GB2230958A

GB2230958A - Dental model holder

Info

Publication number: GB2230958A
Application number: GB9008555A
Authority: GB
Inventors: Colin Bishop-Bailey
Original assignee: BISHOP BAILEY COLIN
Current assignee: BISHOP BAILEY COLIN
Priority date: 1989-04-13
Filing date: 1990-04-17
Publication date: 1990-11-07
Also published as: GB8908330D0; GB9008555D0

Abstract

A dental model holder comprises a cast holder (1), a base plate (2) to which the cast holder is mountable, and a sealing plate (3) to secure the cast holder to the base plate. The sealing plate (3) is slidably affixable to the base plate (2) on a side thereof remote from the cast holder (1). The sealing plate (3) has a rim adapted for engagement with the periphery of the cast holder (2). <IMAGE>

Description

DENTAL MODEL HOLDER This invention relates to dental model holders, particularly for use by dental technicians in modelling or constructing artificial crowns and/or bridges.

In preparing a model of a patient's teeth it is usual for a dentist to make a template using a tray including soft thermoplastic material, and which is inserted into the patient's mouth. When the template, bearing an impression of the teeth, has hardened, it is filled with pourable casting stone to form a die. During the casting step it is advantageous to mould the cast onto a holder to facilitate subsequent handling of the die.

Once the cast has set in the holder it is then removed from the template and the assembly of cast and holder is fitted into a base plate. In modelling crowns and/or bridges, it is necessary to be able to section the cast and remove dies of individual teeth or groups of teeth for detailed alteration work and yet be able to re-assemble them accurately with the remaining teeth in the cast to test their articulation.

One important feature of the model holder, comprising cast holder and base plate, is that it should comprise means for securing the cast holder to the base plate. In the prior art the locking means used for this purpose are vice mechanisms which are expensive and generally incapable of reliably releasing an individual tooth die from the base plate without simultaneously releasing adjacent tooth dies.

It is an object of the present invention to provide a dental model holder which overcomes or at least diminishes the above disadvantages.

According to the present invention there is provided a dental model holder comprising a cast holder, a base plate to which the cast holder is mountable, and locking means to secure the cast holder to the base plate, characterised in that said locking means comprises a sealing plate affixable to the base plate on a side thereof remote from the cast holder, and having a rim adapted for engagement with the periphery of the cast holder.

In a preferred embodiment the rim of the sealing plate is adapted for engagement with the periphery of the cast holder by the provision of a groove therein to engage with a flange provided on the periphery of the cast holder.

Alternatively, the rim of the sealing plate may be adapted for engagement with the periphery of the cast holder by provision of an inwardly directed flange thereon, to engage with a groove provided on the periphery of the cast holder.

It is preferred that the locking means further comprises means for engagement between the base plate and sealing plate, provided adjacent the rear ends thereof, restricting sliding motion of the sealing plate relative to the base plate.

Preferably the means for engagement between base plate and sealing plate to restrict sliding motion thereof comprises a ridge provided on the base plate so as to engage with a notch provided on the sealing plate.

A preferred embodiment of the present invention will now be more particularly described with reference to the accompanying drawings, in which: FIGURE 1 is a perspective view of a preferred embodiment of dental model holder with only a portion of each of the cast holder and securing plate shown, to illustrate their interconnection; FIGURES 2a to 2c are top plan, transverse section and bottom plan views, respectively, of the cast holder of the preferred embodiment; FIGURES 3a to 3c are top plan, transverse section and bottom plan views, respectively, of the base plate of the preferred embodiment; FIGURES 4a to 4c are top plan, transverse section and bottom plan views, respectively, of the sealing plate of the preferred embodiment.

As illustrated in Figure 1, a dental model holder comprises a cast holder 1 mounted on a base plate 2, and secured thereto by the rim 21 of a sealing plate 3 affixed to the underside of the base plate 2. The cast holder illustrated in Figures 2a to 2c is a jaw-shaped tray having an inner wall 5, an outer wall 4, and a base 6. The inner and outer walls 5,4 of the cast holder have opposing rims 9 projecting therefrom which, in conjunction with pins 8 located either side of or in a trough 7 extending along the base 6 of the tray, serve to retain the cast. The outer wall 4 of the cast holder is provided with a downwardly extending extension 25, having an outer peripheral flange 11 projecting from its lower edge.The outer wall extension 25 of the cast holder 1 enables engagement with the rim 21 of the sealing plate 3 via interconnection between the outer peripheral flange 11 of the cast holder outer wall extension 25 and an inner groove 22 in the rim 21 of the sealing plate 3.

Corrugations 10 are provided on the underside of the cast holder 1 at the radially inner surfaces of the outer wall extension 25 and the inner trough wall to allow the portions of cast holder 1, from sectioning of the die, to be re-assembled accurately on the base plate 2 by alignment of the corrugations 10 with corresponding corrugations 16 on the upper side of the base plate 1.

Provision of the corrugations 10 of the cast holder outer wall extension 25 terminating above the lower edge of the extension 25 creates an inner ledge 26 thereat which sits upon a corresponding ledge 27 formed on the base plate 2 at the termination of the corrugations 16 of the base plate peripheral wall 14, when the intact or segmented cast holder 1 is assembled upon the base plate 2. Because the corrugations 10,16 terminate above the lower edge of the base plate peripheral wall 14, reinsertion of portions of the die into the holder to reassemble the full model is facilitated. If the corrugations 10,16 were extended over the entire depth, marginal misalignment of the die during reinsertion would make accurate replacement difficult.

However, having a smooth lower portion to the base plate peripheral wall 14 allows the reinserted die to be laterally displaced during the act of insertion enabling correction of alignment.

The base plate 2, illustrated in Figures 3a to 3c, is formed to provide surfaces corresponding to those of the cast holder 1 for effective assembly. Thus, the base plate 2 comprises a jaw shaped tray having an inner wall 15, an outer wall 14, and a base 13, into which the trough 7 of the cast holder 1 may be fitted. A platform 12 extending between the upper edges of the inner walls 15 gives the base plate 2 rigidity, and serves to support the inner portion of the base 6 of the mounted cast holder 1.

As aforementioned, corrugations 16 are provided on the base plate 2, on the radially outer surfaces of the inner and outer walls 15,14, corresponding to the corrugations 10 of the cast holder 1. The upper edge of outer wall 14 is provided with a plurality of projections 28, which in the preferred embodiment have a long projection alternating with a short projection. Corresponding recesses are provided in the underside of the cast holder 1, at region 29, interior of the outer wall 4 thereof. This plurality of projections forms a serrated pattern along the locating edge and ideally a repeat pattern of projections occurs every 8-10 mm. Thus, any individual die should be placed either in place or at least 8-10 mm away.It should be obvious to a skilled technician when a part of the cast is so far out of place and therefor the projections 28, in combination with corrugations 16, define almost exactly where any die should be located. A further feature of the base plate 2 is the provision of a peripheral flange 18 projecting from the lowermost extremity of a downward extension 27 of the base plate outer wall 14. This peripheral flange 18 may engage with the inner groove 22 in the rim 21 of the sealing plate 3. A pair of ridges 19 provided towards the rear of the base plate 2 project from the peripheral flange 18, one on each side of the base plate 2. The ridges 19 engage with corresponding notches 23 in the base 20 of the sealing plate 3 to prevent the base plate 2 from freely sliding from the sealing plate 3 in reverse of the mounting procedure.

To assemble the dental model holder initially the cast holder 1 is simply placed atop the base plate 1, and the combined holder is then inserted slidingly into the sealing plate 3, with the peripheral flanges 11,18 of the cast holder 1 and base plate 2 engaging the inner groove 22 of the rim 21 of the sealing plate 3.

Removal of individual tooth dies from the base plate 2.is achieved by utilising extension 25 and simply prising them from engagement with the sealing plate.

Conversely, replacement simply involves hooking the peripheral flange 11 of the cast holder 1 of the die into the groove 22 of the sealing plate 3.

It may be necessary that the rim 21 of the sealing plate 3 be cut consistent with the cuts to the cast and cast holder for isolating the individual or group tooth die. The sectioning of the cast holder 1 and partial sectioning of the sealing plate 3 renders these components necessarily disposable, but compared with the prior art, in which reusable clamp-typelocking means are employed in place of a sealing plate 3, substantial cost benefit is still achieved.

Thus, it can be seen that the present invention provides an improved means of securing a dental cast holder to a base plate which serves the basic purpose of enabling reassembly of individual teeth (or groups of teeth) from the die after they have been isolated for detailed work, with the advantage that removal and reinsertion of the individual teeth (or groups of teeth) is achievable without disturbing the remaining teeth in the model holder.

Claims

1. A dental model holder comprising a cast holder, a base plate to which the cast holder is mountable, and locking means to secure the cast holder to the base plate, wherein said locking means comprises a sealing plate affixable to the base plate on a side thereof remote from the cast holder, and having a rim adapted for engagement with the periphery of the cast holder.

2. A dental model holder as claimed in claim 1, wherein the rim of the sealing plate is adapted for engagement with the periphery of the cast holder by the provision of a groove therein to engage with a flange provided on the periphery of the cast holder.

3. A dental model holder as claimed in claim 1, wherein the rim of the sealing plate is adapted for engagement with the periphery of the cast holder by provision of an inwardly directed flange thereon, to engage with a groove provided on the periphery of the cast holder.

4. A dental model holder as claimed in any one of the preceding claims, wherein the locking means further comprises means for engagement between the base plate and sealing plate, provided adjacent the rear ends thereof, restricting sliding motion of the sealing plate relative to the base plate.

5. A dental model holder as claimed in claim 4, wherein the means for engagement between base plate and sealing plate to restrict sliding motion thereof comprises a ridge provided on the base plate so as to engage with a notch provided on the sealing plate.

6. A dental model holder as claimed in any one of the preceding claims, wherein corresponding abutment and recess means are provided on said cast holder and said base plate, whereby they may be accurately located after separation.

7. A dental model holder substantially as described herein with reference to the accompanying drawings.