Abstract:
A removable centric stop mechanism  10  for use in a system for making dental restorations. The stop mechanism  10  includes an elongate stop member  11  that can be firmly attached or connected to the dental model and can further be removed from the dental model when so desired. The elongate stop member  11  further incorporates a threaded elongate member  36  that can be threaded to and fro in a bore  34  in the elongate stop member  11  to thereby adjust the effective length of the elongate stop member  11.

Description:
This application claims the benefit of U.S. Provisional Application No. 60/669,337, filed Apr. 6, 2005. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to solid centric stop mechanisms or apparatus which are used in locating solid centric location with a dental model system which includes a flexible articulation means. The present invention provides improved centric stop means for dental model systems that are similar to those disclosed in U.S. Pat. No. 5,846,076 and PCT Pub. No. US 2003/0207230 A1. The present invention discloses additional, new centric stop apparatus that is to be used with the dental models and articulation means that are disclosed in U.S. Pat. No. 5,846,076 and PCT Pub. No. US 2003/0207230 A1, and the complete disclosures in those publications are included herein by reference. 
   2. State of the Art Prior to the Invention 
   The present invention provides an improved centric stop mechanism that is used in locating solid centric location when a dental model is being used that incorporates flexible articulation members. As disclosed in U.S. Pat. No. 5,846,076 and PCT application No. PCT/US01/05683, the dental model can consist of two base stones that are cast from dental casting material. One leg of an articulation member is either encapsulated within the casting material (as in U.S. Pat. No. 5,846,076) as each of the base stones are being cast, or a base stone is cast on a tray that has a leg of an articulation member either formed integrally with the tray or firmly attached and connected to the tray. In either case, the leg of the articulation member projects from respective base stone, with the leg of the articulation member having a free end that extends from the respective base stone. The free end of the leg of one articulation member extending from one base stone is adapted to be pivotally connected to the free end of the leg of a complimentary articulation member extending from a complimentary base stone to form a dental model, wherein the two base stones of the dental model are restrained by the articulation member so that the two base stones can be pivoted about the pivot axis of the pivotal connection connecting the complimentary legs of the articulation members to replicate biting action between the upper teeth and lower teeth of the dental model. This procedure is well known now in the art and is explained in detail in my U.S. Pat. No. 5,846,076. 
   Inasmuch as the legs of the articulation member are elongate and relatively thin, they have at least some flexibility. The flexibility is advantageous when the technician desires to move the parts of the dental model in a grinding type motion to check proper alignment of the dental model during such a grinding motion. This grinding type motion is produced by moving the complimentary base stones so as to flex the legs of the articulation member to allow the base stones to move back and forth in a lateral grinding motion relative to each other. 
   However, when the technician attempts to bring the base stones together to establish proper centric occlusal positioning, any flexing of the legs of the articulation member that allows undesirable up and down movement of the base stones relative to each other due to such flexing of the legs as opposed to the pivotal movement of the respective pair of pivotally connected legs is highly undesirable. In particular, when teeth are being restored at the posterior end of the dental model and no occluded opposing teeth are present to create a natural stop, it becomes necessary to artificially create a vertical stop in order to prevent the over closure of the opposing model. Thus, the technician is able to create accurate solid vertical relationship of the opposing dentition that is being restored with a crown or bridge. 
   In recognizing the need for a vertical stop, artisans in the past have used the following ways to achieve such a stop. In one method, a vertical rod or shore is glued to the model or articulation frame or model base, with the rod being cut at the required length to prevent over closure of the opposing models. In a second method, a mound of model stone is placed at the area needed to stop over closure against opposing models. In a third method, a cast in place post is immersed into the wet model stone of the second cast model positioned against the opposing model at the required height to set the vertical stop position. All these previous methods are cumbersome and require extra time spent by the technician. These methods also frequently require readjustment procedures and are difficult to adjust or fine tune the final vertical elevation of the cast models. 
   3. Objectives of the Invention 
   It is a broad object of the present invention to provide a solid centric stop mechanism that prevents the base stones of a dental model from being moved to an improper position that might otherwise be allowed by improper up and down type flexing of the legs of the associated articulation member. 
   A principal object of the present invention is to provide a solid centric stop mechanism that is either removably attached to the base stone of the dental model or removably attached to a leg of an articulation member that is in turn firmly attached to or encased in the base stone of the dental model. 
   An equally important object of the present invention is to provide a centric stop mechanism that is removably attached to the dental model, with the stop mechanism being further provided with means for adjusting or fine tuning the final vertical positioning of the upper and lower base stones of the dental model. 
   SUMMARY OF THE INVENTION 
   The present invention provides a removable centric stop mechanism that greatly simplifies procedures and saves valuable time of the technician. The centric stop mechanism of the invention comprises a vertical stop member that can be firmly attached or connected to the dental model and can further be removed from the dental model when it is not needed. In addition, the removable stop member of the present invention has means that allow for quickly and accurately adjusting and fine tuning the final vertical positioning of the base stones of the dental model. 
   In accordance with the present invention, a solid elongate centric stop member or locator is provided which can be removably affixed in some manner to the articulation member, the tray upon which the base stone is cast or to the base stone itself so that when affixed the stop member is firmly attached to the articulation member, the tray or the base stone, but when it is desired to remove the stop member it is readily removed with the ability to again be affixed to the articulation member, the tray or the base stone when so desired. When the stop member is affixed to the dental model, it provides means for locating solid centric location using the flexible articulation portion of the dental model. 
   The invention will be described in more particularity with reference to the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side view of one embodiment of the stop member of the invention; 
       FIG. 1(   a ) is a cross section of the stop member of  FIG. 1  taken along line  1 ( a )- 1 ( a ) of  FIG. 1 ; 
       FIG. 1(   b ) is a cross section of the stop member of  FIG. 1(   a ) taken along line  1 ( b )- 1 ( b ) of  FIG. 1(   a ); 
       FIG. 1(   c ) is a cross section of a stop member similar to that of  FIG. 1(   a ) taken along line  1 ( a )- 1 ( a ) of  FIG. 1 ; 
       FIG. 2  is a pictorial view of a second embodiment of the invention; and 
       FIG. 3  is a side view of a third embodiment of the stop member of the invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The removably attached elongate stop mechanism  10  of the present invention as shown in the drawings comprises an elongate stop element  11  that is removably attached to the base stone  16  or to a respective leg  12  of each of the articulation members of the articulation system by a mutually respective connector means that is in turn associated with either the base stone  16  or the leg  12  of the articulation member. The stop element  11  can be attached to and removed, repeatedly if so desired, from the base stone  16  or the leg  12  of the articulation member during the process of making a dental restoration or prosthesis. 
   The stop mechanism  10  of the present invention is used or incorporated into or with an articulation system such as or similar to the systems disclosed in my U.S. Pat. No. 5,846,076. Such articulation systems comprise mutually respective elongate legs  12 , each of which has a first end which is firmly attached or connected to a base stone  16  of a dental model. The base stone  16  of the dental model can be cast directly around the first end of the leg  12  as shown in  FIG. 1  or the first end of the leg  12  can be attached to or formed integrally with a tray  14 . When a tray  14  is employed, the base stone is cast directly in the tray  14 . The tray  14  can be molded integrally with the leg  12 , or a mechanical connecting means can be used to securely attach the tray  14  to the first end of the leg  12  as shown in  FIG. 2 . 
   The second or other end of each leg  12  extends from the back end of the base stone  16  during the making of a dental model. The second end of each leg  12  has an arm  20  which is integrally formed therewith and extends substantially perpendicular to the longitudinal axis of leg  12  from the second end of the leg  12 . A leg  12  and its attached arm  20  forms one member of the articulation system. The second member of the articulation system consists of a similar leg  12  and attached arm  20 . The distal end of each arm  20  of one member of the articulation system has a connecting means that can be pivotally connected to a mutually respective connecting means on the distal end of the second member of the articulation system as illustrated in  FIG. 1 . 
   When using the system of the present invention, a mold corresponding to the lower teeth of a person is molded on the base stone  16  of the leg  12  of the first member of the articulation system, and a mold corresponding to the upper teeth of the person is molded on the base stone  16  of the leg  12  of the second member of the articulation system. The arm and leg members  20  and  12  of the first member of the articulation system are essentially similar to and substantially the same as the arm and leg members  20  and  12  of the second member of the articulation system, and the use of the two members of the articulation system in making a dental model is well known and described in my previously mentioned U.S. Pat. No. 5,846,076. 
   The elongate stop mechanism  10  of the present invention comprises a solid, elongate stop element  11  which is designed to be attached to and removed from the leg  12  of the articulation system. When the stop element  11  is attached to the leg  12  of the articulation system it is oriented so that the longitudinal axis of the stop element  11  extends away from the longitudinal axis of the leg  12  in the same general direction as does the arm  20 , with the stop element  11  further being substantially perpendicular to a horizontal plane, generally called the occlusal plane. 
     FIG. 1  is a side view of one embodiment of an articulation system in accordance with the present invention.  FIGS. 1(   a ) and  1 ( b ) are cross-sectional views taken along lines  1 ( a ) of  FIGS. 1 and 1(   b ), of  FIG. 1(   b ), respectfully. As illustrated in  FIGS. 1 ,  1 ( a ) and  1 ( b ) the stop mechanism  10  comprises a base member  30  that in itself is attached to the longitudinal, tapered leg  12  of the articulation member. The tapered leg  12  has a cross-sectional shape that is not round or circular, but instead angular, oval or other non-circular shape as is fully described in U.S. Pat. No. 5,846,076. The base member  30  of the stop mechanism  10  is attached to the tapered leg  12  by sliding longitudinally onto the tapered leg  12 . As such, the base member  30  must have a central opening there through which has the same peripheral shape as the circumferential shape of the leg  12 . 
   The opening in the base member  30  has a size that will allow it to slide onto the leg  12  and move into engagement with the tapered area of the leg  12  where the periphery of the leg  12  matches the periphery of the opening in the base member  30 . The periphery of the base member  30  is sized so that the base member  30  will slide onto the leg  12  to a position that is near the end of the leg  12  to which the arm  20  extends. The base member  30  slides sufficiently along the leg  12  to be positioned so that the base stone  16  can be cast around and along the leg  12 , with the base member  30  positioned adjacent to the back end of the base stone  16 . It should, of course, be recognized that the base member  30  could be permanently affixed to the leg  12 , as by gluing, or the base member  30  could actually be molded and formed as an integral, unitary part of the leg  12 . 
   Means are provided on the base member  30  to accept the elongate stop element  11  so that the stop element  11  can be attached to and removed from the base member  30  repeatedly if so desired. The means for such attachment and detachment of the stop element  11  from the base member  30  as best shown in  FIGS. 1(   a ) and  1 ( b ) comprise a recessed receptacle  40  formed in the upper surface of the base member  30 . The open receptacle  40  faces away from the longitudinal axis of the leg  12  of the articulation member, with the central axis of the receptacle  40  oriented substantially perpendicular to a horizontal plane, generally called the occlusal plane. The receptacle  40  has tapered sidewalls and the peripheral shape of the receptacle  40  is non-round or non-circular. Its peripheral shape can be oval or multi-sided or some similar non-circular shape, but as shown in  FIG. 1(   b ), can in its simplest form, have the shape of a half circle. The purpose of the non-round or non-circular shape of the receptacle  40  will be further discussed hereinafter. 
   The elongate stop member  11  has a lower end portion that can be removably received into the receptacle  40 . The lower end portion is itself elongate and tapers inwardly, i.e., gets smaller, in a direction downwardly toward its free end that is inserted into the receptacle  40 . The peripheral shape of the lower portion of the stop member  11  is the same as the peripheral shape of the receptacle  40  and the sides of the lower portion of the stop member  11  taper at the same degree of slope as the taper in the sidewalls of the receptacle  40 . As shown in  FIG. 1(   b ), the lower portion of the elongate stop member  11  has a cross-sectional shape of a half circle, and as shown in  FIG. 1(   a ), the lower portion of the elongate stop member  11  is tapered so as to fit snugly within the tapered receptacle  40 . The purpose of the non-round shapes of the receptacle  40  and lower portion of the stop member  11  becomes evident. When inserted into the receptacle  40  the lower end portion of the stop member  11  can fit in only one orientation so that the stop member  11  is properly positioned and more importantly, the stop member  11  is held securely in its proper position so that it cannot rotate or turn on its longitudinal axis. The stop member  11  is in essence securely locked in its proper position and restrained from rotational movement when its lower end is fit snugly into the receptacle  40 . 
   The upper end portion of the stop element  11  can be a simple extension of the lower end portion, but preferably has a shape that is sufficiently different and somewhat larger than the half circle shape of the lower end portion so that a flat abutment or seat  15  as shown in  FIG. 1(   a ) is formed at the lower end of the upper end portion at the juncture of the lower end portion and upper end portion of the stop element  11 . As further shown in  FIG. 1(   a ), the upper end portion of the stop element  11  extends upwardly from the lower end portion. This upper end portion of the stop element  11  has a full circular cross-sectional shape, with the diameter of the circular shape at the junction between the lower end portion and the upper end portion being essentially the same as the diameter of the half circular shape of the lower end portion of the stop element  11 . 
   As illustrated in  FIG. 1(   a ), the sides of the upper end portion of the stop element  11  taper in the same fashion as do the sides of the lower end portion of the stop element  11 . However, it should be recognized that the upper end portion of stop element  11  could have any cross-sectional shape and its side walls need not necessarily taper. The upper end portion must, of course, have a larger cross-sectional area than the cross-sectional area of the lower end portion of stop element  11  to provide the seat  15  as mentioned previously. 
   It should be recognized that the male-female relationship of the system for connecting the stop element  11  to the base member  30  as shown in  FIG. 1(   a ) could be reversed as illustrated in  FIG. 1(   c ). The base member  30  would incorporate a male projection element  31  that extends upwardly from the upwardly facing top of the base member  30 . In that situation, the male projection  31  would be received in a female receptacle  32  that extends upwardly into the elongate stop element  11 . The male and female elements  31  and  32  would have the same tapering features and relative sizes as discussed with the receptacle  40  and the lower end portion of the stop element  11  of  FIGS. 1 ,  1 ( a ) and  1 ( b ). 
   The stop element  11  of the present invention has a bore  34  that extends inwardly from the top surface of the upper end portion of the stop element  11 . A screw  36  is threaded into the bore  34 . As shown in  FIG. 1 , when two articulation members are pivotally attached to each other with mutually respective molds of a patient&#39;s upper and lower teeth, the molds of the teeth can be moved toward and away from each other in a biting and chewing movement with the teeth being maintained in proper occlusal position when moved to the closed position by the stop element  11  as will now explained. The stop element  11  on the lower articulation member of  FIG. 1  has the screw  36  threaded into the bore  34 . The stop element  11  on the upper articulation member need not have such a screw threaded there into. The screw  36  on the lower articulation member can be adjusted in an out of the bore  34  so that the head of the screw  36  will engage the top of the mutually respective stop element  11  of the upper articulation member and form a stop in the movement of the upper teeth toward the lower teeth and maintain proper occlusal positioning of the teeth in that position. It should be recognized that the upper articulation member need not actually have a stop element  11 . The screw  36  in the stop element  11  of the lower articulation member could be sufficiently long so that its extending end would engage the base stone  16  or even the leg  12  of the upper articulation member. 
   Another embodiment of the invention is shown in  FIG. 2  where each member of the articulation system (only one such member being illustrated in  FIG. 2 ) comprises an elongate lateral leg  12  similar to the leg  12  of  FIG. 1 , but a tray  14  extends from the leg  22 . The base stone (not shown in  FIG. 2 ) is cast in place in the tray  14 . The tray  14  can be formed as an integral unit with the leg  22  or as shown in  FIG. 2 , the tray  14  can be formed so as to be integrally attached to the leg  22  by a connector having a slide element  25  that is received in a slot  26  in a relatively thick back side wall  27  of the tray  14 . As in the articulation members of the articulation system of  FIG. 1 , the articulation member shown in  FIG. 2  has an arm  20  that is integrally formed with the leg  22  and extends substantially perpendicular to the longitudinal axis of leg  22  from the free end of leg  22 . The distal end of the arm  20  has connecting means that are adapted to pivotally engage the end of the arm  20  of a mutually corresponding articulation member to form a working articulation system. 
   In the embodiment of the invention as shown in  FIG. 2 , the back wall  27  functions as the base member of the stop member  10 . A recessed receptacle  40  extends downwardly from the top surface of the back wall  27 . The elongate stop element  11  is designed to slide into the open receptacle  40  so that the stop element  11  can be attached to and removed from the back wall  27  of the tray  14 . The receptacle  40  and the stop element  11  and their inter-relationship and operation are in all respects similar to and the same as previously described with respect to the embodiment of the inventions shown in  FIGS. 1 ,  1 ( a ) and  1 ( b ) and need no further description at this point. 
   It should be noted that the male-female relationship of the engagement between the back wall  27  and stop element  11  could be reversed in a manner as previously discussed with the embodiment of  FIGS. 1 ,  1 ( a ),  1 ( b ) and  1 ( c ). Accordingly, a male type connector could extend upwardly from the top of the back wall  27  of the tray  14 , and a female type receptacle for receiving the male type connector could be recessed upwardly from the lower end of the stop element  11 . 
   In an alternative embodiment of the invention which is not presently considered to be as commercially valuable as the embodiments discussed heretofore, the receptacle  40  of the removable stop mechanism of the present invention could be formed directly in the base stone  16  of the dental model. As is shown diagrammatically and in cross-section in  FIG. 3 , the lower end portion of the stop element  11  can be pushed into the top surface of the green casting material of the base stone  16  as the base stone  16  is being cast. After the casting hardens, the stop element  11  can be removed from the base stone  16  so as to leave an open ended receptacle that the stop element  11  can be inserted into. This latter procedure is more time consuming than where the receptacle  40  is incorporated integrally into the elements that are used in making the articulation system, and in addition, the dental technician must exercise special care in properly positioning the stop element in the green casting material as the dental model is being cast.