Dentistry – Apparatus – Having gauge or guide
Patent
1999-03-09
2000-11-21
Wilson, John J.
Dentistry
Apparatus
Having gauge or guide
433 34, A61C 1900
Patent
active
061494283
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The present invention relates to a mould for casting a base for a dental model when reconstructing teeth for dentures or parts thereof and comprising a base plate, along the edge of which a mould cavity is placed, said mould cavity comprising a bottom with fixating means for the dental model or parts thereof in the form of at least substantially cylindrical pins which can be inserted in corresponding holes in the bottom of the mould cavity and which each comprises a portion suitable for being cast in the base of the dental model, and walls provided with ribs extending from the bottom, the mould cavity having the shape of at least a part of a jaw.
DESCRIPTION OF THE BACKGROUND ART
DE A1 3 837 551 discloses a device for making a dental jaw model divided into segments, the device comprising a carrier plate, on which a socket can be mounted, said socket being provided with guiding grooves which receive separation plates for dividing the model into segments. The carrier plate forming the bottom of the mould cavity constituted by the carrier plate and the socket is provided with preferably conical holes adapted to receive pins or taps, the projecting parts of which are cast in the model.
A mould of a similar type is known from U.S. Pat. No. 5,328,366. When reconstructing teeth in a denture it is usual to cast the model of the denture in a base which is later connected with an articulator, by means of which it is controlled whether the reconstructed teeth are able to correctly engage the corresponding teeth in the opposite jaw. In the known mould it possible to remove the cast model from the mould and mount it again after it has been divided in several pieces, in which connection the tooth to be reconstructed constitutes one of the pieces. When mounting the model in an articulator, the mould is used as a connecting link to the connecting arms of the articulator. When remounting parts of the model in the mould it is important that the individual parts are effectively fixed in the mould. In the known mould it has turned out that the middle part of a model divided in three is not sufficiently fixated, even though it is clamped in a slot extending along the cavity of the mould by means of a fixating means cast into the base part. The middle part can be rocked a few tenths of a millimeter, which means that it is not possible to reconstruct a tooth with optimal accuracy.
SUMMARY OF THE INVENTION
It is, in view of this, the object of the present invention to provide a mould, in which the drawbacks of known moulds have been obviated in practice. This object is met by a mould which is characterized by the novel subject matter of the present.
The invention resides in the realization that even though for the reconstruction of individual teeth in a denture for the jaw model gypsum is used, which has a very little extension during the setting, it is necessary to particularly take this condition in consideration when designing the mould and the fixating means, which are to hold sections of the jaw fixed during the subsequent remodelling. Thus, the profiling of the wall of the mould cannot be expected to be sufficient for securing a jaw section, when, after having been cut away, it is once more mounted in the mould. In the new embodiment the pins are designed as straps which are cast in the jaw model and safely secured, the risk of the model being ruptured being thus eliminated, and each strap comprises two pins, whereby the section is solely fixed in the mould by means of the pins arranged pairwise in this way in the pre-defined position.
A particularly advantageous pattern of placing the holes is created thereby that the sum of the distances in the two rows of holes between adjacent holes is constant in respect of all pairs of holes in the mould, which means that the holes pairwise will acquire the same distance over the whole length of the mould cavity.
In a particularly practical design, the taps are joined into a ribbon by means of a longitudinal rib connecting t
REFERENCES:
patent: 3937773 (1976-02-01), Huffman
patent: 4139943 (1979-02-01), Dragan
patent: 4449931 (1984-05-01), Saito
patent: 5328366 (1994-07-01), Callne
patent: 5466152 (1995-11-01), Walter
patent: 5658143 (1997-08-01), Kuperman
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