Columbus Dental Mfg. Co. v. Ideal Interchangeable Tooth Co., Inc.

• Decision Date: 02 January 1924
• Docket Number: 1638.
• Citation: 294 F. 422
• Parties: COLUMBUS DENTAL MFG. CO. v. IDEAL INTERCHANGEABLE TOOTH CO., Inc.
• Court: U.S. Court of Appeals — First Circuit

294 F. 422

COLUMBUS DENTAL MFG. CO. v. IDEAL INTERCHANGEABLE TOOTH CO., Inc.

No. 1638.

United States Court of Appeals, First Circuit.

January 2, 1924

Frederick L. Emery, of Boston, Mass. (Edwin S. Clarkson, of Washington D.C., and Everett S. Emery, of Boston Mass., on the brief) for appellant.

Odin Roberts, of Boston, Mass. (Robert Cushman, Charles D Woodberry, and Roberts, Roberts & Cushman, all of Boston Mass., on the brief), for appellee.

Before BINGHAM, JOHNSON, and ANDERSON, Circuit Judges.

BINGHAM Circuit Judge.

The plaintiff, the Columbus Dental Manufacturing Company, an Ohio corporation, is the owner of United States letters patent No. 997,472, issued to it July 11, 1911, on application of Thomas Steele, filed June 13, 1910, and complains of its infringement by the defendant, the Ideal interchangeable Tooth Company, Inc., a Massachusetts corporation, which has an established place of business at Boston, where the alleged acts of infringement were committed.

The patent is for an improvement in an artificial tooth or cuspid.The defenses are invalidity and noninfringement.In the District Court the patent was held invalid for want of invention and the case was dismissed.

The object of the invention is to provide an artificial tooth so formed as to be interchangeable and capable of replacement upon a metal base attached to a bridge.The bridge is made of metal and furnishes support for the tooth and its metal base.It is anchored at its ends to the natural teeth at either side of the space that is to be filled.The bridge proper usually comprises a series of metal plates, to each of which a tooth is attached; the plates being joined to the bridge by soldering.The teeth are made of porcelain and the interchangeable or removable character given to them is important, for if a tooth breaks it may be replaced without removing the bridge, and the metal backs may be soldered to the bridge proper without causing damage which the heat employed might otherwise occasion.It is desirable in these teeth that the attaching means be such as to secure accuracy of alignment and setting, and that they be sufficiently strong to withstand the operation of biting or masticating, and also of such a nature and so located as not to impair the requisite strength of the tooth while performing either operation.

It is claimed that the problem of providing front teeth that are interchangeable differs from that presented in the case of back teeth; that front teeth are used for biting, not grinding; that the back teeth perform the act of mastication, when substantially closed, by a slipping or sidewise motion; and that it is this sidewise motion and the difference in the shape of the back teeth that cause the difference in the problem.But, in the view we take of the case, we find it unnecessary to discuss whether the two problems are so different in character that improvements made in the construction of front teeth are not to be regarded as proper references upon questions relating to the construction of back teeth.

There are two claims in issue, which read as follows:

'1.An artificial tooth cusp having a flat base ground at an angle divergent to the plane of the masticating cusp and having a longitudinal recess therein arranged at an angle to the base of the cusp and a slot of less diameter than the recess opening the latter perpendicularly to the plane of grinding to a point near the lingual termination of the plane of grinding.

'2.An artificial tooth cusp having a flat base at an angle divergent to the plane of the masticating cusp from the lingual aspect of the tooth, meeting a second plane in a line parallel to its lingual aspect, a tubular recess of one standard size, perpendicular to said flat base and centrally disposed therein, a slot of less diameter than the recess opening from the recess vertically to the flat surface to a point near the lingual surface of the cusp.'

The first claim, which is the broader one, embodies the following elements:

(1) A flat base located in a plane divergent to the plane of the masticating surface of the tooth; (2) a recess running lengthwise of the tooth and located in the flat base, the recess being at an angle to that base; (3) a slot of less diameter than the recess opening into the latter perpendicularly to the base and extending from the recess across the plane of the base to a point near the lingual termination of that base.

The second claim embodies all the elements of the first and has in addition a second plane or base with which the flat base called for in the first claim meets in a line parallel to the lingual aspect of the tooth.The recess is made tubular in shape, is centrally disposed in the flat base, and is perpendicular thereto.

An artificial tooth having a flat base, or having a flat base meeting a second plane in a line parallel to its lingual aspect, is old in the art.Mitchell patent, No. 770,768September 27, 1904.An artificial tooth having a flat base,...