Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
  • A61C9/00—Impression cups, i.e. impression trays; Impression methods
  • A61C9/002—Means or methods for correctly replacing a dental model, e.g. dowel pins; Dowel pin positioning means or methods

Definitions

• This invention relates in general to the precision mating of two elements, more particularly, to the making of cast models, such as for the precise fabrication of models of teeth, gums and jaws.
• the working model is removed from the original negative impression, prepared for placement or acceptance on an articulator platform and sectioned. Sectioning facilitates the removal and consequent replacement of the individual dies. On occasion, during their removal, or during efforts to effect separation, the two halves fracture or break apart and the formerly rigid pins either vend, loosen, collapse, or dislodge due to loss of perimeter support.
• a more particular object of this invention is to facilitate the removal and precise return of individual segments of a hardened dental casting to its or their orginal positional relationship, during processing.
• the precision plates of the pair are preferably formed so as to be completely interchangeable (any upper mounting plate fitting any lower mating plate) . They invariably mate together snugly to provide a fixed registration. Unrestricted compound cuts and required separations may - - be executed on the cast model clean through the plate section upon which the model is fastened without destroying the segment's replacement accuracy. Since each half or individual plate of the mating sandwich is precisely fabricated by the manufacturers in advance, and construct ⁇ ed of durable materials, they are not subject to technician or operator error. Normal environmental factors such as temperature, humidity, nonhomogeneous gypsum or other molding mixes, or foreign contaminents in dirty water may no longer be of concern. No pins, bushings, sleeves, drilling or boring by • mechanical means and other similar procedures are any longer required in the construction of dies of the types described. The original precision mating fit of the mating plates remains constant throughout the entire working procedure.
• the individual teeth and edentulous areas,if applicable, are sectioned only as far as needed to permit cutting through the mounting plate.
• the lower mating plate need not be cut or sawed into.
• the model, complete with the fastened upper mounting plate may be lifted clear of the lower mating plate and placed to the side; and separation by cutting or sawing may be carried out in this manner.
• the structure of the present invention also facilitates mounting and repositioning the various elements or composites to arti ⁇ ulators.
• the lower mating plate has a configured geometric pattern and a keyed protuberance incorporated on the underside for engagement by whatever method of fastening, bonding, holding, latching, or clamping that one may elect to utilize. For example, gypsum, plasters, glues, adhesives, or mechanically " designed key-way5 clamps, latches or magnetic assisting or adhering devices may be chosen.
• the precision mating plates may be provided with built-in venting openings to the underside of each of the elements of a pattern to eliminate the inadvertent or sporadic possible trapping of debris inside the geometric patterns which might otherwise prevent their precise seating or joining.
• the mating plates may be keyed, indexed and/or color coded on their inner and/or outer perimeter edges, so that an immediate visual indentification permits placement of appropriate segments or sections to the correct quadrant or location without "trial and error" locating techniques.
• notchings may be provided around the outer edges in between the two mating plates which may serve to assist in the quick removal and separation of individual sections when needed.
• a further desirable feature which may be incorporated as part of the combination of the present invention is a slightly extended overhang of adequate cross section located along the outer and inner perimeter of the upper mounting plate that holds the model. This feature not only provides a grasping ledge which permits the operator to avoid excessive fingering of the work die on its critical surface areas, but it also helps avoid rocking or prying adjacent segments off their respective seats.
• Applicant's device has a multitude of advantages over prior art methods, gadgets and apparatus available for prefabricating the processing cast models, particularly models of teeth, gums, and jaws.
• any model be it teeth, gum or jaw section
• individual sections can be promptly cut, removed and worked upon an indefinite number of times and precisely replaced in exact spatial relationship to the other elements of the model as it originally existed, without need for the exercise of constant caution, care and anxiety on the part of the operator, and without the detrimental wear and tear and consequent loss of accuracy due to looseness developing in one or more individual die segments.
• Fig. 1 shows an articulator including a hardened upper jaw model mounted thereon, and an exploded view of a lower jaw model mounted in accordance with the present invention to include a lower mating plate disengaged from the patterned supporting base of the articulator, and an individual tooth segment disengaged from the geometrically patterned lower mating plate.
• Fig. 2 is a perspective view, looking from one side, of the lower jaw model mounted on the articulator with one tooth sector removed from mating relating with the lower mating plate.
• Fig. 3 is an inside perspective view, looking down from above, of a lower jaw model in accordance with the present invention, showing a portion of the geometrically patterned lower mating plate with several sectors of individual tooth models removed therefrom.
• Fig. 4 are perspective views, respectively -8- fro the bottom, side, and top, of an individual tooth sector showing the geometrically shaped projections designed to mate with the exposed portion of the lower mating plate Fig. 3 from which it was removed.
• Fig. 5 shows the geometrically patterned under ⁇ side of a mounting plate, in accordance with the present invention, whose upper sur ace is constructed for the mounting of a hardened dental model.
• Fig. 6 shows the upper surface of a lower mating plate which is geometrically patterned to mate with the mounting plate underside of Fig. 5.
• Fig. 7 shows a fragment, a modification of the pattern which may alternatively be employed for the mating surface of either the mounting plate or the lower mating plate.
• Fig. 8 shows the underside of the lower mating plate of Fig. 6 which has an alternative pattern designed to mate with a matching pattern on the supporting surface of an articulator.
• the first step in making a dental model is to make an impression of the relevant portions of the patient's tooth, gum or jaw structure.
• this is carried out by placing a tray of dental impression material in the patient's mouth. When the material has set, the tray is removed.
• the impression material now shows a negative outline of the subject's teeth, gum, or jaw.
• Gypsum or other molding material is then poured into the impression and allowed to harden.
• the hardened model is then separated from the impression to provide a working model of the patient's teeth, gum or jaw.
• the patient's model is then attached by suitable bonding means, such as, for example, a cement sold by the DuPont
• the articulator is a device comprising upper and lower mounting platforms which may be connected in a variety of manners on the inside to receive the upper and lower jaw elements and to simulate the relationships or the actual movement or bite of the human jaw.
• the gypsum model could be separated from the impression, and cut at the desired place, so that the tooth model could be removed, worked on, and returned to its proper location. It is apparent that the accuracy and efficiency of this method leaves much to be desired. The repeated removal and replacement of segments tends to erode the original fit and postion of the pin so that is precise relation ⁇ ship no longer exists and collective alignment accuracy is no lon ⁇ er possible.
• the articulator 1 to which casts of the jaws are convention ⁇ -10- ally attached during the process of preparing false teeth, or bridges, crowns, inlays and the like, has upper and lower supporting platforms 2 and 3 which are arranged to open and close about a hinge la.
• the upper jaw model 4 (which to simplify the description is shown as permanently secured by plastering, but which may alternatively be assembled as taught in accordance with the present invention, and as described hereinafter with reference to the lower jaw model 5) is mounted in a downwardly- projecting manner from the articulator platform 2.
• Fig. 1 shows, in exploded view, the lower jaw model 5 which is constructed for mounting on the lower platform 3 of the articulator 1.
• the bottom surface of gypsum jaw model 5 is bonded with an adhesive cement, epoxy, or the like, to the substantially plain upper surface of mounting plate 6, forming a rigid bond 8.
• the lower surface of mounting plate 6, which,in accordance with the present invention is covered with an elaborate and abundant interdigitation of geometric patterns 6a of varying depths and sizes, is constructed to mate with inverse patterns 7a on the upper surface of the lower mating plate 7 ' .
• the plates 6 and 7 are preferably formed of a suitable blend of injection molding resin, such as, for example, a commercially available formul ⁇ ation of acrylonitrile butadiene styrene, (known as AEs) but can be formed of any rigid thermo-plastic material such as a high impact polymer resin which can be permanently molded (preferably by injection molding) to a precision of within approximately one thousandth ( 0.001) of an inch, has a Rockwell-(R) hardness number within the range 75-150, and a flexural modulus (when hardened ) within the range 200,000-600,000 p.s.i.g.
• injection molding resin such as, for example, a commercially available formul ⁇ ation of acrylonitrile butadiene styrene, (known as AEs)
• AEs acrylonitrile butadiene styrene
• the botton surface of 7 may also be embossed and configures with a pattern 7b, which is less elaborate than pattern 7a and which is so formed that it meshes with a pattern 3a on the surface of supporting platform 3.
• the supporting platform 3 is engraved on its upper surface 3a with a plurality of radially-directed grooves 3b of triangular cross-section which are constructed to accommodate the projections 7b on the lower surface of lower mating plate 7.
• any adequate and acceptable adhesive, suitable bonding method, or mechanical or other suitable securing means may be interposed at this point to retain supporting plate 7 fixed to platform 3.
• a rubber based solvent contact adhesive has been found suitable.
• the intermeshing patterns 6a-7a may take many different geometric forms and shapes.
• the pat ⁇ terned surface 6a may take the form of a plurality of projections, each projection being slightly frustoconical, say 0.060 inches across the base, and 0.030 inches across the top, and extending out 0.220 inches from the surface. the centers of adjacent projections being separated, by say, 0.200 inches.
• the mating surface 7a may comprise a plurality of frustoconical recesses separated and shaped to exactly accommodate the projections on 6a.
• the recesses on 7a may be extended through the thickness of 7 forming small perforations in order to facilitate the removal of molding particles, dirt, debris, or other contaminents which might otherwise collect in the recesses on 7a.
• many different types of geometric patterns might be substituted for the patterns 6a and 7a shown in Figures 1-4.
• alternative intermeshing patterns 6a 1 and 7a' are shown for the mounting plate 6' and the lower mating plate 7' , in Figs. 5 and 6, respectively.
• the mating surfaces may comprise a number of different interlocking planes; and the supporting plate 7' and the mounting plate 6' may each comprise projections and recesses which are designed to exactly and precisely mesh with recesses and projections in the corresponding position in the order.
• the plate 7' may include a plurality of frusto ⁇ conical projections 10 which are designed to protrude into recesses in plate 6' ; but these are much shorter than the vertical, downward projections on 6a'.
• the plates 6' and 7' having intermeshing patterns 6a' and 7a' are each in the shape of an arch, having a maximum width of approximately 2-1/2 inches from the rounded to the flat end, and an overall width of approximately 2-7/8 inches across the flat end.
• the central arched opening is approximately 1-5/8 inches long to the point of maximum curvature, and approximately 1-1/8 inches across the flat base.
• the mounting plate 6' and the lower mating plate 7' may include on their matching lateral surfaces indexing lines
• one or more lateral notches 13 assist the operator by providing a position at which a prying tool can be inserted to pry the closely mated plates 6' and 7' apart.
• the mounting plate 6 (referring again to Fig. 1) may be dimensioned to be slightly broader in extent in its principal plane than lower mating plate 7, so as to provide a slight overhang 6c of, say, l/8th inch on one or both to is lateral inner and outer edges to serve as a finger-nail hold for the operator to facilitate in separating plates 6 and 7 when they are in intermeshed relation.
• Fig-. 8 shows the opposite side 7b' of the plate 7', which contains an arched-shaped projection, including a pattern of concentric steps 14 which key into the intermesh with a modified form of articulator platform which has a matching arch-shaped depression.
• the articulator platform surface is designed to be secured or may be bonded to the underside 7b' of lower mating plate 7' for increasing the stability of the assemblage.
• the present invention facilitates quick removal and precise repositioning of individual sections by means of the mating geometric patterns and grooves, indexing and coding and by the grasping ledge that reduces the necessity of the operator to touch the critical surfaces of the actual die reproduction.
• the matching mounting and lower mating plates which may be used for either maxillary or mandibular jaw models, or both together, are fabricated for quick attachment and removal from the articulator platforms. Further, a single section without a geometric pattern on top can be used for

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• Health & Medical Sciences (AREA)
• Oral & Maxillofacial Surgery (AREA)
• Dentistry (AREA)
• Epidemiology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Dental Prosthetics (AREA)
• Dental Tools And Instruments Or Auxiliary Dental Instruments (AREA)
• Instructional Devices (AREA)

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Cited By (3)

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Citations (3)

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• 1979
  • 1979-07-09 US US06/055,502 patent/US4265619A/en not_active Expired - Lifetime
• 1980
  • 1980-05-21 WO PCT/US1980/000610 patent/WO1981000047A1/en active IP Right Grant
  • 1980-05-21 JP JP55501550A patent/JPH0234616B2/ja not_active Expired - Lifetime
  • 1980-05-21 AT AT80901287T patent/ATE17644T1/de not_active IP Right Cessation
  • 1980-05-21 DE DE8080901287T patent/DE3071378D1/de not_active Expired
  • 1980-06-04 CA CA000353353A patent/CA1151854A/en not_active Expired
• 1981
  • 1981-01-26 EP EP80901287A patent/EP0032146B1/en not_active Expired

Patent Citations (3)

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