US2696667A

US2696667A - Porcelain jacket crown

Info

Publication number: US2696667A
Application number: US63194A
Authority: US
Inventors: Sacchi Hector
Original assignee: Individual
Current assignee: Individual
Priority date: 1948-12-02
Filing date: 1948-12-02
Publication date: 1954-12-14
Anticipated expiration: 1971-12-14

Description

Dec. 14, 1954 H. sAccHl PORCELAIN JACKET CROWN Filed Dec. 2, -1948 United States Patent O PORCELAIN JACKET CROWN Hector Sacchi, Montevideo, Uruguay Application December 2, 1948, Serial No. 63,194

2 Claims. (Cl. 32-12) This invention relates to an improved process for the preparation of porcelain jacket crowns and the resulting crowns.

Prior to my invention, all ordinary techniques for the preparation of porcelain jacket crowns have been based on the principle of the successive melting of porcelain on metallic matrices or dies, while the porcelain is gradually condensed and moulded to desired shape and consistency, depending on the skill of the dental worker.

In the above technique, a number of available porcelains, with varied composition and properties, are used, but the underlying principle is always the same, there being only differences in details, depending on the person using the technique.

In the processes known heretofore, the preparation of jacket crowns presents serious disadvantages; they are troublesome, too slow, and the results are not always positive as regards shape, color and resistance to fracture.

It is a primary object of the invention to provide an improved method of forming jacket crowns overcoming the disadvantages of the ordinary techniques for the preparation of porcelain jacket crowns.

Another object of the invention is to reduce the time of preparation of jacket crowns.

Still another object of the invention is to improve the technique of forming jacket crowns so that the technique is within the skill of non-specialized workers and therefore not requiring the skill and training of dental technicians.

A further object of the invention is to improve the technique of forming jacket crowns so that the correct colors and shades are secured before starting work.

Another object of the invention is to provide an improved technique in forming jacket crowns so that higher over-all resistance does not depend to a large extent on manipulation or baking.

Another object of the invention is to provide an improved porcelain jacket crown, a portion thereof including a high melting point porcelain, and the remainder completed with a porcelain from substantially low to middle melting point, together with a compensating porcelain.

Another object of the invention is to provide a compensating porcelain for fabricating porcelain jacket crowns including porcelains of different melting points.

Further objects and advantages will become apparent from the following description in which I have set forth a preferred embodiment of my invention.

Referring to the drawings:

Fig. la illustrates a vestibular view of a prefabricated partial crown for a superior incisive;

Figs. 2a and 3a illustrate vestibular views of a prefabricated partial crown for an inferior premolar and a superior molar, respectively;

Figs. 1b, 2b, and 3b illustrate the same crowns as Figs. la, 2a, and 3a, respectively, viewed from their proximal faces where their prornixal extension as well as the hollow portions may be seen;

Figs. lc, 2c and 3c illustrate the lingual view of the crowns of Figs. la, 2n, and 3a, respectively;

Figs. 4 and 5 illustrate a longitudinal section of matrices or dies suitable for use in the preparation of biscuited porcelain jacket crowns of a superior incisive and an inferior molar, respectively;

Figs. 6 and 7 show the partial prefabricated crowns in place on the matrices or dies, together with a layer of compensating porcelain;

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Figs. 8 and 9 illustrate a later stage in the production of the crowns; and

Figs. 10 and 1l illustrate the incisive and premolar jacket crown finished and separated from their corresponding matrices or dies.

According to my invention, the new jacket crown technique described herein overcomes the above-mentioned disadvantages in a simple and rapid way ensuring in advance substantial success as regards shape, color and resistance.

The basic differences between the new technique submitted herein and the ones known heretofore are:

1. On the basis of the clinical determinations of a pure gold matrix, instead of a platinum one, is prepared. The advantages of this are a lower cost and easier manipulation.

2. A tooth of a high melting point porcelain is selected with a prosthetic purpose (whole set of teeth or partial set, bridges, etc.) choosing the most suitable as regards shape and color. The crown is then prepared so as to enable the setting thereof on the stump in a correct position, leaving a space between the prepared tooth and the gold matrix. In this manner, I obtain a high melting point porcelain face that will reproduce the interior face of the crown. The possibility of prefabricated faces embracing one half or two thirds of the crown will make the technique even faster and more successful and simpler as well.

In this manner, it is then only necessary to finish the crown with porcelain of a lower melting point than that of the face so as not to submit this latter to conditions of overmelting which would cause loss of stain and of resistance.

On trying to join the face with the fresh mass of porcelain, which has a lower melting point than that of the face, cracks are brought about as a result of differences in expansion coefficients, preventing the close union of the two porcelains, owing to the thickness of the mass required.

In order to overcome this diiculty, my technique provides for the employment of granulated porcelain of high melting point and comprising particles of various sizes, which is laid between the above-mentioned face and the fresh mass of low melting point porcelain added in order to nish the crown.

With this granulated porcelain substance a regulation of contraction differences is obtained, thus ensuring the close union of both porcelains and, as a result thereof, the resistance of the entire mass and consequently that of the jacket is increased, so that in trying to break the jacket, a fracture will not occur where the welding caused by the compensating substance has taken place. Furthermore, if the resistance of the face is increased by the process of addition elaborated above, it is evident that the jacket as a whole is by far more resistant than those obtained by the known techniques.

Due to my special process for the prefabrication of one half or two thirds of the crowns to be used in jacket crown preparation as illustrated in Figs. ltr-3c, inclusive, my technique will permit an easier application to all dental pieces and will no longer be exclusively for the anterior teeth as heretofore.

Also, this higher resistance brings about a simplification in the clinical preparation of the tooth; a feature to be taken well into account considering the present dili'lculties.

Referring to Figs. 4-11, inclusive, there are illustrated two instances of my technique for the production of biscuited porcelain jacket crowns for a superior incisive and an inferior molar following the disclosure of my process for the preparation of porcelain jacket crowns. The dotted line A indicates the thickness of the $42 or 2/3 prefabricated crown. The space B lying between the 1/ or prefabricated crown and the die is jointly occupied by the low melting point porcelain and the eXtra-tine granulated compensating porcelain that will act as an eXpansion compensator or regulator. The reference character C of Figs. 8 and 9 indicates the portion of the crown to be nished by the dental Worker with low melting point porcelain and compensating porcelain and D the boundary therebetween. The reference character E represents the "corresponding portion of the crown prefabricated with high melting point porcelain. The reference character F represents that part of the crown finished by the dental worker with low melting point porcelain and the various compensating porcelains to be ultimately used on the different zones of the crown.

Comparison of the techniques Time:

Known technique--longer time--4 to bakings. My technique-shorter time-only 2 bakmgs.

i Manipulation:

Known techniquegreat skill and long training required.

My technique-easy manipulation within the reach of non-specialized workers.

1 Color:

Known technique-difficult to obtain requiring very often repeated working.

My technique-color and shades'secured before starting work.

; Resistance:

It is thus evident that I have disclosed a new process which is readily adapted for the production of biscuited porcelain jacket crowns for application in dental work.

Furthermore, I have also disclosed a high melting point biscuited porcelain tooth with a shape similar to a half crown or two thirds of a crown to be used on anterior or posterior teeth.

Likewise, I have also disclosed a new ceramic product that might be termed .compensating porcelain basically made of fine particles of biscuited porcelain, of a number of shapes and sizes, acting as a regulator or compensator of the various expansion coefficients of different porcelains thus facilitating the close union of different porcelains and providing the total mass thereof with a higher resistance to fracture. This particular feature enables the production of every kind of porcelain crowns or similar works, in far fewer fusions than are required when applying previously known techniques and with far better results as regards shape, colour or resistance. Furthermore, with my technique of selecting 1/2 or 2/3 of prefabricated crowns, I have overcome the serious problems arising when dental workers strive for accuracy in jacket crown colour. Prior to my technique, it was necessary for manufacturers to supply the market with large and costly porcelain packages containing a huge assortment of stains and colours to be used by the dental worker in the production of jacket crowns.

It is therefore possible with my technique to use a much simpler porcelain package which would need to contain only: (1) a few basic porcelain colours of middle or low melting point to be employed in finishing the crown; (2) staining elements of the kind currently used; 3 glazing porcelain to suit the porcelains used in the production of jacket crowns of high and low melting points; and (4) compensating porcelain (unknown heretofore) to be jointly used with the low or middle melting point porcelain in the finishing of the porcelain crown.

Although I have shown and described preferred forms of my invention, I contemplate that various departures may be made therefrom without departing from the spirit of my invention.

What I claim is:

1. A jacket crown for teeth, comprising a Prefabricated member made from high meltingv point porcelain, and a second member made of a mixture-here called compensating porcelainw-consisting of a low melting point porcelain and granules of a high melting point porcelain, said members being joined together by baking.

2. A jacket crown as set forth in claim 1, in which said Prefabricated member forms the vestibular parts of the tooth, while said second member forms the lingual parts of the tooth.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 643,989 Sehr Feb. 20, 1900 1,248,242 Babcock Nov. 27, 1917 1,671,104 Eberly May 29, 1928 1,794,129 Walsh Feb. 24, 1931 2,314,957 Thornton et al Mar. 30, 1943 2,341,908 Lee et al. Feb. 15, 1944 2,391,106 Safr Dec. 18, 1945 FOREIGN PATENTS Number Country Date 561,526 Great Britain May 23, 1944