T 0935/21 12-12-2023

Reasons for the Decision

1. Auxiliary request 4 - admittance into the proceedings

1.1 Auxiliary request 4 was filed together with the statement setting out the grounds of appeal dated 27 August 2021.

1.2 The opponent had requested in writing that this request not be admitted into the proceedings on the grounds that it was late filed and not prima facie allowable. According to the opponent, the request should have been filed in the proceedings before the opposition division. Moreover, the request was unclear and did not involve an inventive step over D8 in combination with D6 or D5.

1.3 During oral proceedings before the opposition division, the proprietor had filed an auxiliary request 3 which differed from the present auxiliary request 4 in feature 3.1, which then read as follows.

3.1') a Core Roughness Depth Sk of between 0.4 mym and 1 mym

The opposition division had decided not to admit this auxiliary request 3 into the proceedings on the grounds that it was not considered prima facie allowable. In the opposition division's opinion, auxiliary request 3 extended the scope of protection within the meaning of Article 123(3) EPC because it included a Core Roughness Depth Sk of 1 mym, whereas in claim 1 as granted the Core Roughness Depth Sk was defined as less than 1 mym. Moreover, according to the opposition division, the claimed subject-matter was not based on an inventive step under Article 56 EPC, since feature 3.1' was not considered to be a distinguishing feature over the disclosure of D8 (decision under appeal, point 59).

1.4 The proprietor was aware that the objection under Article 123(3) EPC could be overcome by reintroducing the expression "less than 1 mym" into the claim (minutes, point 42). However, it was also aware that reintroducing this expression was very unlikely to affect the opposition division's conclusion on inventive step. Therefore, there can be no doubt that the proprietor could have filed such a request during opposition proceedings. However, there was no reason for it to do so in the sense that the proprietor should have submitted the request within the meaning of Article 12(6), second sentence, RPBA 2020.

1.5 Auxiliary request 4 was filed at the earliest stage of the appeal proceedings and in response to the reasons given in the opposition division's decision. Claim 1 of this request combines the features of granted claims 1 to 4 verbatim. Consequently, it is not to be examined for clarity and conciseness under Article 84, second sentence, EPC (G 3/14).

It reintroduces the expression "less than 1 mym" into Feature 3.1, so that the request prima facie overcomes the objection under Article 123(3) EPC.

As the Board considers that document D8 does not disclose a specific Core Roughness Depth Sk value (see point 2.3 below), it is not prima facie apparent that feature 3.1 is not in principle suitable for establishing an inventive step.

The Board therefore exercises its discretion under Article 12(4) RPBA 2020 and admits the request into the appeal proceedings.

2. Auxiliary request 4 - inventive step

2.1 Document D8 discloses a (references in parentheses refer to D8)

1) dental implant having a surface made of a ceramic material based on zirconia (abstract; paragraph [0018]; claim 1).

2.2 It was undisputed that D8 does not disclose that

2) the ceramic material has an average grain size from 0.1 mym to 0.6 mym.

2.3 D8 does also not disclose a specific Core Roughness Depth Sk value in the sense of feature 3.1. What is disclosed in D8 is that the surface has a topography defined by a maximum surface roughness Rmax of 1 mym (D8, paragraph [0029]; claim 4). It was undisputed that this implies that the Core Roughness Depth Sk must be less than 1 mym. However, this does not lead to the conclusion that the Core Roughness Depth Sk necessarily falls within the claimed range. Indeed, the Core Roughness Depth Sk of the dental implant of D8 could just as well be below 0.4 mym. Therefore, D8 does not directly and unambiguously disclose that the surface has a topography defined by

3.1) a Core Roughness Depth Sk of less than 1 mym, the Core Roughness Depth Sk being between 0.4 mym and 1 mym.

2.4 It was undisputed that D8 does not explicitly disclose that the surface has a topography defined by

3.2) a Skewness Ssk of less than 0.

In the written procedure, the opponent had argued that D8 implicitly disclosed feature 3.2. According to the opponent, a Skewness Ssk of less than 0 was the inevitable result of following the manufacturing steps of D8. However, the opponent provided no (experimental) evidence of this.

2.5 The only example disclosed in D8 (paragraph [0080]) differs from the examples in the patent in suit in the etching solution used. While D8 etches with phosphoric acid, the examples in the patent in suit use an etching solution containing hydrofluoric acid. Moreover, D8 does not specify the grain size of the ceramic material. According to the patent in suit (paragraph [0044]), the etching removes discrete grains or agglomerates of grains from the ceramic material. The proprietor argued that the size of the removed and remaining grains or agglomerates of grains thereby determines the surface topography. This was not disputed by the opponent.

Therefore, the Board is not convinced that the manufacturing steps disclosed in D8 inevitably result in a surface that has a topography defined by a Skewness Ssk of less than 0.

2.6 Based on the above-identified distinguishing features

2 and 3, 3.1 and 3.2, the objective technical problem can be formulated as providing a dental implant with a ceramic material that exhibits high osseointegration.

2.7 Starting from the ceramic dental implant disclosed in D8, the skilled person will not find in D8 itself, or in D6 or D5, any hint or suggestion for designing the surface topography of the dental implant in accordance with features 3.1 and 3.2. In fact, all these prior-art documents are silent on the topography parameters of Core Roughness Depth Sk and Skewness Ssk.

With respect to the ceramic dental implants of the prior art listed in the patent in suit (paragraph [0091]), they all have a surface topography defined by a Core Roughness Depth Sk of more than 1 mym and a skewness Ssk of less than 0 (figure 13). Consequently, these prior-art implants do not teach or suggest the claimed surface topography, either, which requires that

3) the surface has a topography defined by

3.1) a Core Roughness Depth Sk of less than 1 mym, the Core Roughness Depth Sk being between 0.4 mym and 1 mym, and

3.2) a Skewness Ssk of less than 0.

2.8 The claimed subject-matter is not therefore rendered obvious by the prior art cited by the opponent. It is thus based on an inventive step within the meaning of Article 56 EPC.

3. Auxiliary request 4 - sufficiency of disclosure

3.1 The opponent had argued in writing that the definition of the Skewness Ssk in paragraph [0035] of the patent in suit contained a contradiction.

This was undisputed by the proprietor.

However, the Skewness Ssk is a well-known parameter for describing a characteristic of a surface topography, as shown by D16, which is a standard manual "ON SURFACE ROUGHNESS AND IMPLANT INCORPORATION". The skilled person would therefore immediately recognise the incorrectness of the formula given in paragraph [0035] of the patent in suit, and would replace it with the correct formula, given for example in D16.

3.2 The opponent had further argued in writing that documents D13 and D15 to D17 provided different definitions of the Skewness Ssk, so that it was not clear to the skilled person which definition of the Skewness Ssk was the correct one.

However, the opponent has not shown that the different ways of writing the formulae in documents D13 and D15 to D17 actually result in different definitions and thus different results for the Skewness Ssk.

3.3 Finally, the opponent had argued in writing that the skilled person would not be able to implement the invention according to claim 1 across the entire claimed range, because the patent in suit did not contain any instructions on how to achieve a Core Roughness Depth Sk in the range between 0 mym and 0.38 mym.

However, this range is no longer encompassed by claim 1 of auxiliary request 4.

3.4 The patent in suit therefore discloses the invention in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art within the meaning of Article 83 EPC.