Patent Description:
The present invention relates to kit for assembling a dental attachment device.

A denture is a prosthetic device constructed to replace some or all of the missing natural teeth in a patient's mouth. There are two types of dentures: a partial denture and a complete denture. The partial denture replaces a few missing teeth, while the complete denture substitutes the entire maxillary and/or mandibular arch. Dentures can be secured to dental implants or non-vital tooth roots in the mouth of a patient using either a removable or fixed attachment system. In general, a removable denture is designed and fabricated to be attached to dental implants and removed by the patient, whereas a fixed denture is attached to dental implants using cement or screws and can only be removed by a dental care provider. Accordingly, the retention forces of fixed dentures attached to dental implants are quite high and may, in some cases, be at or near the physical breaking points of the various components (e.g., in excess of <NUM> pounds of force). In contrast, retention forces for patient-removable prostheses, whether with ball attachments or <NPL>), range from about <NUM> to about <NUM> pounds.

<CIT> concerns an anchor for securing a tooth replacement.

Both the removable and fixed implant supported dentures have their advantages and disadvantages. Common advantages for both the removable and fixed dentures include: proper chewing, protection of the gums, and improvement in speech and aesthetics. Removable dentures are less costly and allow for easier cleaning to promote oral hygiene on a daily basis. However, they lack the feel of natural teeth and require more maintenance, e.g., replacement and/or adjustment of attachments and attachment components. In contrast, fixed dentures feel more like natural teeth and distribute occlusal load onto the implant and onto the jaw bone, which can be beneficial to the maintenance of the bone ridge height and thickness, bone quality, and oral and facial aesthetics. Fixed dentures also allow less food entrapment and less maintenance. Nevertheless, fixed dentures are more expensive and more difficult to maintain when comprehensive cleaning is required.

Conventional fixed dental implant attachment systems generally have higher treatment costs and involve more complicated procedures. The cost of components and laboratory fees contribute, in part, to high treatment costs that restrict access of such conventional fixed attachment systems. At the same time, complicated techniques, such as accommodating implant angulations, verification of try-ins, and difficulty with administering cement and/or screws, requires highly skilled dental care providers, which further adds to the high cost of treatment. Likewise, maintenance of conventional fixed attachment systems require time consuming procedure and high cost as the system and/or system components are typically damaged and require repair and/or removal and replacement at recall appointments.

Accordingly, there is a need in the art for a simple, low cost, screwless, cementless, fixed dental implant attachment system that is detachable by the dental care provider, but at the same time provides the benefits of a fixed dental attachment system. Disclosed herein is a unique, simple, lower cost, fixed but clinically detachable device for those patients who want the advantages of a "fixed" implant supported denture but cannot afford the current higher end options, and an entry point allowing less experienced dentists to perform fixed restorations due to an easier restorative procedure. Further described herein is a dental implant attachment device that can provide immediate load (function), through components that can be easily used with the provisional denture and then incorporated into the final restoration.

According to the invention, there is provided a kit for assembling a dental attachment device according to independent claim <NUM>. Preferable and/or optional features are set forth in the appended dependent claims. In one embodiment, a dental attachment device comprises a cap for securing a dental appliance, a retainer ring, and an abutment. The cap may be integral with a dental appliance, such as a full denture, overdenture, or partial denture. Depending on the extent of the dental appliance, one or more abutments may be present in the subject's mouth with corresponding caps being integral with the dental appliance.

Though the fixed abutment and denture cap have internal features generally consistent with the geometry of O-ring or O-ball attachment systems, it is substantially differentiated in two principal ways. First, the fixed abutment is designed to rigidly connect the prosthesis (i.e. denture) to dental implants and remain in place with only periodic removal (i.e. once or twice a year for hygiene maintenance) by a clinician with use of a tool specifically designed for that purpose. Conversely, O-ring or O-ball attachment systems provide substantially less retentive force and are designed to be used with a removable prosthesis, allowing the patient to easily take out and replace their denture on a routine (i.e., daily) basis.

Second, the fixed abutment system attaches the prosthesis directly to a dental implant thereby transferring all mastication loads to a series of implants that are integrated in the patient's jaw. The O-ring or O-ball systems are solely intended to provide resilient retention of the denture in the mouth with the prosthesis seating directly on the soft tissue, or gingiva, which absorbs substantially all intra-oral forces such as those from mastication. This is an important distinction as tissue borne dentures are typically more uncomfortable for a patient because the prosthesis can compress, abrade, and pinch the gums during chewing function.

An example of an O-ring attachment systems is described in <CIT> to inventor Mena. Mena discloses a standard O-ring attachment system comprising a ball and socket secured by an O-ring. However, Mena differentiates between existing O-ring attachment systems by placing the socket in the abutment and the ball in the prosthesis. This arrangement allows the prosthesis to engage closer to the bone and surrounding tissue, thereby lowering the stress point. Nevertheless, Mena's attachment system is still fundamental]. ) a conventional, removable O-ring attachment system.

The present invention relates to a kit for assembling a dental attachment device, comprising: (a) a cap for securing a dental appliance having an open end and an inner cavity forming a concave annular wall, and a first attachment portion; (b) an abutment comprising an upper portion and a second attachment portion, the upper portion having a convex outer surface and an open end; and (c) a removable ball having an upper end and a head portion, the removable ball is positioned between the cap and the abutment, wherein the head portion is retentively engaged in the open end of the abutment and the upper end engaged in the cap, wherein the engagement of the removable ball and the abutment has a retention force in an amount sufficient for rigid attachment of the device to the appliance and to prevent, inhibit, or reduce the risk of removal of the device by a patient using the device.

The retention force may vary and in certain embodiments is at least <NUM> pounds; or about <NUM> to about <NUM> pounds; or about <NUM> to about <NUM> pounds; or about <NUM> to about <NUM> pounds as measured using a tensile force measurement device (Instron Corp. Model <NUM>) on a single abutment. In another embodiment, the device further comprises a ring seated in the open end of the abutment and surrounding the head portion of the removable ball.

The details of the present invention, both as to its structure and operation, may be gleaned in part by study of the accompanying drawings, in which like reference numerals refer to like parts, and in which:.

While the present invention is capable of being embodied in various forms, the description below of several embodiments is made with the understanding that the present disclosure is to be considered as an exemplification of the claimed subject matter, and is not intended to limit the appended claims to the specific embodiments illustrated and/or described, and should not be construed to limit the scope or breadth of the present invention.

In certain embodiments, the present invention relates to a kit for assembling a dental attachment device comprising a cap, a ring, and an abutment. The cap secures a dental appliance and has an open end and an inner cavity that forms an annular wall surrounding a retention head. The abutment comprises an upper portion having a convex outer surface. The convex outer surface has an open end and an internal socket for receiving the ring and engaging the retention head. The dental appliance may be secured in a subject's mouth by attaching the abutment into an existing non-vital tooth root or implant, aligning the cap over the abutment, and engaging the retention head through the ring and into the socket of the abutment thereby securing the cap (and dental appliance) onto the abutment.

The fixed abutment and denture cap described herein have internal features generally consistent with the O-ring or O-ball attachment systems, however, it is substantially differentiated in two principal ways. First, the fixed abutment is designed to rigidly connect the prosthesis to dental implants and remain in place with only periodic removal by a clinician with use of a tool specifically designed for that purpose. Conversely, O-ring or O-ball attachment systems provide substantially less retentive force and are designed to be used with a removable prosthesis, allowing the patient to easily take out and replace their denture on a daily basis. Second, the fixed abutment system attaches the prosthesis directly to a dental implant thereby transferring all mastication loads to a series of implants that are integrated in the patient's jaw. In contrast, the O-ring or O-ball systems are solely intended to provide resilient retention of the denture in the mouth with the prosthesis seating directly on the soft tissue, or gingiva, which absorbs substantially all intra-oral forces such as those from mastication. This is an important distinction as tissue borne dentures are typically more uncomfortable for a patient because the prosthesis can compress, abrade and pinch the gums during chewing function.

The present invention further contemplates a kit for assembling one or more hybrid fixed dental attachment devices and one or more tools designed for periodic removal.

As detailed further below, in one aspect of the present invention exemplified in <FIG>, the design and materials of removable ball <NUM> and ring <NUM> are optimized to be retained or affixed to abutment <NUM> to provide a retention force sufficient for the device <NUM> to be secured against movement or disengagement when subjected to the normal mastication loads applied across the dental arch. Such retention force also makes removal of the denture by the patient impractical requiring a clinician to use a specifically designed tool to disengage removable ball <NUM> and cap <NUM> from abutment <NUM>. Accordingly, the retention force is an amount sufficient to handle the mastication loads of conventional fixed devices yet prevent, inhibit, or reduce the risk of removal of the device by the patient.

More specifically, the retention force can vary depending on patient needs. In one embodiment, the force ranges from about <NUM> to about <NUM> pounds as measured using a tensile force measurement (Instron Corp. Model <NUM>) device per abutment. In other embodiments, the force ranges from about <NUM> to about <NUM> pounds, or from about <NUM> to about <NUM> pounds, or from about <NUM> to about <NUM> pounds, or from about <NUM> to about <NUM> pounds. In yet another embodiment, the force is about <NUM> pounds, or about <NUM> pounds, or about <NUM> pounds, or about <NUM> pounds, or about <NUM> pounds, or about <NUM> pounds, or about <NUM> pounds, or about <NUM> pounds, or about <NUM> pounds, or about <NUM> pounds, or about <NUM> pounds, or about <NUM> pounds.

The present invention, therefore, provides a system that has the ability to adjust the amount of retention force based on the large variation of patients and clinical conditions. For example, where loading is applied to a cantilevered area of the restoration, the force of retention should be proportionally larger to ensure that the restoration does not come unseated. Further, the desired retention force can also vary based on the size of the individual and the amount of bite force that a particular individual can generate. In some cases, with low bite forces or no cantilever, it is desirable to have the retention force lower so that the restoration is less difficult to seat and remove when the clinician performs maintenance.

In non-cantilevered applications, the only significant tensile (retention) force that the assembly must withstand is the force to remove the denture from the mouth by the patient. Forces in the range of <NUM> to <NUM> pounds per abutment will be sufficient to keep the prosthesis in place in this situation. Considering the prosthesis as a beam (denture) supported by columns (abutments) on either end, the majority of forces seen at the abutment/cap junction will be compressive forces bearing towards the abutment and implant.

For cantilevered situations, the prosthesis can be considered as a beam (denture) overhanging a column (abutment) on one end and fixed to a column (abutment) on the opposite end. This "fixed" end can resist a certain application of a tensile load. When the mastication force is applied on the free or overhanging end of the beam, the closest column acts as a pivot point, causing the "fixed" end to be subjected to a tensile load. While there are a number of factors that define the resulting tensile force, the system acts, in general, according to the principles of a lever or moment arm which creates a mechanical advantage. The force applied on one end of a pivot point multiplied by the distance from the application of force to the pivot point will be equal to the distance from the pivot point to the reaction point (on the other side) multiplied by the reaction force (e.g., F1 x D1 = F2 x D2). Based on this principle, it generally holds that if the resistance to tensile (removal force) is, for example, <NUM> pounds, up to a <NUM> pound load may be applied to a cantilever that is twice as long as the span between the pivot point and the "fixed" end without overcoming the amount of retention. The possible clinical situations are infinite based on patient bite strength and ratio between the cantilever span and the supported span of the prosthesis. It is estimated from literature that high posterior bite forces will be in the range of <NUM>-<NUM> pounds. In such a case, the cantilever should have a length approximately equal to the length from the pivot point to the "fixed" end so that the fixed point is not overcome by the reaction load and becomes unseated during function. In patients with lower bite force or in an area of the mouth more anterior, where reduced leverage of the jaw muscles creates lower bite forces, the cantilever may be extended one to two times the length of the supported section or more.

To determine the retention forces of the devices disclosed herein, Applicant performed various tests as follows:
Most of the testing was conducted in cantilevered conditions with the understanding that retention forces less than <NUM> pounds can be achieved by reducing the sharpness of the edge on the retention ball and/or reducing the amount of interference between the ball and the ring. Accordingly, a retention force of about <NUM> pounds or greater was the focus of testing. Further, in many cases, an understanding of the mechanical advantage of the lever arm allowed testing for the direct pull off force on a single abutment, so the device was tested in this manner.

The retention force was measured using an Instron Dynamight force testing machine (Instron Corp. Model <NUM>) with load cell and digital controller. The cap is seated on an abutment using a specified compressive load as measured on the force testing machine. For a single abutment, the cap was pulled off of the abutment by application of a tensile load. In a cantilever situation, a compressive load was applied to the distal end of the cantilever until the "fixed" point became unseated. The peak load to unseat the cap was measured at known cantilever and supported lengths. By making this measurement, actual values were measured compared with the calculated values of a simplified mechanical advantage lever problem.

In total, seventy-seven (<NUM>) tests were conducted on various conditions under the cantilever loading situation. This included variations in retention ball and ring configurations and at various cantilever lengths or, more specifically, various ratios of cantilever to supported lengths.

The assembly of <FIG> was found to provide sufficient retention in non-cantilevered situations. In cantilever situations, the assembly of <FIG> was found to provide the necessary retentive strength to maintain the prosthesis. The sharp edge on the retention ball bit into the plastic ring and increase the retention strength. Removal of the ball in this case caused permanent damage to the ring, requiring the ring to be replaced prior to reseating of the prosthesis.

<FIG> is a graphic representation of the retention force of the device in cantilever situation:
<IMG>.

Such test data establish that the range of retention necessary to securely attach a non-cantilevered fixed hybrid denture is approximately <NUM> to <NUM> pounds per abutment. This retention level secures a fixed denture against movement or disengagement when subjected to the normal mastication loads applied across the dental arch. This range of retention also makes removal of the denture by the patient impractical requiring a clinician to use a specifically designed tool to disengage the prosthesis. Although the embodiments of <FIG> and <FIG> were tested, the retention forces apply to the other embodiments disclosed herein.

The retention necessary to secure a cantilever fixed denture (where teeth are distal to the most posterior implant) can range from <NUM> to <NUM> (and could be upward of <NUM> to <NUM> pounds) pounds per abutment based on empirical studies of cantilever forces as discussed above. The increase in retention is required to counteract the tensile forces that are imparted on the anterior abutments by the mastication forces applied to the cantilever or free end portion of the denture. This range of retention continues to make patient removal impractical and requires that a clinician use a special tool to disengage the prosthesis.

In certain embodiments of the present invention, there are two design features of the fixed hybrid attachment system that work together to achieve the above-referenced retention levels. While detailed more specifically in connection with <FIG>, the first feature achieves retention through interference with a ring engaged in the abutment with a barb-shaped removable ball, which is attached to the open-end of the cap. The retention force can be varied by using one of two-barb shaped removable ball configurations, one having a rounded or radius edge and the other having a sharp edge. The rounded or radius edge barb creates the sufficient retention for non-cantilever cases whereas the sharp edge barb provides the additional retention necessary for cantilevered cases by creating a greater interference and resistance to removal with the engaging side of the ring. The ring may be comprised of polyether ether ketone (PEEK) or other plastic.

The second retention feature comprises a metal-to-metal interface between the upper end of the abutment and the inner diameter of the cap. The mating of these two surfaces results in a galling or press fit effect that creates retentive force between the components. The metal-to-metal interference and resulting retention is achieved by the compressive biting force applied at the time of seating the prosthesis and caps on the abutments and then further through the continuous mastication forces imparted by the patient. The two retention features described above are designed to work alone or in conjunction with each other to achieve the final retention level needed for either cantilevered or non-cantilevered cases.

As mentioned, the hybrid devices of the present invention are to be removed by dental professionals using a special tool. In one embodiment, the tool is a pry tool that engages both the anterior and the posterior portions of the denture. By using the posterior abutments as a pivot point, the tool puts a compressive load on the cantilever. It also engages the anterior portion of the denture and pulls up on the underside of the prosthesis, applying a tensile load to the abutment at the "fixed" point. The tool has a long lever arm to allow the clinician to apply a reasonable amount of force to overcome the retention force on the anterior abutment(s). The tool can engage the underside of the prosthesis in a variety of ways, including but not limited to, having a bar that slides under the bottom of the denture. It can also have a flexible cord with sufficient tensile strength. This cord can be passed underneath the prosthesis and secured to the tool, creating a loop. This loop or bar will then pull up on the denture, helping to achieve a secure release. Once the front is released, the tool can be moved to the other side and used to pry up the connection in the posterior in the same way.

<FIG> illustrates one embodiment of the dental attachment device for securing a dental appliance in the mouth of a subject. <FIG> is an exploded view of the dental attachment device <NUM> comprising: a cap <NUM> for securing in the dental appliance, an abutment <NUM> for attachment to a non-vital tooth root, implant or the like, and a retainer ring <NUM>. The cap <NUM> engages with the abutment <NUM> and ring <NUM> as indicated by the center line of <FIG> to secure a dental appliance in the mouth of a subject. The abutment <NUM> may be adapted to be compatible with commercially available implants, such as the Astra implant (Astra Tech Inc. , Waltham, MA), Brånemark implant (Nobel Biocare, Zurich, Switzerland), and the Straumann implants (Straumann USA LLC, Andover, MA), or configured as a tooth root abutment, mini-implant, or in a configuration that can be adapted to an intermediary abutment, which would be secured to a dental implant. Likewise, the cap <NUM> may be designed to integrate in a dental appliance by means of, for example but not limited to, a post, a screw, or an adhesive, such as acrylic, bisacrylic, or other dental cements. Dental appliances include, but are not limited to, full dentures, overdentures, and partial dentures. Thus, depending on the extent of the dental appliance, one or more dental attachment devices <NUM> may be used to fix the dental appliance in the patient's mouth.

<FIG> illustrate one embodiment of the cap <NUM>. The cap <NUM> comprises an attachment portion <NUM> and a body portion <NUM>, the body portion <NUM> having an open end <NUM> and an inner cavity <NUM> forming an annular wall <NUM>. The body portion <NUM> may be any shape suitable for securing the cap <NUM> in a dental appliance. By way of example, <FIG> represent the outer shape as generally cup-shaped or cylindrical; however, other shapes known in the art may be employed. The inner cavity <NUM> has an inner annular surface <NUM> with a distal end portion having a concave lip <NUM>. The concave lip <NUM> is designed to correspond with the outer convex surface <NUM> of the abutment <NUM>. The annular wall <NUM> surrounds a retention head <NUM> comprising a head portion <NUM> and a shaft <NUM>. The head portion <NUM> is substantially spherical or ball-shaped. In alternative embodiments, the head portion <NUM> may be substantially polygonal or spheroid. The head portion <NUM> can project above the lip of the annular wall <NUM>. In an alternative embodiment, the head portion <NUM> can be level or below the lip of the annular wall <NUM>. The attachment portion <NUM> is provided to secure in the dental appliance by structures or techniques well known and understood by those skilled in the art, including but not limited to, a short post (<FIG>), a screw (<FIG>), or an adhesive (<FIG>). Such methods and techniques will not be repeated herein, and the figures are provided as exemplary only and not meant to limit the techniques of attaching the cap to a dental appliance.

In one embodiment, the cap <NUM> can be integral with the dental appliance and made of titanium, titanium alloys, cobalt-chromium-molybdenum alloys, stainless steel with a titanium nitride coating, zirconium, tantalum, gold, platinum, palladium, hafnium and tungsten, as well as other materials known to those of skill in the art. Both the attachment portion <NUM> and body portion <NUM> may be recessed in the dental appliance. In another embodiment, the body portion <NUM> may be partially recessed in the dental appliance. In still another embodiment, only the attachment portion <NUM> may be recessed in the dental appliance.

In one embodiment of the cap <NUM>, the head portion <NUM> has a diameter in the range of about <NUM> in to about <NUM> in. Illustratively, the diameter of the head portion <NUM> is about <NUM> in, about <NUM> in, about <NUM> in, about <NUM> in, about <NUM> in, about <NUM> in, about <NUM> in, about <NUM> in, about <NUM> in, about <NUM> in, and about <NUM> in.

<FIG> illustrate one embodiment of the abutment <NUM>. The abutment comprises an upper portion <NUM> having an open end <NUM> and a socket <NUM> for receiving the ring <NUM> and the retention head <NUM> of the cap <NUM>, a cuff portion <NUM>, and an attachment portion <NUM> for attachment to a non-vital tooth root or implant. The upper portion <NUM> has a convex outer surface <NUM> extending from the open end <NUM> to the cuff portion <NUM>. The cuff portion <NUM> may be of different heights to accommodate patients with different tissue heights. The socket <NUM> extends from the open end <NUM> through part or all of the length of the upper portion <NUM> and/or cuff portion <NUM>, and is designed to accommodate the ring <NUM> and the retention head <NUM> of the cap. The socket <NUM> has an annular lip <NUM>, an annular ring <NUM>, a cylindrical cavity <NUM>, and a hemispherical or bowl-shaped portion <NUM>. The socket <NUM> receives the ring <NUM> by snap-engagement over the annular ring <NUM> of the abutment <NUM>, which fits into the corresponding annular groove <NUM> of the ring <NUM>. The head portion <NUM> of the retention head <NUM> snap-fits through the ring <NUM> and is positioned in the hemispherical portion <NUM>, securing the cap onto the abutment. A tool-receiving bore <NUM> extends inwardly from the bottom of the socket <NUM> and can be threaded and/or polygonal, for example, hexagonal with flat faces, for engagement by a suitable tool for attaching the abutment <NUM> to a non-vital tooth root or implant. The attachment portion <NUM> can be adapted to be compatible with commercially available implants, or configured as a tooth root abutment, mini-implant, or an intermediary abutment as discussed below.

The abutment <NUM> described herein can be made of suitably strong material such as titanium, titanium alloys, cobalt-chromium-molybdenum alloys, stainless steel with a titanium nitride coating, zirconium, tantalum, gold, platinum, palladium, hafnium and tungsten, as well as other materials known to those of skill in the art. The abutment <NUM> can be made in a range of different sizes to fit a number of different implants, tooth roots, or intermediary abutment. The length of the abutment <NUM> is in the range of about <NUM> to about <NUM>. In further embodiments, the length can be about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, and about <NUM>.

The ring <NUM>, shown in <FIG>, is adapted for engagement in the socket <NUM> of the abutment <NUM> for retention of cap <NUM>, which is integral with the dental appliance. Referring to <FIG>, the ring <NUM> has two annular flanges <NUM> and <NUM> separated by an annular seat or groove <NUM> to snap-fit engaged the corresponding annular ring <NUM> in the socket <NUM> of the abutment <NUM>. The current embodiment should not limit the type of snap-fit engagement contemplated herein as other forms of snap-fit engagement are known in the art. For example, one or more annular flanges can be used to snap-fit engage the ring <NUM>, as well as other forms for snap-fit engagement. The inner surface <NUM> of the ring <NUM>, as shown in <FIG>, is inwardly tapered from both the top and bottom, forming an hour-glass shape. The ring <NUM> can be made of suitably durable and flexible material such as nylon, PEEK, delrin, and other polymers known in the art, and metals such as titanium, stainless steel, etc., as well as other materials known to those of skill in the art.

<FIG> illustrate one embodiment of the assembled dental attachment device for securing a dental appliance in the mouth of a patient. To assemble the dental attachment device, the ring <NUM> is snap fit over the annular ring <NUM> into the socket <NUM>. The cap <NUM> (which can be integral with a dental appliance) is positioned over the abutment, and the retention head <NUM> is engaged into the socket <NUM> and snap fit through the ring <NUM>. The head portion <NUM>, or a portion thereof, is received into the hemispherical or bowl-shaped portion <NUM>. The snap-fit engagement of the head portion <NUM> of the retention head <NUM> and ring <NUM> secures the cap onto the abutment. At the same time, the annular wall <NUM>, in particular the concave lip <NUM>, is engaged over the convex outer surface <NUM> of the abutment <NUM>. The frictional forces, as well as the angle of convergence, between the two corresponding surfaces <NUM> and <NUM> also secures the cap to the abutment, while at the same time allow for a range of divergence between the cap <NUM> relative to the abutment <NUM>. The tightened fit between the cap <NUM> and abutment <NUM> helps to seal the device from oral fluids in an effort to prevent microbial contamination and plaque traps.

Referring to <FIG>, when the dental attachment device <NUM> is assembled, there is a gap <NUM> between the cap <NUM> and the abutment <NUM> and a gap <NUM> between the ball-type head portion <NUM> and the hemispherical or bowl-shaped portion <NUM>, which allows the cap <NUM> to diverge or pivot or swivel relative to the abutment <NUM>. The range of divergence <NUM> between the cap <NUM> and abutment <NUM> is <NUM>° to about <NUM>°. Illustratively, the cap diverges relative to the abutment at an angle of <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, and about <NUM>°. The divergence of the cap <NUM> relative to the abutment <NUM> is shown as reference numerical <NUM>. However, even at the range of divergence, the annular wall <NUM> (and concave lip <NUM>) maintains contact with the outer surface <NUM> of the abutment <NUM> to ensure frictional contact and help to create a seal between the cap <NUM> and abutment <NUM>.

<FIG> illustrate one embodiment of a pre-angled abutment <NUM>. The pre-angled abutment <NUM> is similar to that of the previous embodiment described in <FIG>. Referring to <FIG>, the pre-angled abutment <NUM> comprises an upper portion <NUM>, a cuff portion <NUM>, an attachment portion <NUM>, and a through bore <NUM>. The through bore <NUM> comprises a first portion <NUM> and a second portion <NUM>. The first portion <NUM> is similar to socket <NUM> of <FIG>, having an annular lip <NUM>, annular ring <NUM>, a cylindrical cavity <NUM>, and a lower portion <NUM>. The socket <NUM> receives the ring <NUM> by snap-engagement over the annular ring <NUM> of abutment <NUM>, which fits into the corresponding annular groove <NUM> of the ring <NUM>. The head portion <NUM> of the retention head <NUM> snap-fits through the ring <NUM> and is positioned in the lower portion <NUM>. The second portion <NUM> comprises a first cylindrical portion <NUM>, that accepts a retaining screw to fasten the pre-angled abutment to an implant, and a second cylindrical portion <NUM>, the second cylindrical portion <NUM> having a smaller diameter than the first cylindrical portion <NUM>.

In one embodiment, the upper portion <NUM> is at an angled of <NUM>° from a central axis of the cuff <NUM> and attachment <NUM> portions as shown in <FIG>. The pre-angled abutment is exemplary and not limiting as the pre-angled abutment can be at an angle of, about <NUM>°, about <NUM>, about <NUM>°, and about <NUM>°. In additional embodiments, the pre-angle abutment can be at an angle between about <NUM>° to about <NUM>°, about <NUM>° to about <NUM>°, about <NUM>° to about <NUM>°, and about <NUM>° to about <NUM>°. By way of example, the <NUM>° pre-angled abutment, together with the range of divergence, allows a divergence up to about <NUM>° of the cap <NUM> relative to the central axis of the cuff <NUM> and attachment <NUM> portions of the abutment <NUM>. Illustratively, the range of divergence of the cap <NUM> is about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, and about <NUM>° relative to the <NUM>° pre-angled abutment <NUM>.

Referring to <FIG>, the pre-angled abutment <NUM> can be secured in an implant <NUM> by means of the attachment portion <NUM>, which is secured in an implant using a retaining screw <NUM>. The implant <NUM> comprises a first end cuff portion <NUM> having an open end comprising a cavity <NUM> for receiving the attachment portion <NUM> of the pre-angled abutment <NUM> and a threaded bore <NUM>, and a second end thread shaft <NUM>. The cavity <NUM> is designed in size and shape to mate with the attachment portion <NUM> of abutment <NUM>. For assembly, the attachment portion <NUM> of the pre-angled abutment <NUM> is fitted into the cavity <NUM> of the implant <NUM>. The retaining screw <NUM> is set through the through bore <NUM> and screwed into the threaded bore <NUM>, thereby securing the pre-angled abutment <NUM> to the implant <NUM>.

An alternative embodiment of a two-piece pre-angled abutment <NUM>' is illustrated in <FIG> and <FIG>. The pre-angled abutment <NUM>' is similar to that of the previous embodiment described in <FIG>, and like reference numbers will be used for like parts. The pre-angled abutment <NUM>' comprises a first component <NUM> having an upper portion <NUM> and a threaded shaft <NUM>, and a second component <NUM> having a body portion <NUM>, an attachment portion <NUM>, and through bore <NUM>. The upper portion <NUM> has an open end <NUM> and a socket <NUM> for receiving the ring <NUM> and the retention head <NUM> of the cap <NUM>, and a convex outer surface <NUM> extending from an open end <NUM> to the threaded shaft <NUM>. The socket <NUM> has an annular lip <NUM>, annular ring <NUM>, a cylindrical cavity <NUM>, and a lower portion <NUM>. A tool-receiving bore <NUM> extends inwardly from the bottom of the socket <NUM>. The body portion <NUM> has a open end <NUM> and a cavity having a thread portion <NUM>, a first cylindrical portion <NUM>, and a second cylindrical portion <NUM> having a smaller diameter than the first cylindrical portion <NUM>.

The thread portion <NUM> is at a predetermined angled <NUM> from a central axis of the first and second cylindrical portions <NUM> and <NUM>, respectively, and in turn, when assembled, the first component <NUM> will be at the same predetermine angle. For example, the pre-angled abutment can be at an angle of, about <NUM>°, about <NUM>, about <NUM>°, and about <NUM>°. In additional embodiments, the pre-angle abutment can be at an angle between about <NUM>° to about <NUM>°, about <NUM>° to about <NUM>°, about <NUM>° to about <NUM>°, and about <NUM>° to about <NUM>°. By way of example, the <NUM>° pre-angled abutment, together with the range of divergence, allows a divergence up to about <NUM>° of the cap <NUM> relative to the first and second cylindrical portions <NUM> and <NUM>, respectively, of the abutment <NUM>'. Illustratively, the range of divergence of the cap <NUM> is about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, and about <NUM>° relative to the <NUM>° pre-angled abutment <NUM>'.

The two-piece pre-angled abutment <NUM>', as shown in <FIG>, can be assembled and secured in an implant <NUM> using a retaining screw <NUM> as shown in <FIG>. The attachment portion <NUM> of the second component <NUM> is fitted into cavity <NUM> of the implant <NUM>. The retaining screw <NUM> is set through the through bore <NUM> and screwed into the threaded bore <NUM>, thereby securing the second component <NUM> to the implant <NUM>. The threaded shaft <NUM> of the first component <NUM> is engaged and secured into the threaded portion <NUM> of the cavity <NUM> of the second component <NUM>.

In another embodiment, the dental attachment device <NUM> comprises a cap <NUM> for securing the dental appliance (not shown) and an abutment <NUM> for attachment to a non-vital tooth root, implant or the like. The cap <NUM> is positioned over and engaged with abutment <NUM> providing a metal-to-metal engagement of the inner annular surface <NUM> (and concave lip <NUM>) of wall <NUM> over the convex outer surface <NUM> of the abutment <NUM>. The mating of these two surfaces results in a galling or press fit effect that creates retentive force between the components and secures the cap <NUM> to the abutment <NUM>. The metal-to-metal interference and resulting retention is achieved by the compressive biting force applied at the time of seating the prosthesis and caps on the abutments and then further through the continuous mastication forces imparted by the patient.

Referring to <FIG>, another embodiment of the dental attachment device for securing a dental appliance is illustrated. Dental attachment device <NUM> comprises a cap <NUM> for securing the dental appliance (not shown), an abutment <NUM> for attachment to a non-vital tooth root, implant or the like, removable ball <NUM>, and a retainer ring <NUM>. The cap <NUM> engages with the abutment <NUM>, removable ball <NUM> and ring <NUM> as indicated by the dotted center line of <FIG> to secure a dental appliance in the mouth of a subject. The abutment <NUM> may be adapted to be compatible with commercially available implants, such as the Astra implant (Astra Tech Inc. , Waltham, MA), Brånemark implant (Nobel Biocare, Zurich, Switzerland), and the Straumann implants (Straumann USA LLC, Andover, MA), or configured as a tooth root abutment, mini-implant, or in a configuration that can be adapted to an intermediary abutment, which would be secured to a dental implant. Abutment <NUM> further comprises a cuff portion <NUM> to indicate the approximate position of the patient's gum line against abutment <NUM> when inserted. Cap <NUM> may be designed to integrate in or connect to a dental appliance by, for example but not limited to, a post, a screw, or an adhesive such as acrylic, bisacrylic, or other suitable cements. In this embodiment (<FIG>), cap <NUM> has threads for attachment into, for example, a CAD/CAM fabricated metal bar.

<FIG> illustrate one embodiment of the cap <NUM> with removable ball <NUM>. The cap <NUM> comprises an attachment portion <NUM> and a body portion <NUM> having an inner cavity <NUM> forming an annular wall <NUM>. While shown as circular in shape, body portion <NUM> may take any shape suitable for securing the cap <NUM> in a dental appliance. Removable ball <NUM> comprises driving feature <NUM>, in this case, but not limited to, an internal hex for engagement of a wrench to seat and torque the removable ball in the cap <NUM> by the dental clinician. <FIG> illustrates a a side view of cap <NUM> and removable ball <NUM>, in this case the CAD/CAM cap. As shown in <FIG>, the inner cavity <NUM> in open end <NUM> has an inner annular, concave surface <NUM>. The concave surface <NUM> is designed to correspond to and engage over the outer convex surface <NUM> of the abutment <NUM>. The annular wall <NUM> surrounds removable ball <NUM>, with a head portion <NUM> that is substantially spherical or ball-shaped. In alternative embodiments, removable ball <NUM> may be other suitable shapes such as polygonal or spheroid. In alternative embodiments, removable ball <NUM> or driving feature <NUM> or both may project above, below, or at level with the lip of annular wall <NUM>.

Attachment portion <NUM> is provided to secure the dental appliance by structures or techniques well-known and understood by skilled artisans, including but not limited to, a short post, a screw, or an adhesive. Such techniques will not be repeated herein, and the figures are provided as exemplary only and not meant to limit the present invention.

Referring to <FIG>, cap <NUM> comprises external threads <NUM>, which engage corresponding threads of a dental appliance. Cap <NUM>, as shown in <FIG>, further comprises internal threads <NUM>, which engage corresponding external threads <NUM> on removable ball <NUM>. Removable ball <NUM> comprises edge <NUM> to increase the retention of removable ball <NUM> when engaged with abutment <NUM>.

<FIG>illustrate three example configurations of removable ball <NUM>, which are interchangeable by the dental professional. In <FIG>, head portion <NUM> is ball-shaped providing a retention force sufficient to prevent detachment by the patient, but less the other two configurations. Head portion <NUM> in <FIG> may be constructed of plastic and/or having a smooth, spherical surface when the ball engages with ring <NUM> in abutment <NUM>.

<FIG> is an example of ball <NUM> with a head portion <NUM> of medium retentive force. This is achieved by making portion <NUM> or the entire ball <NUM> out of metal or other hard material. Ball <NUM> may also have annular lip or edge <NUM> that allows ball <NUM> to be smoothly inserted into ring <NUM> but seats or "bites" when removed thereby increasing the retention force.

A third configuration is illustrated in <FIG> of a ball <NUM> having a head portion <NUM> with a high retention force. This is created by sharpening annular flange or edge <NUM> so that the amount of force to remove it through retaining ring <NUM> and abutment <NUM> is increased. Head portion <NUM> may therefore comprise a surface feature selected from the group consisting of a barb, an annular edge, a partially annular edge or a lip.

Other configurations are possible to vary the retention force within the ring <NUM> and to abutment <NUM>. Such force required is dictated by a number of factors, including but not limited to, by the metal-to-metal contact of the inner diameter of the cap with the spherical surface of the abutment, by the interference between the ball diameter and the inner diameter of the ring, by tightly controlling the vertical height of full seating of the cap to control this engagement, and the sharpness of edge <NUM> on head portion <NUM> to resist a separating movement.

<FIG> illustrate two embodiments of cap <NUM>. The cap <NUM> in <FIG> interfaces with a CAD/CAM denture bar. The arrow <NUM> identifies an acrylic finishing line feature where the acrylic from the surrounding denture can create a smooth finish with cap <NUM>. This feature may be applied to any configuration of cap <NUM>. A similar feature can be used to provide an appropriate contact point for a denture fabricated with a metal bottom. The cap <NUM> in <FIG> is for use with direct application of acrylic. Additional cap configurations may be fabricated for use with other types of denture support structures other than CAD/CAM bars or acrylic pick-up types.

<FIG> show the abutment <NUM> and a cross section thereof, respectively. The abutment <NUM> is similar to that of the previous embodiment described in <FIG>, and like reference numbers will be used for like parts. The cross section of the abutment <NUM> shows an internal thread <NUM> for securing threaded components such as the healing cap <NUM> and the impression coping screw (not shown). There is also an internal bore <NUM> that acts as a driving feature for engagement by a suitable tool in order to tighten the abutment <NUM> into the implant. Finally, there is a socket <NUM> for the ring. In this case, there is a thread <NUM> in the abutment (the large diameter internal thread) that is used to secure the ring which is engaged by the removable balls.

<FIG> show the retention ring <NUM> and a cross section thereof, respectively. The side view of the ring shows the external threads <NUM> that, in this embodiment, are used to secure the ring <NUM> in the abutment <NUM>. The ring <NUM> may be, and in this configuration is intended to be, removable or easily removable by the clinician, so that the ring <NUM> may be replaced if needed when the denture is removed, such as during routine cleaning and general restoration maintenance. The cross section of the ring shows an internal hexagon <NUM> which is an internal driving feature for tightening the ring into the abutment. Finally, smallest inner diameter ring or flange <NUM> in the ring is used to engage the removable balls <NUM> and generate retention. The opening <NUM> of that inner diameter on the left side allows for the balls to create an audible sound or "click" when fully engaged. The cap <NUM> and removable ball <NUM> interfaces with the ring (and the abutment) from right to left in <FIG>. The ring is made out of a soft material such as plastic. In one embodiment, the ring comprises PEEK so that it has enough pliability to allow the removable balls to snap into place, but enough stiffness to maintain a sufficient amount of retention force.

<FIG> illustrate one embodiment of the assembled dental attachment device <NUM> for securing a dental appliance in the mouth of a patient. To assemble the dental attachment device, the ring <NUM> is threadedly connected to a mating threaded portion, <NUM> and <NUM>, respectively, in the socket <NUM>. In alternative embodiments, the ring <NUM> may be snap-fit or pressfit engaged into the socket <NUM>. The cap <NUM> (which can be integral with a dental appliance) and the removable ball <NUM> is positioned over the abutment, and the head portion <NUM> of the removable ball <NUM> is engaged into the socket <NUM> and snap fit through the ring <NUM>. The snap-fit engagement of the head portion <NUM> of the removable ball <NUM> and ring <NUM> provides the retention force and secures the cap onto the abutment. Depending on the configuration of the head portion <NUM> (as described in <FIG>), the retention force may be adjusted to account for variations in patients and/or clinical conditions. For example, where loading is applied to a cantilevered area of the restoration, the force of retention must be proportionally larger to ensure that the restoration does not come unseated.

An additional retention feature of the dental device <NUM> consists of the metal-to-metal engagement of the inner concave surface <NUM> of wall <NUM> over the convex outer surface <NUM> of the abutment <NUM>. The frictional forces, as well as the angle of convergence, between the two corresponding surfaces <NUM> and <NUM> secures the cap to the abutment, while at the same time allow for a range of divergence between the cap <NUM> relative to the abutment <NUM>. The tightened fit between the cap <NUM> and abutment <NUM> helps to seal the device from oral fluids in an effort to prevent microbial contamination and plaque traps.

Referring to <FIG>, when the dental attachment device <NUM> is assembled, there is a gap <NUM> between the cap <NUM> and the abutment <NUM> and a gap <NUM> between the ball-type head portion <NUM> and the hemispherical or bowl-shaped portion <NUM>, which allows the cap <NUM> to diverge or pivot or swivel relative to the abutment <NUM>. The range of divergence between the cap <NUM> and abutment <NUM> is <NUM>° to about <NUM>°. Illustratively, the cap <NUM> diverges relative to the abutment at an angle of <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, and about <NUM>°. The divergence of the cap <NUM> relative to the abutment <NUM> is shown as reference numerical <NUM>. However, even at the range of divergence, the annular wall <NUM> maintains contact with the outer surface <NUM> of the abutment <NUM> to ensure frictional contact and help to create a seal between the cap <NUM> and abutment <NUM>.

<FIG> illustrate another embodiment of a two-piece pre-angled abutment <NUM>". The pre-angled abutment <NUM>" is similar to that of the previous embodiment described in <FIG> and <FIG>, and like reference numbers will be used for like parts. The pre-angled abutment <NUM>" comprises a first component <NUM> having an upper portion <NUM> and a threaded shaft <NUM>, and a second component <NUM> having a body portion <NUM>, an attachment portion <NUM>, and through bore <NUM>. The upper portion <NUM> has an open end <NUM> and a socket <NUM> for receiving the ring <NUM> and the removable ball <NUM> of the cap <NUM>, and a convex outer surface <NUM> extending from an open end <NUM> to the threaded shaft <NUM>. The socket <NUM> has threaded portion <NUM>, a cylindrical cavity <NUM>, and a lower portion <NUM>. A tool-receiving bore <NUM> extends inwardly from the bottom of the socket <NUM>. The body portion <NUM> has a open end <NUM> and a cavity having a thread portion <NUM>, a first cylindrical portion <NUM>, and a second cylindrical portion <NUM> having a smaller diameter than the first cylindrical portion <NUM>.

The thread portion <NUM> is at a predetermined angled <NUM> from a central axis of the first and second cylindrical portions <NUM> and <NUM>, respectively, and in turn, when assembled, the first component will be at the same predetermine angle. For example, the pre-angled abutment can be at an angle of, about <NUM>°, about <NUM>, about <NUM>°, and about <NUM>°. In additional embodiments, the pre-angle abutment can be at an angle between about <NUM>° to about <NUM>°, about <NUM>° to about <NUM>°, about <NUM>° to about <NUM>°, and about <NUM>° to about <NUM>°. By way of example, the <NUM>° pre-angled abutment, together with the range of divergence, allows a divergence up to about <NUM>° of the cap <NUM> relative to the first and second cylindrical portions <NUM> and <NUM>, respectively, of the abutment <NUM>'. Illustratively, the range of divergence of the cap <NUM> is about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, and about <NUM>° relative to the <NUM>° pre-angled abutment <NUM>".

The two-piece pre-angled abutment <NUM>" can be assembled and secured in an implant <NUM> using a retaining screw <NUM> as shown in <FIG>. The attachment portion <NUM> of the second component <NUM> is fitted into cavity <NUM> of the implant <NUM>. The retaining screw <NUM> is set through the through bore <NUM> and screwed into the threaded bore <NUM>, thereby securing the second component <NUM> to the implant <NUM>. The threaded shaft <NUM> of the first component <NUM> is engaged and secured into the threaded portion <NUM> of the cavity <NUM> of the second component <NUM>.

In another embodiment, the dental attachment device <NUM> comprises a cap <NUM> for securing the dental appliance (not shown) and an abutment <NUM> for attachment to a non-vital tooth root, implant or the like. The cap <NUM> is positioned over and engaged with abutment <NUM> providing a metal-to-metal engagement of the inner concave surface <NUM> of wall <NUM> over the convex outer surface <NUM> of the abutment <NUM>. The mating of these two surfaces results in a galling or press fit effect that creates retentive force between the components and secures the cap <NUM> to the abutment <NUM>. The metal-to-metal interference and resulting retention is achieved by the compressive biting force applied at the time of seating the prosthesis and caps on the abutments and then further through the continuous mastication forces imparted by the patient.

Another embodiment of the abutments disclosed herein is incorporated as a mini implant for osseo-integration into the jawbone of a subject. A mini implant is a small-diameter, one-piece root form implant that osseo-integrates into the jawbone and allows immediate loading of a dental appliance. The mini implant come in a number of different sizes. The shaft may range in diameter from about <NUM> to about <NUM>. Illustratively, the diameter of the shaft may be about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM> and about <NUM>. Further, the length of the shaft ranges from about <NUM> to about <NUM>. In further embodiments, the length may be about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, and about <NUM>.

<FIG> illustrate one embodiment of a healing cap <NUM>. The healing cap <NUM> comprises an upper surface <NUM> that is generally flat and an annular skirt <NUM> projecting downwardly from the upper surface <NUM> to surround a shaft <NUM>. The shaft comprises a distal threaded portion <NUM> and a coaxial trunco-conical section <NUM>. A tool-receiving bore <NUM> extends inwardly from the upper surface <NUM>. The tool-receiving bore <NUM> can be, for example hexagonal with flat faces, for engagement by a suitable tool.

Referring to <FIG>, the healing cap <NUM> is positioned over the socket <NUM> of the abutment <NUM> and the shaft is engaged through the ring <NUM> and screwed into the threaded bore <NUM>. The tapered inner surface <NUM> of the ring <NUM> matches the trunco-conical section <NUM> of the shaft <NUM> of the healing cap <NUM>. At the same time, the annular skirt <NUM> is engaged and tightened over the outer surface <NUM> of the abutment <NUM>. The fit between the healing cap <NUM> and abutment <NUM> can help to create a seal that minimizes the penetration of oral fluids into the abutment cavity in an effort to prevent microbial contamination. The healing cap <NUM> can be used with other embodiments of abutment <NUM> disclosed and/or contemplated herein.

Claim 1:
A kit for assembling a dental attachment device (<NUM>), comprising;
a cap (<NUM>) for securing a dental appliance, the cap (<NUM>) having an open end and an inner cavity (<NUM>) forming a concave annular wall (<NUM>), and a first attachment portion (<NUM>);
an abutment (<NUM>) comprising an upper portion and a second attachment portion, the second attachment portion is configured for attachment to a tooth root or implant, the upper portion having a convex outer surface (<NUM>) and an open end,
the convex outer surface is configured for face to face swivel engagement with the concave annular wall (<NUM>) of the cap (<NUM>);
a one piece removable ball (<NUM>) having an upper end and a head portion (<NUM>), the removable ball (<NUM>) being positional between the cap (<NUM>) and the abutment (<NUM>), wherein the head portion (<NUM>) is configured for releasable retentive engagement in the open end of the abutment and the upper end configured for engagement to the cap (<NUM>); and
the removable ball (<NUM>) comprises a driving feature (<NUM>) for engagement of a wrench to seat and torque the removable ball in the cap (<NUM>).