T 1807/07 – Don’t Get It Twisted

This is an appeal against the revocation of the opposed patent by the Opposition Division.

Claim 1 of the main request before the Board (and of the patent as granted) read:

Process for production of a synthetic toothless substitute (28, 38) of pressed fine ceramic powder which can fit on at least one preprepared dental stump (1 0), where taking into account the shrinkage the inner surface (22) of a fully ceramic skeletal structure (14) of biologically compatible material is calculated, where the geometric conditions of the patient’s mouth are scanned and digitised, the data enlarged linear in all directions by a enlargement factor (f) compensating precisely for the sinter shrinkage, transferred to the control electronics of at least one processing machine and suitable tool paths derived from this, the enlarged design form of the skeletal structure (14) dense sintered to the direct end dimensions and then individualised by capping with coating material (24) of porcelain or plastic,

characterised in that on the basis of the scanning and digitisation of a positive model (46, 47) of the situation in the patient’s mouth, taking into account the sinter shrinkage, an enlarged design form of the skeletal structure (14) with an inner and an outer surface (20,22) is produced by material removal from a blank (48) of porous ceramic, where the control commands are sent to a suitable machine tool for production of the enlarged design form of the skeletal structure (14) from the blank (48) temporally decoupled from the digitisation. (my emphasis)

The crucial issue was whether the scanning and digitisation of a positive model of the situation in the patient’s mouth was disclosed in the application as filed.

The opponents pointed out that the application only disclosed the scanning of the skeletal structure.

The patent proprietor argued that claim 1 had to be read through the eyes of the skilled person and based on the description. The description referred to both the “positive model of the situation in the patient’s mouth” and the “positive model of the skeletal structure”, but it was clear to the skilled person that the claimed method only included the scanning of the positive model of the skeletal structure. The scanning of the positive model of the situation in the patient’s mouth was not disclosed or described. This interpretation was a possible variant but not supported by the description. Moreover, the use of the reference signs “(46, 47)” unambiguously indicated that only the positive model of the skeletal structure could have been meant.

The Board was not persuaded:

*** Translation of the German original ***

[2.1] Claim 1 of the main request […] contains the technical feature according to which on the basis of the scanning and digitisation of a positive model (46, 47) of the situation in the patient’s mouth, taking into account the sinter shrinkage, an enlarged design form of the skeletal structure is produced by material removal from a blank of porous ceramic. However, the original application does not disclose such a method step. Contrary to its line of argument in the statement of grounds of appeal as well as in the opposition proceedings, the [patent proprietor] agreed to this assessment by the Board without restriction during the oral proceedings.

The original description of the application (referred to as “the application” in what follows) clearly distinguishes between a positive model of the situation in the patient’s mouth (model 1, mostly made from plaster), which is made from a cast, and a positive model of the skeletal structure (model 2, mostly made from wax or plastic) which is fitted onto the paster model 1 […]. When reading the wording of claim 1 in the light of the description, the skilled person can only come to the conclusion that claim 1 only claims the scanning and digitisation of the “positive model of the situation in the patient’s mouth” because this feature is found both in the preamble and in the characterising portion of claim 1. The scanning and digitisation if the skeletal structure is not mentioned in claim 1 of the main request […].

The [patent proprietor] objected that in the description only the positive model of the skeletal structure (model 2) was scanned and digitised. In view of this contradiction between the subject-matter of the claim and the description only positive model 2 could be meant in claim 1.

The Board cannot endorse this point of view.

It is true indeed that the application does not disclose the scanning and digitisation of the positive model of the situation in the patient’s mouth. If it did, the amendment would not be problematic. However, one cannot conclude from this that the wording “positive model of the situation in the patient’s mouth” has to be interpreted as “positive model of the skeletal structure”. Such an interpretation would be tantamount to twisting the facts, which the skilled person has no reason to do. The application clearly distinguishes between model 1 and model 2 and it is not unreasonable to imagine that the enlaged embodiment of the skeletal structure is obtained by scanning and digitising of the situation in the patient’s mount. This was even stated by the [patent proprietor] during the written proceedings.

Also, the submission of the [patent proprietor] according to which the reference signs (46,47) in claim had to be taken into account in the choice of the “correct” interpretation, cannot alter this assessment. It is true that reference signs may serve to make a claim more clear to the reader, as found in decision T 237/84. Apart from the fact that the reference signs in a claim are not limiting the claim, from the point of view of patent law, in the present case the skilled person would at most assume that the insertion of the reference signs (46,47) was due to an error because they are not related at all to the positive model of the situation in the patient’s mouth.

It follows that the subject-matter of claim 1 of the main request […] extends beyond the content of the original application and, as a consequence, violates the requirements of A 123(2). Thus the claims of the main request […] cannot be granted.

Should you wish to download the whole decision (in German), just click here.

The file wrapper can be found here.