Dentistry – Apparatus – Having static product shaping surface
Patent
1998-12-03
2000-08-08
Lucchesi, Nicholas D.
Dentistry
Apparatus
Having static product shaping surface
433 47, 433 60, A61C 1900, A61C 900
Patent
active
060993057
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a device for the production of a dental working model for preparation of a prosthetic work and to a method of producing a dental working model using such a device.
The production of dental prostheses requires the production of a dental working model which is an exact duplication of the patient's mouth on which a prosthesis can be fabricated. Typically, a dental working model comprises a positive model of the teeth, as well as possibly the gum, mandible portions, palate etc., of one jaw of the patient fixed onto a substrate. The particular teeth of the model on which a dental prosthesis is to be produced can then be sectioned from the whole model (to produce what is termed a "die"). During preparation of the prosthesis, it is necessary to be able to relocate the individual dies into their original positions on the model to ensure that the prosthesis will fit the patient.
Errors in the final product can be caused by any system where the dies appear to have been properly relocated but, in fact, are a minute amount out from their correct position. When the prosthesis is completed, it will fit this working model containing the teeth on which the prosthesis is to be located and will occlude with the opposing model (of the teeth on the other jaw) but will not necessarily fit the patient's mouth. It is then necessary for the prosthesis to be trimmed to obtain a proper fit or indeed for the prosthesis to be totally remade, wasting time and money.
Dental working models are produced typically in dental die stone or other model material which is semi-liquid when cast but hard when cured. First of all, impressions of the two jaws of the patient's mouth are taken, typically in a silicone impression material. This impression is filled with the semi-liquid model material to produce a positive model of the patient's mouth. In addition, some form of tray or model former is also filled with the semi-liquid model material to produce the substrate. A filled impression of one jaw of the patient's mouth is inverted onto the substrate. When the model material has cured, an integral model of the jaw of the patient is produced which can then be sectioned as outlined above.
There has long been a need for dental technicians to have an accurate registration device that will enable them to section dental models into individual dies then reinstate the sections of the model to their former relationship with the adjacent dies and also the opposing model. This correct relationship is crucial to the manufacturing process of the prosthesis.
U.S. Pat. No. 4,283,173 (Browne et al) discloses a device for the production of a dental working model for the preparation of prosthetic works comprising a base presenting an open portion on both sides. A hollow portion adapted to the shape of the jaws presents ribs on both inner surfaces. The ribs act as retaining members for the model material and have the shape of ramps with a constant slope from top to bottom, the hollow portion widening from bottom to top. Because the base presents an open portion on both sides, the relocation of the dies can be checked from both the top and the bottom. However, an open bottom tray cannot contain the soft semi-liquid model material. As the semi-liquid model material is poured into the open bottom tray positioned on a bench surface (or other surface), the semi-liquid model material tends to creep through the gap between the tray and the bench surface causing a flash to appear on the model. This flash cannot be cleaned off the model effectively and causes inaccuracies in the relocation process.
Other devices using a separate bottom cover plate which fixes to the lower edge of the tray have been partially successful in containing the semi-liquid model material. However, there is still a tendency for the semi-liquid to creep through the seal between the separate bottom cover plate and the lower edge of the tray causing a flash to appear on the model. is Because of these problems, the technician must be extremely fastidious when pouring th
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Browne Lawrence Stephen
Clenton Raymond Terence
Neve Derren
Neve Trevor Howard
Lucchesi Nicholas D.
Regency Technologies Limited
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