referring initially to fig1 and 2 , a dental articulator 20 presents a manikin having an upper carrier tray 22 and a lower carrier tray 24 which receive and hold individual modules of imitation gums and teeth , upper such module 26 and two lower modules 28 and 30 being seen in fig1 . also , as will be discussed more fully hereinafter , the upper tray 22 receives and holds an endodontic module 32 having a breakaway insert 34 . the trays 22 and 24 are rotatable about a transverse axis provided by adjustable , left and right hinge components 36 and 38 which establish an axis about which articulated members connected to the trays 22 and 24 rotate ; specifically , axially spaced outer , lower members 40 and 42 connected to the rear edge of lower carrier tray 24 in the conventional manner , and spaced inner , upper members 44 and 46 connected to the rear edge of the upper carrier tray 22 . to open and close the articulator ( shown in the closed condition ), one or both of the carrier trays 22 and 24 are rotated about the axis provided by the hinge components 36 and 38 . a mounting ring 48 is integral with inner members 44 and 46 and centered therebetween to provide a means of supporting the manikin on a post ( not shown ) and tightening ring 48 thereon by a manually adjustable screw 50 , as is conventional . the hinge structure is shown more fully in fig3 - 5 where the hinge component 38 and associated parts are revealed in detail , it being understood that hinge component 36 on the opposite side of ring 48 is constructed in the same manner to provide a continuous axis 52 from outer member 40 to outer member 42 . a hinge component or pin 54 has an enlarged end presenting a knob 55 coaxial with the shaft 56 of the pin 54 , the pin 54 terminating at its opposite end in a threaded portion 58 of smaller diameter . as will be discussed , the hinge pin assembly is completed by a shoulder ring 60 , washer 62 and nut 64 . outer member 40 has a tubular upper end portion 40 a through which shaft 56 extends at a right angle . fig3 shows the hinge pin 54 in place with shaft 56 extending through an elongated opening 68 near the upper end of outer member 40 , across end portion 40 a and inward into an axial opening 70 in the outer end of inner member 44 aligned with axis 52 . the hinge is assembled by inserting shaft 56 with shoulder ring 60 thereon through opening 68 and on into axial opening 70 with washer 62 disposed between members 40 and 44 . an opening 72 in the member 44 communicates with axial opening 70 to permit insertion of nut 64 in the assembly of the hinge . it should be noted that the axial opening 70 in the outer end portion of inner member 44 is oversized with respect to the diameter of the shaft 56 of the hinge pin 54 to permit adjustment of the axis 52 as will be discussed . referring to fig3 and 5 , a compression spring in the hollow outer end of member 40 operates between a removable end plug 76 and a cut 78 that mates with shoulder ring 60 on the shaft 56 of hinge pin 54 . the spring 74 , therefore , maintains shaft 56 at the bottom end of elongated opening 68 as seen in fig2 and 3 . the adjustable hinge component 36 associated with tubular end portion 42 a of member 42 is constructed in the same manner as described above for hinge component 38 and completes the axis 52 about which the upper carrier tray 22 may be rotated to simulate the opening and closing of the jaw . as will be discussed more fully hereinbelow , adjustment of the axis 52 is provided by the oversize opening 70 and cooperating parts in each of the two hinge assemblies . referring to fig6 - 8 , the lower carrier tray 24 is shown in detail . in fig6 the modules 28 and 30 are removed and , additionally , a module 29 ( fig8 ) not visible in fig1 . the tray 24 is composed of a nonmagnetic material such as aluminum and has three magnetic assemblies 80 therein , each of which is secured in a corresponding rectangular recess 82 and creates a closed magnetic field . each of the magnet assemblies 80 comprises three neodymium magnets side - by - side presenting upwardly facing , alternating poles as shown in fig7 ( south , north and south ). each of the three magnet assemblies 80 is held in a non - magnetic , e . g . plastic , frame 84 as seen in fig7 and 7 a . preferably , the total thickness of the magnet and frame assembly is approximately three millimeters with the magnets themselves having a thickness of less than two millimeters , and thus the assembly is accommodated without increasing the thickness of the tray . the rectangular recesses 80 in tray 24 are complimental to the frame 84 and provide a flush fit with the upper surfaces of the magnets 80 co - planar with the interior surface 85 of the tray 24 . upper tray 22 is of identical construction . fig8 shows the two gum modules 28 and 30 ( teeth are not shown ) seen in fig1 and a module 29 hidden from view in fig1 which , as a group , are insertable into lower tray 24 , a tab 86 at the anterior tip thereof being received in a corresponding slot 88 in the tray 24 . each of the modules 28 , 29 and 30 has a rectangular plate 90 of magnetic material ( such as steel ) embedded therein with its outer surface flush with the bottom surface of each of the modules . these plates 90 register with corresponding magnet assemblies 80 upon insertion of the modules into the tray , thereby securing the modules within the tray until forceably released therefrom by a quick manual pull on the module . though illustrated herein in the lower tray 24 , it is to be understood that the magnetic assemblies 80 may also be used to secure modules in the upper tray 22 of the articulator 20 . use of the articulator of the present invention in connection with an endodontic procedure is illustrated in fig9 - 14 . the module 32 comprises a simulated plastic gum 92 , a pre - formed socket 94 in the module , a dummy tooth 96 , and the breakaway insert 34 ( partially withdrawn ) having a dummy tooth 100 and a simulated tooth 102 ( either upper or lower ) upon which an endodontic procedure may be practiced . fig1 shows the bottom of the module 32 where a plate of magnetic material 104 is recessed into the base of the module for releasably securing the module in the upper carrier tray 22 of the articulator ( fig1 ). after a dental procedure is performed on the tooth 102 ( which may be a lower tooth as well as an upper tooth procedure ), the module 32 is released from the manikin so that the tooth 102 may be inspected and the quality of the student &# 39 ; s work determined . the insert 34 is withdrawn as illustrated in fig1 , facilitated by a release hole 105 in the base of the module 32 . a slot 106 in the base of the insert 34 ( fig1 ) permits the breakaway action by insertion of a small coin or similar object ( not shown ) into the slot 106 and , by a twisting action , separating the insert into its two mating sections 34 a and 34 b . fig1 and 14 reveal a small tab 108 on section 34 b which is tightly received within an opening 110 in section 34 a to hold the mating sections together in properly aligned relationship until separation . as may be appreciated from fig1 and 14 , the simulated tooth 102 is received within aligned recesses 112 in section 34 a and 114 in section 34 b when the insert 34 is in its closed condition as seen in fig1 and 12 . accordingly , when the sections 34 a and 34 b are released , the endodontic tooth 102 previously held in the recesses 112 , 114 may be removed as illustrated in fig1 and the work of the student evaluated by the instructor . for example , for a root canal procedure , the instructor can visualize complete treatment of the canals as well as check for perforations that may have been made through the canal or pulp floor during the procedure . this is accomplished by simple visual inspection without the necessity of radiographic analysis , for example , that would be required in order to evaluate an encased tooth . furthermore , the endodontic module 32 may be reused repeatedly by replacing the insert 34 . a modified form of carrier tray 122 is shown in fig1 - 18 and provides additional adjustability to assure proper alignment in the closed condition of the articulator 20 . spaced upper arm members 144 and 146 are interconnected at their distal ends by a crossbar 200 shown in fig1 engaging the rear edge 202 of tray 122 . this is the normal position of the crossbar 200 when the adjustable , left and right hinge components 36 and 38 described hereinabove provide adequate adjustability to properly align the upper and lower carrier trays 22 and 24 as shown in fig1 . however , if additional adjustment is required to provide the proper alignment , the upper carrier tray 122 may be shifted to the left or right as illustrated in fig1 or pivoted upwardly or downwardly as illustrated in fig1 , by a ball and recess connection shown in detail in the exploded view of fig1 . more particularly , the crossbar 200 has a shank or stem 206 at its longitudinal center projecting forwardly and presenting a ball 208 which is received within a corresponding recess 210 in the rear edge 202 of tray 122 to provide a ball - and - socket connection ( fig1 , 16 and 17 ). the ball 208 is held in socket 210 by a cover plate 212 received in an opening 213 and secured by a pair of screws 214 . the plate 212 is removed in fig1 to reveal the shank 206 and ball 208 , and is shown in place in opening 213 in fig1 secured by screws 214 to thereby clamp the ball 208 and lock it in the selected position . in fig1 the ball 208 is essentially fully inserted in the slot 210 and the bar 200 is in engagement with surface 202 , whereas in fig1 an extreme adjustment is illustrated and shows rotation of the tray 122 to the right . accordingly , left to right adjustability is provided by the ball and recess connection upon loosening the screws 214 , shifting the tray 122 to the desired position that will provide proper alignment of the teeth , and then tightening the screws 214 . furthermore , up and down adjustability about the ball 208 is also provided by the ball - and - socket connection upon loosening the screws 214 and swinging the tray 122 to the desired position . comparison of the full and broken lines in fig1 illustrates the capability of providing a range of adjustability that assures accurate positioning of the simulated upper teeth relative to the lower teeth at the proper alignment or demonstration of an intentional misalignment . also , it should be appreciated that the lower carrier tray 24 ( fig1 and 6 ) may be modified in the same manner as described above for upper carrier tray 122 , thereby providing either or both trays with full adjustability . it is to be understood that while certain forms of embodiments of this invention have been illustrated and described , it is not limited thereto , except insofar as such limitations are included in the following claims and allowable equivalents thereof .
a dental articulator for use in dental education simulates the human mouth and has an adjustable hinge that interconnects upper and lower carrier trays for movement to and from a closed position . modules of imitation gums and teeth are secured in the carrier trays by neodymium magnets . the hinge structure in the articulator is selectively movable to shift the jaw axis to a position to provide the desired alignment of the upper and lower teeth when the jaw is closed or demonstrate a misaligned condition . a dental training module may be installed which , upon removal from the articulator , has a pair of separable sections encasing a tooth to permit release of the tooth and removal from the module so that a completed treatment may be evaluated .