Patent Description:
Edentulism, the condition of being toothless to some extent, may be treated by the implantation of a dental assembly. These assemblies require certain components to rest comfortably and securely in the patient's oral cavity. The implant fixture, also known as the dental implant or simply the implant, is the part of the dental assembly that becomes fused with the patient's jaw bone. The implant is available in both cylinder and screw-type varieties and is typically made from titanium or a titanium alloy. Implant abutments are screwed onto the implant and are positioned at or above the patient's gum line. Finally, a dental prosthesis is placed over the abutment and is designed to look and function like a natural tooth.

In extreme cases, it may be necessary to replace multiple or potentially all of the teeth on the maxillary or mandibular jaw. In this case, the dental assembly may include a multi-unit prosthesis, such as a bridge or denture having multiple artificial teeth, which is coupled to the oral cavity using multiple implants. <FIG> illustrates a conventional approach for securing a multi-unit dental assembly, such as denture <NUM>, to a patient. In this case, multiple implants <NUM> are positioned in the patient's jaw. In this case, a four implant 12a-12d dental assembly is shown, but the number of implants may vary. The implants 12b, 12c in the anterior of the mouth may be positioned in the patient's gums in a generally straight line manner such that the long axis of the implant is generally perpendicular to a plane defined by the gum line. However, and as illustrated in <FIG>, in many cases the implants 12a, 12d in the posterior of the mouth are angled in order to improve bone-to-implant integration, avoid expensive bone augmentation, and to avoid contacting vital nerves.

Further, as is well known in the industry, abutments 14a-14d are then coupled to the implants 12a-12d, typically with a fixation screw <NUM>, to facilitate a coupling between the prosthesis and the implant. For the anterior region, the abutments 14b, 14c are generally straight forward in their design and include an axis that is generally parallel to the long axis of the implants 12b, 12c. The abutments 14a, 14d for the posterior region, however, are more complex due to the angling of the implants 12a, 12d in the patient's gums. In this regard, the abutments 14a, 14d are designed to alter the angle at which the prosthesis is ultimately coupled to the implant. More particularly, due to the angling of the implant in the posterior region, it is typically very difficult for a dental practitioner to insert a fixation screw into a straight-on abutment (such as that used in the anterior region) for securing the prosthesis to the implants. For this reason, the posterior abutments typically have an angled, dual axis design. The first axis generally aligns with the long axis of the implant. A first fixation screw <NUM> is then used to couple the abutment to the implant. The second axis is angled relative to the first axis and is configured to be generally perpendicular to the gum line plane, similar to the anterior abutments. In this way, the collection of abutments 14a-14d defines a generally parallel platform for receiving the denture <NUM>. To this end, the denture <NUM> includes a number of cylinders incorporated into the denture <NUM> that defines a screw-access channel for the passage of a fixation screw <NUM> for securing the denture <NUM> to the abutments 14a-14d. Because the posterior abutments 14a, 14d have the dual angle feature, the coupling of the denture <NUM> via the fixation screws <NUM> is somewhat improved.

While the conventional approach has been generally successful for its intended purposes, there are some drawbacks to the current approach. In this regard, the abutments require a complicated manufacturing process to provide the angulated feature, and thus are relatively costly. As a result, angled abutments are typically provided in only a few pre-selected angles. In this regard, current abutments are constrained to operate with either <NUM> degree or <NUM> degree angled implants. In other words, the implants must be placed in the gums at either <NUM> degrees or <NUM> degrees, which can be limiting in some instances. Moreover, the design requires an additional fixation screw, which increases the cost and provides another site for screw-loosening complications. As noted above, sometimes it can be difficult for a medical practitioner to couple the posterior abutments to the angled implants. This has prompted some manufacturers to provide a special carrier or holder to facilitate the coupling of the abutment to the implant. Furthermore, in the conventional approach outlined above, the diameter of the cylinders that define the screw-access channel must be large enough to allow the fixation screw to pass therethough. However, as the diameter of the channel increases, the strength of the prosthesis becomes more compromised. For this reason, the cylinders are typically located lingually of the biting plane of the teeth. This generates large moment forces on the denture, which can result in loosening of the dental assembly or breakage.

<CIT> describes an abutment provided with a screw access hole and a slot in its sidewall adapted to allow a driver to access a screw in the screw access hole at an angle relative to a longitudinal axis of the screw. The abutment may include a screw seat and may be connected to an implant via a screw in the screw seat. A prosthesis, which may include a driver access channel that has a diameter less than the outer diameter of the drive portion of the screw, may be placed over the abutment. The abutment comprises a cylindric body having first and second ends and a passageway therebetween. The first end is buried within the prosthesis and the second end is open to the gingival side. The second end is not flush with, or recessed below, a base surface on the gingival side. Methods of making a dental prosthesis and methods of attaching and removing the dental prosthesis from the implant are also described.

<CIT> describes an interface element for dental prostheses, consisting of a hollow cylindrical body with two different sections, one lower of greater outer diameter and another upper of smaller outer diameter, provided externally with retention circular grooves, internally a seat for the screw head which fixes the implant, and a lower base, wherein it has a side mortise which covers the upper section determining a side opening for the inclined entrance of the screw and screwdriver, whose height and width allow an inclination of up to an angle of <NUM>°, with respect to the axial shaft of the cylindrical body and freedom of lateral movement of the screwdriver of up to <NUM>°. Furthermore, it has two flat areas at diametrically opposite points of the outer surface of the lower section of greater diameter of the circular body.

For the reasons outlined above, there is a need for a dental assembly that addresses the present challenges and drawbacks. More particularly, there is a need to a multi-unit dental assembly that may be coupled to a patient's oral cavity in an improved manner.

According to a first aspect of the present invention there is provided a dental assembly according to appended claims <NUM> to <NUM>. According to a second aspect of the present invention there is provided a method of making a dental assembly according to appended claims <NUM> to <NUM>.

To these and other ends, the dental assembly configured to be coupled to a dental implant and comprises: a prosthesis including a base and a plurality of artificial teeth and defining a gingival side and an occlusal side; at least one connecting element (<NUM>) coupled to the prosthesis and configured to facilitate coupling of the dental assembly to a patient's oral cavity; wherein the at least one connecting element comprises a cylinder with a body having a first end, a second end, and a passageway extending between the first and second ends, the connecting element further comprising an opening through a sidewall of the cylinder that is open to the passageway, the first end is buried within the prosthesis and the second end is open to the gingival side of the prosthesis and is substantially flush with or recessed below a base surface on the gingival side, the dental assembly further comprising: a fixation screw in the passageway that is movable to couple the dental assembly to the implant, wherein the fixation screw (<NUM>) is encased within the dental assembly (<NUM>) such that the screw (<NUM>) cannot be separated therefrom.

The dental assembly is configured as a denture or a bridge. The prosthesis defines a gingival side and an occlusal side, an anterior region, and a posterior region. The at least one connecting element may be positioned in the posterior region of the prosthesis. The second end of the connecting element is open to the gingival side of the prosthesis and the first end is buried within the prosthesis so as not to be readily accessible from the occlusal side. However, the prosthesis may include an access channel through the base and/or one or more of the teeth so as to be open to the occlusal side of the prosthesis and open to the passageway of the connecting element. More particularly, the access channel may extend through the opening in the sidewall of the connecting element. In an advantageous aspect, the connecting element defines a cylinder axis and the access channel defines a channel axis, wherein the cylinder axis and the channel axis are in non-parallel relation to each other to define an acute angle therebetween. This angle may be between about <NUM> degrees and about <NUM> degrees. The access channel in one embodiment may have a cross dimension less than a cross dimension of the passageway of the connecting element, and less than a diameter of a fixation screw that is received in the passageway of the connecting element. The fixation screw may be encased within the dental assembly so as to be inseparable therefrom. However, the fixation screw is configured to have a limited amount of travel within the connecting element.

In an exemplary embodiment, the cylinder body includes an outer surface wherein at least a portion of the outer surface includes perturbations to facilitate retention of the connecting element to the prosthesis. The perturbations may include saw-tooth channels that define undercuts, for example. The entirety of the outer surface may include the perturbations or only a select portion thereof, such as a portion adjacent the second end of the connecting element. The outer surface may have a tapered configuration, a straight configuration, or a combination thereof. Moreover, the outer surface may include an annular groove between the first and second ends. The annular groove may be positioned between about <NUM>% and about <NUM>% of the length of the connecting element from the second end. The passageway defines an inner wall from which an annular lip may project. This defines a first cavity and a second cavity on opposite sides of the annular lip. The inner wall may have a tapered configuration, a straight configuration, or a combination thereof. For example, the second cavity may be tapered while the first cavity may be straight. The opening, which may be a slot, may be open to the first end of the connecting element and extending in a direction generally parallel to the cylinder axis. The slot length may be between about <NUM>% and about <NUM>% of the length of the connecting element. The slot width may be between about <NUM> degrees and about <NUM> degrees of a circumference of the connecting element. A flat may be formed on the outer surface of the connecting element for alignment and orientation purposes during manufacturing. Additionally, the second end of the connecting element may include an outwardly extending flange to facilitate seating of the connecting element on or within the prosthesis.

In another embodiment, a connecting element for use in a multi-unit dental assembly includes a cylinder body having a first end, a second end, and a sidewall; a passageway extending between the first and second ends; and an opening through the sidewall of the cylinder body that is open to the passageway.

In yet another embodiment, a method of making a dental assembly includes forming a prosthesis having a base and a plurality of artificial teeth, and coupling at least one connecting element to the prosthesis, wherein the at least one connecting element includes a cylinder with a body having a first end, a second end, and a passageway extending between the first and second ends, the connecting element further comprising an opening through a sidewall of the cylinder that is open to the passageway. In an exemplary method, a digital workflow procedure may be used to make the dental assembly. In this regard, the method may further include providing data representing a digital scan of a patient's oral cavity; importing the data into a software program on a computer; generating a computer model of the prosthesis using the software; and manufacturing the prosthesis using the computer model. Using the software, the computer model of the prosthesis may be generated with bores that are delineated by an internal boundary. The bores are configured to receive a connecting element upon the formation of the prosthesis. More particularly, the software program may include at least two libraries that provide the internal boundary of bores with different heights. In this way, the prosthetic designer may select from the two libraries such that the bores formed in the manufactured prosthesis are sized to receive a cylinder having the selected height.

In a further embodiment, a method of making a dental assembly includes forming a prosthesis having a base and a plurality of replacement teeth, the prosthesis having at least one bore configured to receive a connecting element having a first size and at least one bore configured to receive a connecting element having a second size different from the first size; providing a plurality of connecting elements, each connecting element corresponding to the first size, each connecting element further including a groove, wherein a connecting element separated at the groove results in the connecting element having the second size; separating one or more of the plurality of connecting elements at the groove; securing a connecting element having the first size to the at least one bore in the prosthesis corresponding to the first size; and securing a connecting element having the second size to the at least one bore in the prosthesis corresponding to the second size. In an exemplary method, a digital workflow procedure may be used to make the dental assembly. Similar to the above, the method may further include providing data representing a digital scan of a patient's oral cavity; importing the data into a software program on a computer; generating a computer model of the prosthesis using the software; and manufacturing the prosthesis using the computer model.

In another embodiment, a method of making a dental assembly includes forming a prosthesis having at least one replacement tooth, the prosthesis having at least one bore configured to receive an abutment having a first size or a second size different from the first size; providing an abutment having a size corresponding to the first size, each abutment having a demarcation line, wherein an abutment separated at the demarcation line results in the abutment having the second size; and determining the size of the at least one bore in the prosthesis. If the at least one bore in the prosthesis is determined to be of the first size, the method further includes securing an abutment to the at least one bore without modifying the abutment. If the at least one abutment is determined to be of the second size, the method further includes separating the abutment at the demarcation line, and securing the abutment to the at least one bore in the prosthesis.

According to an aspect of the present invention there is provided dental assembly, comprising:.

The dental assembly comprises a denture or a bridge.

Preferably the prosthesis includes an anterior region and a posterior region, wherein the at least one connecting element is in the posterior region.

Preferably the posterior region includes a pair of cylinders.

The prosthesis defines a gingival side and an occlusal side, wherein the second end of the at least one connecting element is open to the gingival side of the prosthesis and is substantially flush with or recessed below a base surface on the gingival side.

The first end of the at least one connecting element is buried within the prosthesis.

Preferably the prosthesis includes an access channel, the access channel open to the occlusal side of the prosthesis and open to the passageway of the at least one connecting element.

Preferably the access channel extends through the opening in the side wall of the cylinder.

Preferably the at least one connecting element defines a cylinder axis, and wherein the access channel defines a channel axis that forms an acute angle relative to the cylinder axis.

Preferably the acute angle is between about <NUM> degrees and about <NUM> degrees.

Preferably the access channel has a cross dimension that is less than a cross dimension of the passageway of the at least one connecting element adjacent the opening.

Preferably the dental further comprises a plurality of fixation screws for securing the dental assembly to the plurality of implants positioned a patient's oral cavity.

Preferably the at least one connecting element includes a fixation screw, wherein the fixation screw is movable within the cylinder.

Preferably the fixation screw for the at least one connecting element is inseparable from the dental assembly.

Preferably the cylinder body includes an outer surface, wherein at least a portion of the outer surface includes perturbations.

Preferably the perturbations include undercuts.

Preferably the entirety of the outer surface includes perturbations.

Preferably the outer surface has a straight configuration, a tapered configuration, or a combination thereof.

Preferably the cylinder body further includes an annular groove positioned between the first and second ends.

Preferably the annular groove is spaced from the second end between about <NUM>% and about <NUM>% of the length of the at least one connecting element.

Preferably the passageway is defined by an inner wall and includes an annular lip projecting from the inner wall.

Preferably the annular lip defines a first cavity adjacent the first end and a second cavity adjacent the second end.

Preferably the inner wall in the second cavity has a tapered configuration.

Preferably the inner wall in the first cavity has a straight configuration.

Preferably the annular lip is spaced from the second end between about <NUM>% and about <NUM>% of the length of the at least on connecting element.

Preferably the opening is open to the first end of the cylinder.

Preferably the opening includes a slot and the slot has a length between about <NUM>% and about <NUM>% of the length of the cylinder.

Preferably the opening includes a slot and the slot has a width between about <NUM> degrees and about <NUM> degrees of a circumference of the cylinder.

Preferably the cylinder body includes an outer surface, the outer surface having a flat formed therein.

Preferably the flat is opposite to the opening.

Preferably the dental assembly further comprises at least one implant configured to be positioned in the jaw of the patient.

Preferably the dental assembly further comprises at least one abutment configured to be coupled to the at least one implant.

Preferably the abutment is an angled abutment.

According to another aspect of the present invention there is provided a connecting element for use in a multi-unit dental assembly, comprising:.

Preferably the second end of the cylinder body includes an outwardly extending flange.

According to a further aspect of the present invention there is provided a method of making a dental assembly, comprising:.

forming a prosthesis having a base and a plurality of artificial teeth; and.

coupling at least one connecting element to the prosthesis, wherein the at least one connecting element comprises a cylinder with a body having a first end, a second end, and a passageway extending between the first and second ends, the connecting element further comprising an opening through a sidewall of the cylinder that is open to the passageway.

Preferably forming the prosthesis includes forming a denture or a bridge.

Preferably coupling the at least one connecting element further comprises coupling the at least one connecting element to the prosthesis such that the first end is buried within the prosthesis.

Preferably the step of forming the prosthesis further comprises forming an access channel in the prosthesis having a first end open to an occlusal side of the prosthesis and a second end open to the passageway of the at least one connecting element and extending through the opening.

Preferably the method further comprises forming the access channel to have a channel axis that forms and acute angle with a cylinder axis defined by the at least one connecting element.

Preferably the method further comprises forming the access channel to have a cross dimension less than a cross dimension of the passageway of the at least one connecting element.

Preferably coupling the at least one connecting element further comprises coupling the at least one connecting element to the prosthesis so as to encase a fixation screw within the connecting element such that the fixation screw is inseparable from the dental assembly.

Preferably coupling the at least one connecting element further comprises coupling the at least one connecting element to the prosthesis so that a cylinder axis defined by the at least one connecting element forms a non-orthogonal angle relative to a gingival side of the prosthesis.

Preferably forming the prosthesis further comprises:.

Preferably generating a computer model further comprises forming bores in the computer model of the prosthesis, wherein the bores are delineated by an internal boundary defined by the software, and wherein the bores are configured to receive a connecting element.

Preferably the software includes at least two libraries that provide the internal boundary of bores with different heights, the method further comprising selecting from the at least two libraries such that the bores in the manufactured prosthesis are sized to receive a cylinder having the selected height.

According to yet a further aspect of the present invention there is provided a method of making a dental assembly, comprising:.

Preferably generating a computer model further comprises:.

Preferably the software includes at least two libraries that provide the internal boundary of bores with different sizes, the method further comprising:.

Preferably generating a computer model further comprises:
forming at least one bore in the computer model of the prosthesis, delineated by a first internal boundary defined by the software, the first internal boundary defined so that the manufactured prosthesis is configured to receive an abutment of the first size.

Preferably the software includes at least two libraries that provide the internal boundary of bores with different sizes, the method further comprising:
selecting a first library from the at least two libraries to form the at least one bore in the computer model of the prosthesis delineated by the first internal boundary.

Preferably forming the prosthesis further comprises:
forming at least one bore in the computer model of the prosthesis, delineated by a second internal boundary defined by the software, the second internal boundary defined so that the manufactured prosthesis is configured to receive an abutment of the second size.

Preferably the software includes at least two libraries that provide the internal boundary of bores with different sizes, the method further comprising:
selecting a second library from the at least two libraries to form the at least one bore in the computer model of the prosthesis delineated by the second internal boundary.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the invention and, together with a general description of the invention given above, and the detailed description given below, serve to explain the invention.

<FIG> illustrates a multi-unit dental assembly <NUM> in accordance with an embodiment of the invention. Without being limited to a particular arrangement, the multi-unit dental assembly <NUM> may be a fixed, full-arch or partial-arch prosthesis, such as a full-arch denture or a bridge. The multi-unit dental assembly <NUM> typically includes a prosthesis having a gum-colored base <NUM> made of acrylic resin or similar materials and a plurality of artificial teeth <NUM> made of porcelain, plastic or other suitable materials as is known in the art, and at least one, and preferably a plurality of, connecting elements <NUM> coupled (e.g., permanently bonded) with the base <NUM> and/or the teeth <NUM> to facilitate coupling of the dental assembly <NUM> to the oral cavity of a patient's mouth. For example, the dental assembly <NUM> may be configured to be coupled to a plurality of implants <NUM>, with or without abutments <NUM> coupled thereto, pre-positioned in the oral cavity. The connecting elements <NUM> are configured to receive a fastener, such as a fixation screw <NUM>, for securing the dental assembly <NUM> to the implants <NUM> in the oral cavity. The connecting elements <NUM> that form part of the dental assembly <NUM> is, in the field of dentures, referred to as a cylinder. Thus the term cylinder as used herein may refer to a connecting element <NUM> that forms a permanent part of the dental assembly <NUM> and which is configured to receive a fixation screw <NUM> for securing the dental assembly to the implants <NUM> or abutments <NUM> in the oral cavity. Aspects of the present invention are directed to an improved cylinder <NUM> for use in multi-unit dental assemblies which have an off-axis feature. In this regard, the cylinders <NUM> in accordance with an aspect of the invention provide an improved way for dental practitioners to secure the dental assembly <NUM> to the oral cavity.

A cylinder <NUM> in accordance with an embodiment of the invention is illustrated in <FIG>. The cylinder <NUM> includes a generally cylindrical body <NUM> having a first end <NUM>, a second end <NUM>, and a passageway <NUM> extending between the first and second ends <NUM>, <NUM>. When the cylinder <NUM> is coupled to the dental assembly <NUM>, the first end <NUM> is adjacent an occlusal side <NUM> of the dental assembly <NUM> and the second end <NUM> is adjacent a gingival side <NUM> of the dental assembly <NUM>. In this regard, the second end <NUM> of the cylinder <NUM> is open to the gingival side <NUM> of the dental assembly <NUM> such that the passageway <NUM> is accessible from the gingival side <NUM>. The second end <NUM> is substantially flush with the base surface on the gingival side <NUM> of the dental assembly <NUM>. Alternatively, the second end <NUM> may be slightly recessed below the base surface or project slightly above the base surface on the gingival side of the dental assembly <NUM>. The first end <NUM> of the cylinder <NUM> is essentially buried within the dental assembly <NUM>, i.e., either within the base <NUM> and/or a tooth <NUM>, and may be accessible through an access channel <NUM> extending from the occlusal side <NUM> of the dental assembly <NUM> (see <FIG>). Thus, the cylinder <NUM> does not extend completely through the dental assembly <NUM>. This will be explained in more detail below.

In an exemplary embodiment, at least a portion of the outer surface <NUM> of the cylindrical body <NUM> includes perturbations that facilitate the coupling of the cylinders <NUM> to the base <NUM> and/or teeth <NUM> as described above. By way of example and without limitation, in one embodiment, the outer surface <NUM> of the cylindrical body <NUM> may include one or more saw-tooth annular channels <NUM> that define undercuts <NUM>. The annular channels <NUM> may be provided for the entire length of the cylinder <NUM>, or alternatively may be provided for only a portion of the length of the cylinder <NUM>, such as adjacent the second end <NUM> of the cylinder <NUM>. In addition, the outer surface <NUM> of the cylindrical body <NUM> may include an annular groove <NUM> located between the first and second ends <NUM>, <NUM> so as to define a first portion <NUM> (e.g., an occlusal portion) and a second portion <NUM> (e.g., a gingival portion) separated by the annular groove <NUM>. In this regard, the cylinder <NUM> may be used in different orthodontic applications where the occlusal portion <NUM> of the cylinder <NUM> may not be necessary, and therefore may be removed by a technician or the like using a grinding wheel or similar device. In this regard, the annular groove <NUM> provides a visual indicator of how much of the cylinder <NUM> should be removed in order to use the remaining portion of the cylinder in a prosthetic application. In this way, the cylinder <NUM> may be transformed quickly and easily for use in different applications requiring a cylinder. The groove <NUM> may be positioned from the second end <NUM> between about <NUM>% and about <NUM>% of the length of the cylinder <NUM>. In an exemplary embodiment and without limitation, the length of the cylinder may be about <NUM> and the annular groove <NUM> may be positioned at about <NUM> from the second end <NUM> of the cylinder <NUM>. It should be recognized, however, that the total length of the cylinder <NUM> and the relative position of the annular groove <NUM> may be varied to meet the needs of a particular application. By way of example, a dental assembly in one embodiment may include one or more cylinders having a full height (such as in the posterior of the oral cavity), and one or more cylinders having a reduced height (such as in the anterior of the oral cavity). For the reduced height cylinders, a technician may simply cut or otherwise separate a cylinder <NUM> at the groove <NUM> so as to be at the reduced height.

In various embodiments the outside surface <NUM> of the cylinder <NUM> may have a straight configuration, a tapered configuration, or a combination of the two configurations. As best illustrated in <FIG>, in an exemplary embodiment, the outside surface <NUM> of the cylinder <NUM> may have a generally tapered configuration from the second end <NUM> to the annular groove <NUM>, where the diameter of the cylinder <NUM> is greatest at the second end <NUM> and decreases in a direction toward the groove <NUM>. Moreover, in an exemplary embodiment, the diameter of the cylinder <NUM> (e.g., the outermost diameter) may be substantially constant from the annular groove <NUM> to the first end <NUM> of the cylinder <NUM>. It should be recognized, however, that in alternative embodiments, the outer surface <NUM> may be tapered or straight substantially along the entire length of the cylinder <NUM> and the invention should not be limited to any particular configuration for the outer surface <NUM>.

Turning now to the passageway <NUM> of the cylinder <NUM>, the passageway <NUM> is defined by an inner wall <NUM> extending between the first and second ends <NUM>, <NUM>. The passageway <NUM> includes an annular lip <NUM> extending radially inward of the inner wall <NUM> between the first and second ends <NUM>, <NUM> to define a first ledge or surface <NUM> (e.g., an occlusally-facing ledge) and a second ledge or surface <NUM> (e.g., a gingivally-facing ledge). Accordingly, the annular lip <NUM> defines a first cavity <NUM> (e.g., an occlusal cavity) and a second cavity <NUM> (e.g., a gingival cavity). The annular lip <NUM> may be located along the length of the cylinder <NUM> so as to be closer to the second end <NUM> than the first end <NUM>. By way of example, the annular lip <NUM> may be located between about <NUM>% and about <NUM>% of the length of the cylinder <NUM> from the second end <NUM>. As explained in more detail below, the first cavity <NUM> is configured to receive the fixation screw <NUM> (e.g., the head of the fixation screw <NUM>) and the second cavity <NUM> is configured to receive a portion of an implant <NUM> or a portion of an abutment <NUM> and to which the dental assembly <NUM> is secured. In an exemplary embodiment, the inner wall <NUM> along the second cavity <NUM> may be slightly tapered, where the inner diameter of the passageway <NUM> is greatest at the second end <NUM> and decreases in a direction toward the annular lip <NUM>. Furthermore, the diameter of the inner wall <NUM> along the first cavity <NUM> may be substantially constant. In various alternative embodiments, however, the inner wall <NUM> may have different configurations along the first and second portions <NUM>, <NUM> and remain within the scope of the present invention. For example and without limitation, the inner wall <NUM> along both the first and second portions <NUM>, <NUM> may have a straight or tapered configuration.

In accordance with an aspect of the invention, the cylinders <NUM> of the dental assembly <NUM> may include an opening, such as a slot <NUM>, through the sidewall of the cylinder <NUM> from the outer surface <NUM> to the inner wall <NUM> of the passageway <NUM>. For example, the cylinders <NUM> corresponding to the posterior implants 12a, 12d may include such a slot <NUM>. In any event, the slot <NUM> is open to the first end <NUM> of the cylinder <NUM> and extends in a direction parallel to the axis of the cylinder <NUM> toward the second end <NUM>, but stops short of the second end <NUM>. The terminating end <NUM> of the slot <NUM> may have a generally arcuate configuration so as to avoid corners and stress concentrations. The slot <NUM> may have a length from the first end <NUM> between about <NUM>% and about <NUM>% of the length of the cylinder <NUM>. Of course the length of the slot <NUM> may vary depending on the application and/or desires of the dental practitioner. In one exemplary embodiment, for example, the slot <NUM> may extend from the first end <NUM> and terminate at the annular groove <NUM> formed in the outer surface <NUM> of the cylinder <NUM>. Thus, should the cylinder <NUM> be trimmed at the groove <NUM> for use in other applications, the slot <NUM> would not be present in the remaining part of the cylinder. The slot <NUM> also includes a width (e.g., in a circumferential direction of the cylinder <NUM>). Ideally and as explained in more detail below, the width of the slot <NUM> is dictated by the diameter of the access tool or driver <NUM> used to access the fixation screw <NUM> that resides in the cylinder <NUM>. In an exemplary embodiment, however, the width of the slot may be between about <NUM> degrees and about <NUM> degrees of the circumference of the cylinder <NUM>. In any event, the diameter of the tool or driver <NUM> may be less than the largest diameter of the fixation screw <NUM>.

As illustrated in the figures, the outer surface <NUM> of the cylinder <NUM> may additionally include a flat <NUM>. The flat <NUM> may operate as an anti-rotational feature. Furthermore, the flat <NUM> may operate as an orientation marker during the manufacturing process of the dental assembly <NUM> having the cylinders <NUM> incorporated therewith. In addition, the second end <NUM> of the cylinder <NUM> may include a radially-outwardly extending flange <NUM> defining a shoulder <NUM>. The flange <NUM> facilitates seating of the cylinder <NUM> within or on the dental assembly <NUM>.

The dental assembly <NUM> may be made through two main steps. First, conventional or digital processes may be used to design the dental assembly, which will be unique to each patient and application. Then, the dental assembly may be manufactured either via conventional manufacturing techniques modified to include the driver access channel <NUM> or through computer-aided manufacturing techniques also modified to include the driver access channel <NUM>. Additional details of these processes are disclosed in co-owned <CIT>, the disclosure of which is herewith specifically mentioned. By way of example, in an exemplary embodiment the dental assembly <NUM> may be formed using a digital workflow procedure. First, a dental professional conducts an intro-oral or impression scan using digital impression techniques. The data thus generated is imported into software that determines a number of features, including implant design, abutment design (if any), and cylinder design. The software also designs the prosthesis including the desired off-axis access channel. The prosthesis is fabricated following computer-aided manufacturing procedures. In this regard, an exemplary computer-aided manufacturing process using a 3SHAPE® CAD/CAM system may be used. The data obtained from either an intra-oral or impression scan of the patient's oral cavity are imported into the CAD system. Then, a computer model of the implants <NUM>, the abutments <NUM> (if any), and the cylinders <NUM> having a slot <NUM> in its sidewall, is combined with a computer model of a prosthesis. When designing the dental assembly <NUM> digitally in the software, the height of the cylinder may be appropriately selected depending on the application. As noted above, the cylinder <NUM> includes a groove <NUM> that selectively provides two heights of the cylinder <NUM> during use. The software may include a library for each of the possible heights of the cylinder <NUM> (two in this case). The libraries that form part of the software then define the internal boundaries of a bore that is made during manufacturing of the prosthesis such that when the prosthesis is completed, the bores formed therein are configured to receive cylinders <NUM> with the selected height. If the prosthesis is designed to have a bore with internal boundaries configured to receive a cylinder of a reduced height, then once the prosthesis is made according to the design, a technician may cut or otherwise separate a cylinder <NUM> at the groove <NUM> to thereby provide a cylinder that corresponds to the internal boundaries of the bore(s) formed in the prosthesis. The technician may then secure the reduced height cylinder within the respective bore(s) in the prosthesis, through bonding for example, to form the dental assembly.

In one aspect, the dental assembly <NUM> having the cylinders <NUM> coupled thereto essentially enclose or incase the fixation screw <NUM> within the dental assembly <NUM> such that the fixation screw cannot become separated from dental assembly and fall, for example, into the patient's mouth. More particularly, the fixation screw <NUM> is prevented from passing out of the first cavity <NUM> in one direction (e.g., the gingival direction) due to the presence of the annular lip <NUM>, beyond which the head of the fixation screw <NUM> cannot pass. In the opposite direction (e.g., the occlusal direction), the fixation screw <NUM> is prevented from passing out of the first cavity <NUM> by the presence of the base <NUM> and/or teeth <NUM> combined with the fact that the tool access channel <NUM> may have a diameter smaller than the head of the fixation screw <NUM> and therefore cannot pass through the access channel <NUM>. Thus, the fixation screw <NUM> has limited travel within the cylinder so as to engage and disengage with threads associated with the implant <NUM> or abutment <NUM>, but otherwise is trapped within the dental assembly <NUM> and cannot become separated therefrom. This allows the dental assembly <NUM> to be positioned within the oral cavity and coupled to the oral cavity without concern of the fixation screws falling into the patient's mouth.

<FIG> schematically demonstrate an exemplary use of a dental assembly <NUM> having a cylinder <NUM> with a slot <NUM> in a supra-gingival application. In this regard, an implant <NUM> is positioned within the jaw of a patient in the typical manner. The implant <NUM> includes a supra-gingival region <NUM> having a screw-receiving bore <NUM> with internal threads <NUM> configured to receive a fixation screw <NUM>. The implant <NUM> may be positioned in the patient at a desired angle so as to generally define an implant axis <NUM>. If the angle is not too large, the cylinder <NUM> of the dental assembly <NUM> may be coupled directly to the implant <NUM> without an intervening abutment. For sake of clarity, the cylinder <NUM> of the dental assembly <NUM> is shown without the base <NUM> or the teeth <NUM> illustrated. In any event, the cylinder <NUM> is positioned within the dental assembly <NUM> such that when the dental assembly is positioned within the oral cavity, the cylinder axis <NUM> is generally aligned and parallel to the implant axis <NUM>. At this point, from the inside of the mouth and occlusal side <NUM> of the dental assembly <NUM>, the dental practitioner may insert the access tool or driver <NUM>, which may be a ball-point hex driver for example, through the access channel <NUM> in the dental assembly <NUM> so as to gain access to the first cavity <NUM> of the cylinder <NUM> where the fixation screw <NUM> resides. The driver <NUM> may be rotated so as to engage the fixation screw <NUM> to the internal threads in the implant <NUM>.

As clearly demonstrated in these figures, the angle at which the driver <NUM> engages the fixation screw <NUM> does not have to be parallel to the cylinder axis <NUM>. Due to the presence of the slot <NUM> in the cylinder <NUM>, the driver <NUM> may engage the fixation screw <NUM> along an axis <NUM> that is angled relative to the cylinder axis <NUM>. By way of example and without limitation, the driver axis <NUM> and the cylinder axis <NUM> may include an angle θ between approximately <NUM> degrees and about <NUM> degrees. This off-axis feature afforded by the slotted cylinder <NUM> makes the coupling of the dental assembly <NUM> to the implants in the oral cavity much easier.

<FIG> schematically demonstrate another exemplary use of a dental assembly <NUM> having a cylinder <NUM> with a slot <NUM>. In this application, an implant <NUM> is positioned within the jaw of a patient in the typical manner and an abutment <NUM> is used to couple the dental assembly <NUM> to the implant <NUM>. The implant <NUM> includes a coronal region <NUM> having a screw-receiving bore <NUM> with internal threads <NUM> configured to receive an end of the abutment <NUM>. The implant <NUM> may be positioned in the patient at a desired angle so as to generally define an implant axis <NUM>. The abutment <NUM> includes a threaded end <NUM> configured to be received in the bore <NUM> of the implant and a screw-receiving bore <NUM> at a coronal end <NUM> configured to receive a fixation screw <NUM>. The abutment <NUM> defines an abutment axis <NUM>, which in this embodiment is generally parallel with the implant axis <NUM> when the abutment <NUM> is coupled to the implant <NUM>. The cylinder <NUM> of the dental assembly <NUM> may be coupled to the abutment <NUM>. For sake of clarity, the cylinder <NUM> of the dental assembly <NUM> is shown without the base <NUM> or the teeth <NUM> illustrated. In any event, the cylinder <NUM> is positioned within the dental assembly <NUM> such that when the dental assembly is positioned within the oral cavity, the cylinder axis <NUM> is generally aligned and parallel to the abutment axis <NUM>. At this point, from the inside of the mouth and occlusal side <NUM> of the dental assembly <NUM>, the dental practitioner may insert the access tool or driver <NUM>, which may be a ball-point hex driver for example, through the access channel <NUM> in the dental assembly <NUM> so as to gain access to the first cavity <NUM> of the cylinder <NUM> where the fixation screw <NUM> resides. The driver <NUM> may be rotated so as to engage the fixation screw <NUM> to the internal threads in the abutment <NUM>.

Similar to the above, the angle at which the driver <NUM> engages the fixation screw <NUM> does not have to be parallel to the cylinder axis <NUM>. Due to the presence of the slot <NUM> in the cylinder <NUM>, the driver <NUM> may engage the fixation screw <NUM> along an axis <NUM> that is angled relative to the abutment axis <NUM>. By way of example and without limitation, the driver axis <NUM> and the abutment axis <NUM> may include an angle θ between approximately <NUM> degrees and about <NUM> degrees. This off-axis feature afforded by the slotted cylinder <NUM> makes the coupling of the dental assembly <NUM> to the implants in the oral cavity much easier.

<FIG> schematically demonstrates another exemplary use of a dental assembly <NUM> having a cylinder <NUM> with a slot <NUM>. In this application, an implant <NUM> is positioned within the jaw of a patient in the typical manner and an angled abutment <NUM> is used to couple the dental assembly <NUM> to the implant <NUM>. The use of the slotted cylinder <NUM> in combination with the angled abutment will increase the angle over which the implant may be inserted into the jaw, as discussed below. The implant <NUM> includes a coronal region <NUM> having a screw-receiving bore <NUM> with internal threads <NUM> configured to receive a fixation screw <NUM> to secure the abutment <NUM> to the implant <NUM>. The implant <NUM> may be positioned in the patient at a desired angle so as to generally define an implant axis <NUM>. The abutment <NUM> includes a distal bore <NUM> configured to receive a fixation screw that is received in the bore <NUM> of the implant <NUM>. The distal bore <NUM> defines a bore axis <NUM> that generally aligns with and is parallel to the implant axis <NUM>. The abutment <NUM> further includes a proximal screw-receiving bore <NUM> configured to receive a fixation screw <NUM>. The proximal bore <NUM> defines a bore axis <NUM>. The bore axes <NUM> and <NUM> have a non-parallel relationship and intersect at an angle β. The cylinder <NUM> of the dental assembly <NUM> may be coupled to the abutment <NUM>. For sake of clarity, the cylinder <NUM> of the dental assembly <NUM> is shown without the base <NUM> or the teeth <NUM> illustrated. In any event, the cylinder <NUM> is positioned within the dental assembly <NUM> such that when the dental assembly is positioned within the oral cavity, the cylinder axis <NUM> is generally aligned and parallel to the proximal bore axis <NUM>. At this point, from the inside of the mouth and occlusal side <NUM> of the dental assembly <NUM>, the dental practitioner may insert the access tool or driver <NUM>, which may be a ball-point hex driver for example, through the access channel <NUM> in the dental assembly <NUM> so as to gain access to the first cavity <NUM> of the cylinder <NUM> where the fixation screw <NUM> resides. The driver <NUM> may be rotated so as to engage the fixation screw <NUM> to the internal threads in the abutment <NUM>.

As demonstrated in the figures, the angle at which the driver <NUM> engages the fixation screw <NUM> does not have to be parallel to the cylinder axis <NUM>. Due to the presence of the slot <NUM> in the cylinder <NUM>, the driver <NUM> may engage the fixation screw <NUM> along an axis <NUM> that is angled relative to the proximal abutment axis <NUM>. By way of example and without limitation, the driver axis <NUM> and the abutment axis <NUM> may include an angle θ between approximately <NUM> degrees and about <NUM> degrees. When used in conjunction with the angled abutment <NUM>. The difference in angle between implant axis <NUM> and the driver axis is the sum of the angle β provided by the abutment and the angle θ provided by the slotted cylinder <NUM>. These off-axis features make the coupling of the dental assembly <NUM> to the implants in the oral cavity easier, especially when the implant <NUM> is angled relatively high when placed in the jaw.

In the description provided above, the cylinders <NUM> included a groove <NUM> that allowed the cylinders <NUM> to have two different sizes depending on the particular application. The size of the cylinders may be selected during the digital workflow process described above such that bores are formed in the manufactured prosthesis corresponding to the selected size of the cylinders. A technician would then either secure a full height cylinder within a bore in the prosthesis or cut the cylinder at the groove and then secure the reduced size cylinder within the appropriate bore in the prosthesis. In a further aspect, a similar process may be utilized as it relates to abutments. <FIG> illustrate this concept as it applies to an abutment and an associated dental assembly.

<FIG> illustrate an abutment <NUM> having two different sizes (e.g., heights) in accordance with an embodiment of the invention. The abutment <NUM> includes a cylindrical body <NUM> having a first apical end <NUM> and a second coronal end <NUM>. The apical end <NUM> is configured to engage with an implant secured within the oral cavity, and the coronal end is configured to couple to a prosthesis, as is more fully discussed in co-owned U. Application No. <NUM>/<NUM>,<NUM>. In an exemplary embodiment, at least a portion of the outer surface <NUM> of the cylindrical body <NUM> includes perturbations that facilitate the coupling of the abutment <NUM> to the prosthesis. By way of example and without limitation, in one embodiment, the outer surface <NUM> of the cylindrical body <NUM> may include one or more saw-tooth annular channels <NUM> that define undercuts <NUM> as described above. The annular channels <NUM> may be provided for the entire length of the abutment <NUM>.

However, in an exemplary embodiment, the perturbations may stop short of the coronal end <NUM> such that there are no perturbations for a length of the abutment <NUM>. Similar to the above, the last annular channel <NUM> on the outer surface <NUM> of the abutment <NUM> may represent a line of demarcation to a technician for cutting or otherwise separating the abutment <NUM> at the line of demarcation <NUM> to provide different sizes. This is similar to the groove <NUM> described above. In this regard, the last annular channel <NUM> provides a visual indicator of how much of the abutment <NUM> should be removed in order to provide the abutment with a reduced height. In this way, the abutment <NUM> may be transformed quickly and easily for use in different applications requiring abutments of different sizes. For example, a dental assembly in one embodiment may include one or more abutments having a full height (<FIG>), and one or more abutments having a reduced height (<FIG>). For the reduced height abutments, a technician may simply cut or otherwise separate an abutment at the last annular channel <NUM> so as to be at the reduced height.

Aspects of the invention are not limited to non-engaging abutments, as illustrated in <FIG>. In this regard, <FIG>, in which similar reference numbers refer to similar features, illustrates an engaging abutment <NUM> having a cylindrical body <NUM> with a first apical end <NUM> and a second coronal end <NUM>. The apical end <NUM> includes a depending member <NUM> extending downwardly from a seat <NUM> of the abutment <NUM>. The depending member <NUM> is configured to be received within the bore of the implant to which the abutment <NUM> is coupled. Similar to the above, the outer surface <NUM> of the cylindrical body <NUM> includes perturbations that facilitate the coupling of the abutment <NUM> to the prosthesis. More particularly, the last annular channel <NUM> on the outer surface <NUM> of the abutment <NUM> may represent a line of demarcation to a technician for cutting or otherwise separating the abutment <NUM> at the line of demarcation <NUM> to provide different sizes. In this regard, the last annular channel <NUM> provides a visual indicator of how much of the abutment <NUM> should be removed in order to provide the abutment with a reduced height. In this way, the abutment <NUM> may be transformed quickly and easily for use in different applications requiring abutments of different sizes.

<FIG> illustrates a dental assembly <NUM> including a prosthesis <NUM> (shown in phantom) and an abutment <NUM> having a reduced height (i.e., compare to the height of the abutment in <FIG>). In an exemplary embodiment, the dental assembly <NUM> may be formed using a digital workflow procedure, similar to that described above. In this regard, a dental professional conducts an intro-oral or impression scan using digital impression techniques. The data thus generated is imported into software that determines a number of features, including implant design and abutment design. The software also designs the prosthesis including the desired off-axis access channel. In this regard, a computer model of the implants and the abutments (abutment <NUM> in the embodiment illustrated) is combined with a computer model of a prosthesis. When designing the dental assembly <NUM> digitally in the software, the height of the abutment <NUM> may be appropriately selected depending on the application. As noted above, the abutment <NUM> includes a demarcation line <NUM> that selectively provides two heights of the abutment <NUM>. The software may include a library for each of the possible heights of the abutment <NUM>. The libraries that form part of the software then define the internal boundaries of a bore that is made during manufacturing of the prosthesis <NUM> such that when the prosthesis <NUM> is completed, the bores formed therein are configured to receive abutments <NUM> with the selected height. If the prosthesis is designed to have a bore with internal boundaries configured to receive an abutment of a reduced height, as is the case in the illustrated embodiment, then once the prosthesis <NUM> is made according to the design, a technician may cut or otherwise separate an abutment <NUM> at the demarcation line <NUM> to thereby provide an abutment that corresponds to the internal boundaries of the bore(s) formed in the prosthesis <NUM>. The technician may then secure the reduced height abutment within the respective bore(s) in the prosthesis <NUM>, through bonding for example, to form the dental assembly <NUM>.

Claim 1:
A dental assembly (<NUM>) configured to be coupled to a dental implant (<NUM>), comprising:
a prosthesis including a base (<NUM>) and a plurality of artificial teeth (<NUM>) and defining a gingival side (<NUM>) and an occlusal side (<NUM>);
at least one connecting element (<NUM>) coupled to the prosthesis and configured to facilitate coupling of the dental assembly (<NUM>) to a patient's oral cavity;
wherein the at least one connecting element (<NUM>) comprises a cylinder (<NUM>) with a body (<NUM>) having a first end (<NUM>), a second end (<NUM>), and a passageway (<NUM>) extending between the first and second ends, the connecting element (<NUM>) further comprising an opening (<NUM>) through a sidewall of the cylinder (<NUM>) that is open to the passageway (<NUM>), the first end (<NUM>) is buried within the prosthesis and the second end (<NUM>) is open to the gingival side (<NUM>) of the prosthesis and is substantially flush with or recessed below a base surface on the gingival side (<NUM>),
the dental assembly (<NUM>) further comprising:
a fixation screw (<NUM>) in the passageway (<NUM>) that is movable to couple the dental assembly (<NUM>) to the implant (<NUM>),
wherein the fixation screw (<NUM>) is encased within the dental assembly (<NUM>) such that the screw (<NUM>) cannot be separated therefrom.