T 1775/11 - Parameters and testing methods

T 1775/11

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Key points

• The claims were directed to " amorphous silica for use in a dental composition" having certain parameters.
• The Board first finds that the two examples do not allow for obtaining silicas having properties covering the whole width of the claims.
• More creative and quite ingenious is the following argument of the opponents: "The [opponents] argued convincingly that these highly specific test procedures might be usual in the field of abrasive silicas developed especially for toothpaste applications, but are not common in other important fields of application of finely divided amorphous silicas (e.g. as fillers, thickeners, absorbents etc.). The present claims are however not restricted to amorphous silicas in toothpastes or as abrasives. Therefore, so the [opponents'] argument, it was extremely burdensome for the skilled person to repeat these experiments on a trial and error basis, without proper guidance as to which results could be expected." 

Summary of Facts and Submissions

I. European patent No. 1 456 125 was granted with 32 claims.

Independent claims 1 and 12 read as follows:

"1. An amorphous silica for use in a dental composition having a weight mean particle size in the range 3 to 15 mym with at least 90 per cent by weight of particles having a size below 20 mym, a Radioactive Dentine Abrasion (RDA) determined on an aqueous slurry of the silica powder of 100 to 220, a Pellicle Cleaning Ratio (PCR), when incorporated in a dental composition at 10 per cent by weight, greater than 85, the ratio of PCR to RDA being in the range 0.4 : 1 to less than 1:1 and having a Plastics Abrasion Value in the range 11 to 19."

[..]

II. The opposition division held that claims 1 and 19 of the main request contravened Article 123(2) EPC and that the patent did not meet the requirements of Article 83 EPC. The auxiliary request was also rejected and the patent thus revoked.

IV. A notice of appeal was filed by the patentee (henceforth: the appellant).

Reasons for the Decision

1. Sufficiency of disclosure (Article 83 EPC)
[...]

1.6 Manufacturing information gap

[...] Therefore the board accepts, to the benefit of the appellant, that the examples of the opposed patent, can be reworked without undue burden, despite the above mentioned information gap.

1.7 Feasibility over the whole ambit of the claims

However, the opposed patent is also deficient in another respect. In accordance with the case law, the disclosure of one way of performing the invention, for instance by way of examples, is only sufficient if it allows the invention to be carried out by the skilled person over the whole ambit of the claims. This must be possible without any inventive effort and undue burden, taking into account the original application as a whole and the general common knowledge of the skilled person. In the present case, the board answers this question in the negative, for the following reasons.

The data in Table 1 show that the preparation conditions of two working examples differ from each other by at least 5 parameters (i.e. water volume, silicate ratio, silicate volume, acid volume, temperature, and possibly shear energy input). Under these circumstances it is impossible to deduce which of the several simultaneous modifications in the processes of preparation were responsible for the differences found in the silicas so obtained (see Table 2). These silicas differ considerably in oil absorption (79 and 139 ml/100g, respectively), BET surface (64 and 252 m**(2)/g, respectively), RDA (200 and 133, respectively) and tapped and loose bulk densities (see Table 2). However, they exhibit practically the same PCR value at 10% loading in toothpaste Formulation A (96 vs 93).

Based on these examples and the relevant parts of the specification, the skilled person is not taught how to obtain silicas having substantially different PCRs, for instance closer to the lower end point of 85 stated in the claim for a 10% dental composition. No information is available how to modify the process in order to obtain RDA values other than those exemplified (200 and 133) and how the process conditions determine the interaction between the various parameters characterising the claimed silicas. It is not plausible that essentially the whole host of claimed silicas may be obtained only by modifying the mixing intensity (shear energy input).

In summary, the skilled person can derive no useful guidance from the two examples as to how the process of preparation could be modified in order to obtain silicas having properties covering the whole width of the claims. The situation resembles the one aptly denoted as an invitation to carry out a research programme. See decisions T 435/91 (OJ EPO 1995, 188; Reasons 2.2.1) and T 809/07 (of 15 April 2010, Reasons 3.2).

1.8 Lack of guidance

It must also be observed that some of the tests for determining the characterising parameters may be known and usual in the field of dental abrasives, yet are considerably time-consuming and elaborate.

- The RDA test for instance involves the irradiation of extracted human teeth with a neutron flux and subjecting it to a standard brushing regime. The radioactive phosphorus removed from the dentin in the roots of the teeth is used as an indication for the abrasive action of the dentifrice containing the amorphous silica under examination (see paragraph [0061] of the specification).

- The PCR test uses bovine permanent central incisors, cut to obtain specimens which are then smoothed and polished and immersed for 4 days in a staining broth replenished twice a day.

- The dentifrice containing the test silica at 10% by weight, is applied under 800 double strokes of a soft nylon toothbrush and the specimens are assessed before and after the brushing exercise (see paragraph [0064] of the specification).

The respondents argued convincingly that these highly specific test procedures might be usual in the field of abrasive silicas developed especially for toothpaste applications, but are not common in other important fields of application of finely divided amorphous silicas (e.g. as fillers, thickeners, absorbents et cetera). The present claims are however not restricted to amorphous silicas in toothpastes or as abrasives. Therefore, so the respondents' argument, it was extremely burdensome for the skilled person to repeat these experiments on a trial and error basis, without proper guidance as to which results could be expected.

The board considers that under such circumstances, it would have been indispensable to disclose in a complete and systematical manner which relations exist between the values of RDA, PCR, PVA and PCR/RDA, and how these parameters could be adjusted to desired values within the claimed ranges.

In other words, the patent in suit lacks a technical concept fit for generalisation which makes the host of silicas encompassed by the definition of the claims available to the skilled person without undue experimentation.

1.9 The requirements of Article 83 EPC are thus not met for the main request.

This objection applies mutatis mutandis also to the claims according to the first and second auxiliary requests which recite the same product parameters and ranges.

2. Further auxiliary requests

In the appeal brief, the appellant referred to further requests (third to sixth auxiliary requests). However, these requests were not annexed to the grounds of appeal, but only summarily set out as regards the various proposed amendments to the claims.

The board understands that these requests were filed for consideration only in the event that the board deemed one of the main, first and second auxiliary requests to meet the requirements of Rule 80 and Article 83, 84 and 123 EPC, and decided to address the questions of novelty and inventive step, without remitting the case to the department of first instance.

Since however the claims of the main, first and second auxiliary requests were found not to meet the requirements of Article 83 EPC, this procedural condition is not met. The third to sixth auxiliary requests thus need not be considered by the board for this reason alone and irrespective of their formal deficiencies.

Order

For these reasons it is decided that:

The appeal is dismissed.