US2237350A - Production of artificial teeth - Google Patents

Description

April 8, 1941. H HQLLMANN 2,237,350

PRODUCTION OF ARTIFICIAL TEETH Filed June 4, 193a Jawnfar HEINRICH H01. LMA/VN SFZ Z 5% Him/wags Patented Apr. 8, 1941 entree STATES PATENT QFFICE Application June 4, 1938, Serial No. 211,741 In Germany June 11, 1937 1 Claim.

In order to simplify the production of artificial teeth, it has long been the practice to standardize them. The first steps in this standardization process were the Logan and Davis crowns, but these were not successful, owing to the fact that there was too great a disparity between the metal cap or superstructure of the root pin and the porcelain crown, Attempts have been made to eradicate this defect by modifying more or less the cavity in the crown and the caps of the root pins so as to achieve greater strength and a better hold. All these types of crowns had the common feature that they enabled the face of the crown to be adapted to the face of the root by suitable means, after which the cap or super structure could be cast onto the root pin in the laboratory. Since, however, by far the greater proportion of practising dentists, about 95% do not possess their own laboratories, this method of preparing a porcelain crown demanded greater expenditure of time and money. To overcome this disadvantage the industry adopted the course of putting on the market ready-made root pins with their caps more or less shaped to fit the cavities in the crowns. But as the incisor and eye teeth that came into question chiefly necessitate far more than a hundred different sizes, a corresponding number of pins would naturally have had to be available, with their ready-made caps corresponding with the sockets of the crowns.

This would have necessitated the stocking of an impracticable number of two parts, and therefore, the sizes of crown were subdivided into groups according to their cavities and for each such group root pins were provided, with caps or superstructures shaped in accordance with the cavities of the crowns. The dentist thus had the task on the one hand of first finding a pin that was adapted, as far as its superstructure was concerned, to the tooth to be substituted, and on the other hand, when he had found this, of looking for the crown fitting this superstructure. Thus the dentist was obliged to keep a large stock of crowns and root pins and caps always available.

It is the object of the present invention to solve this problem, and this is achieved essentially by means of an intermediate element adapted to the crown cavity and the root pin cap or superstructure. The tooth structure according to the invention is built up with the following means and in the following manner:

(a) A root pin that is adapted to be inserted and afiixed in the root in any manner, but with a cap that is the same for all teeth.

(b) An intermediate element interposed between the root pin and crown, the cavity of which is shaped to correspond to the cap of the root pin and which, like the latter, is always the same for all teeth, whilst its external dimensions are varied according to the different sizes of teeth or the different dimensions of the cavities of the teeth, the teeth and intermediate elements tallyingwith one another in their internal or external dimensions being first of all assembled loosely;

(c) The crown is fitted to the face surface of the root, for example, by grinding;

(d) The individual parts are attached together, for example, by cementing.

With such a construction it is possible to make the intermediate element of porcelain and to adapt its colour to that of the tooth, and, further, (for facilitating the fitting together of the face surfaces of the crown and root) to utilize an auxiliary check plate shaped in accordance with the support surface that is required.

Further features of the invention concerning the external formation of the intermediate element and its anchoring to the superstructure of the root pin, will be described hereinafter.

Advantages afforded by the invention include simplification of the make-up and assembly of the artificial tooth, with a considerable saving of time, substantial reduction in the number of pins and crowns required to be stocked, with a consequential cheapening of the teeth, independence on a laboratory owing to the fact that the intermediate element enables an individual crown to be made without it first being necessary, as was previously the case, to prep-are the necessary superstructure or cap in the laboratory and then to burn an individual crown thereonto.

To facilitate understanding of the present invention, I have appended hereto a sheet of drawings in which the invention is illustrated by way of example and in which:

Fig. 1 is a longitudinal section through an artificial tooth constructed according to the invention,

Fig. 2 is a side elevation illustrating a check plate for use in adapting the crown to the root,

Fig. 3 is a view illustrating the manner in which the intermediate element in Fig. 1 is applied to the root pin cap, and

Fig. 4 illustrates a modified formation of intermediate element and root pin cap.

Referring to Fig. 1, a is the root of the tooth, b the tooth crown and c the root pin, which can, of course, be of any other form. The root pin 0 is provided with a fixed cap or superstructure d, which is the same for all teeth. Over this cap d an intermediate element e of any suitable material is disposed, the cavity of such element being shaped to correspond to the cap 11 of the root pin and being, like the latter, the same for all teeth, whilst its outer dimensions are varied according to the different sizes of teeth or the different dimensions of the cavities of these teeth. Each tooth b is fitted with the intermediate element e from the outset, although at first only loosely, the parts being complementary to one another in their internal and external dimensions respectively and constituting what may be termed a crown unit. In the examples illustrated in the drawing the intermediate element c has a shoulder ,f on which the crown b is supported by a corresponding recess, thus giving a high resistance to the masticating pressure.

On the root pin cap d and in the interior of the intermediate element e recesses are made which form ledges or tongues g, h spaced apart one above the other. When the space 1' between the element 8 and the cap 01 is filled with cement the ledges or tongues g, h co-operate with the cement and set up a firm anchorage between the pin cap d and the intermediate element 6. The distance between the tongues g, 71. (that is, the size of the recess 1), is made such that the element 8 can be fitted over the pin cap at, this procedure being assisted by the rearward bevelled surface k, inasmuch as when the intermediate element 6 is being applied and is in an oblique position its inner edge I slides past the outer edge m of the root pin cap d (Fig. 3)

The artificial tooth according to the present invention is built up in the following way: After removing the rest of the old crown and fitting the pin bed into the root, the face of the root is ground, using the check plate illustrated in Fig. 2, the shape of which corresponds exactly to the base face of the crown that is to be inserted. The face of the root is corrected until the plate n lies absolutely evenly thereon. Any

differences between the faces of the root and crown are then removed on the crown face. By means of this check plate n, which is fixedly or releasably connected to an auxiliary root pin and is guided by a handle 0, the grinding of the crown face is reduced to a minimum, which undoubtedly means simplification and saving of time for the dentist.

The root pin is then cemented in, the intermediate element is anchored to the root pin cap, and the crown is cemented to the intermediate element.

In the example selected the cap d and the intermediate element 6 are made non-circular in order to simplify assembly of the individual parts to one another and to make such assembly secure.

The example according to Fig. 4 differs from that of Figs. 1 and 3 by the fact that the root pin cap d has on its top surface a channel-like recess p which is engaged on assembly of the parts by a rib q provided in the interior of the intermediate element 6, whereby a statically more favourable effect is achieved.

I claim:

An artificial tooth comprising a root pin of standard size and construction, a cap of standard size and construction integral with said root pin, an outwardly projecting tongue on said cap, a hollow intermediate element mounted on said cap, the cavity formation of said element being standard but its external formation varying according to the size and type of the crown, an inwardly projecting tongue in the cavity of said hollow element adapted to co-operate with the tongue on said cap to anchor the parts together when cement is introduced, crown-supporting shoulders on the exterior of said intermediate element, and a socketed crown whose socket formation corresponds to the external formation of the intermediate element.

HEINRICH HOLLMANN.

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