable to <FIG>. The Ti base <NUM> is embedded in the prosthesis <NUM>. The occlusal surface <NUM> of the prosthesis <NUM> is shown schematically as <NUM>. The Ti base <NUM> is seated on the swivel mount <NUM>, but the prosthetic screw <NUM> has been removed to allow the lock screw interface <NUM> to be accessible to a drive tool <NUM> through prosthetic screw access hole <NUM>. Note that while a <NUM>-lobe drive tool <NUM> is illustrated, a smaller drive tool (not shown) would be required to drive the abutment base <NUM> into the implant <NUM> 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> will be used to describe this in more detail.

Although only one implant is shown in <FIG>, 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>, removing the prosthetic screws <NUM> allow the lock screws <NUM> to be accessed and loosened with drive tool <NUM>. Applying a re-seating force to the prosthesis <NUM> from the occlusal side <NUM> will push the embedded Ti bases <NUM> against the Ti base seats <NUM> thereby redirecting the orientation of the omnidirectional multi-unit abutment. Tightening the lock screws <NUM> with the drive tool <NUM> while maintaining the reseating force on the prosthesis <NUM> will lock this orientation. The prosthetic screws <NUM> can then be reinserted and torqued to secure the Ti bases <NUM> and prosthesis <NUM> in position. If it is desirable to check the torque on the lock screws <NUM> to see if they have loosened over time, this can also be done through the Ti bases <NUM> embedded in the prosthesis <NUM>.

Similarly, if one omnidirectional multi-unit abutment <NUM> of a set fails and needs to be replaced, the prosthesis <NUM> with its embedded Ti bases <NUM> can be removed after removing all of the prosthetic screws <NUM>. Reversing the angle setting and implant attachment processes shown in <FIG> will remove the failed omnidirectional multi-unit abutment assembly100. Repeating the process of <FIG> to attach the new omnidirectional multi-unit abutment <NUM> to the implant <NUM> will result in the abutment base <NUM> being secured into the implant <NUM>, but the shell consisting of the swivel base <NUM>, swivel mount <NUM> and lock screw <NUM> will be loose. Minimal pressure on the lock screw <NUM> 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 <NUM> sufficient to engage the Ti base <NUM> in the prosthesis <NUM> and manually applying pressure to the prosthesis from the occlusal side <NUM> will reorient the newly installed omnidirectional multi-unit abutment to align with the Ti base <NUM> already installed in the prosthesis. The lock screw <NUM> can then be tightened through the aperture <NUM> in the Ti base <NUM> in proper position as shown in <FIG>. Whether the prosthetic screws <NUM> from the original omnidirectional multi-unit abutments <NUM> are used to maintain the alignment pressure on the newly installed omnidirectional multi-unit abutment <NUM> before tightening the lock screw <NUM> is optional.

Since the lock screw drive interface <NUM> is accessible through the Ti base <NUM> and prosthesis <NUM>, 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 <NUM> through the apertures <NUM> of the Ti bases <NUM> installed in the prosthesis <NUM>. In one approach, all of the prosthetic screws <NUM> are removed. While the prosthesis <NUM> remains in place, all of the omnidirectional multi-unit abutment lock screws <NUM> 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 <NUM> 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 <NUM>. Next, a single prosthetic screw <NUM> is removed to provide access to the lock screw <NUM> of the omnidirectional multi-unit abutment in that position. The lock screw <NUM> is torqued to its predetermined value. The prosthetic screw <NUM> is reinserted and torqued to the predetermined value. This is repeated until all of the omnidirectional multi-unit abutment lock screws <NUM> have been tightened and all prosthetic screws <NUM> are tightened.

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 <NUM> 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.

It is preferred that the omnidirectional multi-unit abutment <NUM> embodiments above be adapted to be compatible with Ti bases <NUM> and threaded implants <NUM> 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 <NUM> 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. <CIT> 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.

Claim 1:
A multi-unit abutment (<NUM>) for alignment and attachment of a dental prosthesis (<NUM>) to an implant (<NUM>) with a prosthetic screw (<NUM>), wherein the prosthetic screw (<NUM>, <NUM>) comprises a head (<NUM>) and a threaded shaft (<NUM>), the multi-unit abutment comprising:
an abutment base (<NUM>, <NUM>, <NUM>, <NUM>) having a longitudinal axis, the abutment base (<NUM>, <NUM>, <NUM>, <NUM>) comprising:
a proximal end comprising
a ball portion (<NUM>, <NUM>) and an abutment base drive interface (<NUM>, <NUM>, <NUM>); and
a distal end comprising
screw threads (<NUM>) for attachment to the implant (<NUM>);
a swivel shell (<NUM>, <NUM>, <NUM>) having an inner surface and an outer surface, wherein the swivel shell (<NUM>, <NUM>, <NUM>) includes a swivel aperture (<NUM>) proximate a distal end thereof and a threaded aperture (<NUM>, <NUM>) at a proximal end thereof; and
a lock screw (<NUM>, <NUM>, <NUM>) having a longitudinal axis, wherein the lock screw comprises:
a portion with external threads (<NUM>, <NUM>) compatible with the threaded aperture (<NUM>, <NUM>) of the swivel shell (<NUM>, <NUM>, <NUM>); and
a portion with internal threads (<NUM>, <NUM>) sized to engage the prosthetic screw shaft (<NUM>); and
a lock screw drive interface (<NUM>, <NUM>, <NUM>) being
a through socket for receiving a lock screw drive tool (<NUM>, <NUM>, <NUM>, <NUM>), and wherein the lock screw drive tool (<NUM>, <NUM>, <NUM>, <NUM>) has a longitudinal axis and a maximum width that is less than the maximum width of the threaded shaft (<NUM>) of the prosthetic screw (<NUM>, <NUM>); and
a Ti base (<NUM>), wherein the Ti base (<NUM>) has an aperture (<NUM>) on the proximal end that is larger than the prosthetic screw threaded shaft (<NUM>) and smaller than the prosthetic screw head (<NUM>) and a distal end that is shaped to be supported by the swivel shell (<NUM>, <NUM>, <NUM>) in a known orientation, and wherein the lock screw drive tool (<NUM>, <NUM>) is sized to pass through the aperture (<NUM>) of the Ti base (<NUM>) without interference,
wherein rotating the lock screw (<NUM>, <NUM>, <NUM>) is capable of fixing an orientation of the longitudinal axis of the lock screw (<NUM>, <NUM>, <NUM>) in an orientation that is not parallel to the longitudinal axis of the abutment base (<NUM>, <NUM>).