Abstract:
A dental articulator system including a device and method of forming dental casts with a posterior clip. The clip has a line of holes that receive male bulbs from a dental articulator. The dental articulator has adjustable ball and socket joints, which are secured in place with a hand tightenable screw. The device does not require any glue; thus the dental articulator is easily adjusted and reusable.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     This invention relates to a device and method for a dental articulator for use with dental model casts. Specifically, the invention describes a dental articulator that is easily adjustable by the dental laboratory technician and/or dentist to align as desired the upper and lower dental model casts. 
     2. Related Art 
     Dental articulators, which hold and align together positive dental impressions, are well known in the prior art. Articulators are used to align the upper (maxilla) dental model with the lower (mandible) dental model, to simulate current or desired occlusion. By recreating the teeth and their occlusion (alignment) in model form, false teeth, caps and other dental prosthetics can be made in the precise size and shape necessary for the patient&#39;s mouth. 
     To create the dental models (casts), the dentist makes a negative impression of the patient&#39;s teeth. This impression may be a full mold (bilateral) or a partial quadrant mold (unilateral). The impression is obtained by filling a tray with thermoplastic material, and holding it against the patient&#39;s teeth and gums. After the thermoplastic material partially hardens (sets up), the tray is removed, leaving the negative impression of the teeth. 
     To form a positive impression of the teeth and their position, pourable hardenable stone, often called yellow stone, is poured into the negative impression. The positive impression is allowed to harden, and is then removed from the negative impression, forming a precise positive model of the teeth and their placement. The hard positive impression is then pressed into a forming mold containing new yellow stone. This yellow stone is in a flowable state and forms the base of the dental cast. The positive impression bonds with the new yellow stone base, excess yellow stone is scraped away, remaining yellow stone is allowed to harden, and the complete cast is now formed. This cast is then removed from the forming mold. 
     The casts (upper and lower) are then attached to a dental articulator, which emulates the patient&#39;s jaw for aligning the upper and lower teeth/casts. 
     The prior art describes various devices and methods for fashioning and securing the dental cast base to the positive impression. Prior art also describes various devices and methods for securing the dental casts to a dental articulator. 
     Representative of the early prior art for dental cast bases are devices described in the Tuccillo et al. U.S. Pat. No. 3,510,947 (May 12, 1970) and the Beckwith U.S. Pat. No. 4,319,875 (March 16, 1982). These patents utilize bases having female plastic snap receivers. The positive impressions are fabricated with male studs, which snap into the female snap receivers of the base. This requires precise alignment of each male stud to properly mate with the female receiver. Repeated use wears down the male stud, causing loose snapping with the female receiver, thus making the alignment loose. 
     An alternative base system is described in the Cho U.S. Pat. No. 5,622,497 (Apr. 22, 1997). A plastic base is adhered to a positive impression with a layer of stone material. The plastic base has a slot in which a disk is inserted and secured with a setscrew. The disk is attached to a stem having a ball at the other end, which connects to a reusable articulator. The system is requires plastic bases that are relatively expensive, as is the non-disposable dental articulator. 
     The most common type of base system, however, is the type utilized in the Huffman series of U.S. Pat. Nos. (4,533,323; 4,548,581; 4,734,033; 4,842,242). These patents and several others utilize base formers. Soft stone material is placed into a (typically) rubber base former, having a continuous sidewall, a floor and an open top. A hard positive impression is pressed into the soft stone material, excess overflow material is scraped away, and the soft stone material allowed to harden, adhering to the positive impression. The base and positive impression combine to form the dental cast, which has a uniform appearance due to the similar stone used in both the base and positive impression. 
     Dental casts formed by pressing positive impressions into base formers are affixed to dental articulators in a variety of methods in the prior art. Young (U.S. Pat. No. 5,605,456—Feb. 25, 1997) utilizes a cam clamp of the type used to secure automotive hoses. This hose clamp is wrapped around the base of the dental cast, and secured to a substantial dental articulator. Callne (U.S. Pat. No. 5,221,203—Jun. 22, 1993) utilizes a wire loop that clips into brackets integral with the top of the base. The wire loop is attached to a screw wheel adjustable dental articulator. Both systems require articulators that are difficult to use and are expensive. 
     The Huffman patents utilize a variety of means to secure the dental base/cast to an articulator. Huffman utilizes a disposable single-use plastic articulator having hinged articulator arms with socket balls that snap into retention sockets mounted to the dental cast base. The retention sockets may be inserted into the still soft stone (Huffman &#39;323), which requires the “proficiency and expertise of the technician” to decide when to insert the mounting such that a proper alignment and securement is achieved. Other Huffman methods involve slots formed in the base by a shelf protruding into the interior cavity of the base former. When the former is removed (peeled off), slots and/or channels remain, into which a ridge tab is inserted and glued. The ridge tab has a socket that accepts a socket ball of the single-use articulator. When the upper and lower casts are aligned, a drop of quick drying glue is placed on the socket ball, and held until set. Some of the limitations of the Huffman devices are 1) the difficulty in positioning the upper and lower casts while gluing their socket joints; 2) inability to make adjustments after gluing the socket joints; 3) inability to make adjustments/corrections to the lateral and vertical placement of the ridge tabs after gluing; 4) difficulty in storing dental casts due to space taken by the non-removable articulator; and 5) expense associated with not being able to reuse articulators on different casts. 
     It would therefore be useful improvement of the prior art for a dental articulator system to utilize existing techniques for forming positive impressions, mounting these positive impressions on bases that use common stone material, and is flexible in adjustability during and after attachment to a re-usable articulator. 
     BRIEF SUMMARY OF THE INVENTION 
     Accordingly, the objectives of this invention are to provide, inter alia, a new and improved dental articulator that: 
     is easily adjustable; 
     is inexpensive; 
     does not require the use of glue; and 
     can interchange and re-use articulator arms between different sets of casts. 
     These objectives are addressed by the structure and use of the inventive device and method. Re-usable articulator arms attach via ball and socket joints to a base clip, which is adhered to the dental cast base during the base formation process. Gross horizontal alignment is accomplished by a plurality of female recesses that accommodate male bulbs of a clip that attaches to the articulator arm via a screw adjustable ball and socket joint. Vertical adjustment and fine horizontal adjustment are accomplished by adjusting the orientation of the articulator arm ball and socket joint. 
     Other objects of the invention will become apparent from time to time throughout the specification hereinafter disclosed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 depicts the inventive full arch former with articulator. 
     FIG. 2 depicts the inventive half arch (quadrant) former with articulator. 
     FIG. 3 depicts the inventive former and articulator in exploded view. 
     FIG. 4 depicts detail of the articulator arm adjustable ball and socket joint. 
     FIGS. 5 a  and  5   b  depict an alternative preferred embodiment of the articulator arm adjustable ball and socket joint. 
     FIG. 6 depicts a dental cast with the inventive attachment sliding clip. 
     FIG. 7 depicts the inventive articulator attached to upper and lower dental casts. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is described as dental articulator system  10 , as depicted in FIGS. 1-7. Dental articulator system  10  comprises base former  60 , sliding clip  80  and dental articulator  15 . As seen in FIGS. 1 and 2, dental articulator system  10  can be a full arch articulator  20  or a half arch articulator  30 . 
     Base former  60 , as seen in FIG. 3, is similar, if not identical, for the upper (maxilla) dental casting model and the lower (mandible) dental model. Upper maxillary base former  65  is used to form upper dental cast  76 , and lower mandibular base former  70  is used to form lower dental cast  78 . Base former  60  is preferably made of flexible rubber as known in the art for base formers. Base former  60  comprises a flexible former wall  67 , said former wall  67  having a height adequate to hold casting stone upon which a positive impression can be pressed/bonded, and a thickness adequate to support lateral pressures of said casting stone. Base former further comprises former floor  62  to contain the casting stone. 
     Novel and unique to base former  60  is base former posterior opening  61 , which is defined by two vertical ridge guides  64  protruding from the interior of former wall  67 , and floor ridge  63 , protruding normal from former floor  62 . Sliding clip  80 , as seen in FIGS. 1,  2  and  3 , has a generally rectangular shape with clip channels  84  inset the length of each end. On one side of sliding clip  80  is a means of anchorage of sliding clip  80  to pourable hardenable casting stone. This means of anchorage is provided by a plurality of anchorage bulbs  82 , typically protruding out ⅛″ to ¼″ inch, and having a diameter thickness of ⅛″ to ¼″. On the opposite side of sliding clip  80  are a plurality of sliding clip female recesses  57 . Sliding clip female recesses  57  are horizontally aligned along the width of sliding clip  80 , and provide different connection points for dental articulator  15 . In the preferred embodiment, sliding clip  80  is made of hard plastic or similar material having rigid strength, capable of bonding to pourable hardenable casting stone, and able to accommodate and secure sliding clip male bulbs  56 . 
     Sliding clip  80  slides into and occludes former posterior opening  61  by aligning clip channels  84  above ridge guides  64 , and slidably connecting sliding clip  80  to former sides  67  by sliding ridge guides  64  through clip channels  84  until the base of sliding clip  80  seals against floor ridge  63 . In one embodiment, a channel (not shown) traverses the bottom edge of sliding clip  80  to facilitate mating with floor ridge  63 . In another embodiment, floor ridge  63  is missing, and the bottom of sliding clip  80  mates directly against the posterior portion of former floor  62  below former posterior opening  61 . 
     Sliding clip  80  is connectable to attachment clip  55 . Attachment clip  55  comprises clip plate  52 , which comprises at least one, preferably a plurality in linear alignment, sliding clip male bulb  56 . Sliding clip male bulb(s)  56  are capable of snapping into sliding clip female recess(es)  57  (FIG.  1 ). On the opposite side of clip plate  52  is attachment shaft  51 , which connects to clip socket ball  50 . All components of attachment clip  55  are preferably constructed of hard plastic or other material having adequate support strength and flexibility of engagement units, including sliding clip male bulb  56 . 
     Clip socket ball  50  mates inside arm socket  40 , which is connected to the v-base of articulator arm  25 . Clip socket ball  50  is preferably a semi-split ball, allowing for partial compression while being inserted into arm socket  40 , and then snapping back outwardly after insertion for a snug fit. Of course, alternatively clip socket ball  50  and arm socket  40  can switch places, such that attachment shaft  51  terminates in a socket and articulator arm  25  terminates to a ball, thus forming an equivalent ball-and-socket joint as described in detail herein. In the preferred embodiment, inside arm socket  40  (FIG. 4) is at least one resistance nib  42 . Resistance nib  42  is a short nib protruding into the interior cavity of arm socket  40 , and is sized to mate against one of the ball dimples  54  located on the exterior surface of clip socket ball  50 . Arm socket  40  further comprises ball securement  35 , which is a screw, preferably hand-tightenable, that projects into the interior of arm socket  40  through socket threaded channel  36 . In the preferred embodiment, socket threaded channel  36  is threaded, but alternatively may be sized such that friction, adhesives, or similar securement means retain ball securement  35 . Further, if threaded, socket threaded channel  36  should be capable of supporting axial and lateral forces exerted by ball securement  35  when ball securement  35  is screwed down tight. Thus, arm socket  40  should be composed of material strong enough to provide such support, such as metal or a hard plastic. Alternatively, socket threaded channel  36  may be lined with a threaded channel insert (not shown), typically metal, providing engagement support for ball securement  35 . 
     After clip socket ball  50  is snapped into arm socket  40 , it is locked into position by tightening down ball securement  35 , which mates against a ball dimple  54  on clip socket ball  50 . This force also engages at least one resistance nib  42  against another ball dimple  54 , locking clip socket ball  50  in place. In the preferred embodiment, there are three resistance nibs  42  on the interior surface of arm socket  40  placed 120° apart as measured on arcs of the sphere defined by the interior of arm socket  40 , with ball securement  35  also positioned 120° from the three resistance nibs  42 . Alternatively, there are two resistance nibs  42  placed 120° apart on a plane with ball securement  35 , such that the two resistance nibs  42  and ball securement  35  are each 120° apart. Alternatively, only one resistance nib  42  is interior arm socket  40 , and is oriented opposite ball securement  35 . The selected orientation of resistance nibs  42  relative to ball securement  35  afford uniform force against clip socket ball  50 , thus providing maximum locking support. 
     In an alternative embodiment, arm socket  40  is replaced by a arm open socket  140 , and clip socket ball  50  is replaced by clip socket expandable ball  150 , as shown in FIGS. 5 a  and  5   b . Arm open socket  140  comprises ball opening  142 , through which clip socket expandable ball  150  is inserted, and expander opening  144 , which affords access and movement for ball expander  135 . Ball opening  142  and expander opening  144  are sized small enough such that clip socket expandable ball  150  is supported and retained when expanded. Ball opening  142  is sized large enough to afford insertion of expandable socket ball  150 . Expander opening  144  is sized large enough to allow lateral rotation of expandable socket ball  150  during alignment prior to tightening of expandable socket ball  150 . Preferably, within the interior of arm open socket  140  are resistance nibs  42 , which impede against ball dimples  54  as in the first preferred embodiment. Ball expander  135  screws through ball threaded channel  136  through a first half of the split clip socket expandable ball  150 . Ball expander  135  terminates against a second half of the split clip socket expandable ball  150  against ball interior split surface  154 , pushing against it and spreading apart expandable socket ball  150 . 
     Dental articulator  15 , as seen in FIGS. 1 and 2, comprises two articulator arms  25 . Each articulator arm  25  comprises a ball arm  28  and a socket arm  29  that meet at arm socket  40 . Ball arm  28  and socket arm  29  emerge diversely away from arm socket  40 . At the end opposite arm socket  40 , ball arm  28  comprises an articulator arm socket ball  26 . At the end opposite from arm socket  40 , socket arm  29  comprises an articulator arm socket  27 . Two articulator arms  25  mate together to form a movable hinge. This mating is accomplished by articulator arm socket ball  26  from a first articulator arm  25  snapping into an articulator arm socket  27  of a second articulator arm  25 , while simultaneously articulator arm socket ball  26  from a second articulator arm  25  snaps into an articulator arm socket  27  of the first articulator arm  25 , as seen in FIG. 1 and 2. Articulator arm socket balls  26  are preferably semi-split, allowing them to compress while snapping into articulator arm socket  27 , and then releasing outwardly to provide a snug fit to provide friction resistance for smooth hinge action. 
     OPERATION 
     Former posterior opening  61  is first occluded by sliding along ridge guides  64  sliding clip  80 , forming base former  60  as a receptacle. Optionally, a lubricant can be sprayed or wiped on the interior surface of former floor  62  and/or former wall  67 , but not sliding clip  80 , to afford ease in later peeling away base former  60  from the hardened casting stone. Pourable hardenable casting stone is poured into base former  60 , flowing around anchorage bulbs  82 . The positive dental impression  75  is then pressed into the soft stone, and excess soft stone flowing over former top edge  66  is wiped or scraped away. The positive dental impression  75  is positioned in base former  60  such that is protrudes away from the soft stone to emulate the patient&#39;s dental orientation, as is typical in the art. As the soft stone hardens forming base  77 , it binds to the positive dental impression, which together form dental cast  79  (FIG.  6 ). 
     When dental cast  79  has hardened, base former  77  is pulled away for later re-use, leaving dental cast  79  with sliding clip  80  embedded and attached via the surface of sliding clip  80  and anchorage bulbs  82 . As seen in FIGS. 1 and 2, sliding clip  80  comprises a plurality of sliding clip female recesses  57  that are horizontally aligned. 
     In the preferred embodiment, dental articulator  15  is pre-assembled. Two articulator arms  25  are snapped together by snapping articulator arm socket balls  26  into articulator arm sockets  27 , forming a hinged connection. Clip socket balls  50  are snapped into each arm sockets  40 , and ball securement  35  is left untightened. 
     Upper dental cast  76  and lower dental cast  78  are aligned to mechanically simulate axes of articulation, planes and arcs of occlusion, lines, planes and axes of symmetry found in the patient&#39;s mouth, as seen in FIG.  7 . Attachment clips  55 , each having preferably at least two sliding clip male bulbs  56  horizontally aligned and spaced equal to the spacing of sliding clip female recesses  57 , snap into the upper and lower sliding clips  80  such that upper dental cast  76  and lower dental cast  78  are roughly aligned horizontally, and the upper attachment clip  55  is roughly aligned vertically with the lower attachment clip  55 , preferably in the centers of sliding clips  80 . 
     Fine vertical and horizontal alignment adjustments of the upper and lower dental casts are made while the ball securements  35  are still loose. When the alignment of the upper and lower dental casts is proper, the ball securements  35  are tightened down, impinging on ball dimples  54  and pressing clip socket ball  50  against resistance nibs  42  inside arm socket  40 . In the alternative preferred embodiment utilizing clip socket expandable ball  150 , ball expander  135  is screwed down, pressing against ball interior split surface  154 . As additional pressure is placed against ball interior split surface  154 , clip socket expandable ball  150  expands, impinging against resistance nibs  42  inside arm open socket  140 . At this stage, the only dental articulator  15  free movement is that which is about the hinge formed by articulator arm socket ball  26  and articulator arm socket  27 . Thus, the upper dental cast  76  and lower dental cast  78  are free to rotate vertically in simulation of the patient&#39;s natural jaw motion. 
     By unsnapping attachment clips  55  of articulator arm  15  off sliding clips  80  of the dental casts, the dental casts can be shipped and stored in a smaller volume, thus providing additional storage space and smaller shipping containers. Articulator arm  15  can easily be snapped in and adjusted by the dentist, the dental technician or the laboratory technician. The same articulator arm  15  can be re-used on any dental cast  79  having the inventive sliding clip  80 . 
     The foregoing disclosure and description of the invention is illustrative and explanatory thereof. Various changes in the details of the illustrated construction may be made within the scope of the appended claims without departing from the spirit of the invention. The present invention should only be limited by the following claims and their legal equivalents.