Silvano D'Ambrosio v SDI Limited
[2023] APO 65
•14 December 2023
IP AUSTRALIA
AUSTRALIAN PATENT OFFICE
Silvano D’Ambrosio v SDI Limited [2023] APO 65
Patent Application: 2019217656
Title:Silver fluoride solutions for dental compositions
Patent Applicant: SDI Limited
Opponent: Silvano D’Ambrosio
Delegate: Leslie. F. McCaffery
Decision Date: 14 December 2023
Hearing Date: 5 October 2023 by videoconference
Catchwords: PATENTS – opposition to the grant of a patent under section 59 – novelty – “whole of contents” novelty – inventive step – evidence in relation to sales and public disclosure – evidence adduced does not establish what was conveyed to the public – clear enough and complete enough disclosure – none of the grounds have been made out – opposition unsuccessful – costs awarded against the opponent.
Representation: Patent attorney for the applicant: Daniel Beck, Zhi Ling Zeng and Gary Cox of Wrays.
Silvano D’Ambrosio was self-represented at the hearing.
IP AUSTRALIA
AUSTRALIAN PATENT OFFICE
Patent Application: 2019217656
Title:Silver fluoride solutions for dental compositions
Patent Applicant: SDI Limited
Date of Decision: 14 December 2023
DECISION
The opposition is unsuccessful.
The claims are novel and inventive in view of the evidence provided in the opposition.
The specification provides a clear enough and complete enough disclosure for the invention to be performed by a person skilled in the relevant art.
Subject to an appeal, I direct that the application proceed to grant.
Costs are awarded against the opponent, Silvano D’Ambrosio.
REASONS FOR DECISION
1. Australian application 2019217656 (the application) was filed on 7 February 2019 by SDI Limited (the applicant). The application claims an earlier priority date of 12 February 2018. Examination was requested on 22 September 2020, and the application was advertised as accepted on 19 August 2021.
2. On 18 November 2021, a notice of opposition was filed by Dr Silvano D’Ambrosio. A statement of grounds and particulars (SGP) was filed on 18 February 2022. The SGP was filed without a Schedule and/or any mentioned documents. An amended SGP was filed on 18 March 2022, but a delegate determined that this amendment incorporated additional grounds of manner of manufacture, usefulness (utility), support and clarity, new prior art for the grounds of novelty and inventive step, and expanded particulars under novelty, inventive step and sufficiency (section 40(2)(a)) and was not allowable. A third SGP was filed on 13 May 2022. A direction was made that the opposition proceed on the basis of this SGP. Later requests to amend the SGP on 27 January 2023 and 27 March 2023 were refused by a delegate on 24 April 2023 and 9 May 2023 respectively.
3. On 27 September 2022, following completion of the EIS, the applicant proposed amendments to the specification and claims. Allowance of the amendments was advertised on 16 February 2023.
4. After completion of the evidence, the matter was set for hearing on 5 October 2023. The opponent provided a written summary of submissions (OS) on 21 September 2023. The applicant noted that these were filed outside the due time (20 September 2023), as well as introducing new grounds of clarity and inutility, as well as new prior art. The applicant filed their summary of written submissions (AS) on 27 September 2023.
The grounds of opposition
5. The opposition processes can present problems for even the most experienced of players. The opponent in the present matter has been represented by patent attorneys at times during the opposition process, but for most of it has been self-represented. It is perhaps therefore not surprising that there have been some issues arise, particularly with the introduction of new grounds and particulars on several occasions, including with the submissions made for hearing. I will deal with this particular issue before considering the substantive matters.
6. As indicated above the relevant SGP was filed on 13 May 2022. This set out grounds of opposition under novelty, inventive step and clear enough and complete enough disclosure (“sufficiency”). The following documents were listed as being relied on in the opposition:
AU 2017333603 (D1).[1]
[1] The SGP referred to AU 2021105210, which is a divisional Innovation Patent of AU 2017333603. The applicant noted that these were identical and accepted that it made no difference if the parent document was cited.
Chemika Laboratory Certificate of Analysis P1868825, dated 15/07/2018 (D2).
Vinh et al., Potassium Iodide. The solution to Silver Diamine Fluoride; Advance in Dentistry Oral Health, Volume 5 (Issue 1), 2017 (D3).
Table of Solubility of Silver Compounds in Water/ Salt Lake Metals dated 2017 (D4).
WO 2019/156033 (D5).
AU 2019217656 (D6).
WO 2018/058199 (D7).
7. At hearing the opponent pressed the grounds of novelty, inventive step, and insufficiency. The applicant noted that a number of new grounds were also included in the opponent’s submissions: clarity, usefulness (utility) and lack of support, as well as expanding their arguments relating to priority.[2] They identified the following new evidence:
Annexure SDA-3-4-1: Chemika Certificate of Analysis dated 10 October 2017.
Annexure SDA-3-5: Sales from July 2017 – Feb 2018.
Annexure 3-6-13: Measurement of pH of silver fluoride in Riva Star Aqua (SDI) by Graham G Craig.
Annexure SDA-3-6-14a: Accelerated Aging Calculator.
[2] The SGP stated that only Claim 3 was not entitled to priority because the provisional application did not disclose the featured defined in this claim.
8. The applicant also submitted that new prior art was cited in the Schedule of Documents annexed to the opponent’s submissions:
AU 20176900397
Chemika Laboratory Certificate of Analysis dated 15 July 2018.
Database link relating to online sales orders and enquiries received between October 2016 and 11 February 2018.
Database link that appears to correspond to document D2a mentioned in the SGP but provided with the opponent’s evidence in support only.
IPEA PCT/AU2017/05171.
Creighton aqueous silver fluoride (CSDS) test AgF silver assay, specification 30.6 to 37.4 w/v Batch 57409.
Chemicals/Thermo Fisher Scientific (accessed 6 August 2023)
The annexures relating to new evidence identified above.
9. The applicant also noted that new prior art was referenced at paragraph 1.a(vi) of the opponent’s submissions, but not listed in the accompanying Schedule:
Gao et al., Global oral Health Policies Guidelines Using Silver Diamine Fluoride for Caries Control, 2021.
The applicant’s submissions express a degree of frustration at the “general pattern of behaviour” exhibited by the opponent, and in particular their repeated attempts to introduce new grounds that are not derivable from the SGP of May 2022. They submitted that none of the new grounds, particulars, prior art documents and evidence set out above should be admitted in the opposition proceeding.
While it may be the result of a lack of experience with the opposition processes on the part of the opponent, I can appreciate the applicant’s frustrations at the shifting sands in the case they are required to answer. The opponent has filed five different statements of grounds and particulars, several of which have been refused on the basis that they have introduced new grounds or new particulars. Despite the material being refused, the opponent has still sought to introduce some of this material, as well as several new grounds and particulars, in their submissions for hearing.
It is open to the Commissioner, subject to certain conditions, to have regard under Regulation 5.23 to a document that has not been previously entered in the opposition. If a document is excluded from the opposition, it can still form the basis of a re-examination once the opposition is concluded. Section 60(3) also allows the Commissioner to take into account any ground on which the grant of a standard patent may be opposed, whether relied upon by the opponent or not. So, while it is not ideal that evidence be introduced late in opposition proceedings, the legislation provides mechanisms for the Commissioner to consider the material whilst also ensuring that parties are afforded administrative fairness and given the opportunity to respond to such evidence. The late introduction of evidence can also be a consideration in the award of costs.
The public interest in not being inconvenienced by the grant of invalid patents is a key consideration in whether the Commissioner has regard to newly introduced evidence in an opposition. To this end, the consideration is generally whether a document is likely, if not certain, to change the outcome of the opposition in a significant way. If the new information is not likely to change the outcomes of the opposition, then there is little advantage gained by bringing it into the opposition.[3]
[3] Merial Limited v Bayer Intellectual Property GmbH [2015] APO 16 at [24] to [25].
In the present case, a prima facie view of the documents identified above suggests to me that they will not change the outcome of the opposition in a significant way. I therefore do not consider it appropriate to have regard to this evidence under Regulation 5.23, or to consider any additional grounds under section 60(3). More detailed reasoning is given below.
Onus
The substantive amendments to the Patents Act 1990 (Cth) (the Act) brought about by the Intellectual Property Laws Amendment (Raising the Bar) Act 2012 (Cth) (the Raising the Bar Act) apply to the present case. The standard of proof in opposition proceedings is the balance of probabilities. If the Commissioner is satisfied, on the balance of probabilities, that a ground of opposition to the grant of the standard patent exists, the Commissioner may refuse the application. The opponent bears the onus of proof.
Principles of construction
The principles underpinning construction are well-established. As noted by Middleton J in Eli Lilly and Company Limited v Apotex Pty Ltd:
“It is well settled that the Court should, from the outset, approach the task of patent construction with a generous measure of common sense. The Court must place itself in the position of a person skilled in the relevant art, being the subject matter of the patent. From this perspective, the patent is to be read as a whole, in the context of the specification and in light of the prevailing common general knowledge and state of the relevant art at the priority date.”[4]
[4] [2013] FCA 214; 100 IPR 451 at [139].
The Full Court in Airco Fasteners Pty Ltd v Illinois Tool Works Inc.,[5] recently reiterated the principle that experts can give evidence on the meaning which those skilled in the art would give to technical or scientific terms and phrases and on any unusual or special meanings that would be given by skilled addressees to words which might otherwise bear their ordinary meaning,[6] and the Court is to place itself in the position of some person acquainted with the surrounding circumstances as to the state of the art and manufacture at the time.[7] However, it is for the Court, not for any witness however expert, to construe the specification.[8] A similar approach is taken in matters before the Commissioner.
[5] [2023] FCAFC 7 at [48].
[6] Sartas No 1 Pty Ltd v Koukourou & Partners Pty Ltd [1994] FCA 1529 (Sartas No. 1); (1994) 30 IPR 479 at [485]-[486].
[7] Kimberley-Clark Australia Pty Ltd v Arico Trading International Pty Ltd [2001] HCA 8; 207 CLR 1 at [24].
[8] Sartas No 1, supra at [485]-[486].
The person skilled in the art
The task of construing the specification is undertaken from the viewpoint of a person skilled in the art and the prevailing common general knowledge at the priority date. The person skilled in the art is a hypothetical non-inventive person or team likely to have a practical interest in the subject matter of the invention.[9]
[9] Root Quality Pty Ltd v Root Control Technologies Pty Ltd [2000] FCA 980 at [70]-[72].
The following evidence was provided in the opposition:
| Declarant | Date | Exhibits | |
| Evidence in Support (EIS) | Silvano D’Ambrosio (D’Ambrosio 1) | 17 May 2022 | SDA-1 consisting of Tabs A-N |
| Evidence in Answer (EIA) | Martina Stenzel (Stenzel) | 30 September 2022 | MS1 and MS2 |
| Evidence in Reply (EIR) | Graham G. Craig (Craig) | 16 December 2022 | GC-1 |
| Silvano D’Ambrosio (D’Ambrosio 2) | 18 December 2022 | SDA2-1 to SDA2-4 |
Dr D’Ambrosio is a registered dentist. He states that he has over 50 years’ experience in dental and oral health, including the development and use of silver fluoride products for dental and oral treatment. He has worked with Professor Craig on aqueous stabilised silver fluoride products since 2011, including a silver fluoride product containing 30-40 w/v silver fluoride and 3%-5% of nitric acid.[10]
[10] D’Ambrosio 1 at [1] to [6].
Professor Stenzel is a Professor in the School of Chemistry at the University of New South Wales. She has over 25 years of experience in various fields of chemistry. Her research has included drug delivery systems for metal-based drugs, complex polymer architectures and nanoparticle delivery systems.[11]
[11] Stenzel at [11] to [12].
Dr Craig was an Associate Professor in the Faculty of Dentistry, University of Sydney. His research in the areas of metals and metal fluorides began in the early 1970s. He stated that he had worked with the present applicant in several roles, including the development of the silver diamine fluoride (SDF)/potassium iodide product, Riva Star, designing and conducting the first clinical trial of Riva Star and assisting with the registration of the product with the Therapeutic Goods Administration.[12]
[12] Craig at [2] to [3].
There was some dispute between the parties as to the skills and knowledge that should be attributed to the hypothetical person skilled in the art. The opponent did not identify a specific person skilled in the art. However, their comments in relation to the suitability of Professor Stenzel as an expert witness infer the skills and knowledge that they consider necessary in the skilled person. For example, they submitted that:
“Professor Stenzel and chemists like her, working in “our laboratory” in a biomolecular setting are not skilled in the art of, silver fluoride chemistry, delivering a medical device (silver fluoride) in vivo, under the specialised setting of a dental clinic, manually, overcoming all the complications associated with delivering such a medical device in the confines of the oral cavity, overcoming all related challenges.”
I understand from the opponent’s submissions that they consider the person skilled in the art would be a team comprising an inorganic chemist with specialty knowledge of silver fluoride chemistry, a formulation chemist with knowledge of dental formulations, and a dentist. The applicant disagreed that the skilled person needed such a specialist knowledge of silver fluoride, nor that they needed clinical experience in a clinical dental environment, particularly as the skilled person should not possess any capacity for invention.
On balance I agree with the applicant’s submissions on this point. The invention relates to the stabilisation of a dental formulation, and in particular a formulation comprising silver fluoride. While I consider a knowledge of silver fluoride chemistry would be required, I do not consider that an inorganic chemist as a member of the team would necessarily need to be a highly specialised in such chemistry. Similarly, while the invention relates to dental formulations for use in clinical dental environments, I do not consider it necessary that the skilled person need have a highly specialised knowledge of dental caries or the like. Moreover, the skilled person can comprise a team of different members with different skills and knowledge. In this regard, the opponent’s submissions appear to be directed at the relative skills and experience of Dr Craig and Professor Stenzel. However, as noted by the High Court in AstraZeneca AB v Apotex Pty Ltd,[13] the person skilled in the art is an artificial construct, and that:
“The notional person is not an avatar for expert witnesses whose testimony is accepted by the court. It is a pale shadow of a real person – a tool of analysis which guides the court in determining, by reference to expert and other evidence, whether an invention as claimed does not involve an inventive step.”
[13] [2015] HCA 30 at [23].
A similar consideration applies to Dr Craig. The applicant agreed that Dr Craig has relevant knowledge, experience and expertise in the art. However, they noted Dr Craig’s decade-long involvement in CSDS[14] products and close association with the Opponent. They submitted that it is questionable whether Dr Craig can be considered a truly independent witness in the opposition.
[14] Caries Status Disclosing Solution.
On balance I do not see a need to entirely exclude either witness. I acknowledge that Professor Stenzel may not have the same specialist experience in silver fluoride chemistry, nor in a clinical dental environment, as Dr Craig. However, this does not mean that Professor Stenzel is entirely unsuited to give evidence in the present matter. As an inorganic chemist, I consider that Professor Stenzel has knowledge and experience that is relevant to the present issue. Similarly, while Dr Craig may not be entirely independent, he has relevant knowledge and experience in the field. It is the relevance of the evidence given and whether it is representative of the hypothetical person skilled the art, rather than the extent of experience of the respective experts, that is the key consideration. In this regard, the parties have raised certain points that potentially impact on how I should view the evidence. As with any consideration of the evidence in an opposition, these types of issues will be taken into account in the determination of the weight that evidence can be given.
The specification and claims
The invention is said to relate to silver fluoride solutions for dental compositions. Silver fluoride solutions have apparently been known for many years to provide therapeutic benefits in the treatment of dental caries and reduction of tooth sensitivity. Silver fluoride solutions have generally been provided as aqueous solutions of silver fluoride, silver nitrate or SDF. However, these have the drawback that the carious affected tooth can be permanently stained black due to oxidation of the silver ions. Soft tissues can also stain if contacted with the silver fluoride solution, though this wears off over the proceeding days. One means of addressing this issue is to apply an iodide salt solution which reacts with free silver ions to form water insoluble silver iodide salts. Rather than turning black, carious lesions take on a brownish tinge, while the colour of other dentinal tissues remains unchanged.
Silver fluoride solutions often display poor storage stability, with precipitates tending to form. The resulting reduction in the concentration of soluble ions diminishes the therapeutic effectiveness of the dental treatment. Addition of ammonia can stabilise silver fluoride solutions by forming SDF, but these can be difficult to store due to the high volatility of ammonia. Extended storage, particularly at high temperatures, can lead to a loss of ammonia and precipitation. Ammonia can also increase the pH of the solutions to hazardous levels (pH>10), as well as causing irritation and potentially burning of soft tissues if left in contact for too long.
The specification goes on to state that it would be advantageous to develop a storage stable silver fluoride containing solution that exhibits caries arrest and desensitization of teeth whilst being gentle to the oral soft tissues. A suitable system is said to be based on substantially aqueous silver fluoride solutions that are stabilized in the region of pH 4 to 5.3.
The first aspect of the invention is said to reside in an aqueous silver fluoride containing solution with pH 4.0-5.3, wherein the solution is stabilized with an acid, and is formulated for dental use.
The specification states that a freshly made 38% w/v silver fluoride solution typically has a pH of 6.2-6.4. Such solutions are not stable, but by adjusting the pH of the solution to pH 4.0-5.3, stability is achieved. pH values below 4 are unsuitable as the corrosive nature of the acidic solutions can cause chemical burns and irritation. pH values above 5.3 are said to be unstable for long term storage as silver precipitates from the solution. The acid is preferably nitric acid, but other organic and inorganic acids that form soluble silver salts can apparently also be used.
The specification contains a single example showing a comparison of a 38% silver fluoride solution “stabilized with nitrate” and having a pH of 5.1 (Example 1) with corresponding solutions that are unstabilized (Comparative Example 1) or stabilized with ammonia (Comparative Example 2).
The specification concludes that Example 1 has good stability upon storage, good tubule occlusion and biologically compatible pH (indicated as the absence of soft tissue irritation).
The specification ends with four claims, as follows:
An aqueous Silver Fluoride (AgF) containing solution with pH 4.0 – 5.3, wherein the solution is stabilized with an acid, and is formulated for dental use.
An aqueous silver fluoride solution as defined in Claim 1, wherein the acid is nitric acid.
An aqueous silver fluoride solution as defined in Claim 1 or 2, wherein the quantity of Silver Fluoride in the aqueous Silver Fluoride solution is about and up to 50% w/v.
An aqueous Silver Fluoride solution as defined in any one of Claims 1 to 3, wherein
(i) the quantity of Silver Fluoride in the aqueous Silver Fluoride solution is about 38% w/v; and
(ii) the Silver Fluoride in the aqueous Silver Fluoride solution is stable for at least 1 year at 23 degrees C.There was little real dispute between the parties as to the meaning of the terms used in the claims, though the breadth and meaning of the terms were linked to the issues raised under section 40. I do not consider there are any significant construction issues but have provided an analysis of a couple of terms that potentially impact on subsequent considerations.
Stabilised
The parties did not appear to dispute the meaning of the term stabilise. The applicant acknowledged that there is no explicit definition of the term but noted that the description discloses that aqueous silver fluoride solution can be unstable upon storage and silver fluoride (or more precisely the silver component) can precipitate out of solution.[15] I therefore consider that the term stabilise can be taken to mean that such precipitation is inhibited or prevented. This also applies to Claim 4, which defines that the solution is stable for at least 1 year at 23°C, which I understand to mean that silver species do not precipitate from the solution for that period of time.
The pH of the solutions
[15] Specification at [0005] and [0009].
Claim 1 defines that the solutions have pH in the range 4.0 to 5.3. I note that the pH range defined in the claim is not qualified in any way (that is the claims do not define the range to be about 4.0 to 5.3). Moreover, while a purposive construction of a claim might allow for a degree of imprecision based on the understanding of the skilled addressee, that does not appear to be the case here. The references to the pH range given in the specification use similarly precise values that are apparently being selected for specific reasons:
“By adjusting the pH of the solution with an acid to a pH of 4.0-5.3, stability of the solution is achieved. pH values less than 4.0 are deemed unsuitable as this may cause chemical burns and irritation die to the corrosive nature of acidic solutions. pH values above 5.3 prove to be unstable for long term storage, with precipitation of silver from the solution.”
This interpretation of the pH range is consistent with that provided by Professor Stenzel, who stated that:
“I understand that an essential feature of the claimed invention is that the AgF solution is stabilised at a pH of 4.0 to 5.3. The pH range identified in the claimed invention is specific and as I understand it essential to the invention.”[16]
[16] Stenzel at [56].
However, the opponent made submissions in relation to a product sold by the applicant under the name of Riva Star Aqua. Dr Craig measured the pH of the Riva Star Aqua product using pH test strips, as well as using a pH electrode.[17] Neither test showed the pH to be in the range defined by the present claims. The gist of the opponent’s submissions was that claim 1 defines a specific pH range which is said to be essential to the invention and to provide certain advantages.[18] However they submitted that the pH of the Riva Star Aqua product showed this assertion to be “false” as the invention could be performed outside this range.
[17] Exhibit SDA-3-6-13.
[18] OS at 1.a(viii) to 1.a(x).
I do not consider this submission is relevant to the present determination, and certainly does not change the meaning I give the terms used in the claim. The claim is clearly limited in scope to formulations having a pH in the range defined by the claim. That the applicant has sold products that do not fall within this range does not bring into question the construction that should be given to the range defined in the present application.
To the extent that pH test strips do not give as accurate an answer as a pH electrode, I do not consider this issue impacts on my interpretation of the claim. The skilled person would understand the shortcomings of any particular test method and would choose one that is fit for purpose and provides a sufficient degree of accuracy.
In short, the claim is limited to formulations having a pH in the range of 4.0 to 5.3.
Novelty
44. An invention is taken to be novel when compared with the prior art base unless it is not novel in light of certain types of prior art information, each of which must be considered separately:[19]
Prior art information made publicly available in a single document or through doing a single act;
Prior art information made publicly available in 2 or more related documents, or through doing 2 or more related acts, if the relationship between the documents or acts is such that a person skilled in the relevant art would treat them as a single source of that information.
[19] Subsection 7(1) of the Patents Act.
45. Relevant to the present case, the prior art base includes “whole of contents” Australian patent applications:
Information contained in a published specification filed in respect of a complete application where:
(a) if the information is, or were to be, the subject of a claim of the specification, the claim has, or would have, a priority date earlier than that of the claim under consideration; and
(b) the specification was published on or after the priority date of the claim under consideration; and
(c) the information was contained in the specification on its filing date.
46. It is well-established that the general test for anticipation is the reverse infringement test as articulated by Aickin J in Meyers Taylor v Vicarr Industries:
“The basic test for anticipation or want of novelty is the same as that for infringement and generally one can properly ask oneself whether the alleged anticipation would, if the patent were valid, constitute an infringement.”[20]
[20] Meyers Taylor Pty Ltd v Vicarr Industries Ltd [1977] HCA 19 at [20]; 137 CLR 228 at [235].
47. Thus, the test is satisfied if the alleged anticipation discloses all of the essential features of the invention as claimed. Furthermore, as stated by the Full Court in AstraZeneca v Apotex:
“… for a prior art document to be anticipatory, there must be … a clear description of, or clear instructions to do or make, something that would infringe the patentee’s claim if carried out after the grant of the patentee’s patent.”[21]
[21] AstraZeneca AB v Apotex Pty Ltd [2014] FCAFC 99 at [301].
48. A classic formulation of this principle was given in General Tire v Firestone, which stated that the prior art must provide clear and unmistakable directions to the invention:
“When the prior inventor’s publication and the patentee’s claim have respectively been construed by the Court in the light of all properly admissible evidence ... the question whether the patentee’s claim is new ... falls to be decided as a question of fact. If the prior inventor’s publication contains a clear description of, or clear instructions to do or make, something that would infringe the patentee’s claim if carried out after the grant of the patentee’s patent, the patentee’s claim will have been shown to lack the necessary novelty, that is to say, it will have been anticipated. The prior inventor, however, and the patentee may have approached the same device from different starting points and may for this reason, or it may be for other reasons, have so described their devices that it cannot be immediately discerned from a reading of the language which they have respectively used that they have discovered in truth the same device; but if carrying out the directions contained in the prior inventor’s publications will inevitably result in something being made or done which, if the patentee’s patent were valid, would constitute an infringement of the patentee’s claim, this circumstance demonstrates that the patentee’s claim has in fact been anticipated.
If, on the other hand, the prior publication contains a direction which is capable of being carried out in a manner which would infringe the patentee’s claim, but would be at least as likely to be carried out in a way which would not do so, the patentee’s claim will not have been anticipated, though it may fail on the ground of obviousness. To anticipate the patentee’s claim the prior publication must contain clear and unmistakable directions to do what the patentee claims to have invented… a signpost, however clear, upon the road to the patentee’s invention will not suffice. The prior inventor must be clearly shown to have planted his flag at the precise destination before the patentee.”[22]
[22] The General Tire & Rubber Company v The Firestone Tyre and Rubber Company Limited [1972] RPC 457 at 485-486.
49. The basis of the opponent’s case on novelty is not entirely clear from their written submissions for hearing. The submissions appear to conflate several different grounds, including section 40. The only prior information that I can glean from the submissions relates to the purported disclosure by sale of silver fluoride products and a lecture at Sydney University prior to the priority date of the present claims.[23] However the pH range of the present claims is not disclosed by this evidence, and the opponent instead submitted that the use of nitric acid to stabilise silver fluoride was “common public knowledge”. This line of reasoning, and what seems to be a mosaic of prior art information, is more in line with an inventive step consideration rather than novelty. I do not consider the opponent has made out their case based on the submissions made on this evidence.
[23] OS at 1.a(vii).
50. Further to the above submissions, I note that the opponent raised AU 2017333603 (‘603) in their SGP. While they did not specifically press the document under the ground of novelty, they made submissions referring to the information in this document being “public knowledge” and I sought verbal submissions on the document at hearing. For completeness I will briefly deal with this document, even though ultimately I do not consider it impacts on the validity of the present claims.
51. ‘603 discloses a Caries Status Disclosing Solution (CSDS) comprising an aqueous solution of silver fluoride which is stabilised by the addition of nitric acid. The specification states that:
“We discovered that, in one experiment, the addition of 3-5% (w/v) nitric acid, using ultra-pure water purged with argon gas, to a CSDS silver fluoride solution brought the pH down to pH 5.5-6.0 and resulted in there being substantially no observed change in silver ion levels after aging at 55°C for 60 days, (thereby being equivalent to 18 months at an ambient temperature of 23°C”[24]
[24] AU 2017333603 at [23].
52. The applicant submitted that D1 only discloses that the pH of the silver fluoride solution is brought down to pH 5.5-6.0. There is no actual experimental data provided to demonstrate the stability of the water-based silver fluoride solution. It is only in paragraph [34] and claim 4 that “mere statements” assert that the nitric acid is added in sufficient quantity to substantially stabilise the silver fluoride solution such that the silver ion levels do not decrease by more than 5% over a period of at least 9 months at approximately 25°C. They argued that ‘603 does not provide an enabling disclosure of the claimed invention.[25]
[25] OS at [82].
53. On balance I find the applicant’s submissions on this point to be persuasive. To anticipate the present claims, the prior art must provide clear and unmistakable directions to the present invention. Admittedly, ‘603 broadly discloses the use of nitric acid to stabilise aqueous silver fluoride solutions. However, a broad disclosure does not necessarily anticipate a subsequent, narrower claim. As noted by the applicant, the teaching in ‘603 is directed towards solutions having a pH of 5.5-6.0. There is no explicit disclosure of solutions having a pH in the range 4.0-5.3, or the purported advantages that such compositions are said to have in comparison to compositions having a pH greater than 5.3. I therefore do not consider that ‘603 provides the clear and unmistakable directions required to anticipate the present claims.
54. In summary, I consider that the claims are novel in view of the material raised in the opponent’s written submissions for hearing, as well as in view of AU 2017333603.
Inventive step
55. Section 7(2) of the Act sets out that an invention is taken to involve an inventive step unless it would have been obvious to a person skilled in the relevant art in the light of the common general knowledge as it existed before the priority. The consideration may be in light of the common general knowledge alone, or in light of the common general knowledge combined with the following information:
(a) any single piece of prior art information; or
(b) a combination of any 2 or more pieces of prior art information that the skilled person mentioned in subsection (2) could, before the priority date of the relevant claim, be reasonably expected to have combined.
56. A useful statement of relevant principles for assessing inventive step was provided by Nicholas J in Hood v Bush Pharmacy Pty Ltd:
“Section 7(2) of the Act uses the word ‘obvious’ in the course of describing what must be established before an invention can be held not involve an inventive step. Something may be ‘obvious’ in light of the common general knowledge, or the common general knowledge coupled with the relevant s 7(3) information, if it is ‘plain or open to the eye or mind, something which is perfectly evident to the person thinking on the subject’ or something which ‘would at once occur to anyone acquainted with the subject and desirous of accomplishing the end’.
An invention may also be obvious in light of the common general knowledge if the person skilled in the art faced with the same problem as the inventor would have taken as a matter of routine whatever steps might have led from the prior art to the invention, whether they be the steps of the inventor or not or (using the language of the ‘modified Cripps question’) if the person skilled in the art would be directly led as a matter of course to take such steps in the expectation that doing so might well produce a useful or better alternative to the prior art. However, a claimed invention is not obvious merely because the person skilled in the art would consider that it was ‘worthwhile to try’.”[26]
[26] [2020] FCA 1686 at [116]-[117] (citations omitted).
57. It is important to note the requirement for a reasonable expectation of success. This is explicit in the expectation that an approach “might well” succeed, and implicit in the characterisation of steps as those to be taken as a matter of routine.[27] However, success need not be guaranteed: “the relevant test is not knowing that steps will or would or even may well work, but merely expecting that the steps may well work.”[28]
[27] Generic Health Pty Ltd v Bayer Pharma Aktiengesellschaft [2014] FCAFC 73; 314 ALR 91 at [71].
[28] Nichia Corporation v Arrow Electronics Australia Pty Ltd [2019] FCAFC 2 at [99].
58. In the present case, the opponent submitted that “the technology” was disclosed to the public by sales, sales information circulated in lectures (Sydney University) and order enquiries between October 2016 and 11 February 2018.[29] The applicant submitted that the opponent’s written submissions refer to inadmissible evidence that was filed out of time (Annexes SDA3-4-1 to SDA3-6-14a) and to documents and particulars that are not derivable form the SGP of May 2022.[30] They also noted that the SGP asserts that the claims lacked inventive step in light of a Chemika Laboratory Certificate of Analysis dated 15 July 2018 and AU 2017333603.[31] Both of these documents were published after the priority date of the present application, and are not relevant in the consideration of inventive step.
[29] OS at 2.a(i) to (iv) and 1.a(v).
[30] AS at [113].
[31] AS at [100].
59. I agree that the documents raised by the opponent in their submissions for hearing were not mentioned in the relevant SGP. Nevertheless, I note the sales records and enquiries were mentioned in evidence.[32] Dr D’Ambrosio referred to a lecture at Sydney University on 2 February 2018,[33] as well as a copy of an email enquiry following the lecture.[34] Similarly, Dr Craig stated that:
“I refer to the paragraph 57 of the MS Declaration regarding the aqueous silver fluoride marketed as AgF by Creighton which I had made and disclose [sic] in public around 12 February 2018. To the contrary of the assertion made in paragraph 57 of the MS Declaration, the aqueous silver fluoride marketed as AgF by Creighton was stabilised with nitric acid and the pH of that product was between 5.5 to 6.0.”[35]
[32] D’Ambrosio 1 at [21] and Confidential Annexure SDA-2 Tab B.
[33] D’Ambrosio 1 at [23].
[34] Exhibit referred to as Confidential Annexure SDA-2 Tab D.
[35] Craig at [17].
60. Professor Stenzel had the opportunity to address this evidence in her evidence in answer.[36] Thus, while it may be arguable whether this evidence has been properly entered into the opposition, both parties have had the opportunity to provide evidence on this material. There has been no apparent disadvantage to either party and no further evidentiary steps required.
[36] Stenzel at [68].
61. Turning now to the evidence, even though the present consideration relates to inventive step rather than novelty, the overarching principles relating to “prior use” are relevant. To that end, as noted in Aspirating IP Ltd v Vision Systems Ltd:
“The correct principle is that a prior use must be strictly proved and evidence which is not corroborated must be scrutinised with care.”[37]
[37] [2010] FCA 1061 at [200].
62. Bennett J stated in Damorgold Pty Ltd v JAI Products Pty Ltd that:
It is necessary to prove not only that the prior product that the prior product or process was publicly available but also to adduce evidence as to what information was conveyed by the use to the notional skilled addressee.[38]
[38] (2015) 229 FCR 68 at [48].
63. The evidence suggests that there has been a disclosure of relevant information through these prior acts. However, the opponent has provided no specific details what was disclosed to the public. There is no corroborative evidence of the information that was disclosed in the Sydney University lecture, such as transcripts or copies of slides and the like. None of the sales documents or enquiries shows details of the product that was supplied. For example, the sales records refer only to “Creighton 3ML AgF + 3ML SnF2”.[39] There is no indication that the products contain nitric acid let alone the specific pH of the compositions.[40]
[39] Exhibit SDA 3-5, which appears to correspond to sales records filed with an amended SGP on 18 March 2022.
[40] I note that a section 27 notice was also filed by Dr D’Ambrosio just before the notice of opposition was filed. The material filed with the notice dates back to 2014 and includes manufacturing details of an aqueous silver fluoride solution which appears to contain 5% nitric acid. This material is dated 11 December 2015, which would pre-date all of the evidence in the opposition, including the ‘603 patent. However, there is no clear indication that the composition was made publicly available. I therefore have not given this material any further consideration.
64. There are also inconsistencies in the evidence that raise doubts as to whether the sales evidence clearly establishes that the acid-stabilised product was sold prior to the priority date. For example, Dr Craig refers to a product marketed as AgF prior to 12 February 2018 which he states was stabilised by nitric acid.[41] However, he also stated that he knew of at least three silver fluoride-containing products that were available prior to 12 February 2018, including “aqueous silver fluoride (not stabilised with nitric acid) marketed as AgF by Creighton Pharmaceuticals in Australia”.[42] He went on to state that from his research, he identified “AgF stabilised with nitric acid approximately pH 5.5-6.0”. This would seem to suggest that there were different silver fluoride products sold by Creighton prior to February 2018, but the sales records do not clearly identify the composition of the products referred to in evidence.
[41] Craig at [17].
[42] Craig at [19].
65. In my opinion, the lack of detail and corroborative evidence about what the sales and lecture disclosed to the public precludes any consideration of whether the present invention would have been obvious. There is simply no clear evidentiary starting point, and in particular what the specific information was that was disclosed to the public, from which to make the determination.
66. In summary, I do not consider the evidence, as it currently stands, establishes that the claims are obvious. To the extent that it is relevant, I do not consider it necessary to formally have regard to the documents under regulation 5.23. The evidence, as it currently stands, would not change the outcome of the opposition significantly. This, as previously noted, does not stop the opponent from filing additional material to address the shortcomings identified above, but it would be dealt with in (an ex parte) re-examination process.
67. The opposition fails on this ground.
Section 40(2)(a) (sufficiency)[43]
[43] I note the opponent also submitted that the present application was not entitled to priority from AU 2018900432 under the ground of sufficiency. This potentially impacts on the ground of inventive step. However, the submissions on sufficiency were unsuccessful, and for similar reasons I consider the priority claim is valid.
68. Section 40(2)(a) of the Act requires that the complete specification must disclose the invention in a manner which is clear enough and complete enough for the invention to be performed by a person skilled in the relevant art (referred to as sufficiency). The Explanatory Memorandum to the Raising the Bar Act stated that the changes to section 40(2)(a) were:
“… intended to align the disclosure requirement with that applying in other jurisdictions with the effect that sufficient information must be provided to enable the whole width of the claimed invention to be performed by the skilled person without undue burden, or the need for further invention…”
69. The Explanatory Memorandum noted that the similarity of the wording of section 40(2)(a) with section 14(3) of the UK Patents legislation, and Art 83 of the European Patent Convention, and went on to state that:
“The intention is that paragraph 40(2)(a) be given, as closely as is practicable, the same effect as the corresponding provisions of UK legislation and the European Patent Convention.”
70. A growing body of judicial decisions is providing guidance on the application of section 40(2)(a).[44] Consistent with the guidance provided in the Explanatory Memorandum, these have drawn on UK and European Patent Office decisions. For example, in Merck v Wyeth,[45] Burley J endorsed the key elements of sufficiency set out by Kitchin J in Eli Lilly v HGS:
(i) the first step is to identify the invention and that is to be done by reading and construing the claims;
(ii) in the case of a product claim that means making or otherwise obtaining the product;
(iii) in the case of a process claim, it means working the process;
(iv) sufficiency of the disclosure must be assessed on the basis of the specification as a whole including the description and the claims;
(v) the disclosure is aimed at the skilled person who may use his common general knowledge to supplement the information contained in the specification;
(vi) the specification must be sufficient to allow the invention to be performed over the whole scope of the claim;(vii) the specification must be sufficient to allow the invention to be so performed without undue burden.[46][44] Merck Sharp & Dohme Corporation v Wyeth LLC (No 3) (2020) 155 IPR 1; [2020] FCA 1477; Cytec Industries Inc. v Nalco Company [2021] FCA 970; Rakman International Pty Limited v Boss Fire & Safety Pty Ltd [2022] FCA 464; Jusand Nominees Pty Ltd v Rattlejack Innovations Pty Ltd [2022] FCA 540; Jusand Nominees Pty Ltd v Rattlejack Innovations Pty Ltd [2023] FCAFC 178; TCT Group Pty Ltd v Polaris IP Pty Ltd [2022] FCA 1493; Calix Limited v Grenof Pty Ltd [2023] FCA 378; ToolGen Incorporated v Fisher (No 2) [2023] FCA 794.
[45] Merck Sharp & Dohme Corp v Wyeth LLC (No 3), ibid at IPR 107 [526].
[46] Eli Lilly & Co v Human Genome Sciences Inc [2008] EWHC 1903; [2008] RPC 29.
71. The general approach taken by the Patent Office to determine sufficiency of disclosure, and which have been approved by the Federal Court in, for example, Cytec v Nalco,[47] is as set out in CSR:
(i) Construe the claims to determine the scope of the invention as claimed
(ii) Construe the description to determine what it discloses to the person skilled in the art, and
(iii) Decide whether the specification provides an enabling disclosure of all the things that fall within the scope of the claims.[48]
[47] Cytec Industries Inc. v Nalco Company supra.
[48] CSR Building Products Limited v United States Gypsum Company [2015] APO 72.
72. A key consideration is whether the claimed invention as a whole, or an individual feature of the invention, represents a principle of general application. As set out in the Explanatory Memorandum, an enquiry is also made as to whether the invention can be performed across the full scope of the claim without an undue burden of experimentation or need for further invention. To that end, an expanded approach was taken in Evolva to the third of the CSR enquiries:
(1) Is it plausible that the invention can be worked across the full scope of the invention?
(2) Can the invention be performed across the full scope of the claims without undue burden?[49]
[49] Evolva SA [2017] APO 57.
73. The opponent made a number of submissions under the various section 40 grounds, as well as utility. As noted previously, these include grounds and particulars that were not previously raised in the opposition or were not set out in the grounds and particulars dated 13 May 2022. Nevertheless, I note that there is significant overlap between the different issues, and I consider my determination on the grounds properly raised in the opposition will also cover these other issues. I will deal with the issues raised by the opponent in turn. However, I will make the observation that several issues arise as a result of an overly meticulous verbal analysis of the specification and claims. I have dealt with these issues only briefly.
“nitrate”
74. My understanding of the opponent’s concerns on this point stem from the reference in the second column of Table 1 refers to “38% AgF w/v (stabilized with nitrate)” rather than nitric acid. They submitted that the Thermo Fisher Scientific chemical catalogue listed 367 nitrate products, and that in order to work the invention the skilled person would need to test all of these products. The submission appears to be that the specification is suggesting that nitrate salts can be used to stabilise the silver fluoride solutions.
75. The disclosure, including the claims, is clearly directed to the stabilisation of silver fluorides by acids, including nitric acid, and not nitrates such as inorganic salts. I do not consider, given that general disclosure, that the skilled person would undertake an entirely different research project based on a single reference to nitrate in the table. If there is an error in the use of this term, noting that nitrate is the conjugate base of nitric acid, I consider the skilled person would, as a matter of commonsense, be able to clarify it. The opponent has not made out their opposition on this point.
“the quantity of silver fluoride… is about and up to 50% w/v”
76. The opponent submitted that the definition in Claim 3 of about and up to 50% includes compositions where no silver fluoride is present. I disagree. The preamble of the claim defines an “aqueous silver fluoride solution”. Clearly if there is no silver fluoride present it would not be a silver fluoride solution. This argument fails.
77. The opponent also submitted that the specification does not enable the invention across the full range of silver fluoride concentrations claimed. They stated that the skilled person would need to perform a series of experiments, increasing the concentration in 1% increments, amounting to at least 25 batches, each requiring 25 tests on 25 teeth to determine whether the solutions were capable of arresting caries and provided desensitisation.[50]
[50] OS at 4c(iii).
78. Despite the opponent’s submissions, I do not see that it would require an undue burden to work the invention across the full scope of the claims. The specification indicates that silver fluoride containing products, including aqueous solutions of silver fluoride, have been used in dentistry for many years. The invention lies in the stabilisation of such aqueous silver fluoride solutions using an acid. This is perhaps reflected in the fact that Claim 1 defines stabilisation by an acid but does not limit the claim to any specific silver fluoride concentration.
79. The specification provides an example containing 38% silver fluoride to demonstrate the stability and desensitising effect of the solution. This specific concentration appears consistent with prior art adduced in evidence.[51] Given that the use silver fluoride appears to have been known for many years, the selection of a suitable concentration would not require a de novo determination in the manner suggested by the opponent. To the contrary, given the evidence before me, I am satisfied that it would be a matter of routine to determine suitable concentrations for use in dental compositions according to the claimed invention, and this task would be assisted by what was already known in the art of silver fluoride solutions. The opponent has not made out their case on this point.
“an acid”
[51] Annexure SDA-1, Tab E.
80. The opponent made the submission that while the specification states that other organic or inorganic acids can be used in place of nitric acid, only nitric acid does not precipitate insoluble salts when added to silver fluoride solutions.[52] This was raised at the hearing under the ground of usefulness, but in the SGP under the ground of sufficiency.[53]
[52] OS at 5.a(ix).
[53] SGP, 13 May 2022 at 4.5.3.
81. The applicant submitted that it is not the essence of the invention as to which acid in particular is used provided the acid is able to acidify and stabilise the silver fluoride solution in the required region of pH 4.0-5.3. They referred to the evidence of Professor Stenzel, who stated that identifying acids for this purpose is entirely routine and would only require a routine bank of acids to be run to identify whether silver fluoride precipitates out as insoluble silver salts.[54]
[54] Stenzel at [168].
82. The applicant also submitted that, contrary to the opponent’s submissions that no other organic or inorganic acids are known to form soluble silver salts, Dr Craig acknowledged that both silver fluoride and silver acetate are water soluble. In particular, Dr Craig stated that:
“I know of no other inorganic acid other than nitric acid and no organic acids that form soluble silver salts; there are only two silver salts that can be considered soluble in water i.e. silver nitrate the most soluble: 2750 grams/litre at 25°C, and silver fluoride: 1000+ grams/litre at 25°C; by… comparison organic acids forming salts; silver acetate is the most soluble organic salt with a solubility of: 11.11 grams/litre at 25°C, and silver carbonate another organic salt formed by carbonic acid: silver carbonate is even less soluble at 0.33 grams/litre.”
83. The applicant noted that Dr D’Ambrosio alleged that a total of 195 tests would be required in order to identify a suitable acid.[55] They submitted that no inventive skill would be required to conduct such tests, which would not amount to an undue burden. They argued that without such a bank of tests, if a particular acid within the scope of the claim failed to work, it would be an issue of inutility, not of disclosure. Inutility is not a ground of opposition set out in the SGP.
[55] D’Ambrosio 2 at [50].
84. While I have concerns about the term “acid”, I am not satisfied, based on the evidence before me, that it would be an undue burden to work the invention across the scope of the claim. The claim characterises the compositions of the invention in terms of a function: namely that the solution is stabilised by an acid. That does not require that all acids are capable of that function, though in practical terms only a small number of acids might be suitable for that purpose. Nitric acid is particularly suitable in stabilising silver fluoride compositions as it forms highly soluble silver salts.
85. The key consideration is whether the invention relates to a principle of general application, or whether it relates to a more specific embodiment (that is, the use only of nitric acid). Some of the factors that come into consideration when determining whether the level of experimentation is an undue burden include uncertainty and a lack of predictability, incomplete experimental details, and a lack of guidance in the specification including instructions on how to proceed in case of failure.[56]
[56] Evolva at [34].
86. In the present case, the parties appear to be in agreement that the stability of the dental composition depends, at least in part, on the solubility of the silver salt formed on addition of the acid. The evidence shows that the skilled person can readily ascertain the solubility of silver salts. The main difference between the parties lies in whether silver salts other than nitrate would be considered “soluble” and therefore suitable for use in the invention. Dr Craig stated that he knows of only two silver salts that are soluble in water. But his evidence shows that silver forms other salts such as acetate, that, while not as highly soluble as silver nitrate, are relatively soluble. There is no evidence that such salts would not stabilise silver fluoride solutions. Even in the case of less soluble salts, there is no evidence that would establish that they would not provide stable solutions under the conditions used in the present solutions (including the specific pH conditions).
87. On balance, and based on the evidence before me, I consider it plausible that other acids could be used in the compositions of the invention. Moreover, given the knowledge of the properties of silver salts and the nature of the research, I do not consider it would represent an undue burden to identify other suitable acids.
Other issues and undue burden
88. The opponent made various other submissions concerning the nature of the experimentation required to work the claimed invention. These included that the specification does not provide specific information as to make a solution of aqueous silver fluoride (for example, the quantity of nitric acid added to bring the pH to the desired range),[57] that the specification does not specify the use of ultra-pure or argon-purged water,[58] and that the need to use accelerated ageing protocols to measure the stability of the formulations.[59] Dr Stenzel stated that she would expect this would be the type of laboratory work she would expect of her students.[60]
[57] OS at 4.a(xi).
[58] OS at 4.c(xii) and (xiii).
[59] OS at 4.d(vi) and (vii).
[60] Stenzel at [71] to [74].
89. The opponent’s submissions appear to be predicated on the provision of a commercial product rather than a workable prototype.[61] But in any case, I do not consider these experimental methods and protocols would present the skilled person with any difficulties that would require anything more than routine experimentation. Indeed, Dr D’Ambrosio referred to the modification of the (allegedly) existing CSDS products from pH 5.5-6.0 to 5.3 as “an obvious tinkering for no additional benefit”.[62]
[61] Mentor Corporation v Hollister Incorporated [1991] FSR 557 at 561.
[62] D’Ambrosio 1 at [86].
90. In summary, I am not satisfied that the opponent has not made out this ground of opposition.
Conclusion
91. The claims are novel and inventive in light of the prior art raised by the opponent. The specification provides a clear enough and clear enough disclosure for the invention to be performed by a person skilled in the relevant art. The opposition fails on all grounds.
92. Subject to an appeal, I direct that the application proceed to grant.
Costs
93. Costs generally follow the event. I see no reason to depart from that approach. I award costs according to Schedule 8 against the opponent, Silvano D’Ambrosio.
Dr Leslie F. McCaffery
Delegate of the Commissioner of Patents
0
6
0