DETAILED ACTION
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
Status of the Claims
The response and amendment filed 04/16/2025 is acknowledged.
Claims 1-3 and 6-11 are pending.
Claims 7-11 are new.
Claims 1-3 and 6-11 are rejected.
The following rejections and/or objections are either reiterated or newly applied. They constitute the complete set presently being applied to the instant application. Rejections not reiterated herein have been withdrawn.
Response to Arguments
Applicant's arguments filed 04/16/2025 have been fully considered but they are not persuasive.
Applicant’s arguments and the declaration have been fully considered but are not persuasive. The critical teaching of Craig is the stabilization of silver fluoride solutions by removing dissolved oxygen and optimizing the concentration of nitrate ion using nitric acid to take advantage of the high solubility of silver nitrate. Consequently, Applicant’s arguments which are predicated on the incorrect assumption that pH is the critical aspect of Craig’s teachings are not persuasive. The evidence provided, focusing solely on pH and absent details on dissolved oxygen, does not address the actual inventive concept of the prior art and is insufficient to establish the criticality of the claimed pH range and non-obviousness of the claimed invention.
Craig had already identified the problem of silver precipitation in AgF solutions (Craig, e.g., 15), stated the need for finding alternatives to the use of ammonia to stabilize silver ions (Craig, e.g., 17-21), and proposed resolving the problem of silver ion precipitation by removing dissolved oxygen (Craig, e.g., 96 and claim 9) and using an effective concentration of nitric acid (Craig, e.g., 24, claims 1 and 3 and 4 and 5). Craig reported the concentration of nitric acid as a parameter effective to reduce silver precipitation (Craig, e.g., claims 1, 3, and 5) due to fact that silver ion solutions show improved stability in the presence of fluoride and nitrate ions (Craig, e.g., 29). Because of this key teaching in Craig, the skilled artisan would have used the concentration of 3-5wt% as a starting point to optimize the concentration of nitric acid in the solution for the expected result of reduced silver precipitation. Craig reports an approximate pH range but does not require a particular pH for improved stability because the stability arises from the lack of oxygen and effective concentration of nitrate ion rather than the hydronium ion concentration (pH). Based on Craig, improvement of silver ion solubility by optimizing the concentration of nitric acid is an expected result of optimizing the nitrate ion concentration from nitric acid in deoxygenated silver fluoride solutions thereby offering a high solubility counter ion for silver ions.
The Declaration under 37 CFR 1.132 filed 04/16/2025 is insufficient to overcome the rejection of claims 1-3 and 6 under 35 U.S.C. based upon Craig, WO 2018058199 A1 as evidenced by Ricca Chemical, 5% (v/v) Nitric Acid, 2024 as set forth in the last Office action because:
The declaration lacks statistical significance.
The compositions of the tested solutions are not disclosed. Therefore, their relevance to the claimed invention has not been established in the evidence of record.
The claimed invention encompasses any acid, but the evidence is limited to nitric acid which supports Craig’s recognition of the stabilizing effect of nitrate ion rather than the pH when optimizing the concentration of nitric acid in the composition.
The declaration makes qualitative assessments, e.g., severe precipitation, but offers no quantitative data on residual silver ion concentration of the tested compositions which would allow for a more direct comparison to Craig’s reported stability.
Applicant’s declaration and exhibit do not support Applicant’s argument that the claimed range is critical. The exhibit states that solutions with a pH > 5.2 showed ‘worse stability’. However, the claimed range of 4.0-5.3 explicitly encompasses pH 5.3 which is greater than pH 5.2. This data suggests that Applicant’s the upper limit of the claimed range extends to compositions having ‘worse stability’ which weighs against the assertion that the entire 4.0-5.3 pH range is critical and non-obvious. Moreover, the fact that Exhibit PF-1 characterizes solutions with a pH > 5.2 as having ‘worse stability’ suggests the solutions still show some stability even if the stability is not optimal.
Craig also teaches the water may be ultra-purified and may be deoxygenated, such as by being purged with argon gas to remove dissolved oxygen from the water (See Craig, e.g., 85: silver fluoride added to argon purged water), thereby reducing the possibility of (silver ion) oxidation (Craig, e.g., 84-85). It is noted that the results presented by Applicant indicate the precipitate is due to the presence of AgOH which is an oxidation product of silver (Dec., e.g., 14).
Thus, the data proffered does not appear to be a comparison with the closest prior art since the PF-1 compositions do not appear to have been purged of dissolved oxygen, e.g., using argon, to prevent oxidation of silver by dissolved oxygen. Even if, arguendo, the skilled artisan optimized the pH within the explicit range suggested by Craig, e.g., 5.5-6.0, the skilled artisan would have understood that any precipitate caused by oxidation of silver may be remedied by purging the water with argon to remove dissolved oxygen before storage. Since Applicant does not reveal the composition and whether any or all of the PF-1 compositions were purged with nitrogen to remove dissolved oxygen, it cannot be determined if the results presented are, in fact, unexpected due to pH alone in view of the prior art of record.
The declaration uses terms like severe (Declaration, e.g., ¶ 14) to describe the precipitation at pH 5.5. However, Exhibit PG-1 states that solutions with a pH > 5.2 showed a worse stability (Exhibit PF-1, Background). It is noted that the claimed range reads on pH 5.3 which is greater than 5.2. Further, characterizing the stability as “worse” still acknowledges there is at least some degree of stability which is the result expected from Craig. Thus, there is no showing that the proffered evidence of nonobviousness is commensurate in scope with the claims as presently presented. See MPEP § 716. Applicant’s data has shown less silver precipitation at the pH of 4.76 and 5.1 compared to solutions having a pH of 5.5 and 5.73 (Exhibit PF-1 and Declaration 11-20) for single silver fluoride solutions of unknown composition. It is noted that the pH values shown present a narrower range than the pH range claimed. Further, there is no objective evidence showing the result is statistically significant. Further still, Applicant has provided no data regarding the presence or absence of dissolved oxygen or residual silver concentration at the conclusion of the study which may shed light on whether the silver concentration is stabilized to an unexpected degree at a pH of 4.3-5.3 relative to the range of 5.5-6.0.
For these reasons, the data is ineffective to show the claimed pH range is critical and commensurate in scope with the invention as presently claimed.
Each of these points are addressed in detail below.
In the Remarks, pp. 4-5, Applicant argues the technical problem to be solved by the present invention is to find an alternative solution to the SDF approach for stabilizing AgF in aqueous environments, and the technical solution provided by the present invention is acid stabilization of AgF through a critical pH range discovered by the present inventors. Applicant argues that it can be seen from the enclosed Declaration and Exhibit that the claimed pH range of 4.0 - 5.3 is, indeed, a critical pH range required to achieve storage stability of aqueous AgF solutions, which may be subjected to unpredictable storage periods/conditions. Applicant argues this data rebuts the prima facie case of obviousness. The declaration, e.g., ¶’s 11-20 and Exhibit PF-1 presents evidence and opinion on how the pH relates to the stability of silver fluoride solutions.
The declaration at 11 states: When fresh 38% w/v AgF solutions were prepared, solution pH tends to be in the range of pH 6.2-6.4. We discovered that this mildly acidic pH range is not sufficient to retain the AgF in solution upon storage.
The declaration at 14 states: Surprisingly, pH 5.5 appears to be a critical pH (e.g. as seen in Figure 4 of Exhibit PF-1 showing the conditions of the solutions at the end of the first thermocycle), at which a brown precipitate of silver (possibly as the sparingly soluble AgOH) is rather apparent. It was rather unexpected that the precipitation of silver at pH 5.5 was even more severe than at pH 5.73. Therefore, whilst we learnt that acid stabilization of silver might be possible, however, it will need to be within the condition of pH < 5.5, which is critical to the stability of aqueous AgF solutions over time, including over changing temperature conditions during storage and/or transport of the AgF solutions.
The declaration at 15 states: We later performed further experimentation to verify this understanding, including the key studies as in the Examples of this Application, with Example 1 clearly confirming that an aqueous solution of AgF can, indeed, be acid stabilised at a pH of 5.1 for a one-year period at a room temperature of 23 °C.
Exhibit PF-1 states Previous results (Figures 1 and 2) showed that AgF solutions with pH 4.76 (Batch# ML.160418C) and pH 5.01 (Batch II ML 160412A) have acceptable stability after 24 clays of storage at both 35 and 42 °c, while solutions with pH> 5.2 showed worse stability under the same conditions (Background, pg. 1).
Applicant argues the Office Action, in the penultimate paragraph on page 3, notes that Craig does not expressly teach the pH range of 4.0-5.3. Applicant argues that the Examiner in earlier parts of page 3 asserts that Craig teaches adding 3-5% nitric acid, and the Ricca Chemical citation confirms that the pH of a 5% nitric acid solution has a pH <1, therefore Craig suggests that the pH of the AgF solution may range from less than 1 to approximately 6 to stabilize silver ions in solution. Applicant argues that the understanding in this regard is incorrect, and would refer the Examiner specifically to paragraphs 25-29 of the enclosed Inventor Declaration, which also explains the chemical principles that would ultimately determine the pH of a salt solution.
These arguments are unpersuasive.
It is respectfully pointed out that Applicant’s arguments regarding Craig’s expressly disclosed pH range are based on a misunderstanding of Craig’s teachings, i.e., that Craig teaches the pH of 5.5-6.0 is critical. Although Craig teaches this pH range is suitable for stabilized silver fluoride solutions, it is not seen where Craig suggests the pH range of 5.5-6.0 is required for stability and the evidence of record suggests the skilled artisan would have recognized that Craig teaches a broader pH range while maintaining stability. Applicant’s evidence of criticality is not commensurate in scope with the presently claimed invention. The evidence of record is insufficient to establish that the pH alone is critical irrespective of the acid used to modify the pH or the concentration of dissolved oxygen.
Paragraphs 25-29 of the declaration are addressed in detail below.
The following response is provided which addresses in detail each of the issues raised by Applicant’s remarks and declaration filed 04/16/2025.
Each of Applicant’s arguments relate to the pH range disclosed in Craig. Applicant’s arguments regarding Craig with respect to pH have been considered but are not persuasive.
It is maintained that the claimed pH range is within the range of from about 1 to about 6 suggested in Craig when considering Craig’s teachings of the concentration of nitric acid (Craig, e.g., claim 5) and the range of approximately 5.5-6.0 explicitly reported (Craig, e.g., claim 6). Craig’s teachings with respect to amount of acid and pH is not limited to the explicit pH range identified above. In light of Craig teaching that the nitric acid concentration may be 5%, and the fact that a 5% nitric acid solution is expected to have a pH of less than 1, the skilled artisan would have understood the teachings of Craig as suggesting a silver fluoride solution having a pH of from less than 1 to 6 are effective for improved stability. The claimed range is entirely within the range suggested by Craig as evidenced by Ricca Chemical, 5% (v/v) Nitric Acid, 2024. In the case where the claimed ranges “overlap or lie inside ranges disclosed by the prior art” a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990). MPEP 2144.05. Here the claimed range is entirely within the full range suggested by Craig and the composition as claimed appears to have the same stability properties expected from the teachings of Craig.
Applicant’s evidence and arguments have been given full consideration. However, they are not found persuasive. The skilled artisan would have understood that Craig reveals that the pH is not the critical aspect of Craig’s nitric acid teaching. Rather, it is the concentration of nitrate ion offered by nitric acid in combination with removing dissolved oxygen which affords the improved silver ion retention and reduced silver precipitation. In this regard, Craig teaches silver fluoride and silver nitrate are by far the most soluble silver salts (Craig, e.g., ¶ 29) which led Craig to modify silver fluoride solutions with an effective concentration of nitric acid despite the fact that silver nitrate has a recommended shelf life of only 6 months (Craig, e.g., 30). The skilled artisan would have understood that Craig’s report of silver ion stability over at least 9 months at room temperature by combining the two most soluble silver salts in the silver fluoride solution represents an unexpected stability improvement compared to solutions containing only silver fluoride or silver nitrate alone.
The most likely reason that Craig teaches an “approximate” pH of from 5.5-6.0 (Craig, e.g., ¶ 37), is that the pH of the composition, by itself, is not critical to achieving greater silver ion stability in silver fluoride solutions according to Craig. As pointed out by Applicant, the pH of a composition may depend on a number of factors including salt concentration (which is not specified in the claimed invention) and buffering effects from counter ions (Declaration, e.g., 26-28). Craig’s answer to the silver precipitation problem is to purge dissolved oxygen and employ nitric acid because silver nitrate is one of the most soluble silver salts. Therefore, as pointed out in the previous Office action, Craig teaches the composition comprising a sufficient amount of nitric acid so as to stabilize the silver fluoride solution such that the silver ion levels do not decrease by more than 5% over a period of up to 24 months at approximately 25oC (Craig, e.g., ¶ 35).
The skilled artisan would have understood that Craig actually teaches that purging dissolved oxygen to prevent oxidation of silver ion and optimizing the concentration of nitric acid are critical.
Applicant’s arguments are directed to the hydronium ion concentration (pH) rather than the contribution of the nitrate ion concentration illuminated by Craig as critical for improved silver ion stability. If the hydronium ion concentration (pH) was critical, the nature of the acid counter ion (conjugate base) would not matter. However, Craig clearly calls out the contribution of nitrate from nitric acid specifically for stabilizing silver ions directly and clearly states the effect is a result of the nitric acid quantity (concentration) in the silver AgF solution.
With this understanding, it is the position of the office that the skilled artisan would have recognized that removing dissolved oxygen and optimizing the concentration of nitric acid are the critical aspects of Craig’s invention rather than the measured pH of the composition. On this basis the skilled artisan would have started optimization of an oxygen purged silver fluoride solution using the concentration of nitric acid explicitly disclosed in Craig which has a pH of less than 1 - rather than limiting optimization to the 5.5-6.0 pH range disclosed in Craig - to improve the retention of silver ion and reduce the precipitation of silver ions from the solution when stored. This point is further illustrated in Craig with respect to stabilization of silver ions with ammonia. Craig clearly teaches ammonia has been used to prevent precipitation of silver ions from solution, not because of ammonia’s effect on pH - which is the opposite of nitric acid’s effect on the pH – but because ammonia forms stable silver complexes (Craig, e.g., 15).
Craig’s insight was to purge the water with nitrogen and use nitric acid which provides a soluble counter ion for silver ions, like fluoride, thereby improving stability of the AgF solution by increasing solubility of silver ions in the solution based on the nitrate concentration offered by dissociation of nitric acid. Craig teaches adding nitric acid in a sufficient quantity (concentration) to substantially stabilize the silver fluoride solution because the concentration of nitric acid directly relates to the nitrate concentration of the silver fluoride solution, not because of nitric acid’s modification of the pH of the silver fluoride solution. Craig clearly teaches the concentration of nitric acid is a result effective parameter the skilled artisan would have modified for improved silver ion solubility.
Craig had already recognized the desire to find an alternative solution to the SDF stabilized by ammonia approach for stabilizing AgF in aqueous environments and had already recognized the technical solution was to purge the water with nitrogen and stabilize the AgF using an effective concentration of nitric acid to reduce precipitation of silver and retain at least 95% of the silver ions in the solution over storage time frames, e.g., at least 9 months or at least 18 months (Craig, e.g., Abstract, ¶ 11-22, and claims, e.g., claims 1-4). See, e.g., Craig, e.g., a problem exists with the use of silver fluoride in that the silver ion level in silver fluoride is reduced over time by the precipitation and adsorption of silver to the container walls (previously solved by using ammonia, Craig, e.g., ¶ 15). Silver ions have the tendency to "clump" once reduced to metallic silver and so the depletion of silver ions from solution can be marked (Criag, e.g., ¶ 13). Thus, the problem of silver fluoride instability was known before the effective filing date of the presently claimed invention.
Any differences between the claimed invention and the prior art may be expected to result in some differences in properties. The issue is whether the properties differ to such an extent that the difference is really unexpected. See MPEP 716.02.
In this case since Craig teaches the nitric acid concentration is a result effective parameter for reducing silver precipitation and maintaining desired silver ion concentration in the solution over storage times, it is not surprising that Applicant observed a difference in silver precipitation when the pH was modified with a concentration of nitric acid effective to provide sufficient nitrate ions to improve stability of silver ions in solution.
While the pH of the solution is modified by nitric acid by corollary, the measured pH (concentration of hydronium) is less significant than the nitrate ion concentration in the nitrogen purged composition provided by nitric acid. This is the crux of Craig’s teachings. Neither the precipitation difference, nor the retained silver ion concentration in the tested solutions are statistically addressed; therefore, it is not clear that the result is statistically significant. Moreover, the amount and type of ingredients, e.g., nitrogen purged water or tap water, of the tested compositions is not reported. Therefore, it is not clear that the results are an apples-to-apples comparison of Craig’s composition and the results do not appear to be commensurate in scope with the claimed invention.
Craig expressly teaches the water may be ultra-purified and may be deoxygenated, such as by being purged with argon gas to remove dissolved oxygen from the water (See Craig, e.g., 85: silver fluoride added to argon purged water), thereby reducing the possibility of (silver ion) oxidation (Craig, e.g., 84-85). It is noted that the results presented by Applicant indicate the precipitate is due to the presence of AgOH (Dec., e.g., 14). Thus, the data proffered does not appear to be a comparison with the closest prior art since the PF-1 compositions do not appear to have been purged of dissolved oxygen, e.g., using argon, to prevent oxidation of silver by dissolved oxygen. Even if, arguendo, the skilled artisan optimized the pH within the explicit range suggested by Craig, e.g., 5.5-6.0, the skilled artisan would have understood that any precipitate caused by oxidation of silver may be remedied by purging the water with argon to remove dissolved oxygen before storage. Since Applicant does not reveal the composition and whether any or all of the PF-1 compositions were purged with nitrogen to remove dissolved oxygen, it cannot be determined if the results presented are, in fact, unexpected due to pH alone.
See MPEP 716.02(c): “Expected beneficial results are evidence of obviousness of a claimed invention, just as unexpected results are evidence of unobviousness thereof.” In re Gershon, 372 F.2d 535, 538, 152 USPQ 602, 604 (CCPA 1967) (resultant decrease of dental enamel solubility accomplished by adding an acidic buffering agent to a fluoride containing dentifrice was expected based on the teaching of the prior art); Ex parte Blanc, 13 USPQ2d 1383 (Bd. Pat. App. & Inter. 1989) (Claims at issue were directed to a process of sterilizing a polyolefinic composition which contains an antioxidant with high-energy radiation. Although evidence was presented in appellant’s specification showing that particular antioxidants are effective, the Board concluded that these beneficial results would have been expected because one of the references taught a claimed antioxidant is very efficient and provides better results compared with other prior art antioxidants.)
Here, the result demonstrated is the expected result of stabilizing a silver fluoride composition using the same solution proposed by Craig to resolve the known problem of silver precipitation, i.e., by optimizing the concentration of nitric acid and the resulting nitrate ion concentration from nitric acid dissociation to reduce silver precipitation thereby stabilizing the concentration of silver ion in the solution over time during storage. Even if the range of 5.5-6.0 showed some precipitation due to silver oxidation, the skilled artisan, reading Craig, expected that purging with nitrogen would reduce the likelihood of silver ion oxidation during storage and that the concentration of nitrate could be modified by optimizing the amount of nitic acid and resulting pH to resolve the known problem of precipitation based on Craig’s explicit teaching that the concentration of nitric acid may be 3-5% (Craig, e.g., claim 5).
Criticality requires an unexpected result. See MPEP 2144.05 III A and MPEP 716.02 I and II.
Here, the result proffered by Applicant is an expected result. Applicant argues that optimizing the pH (using nitric acid) of the silver fluoride solution within the claimed pH range additionally optimizes silver precipitation and maintains the pH above 4 to avoid irritation of tissues. However, since the precipitation of silver is the problem identified in Craig which results in reduction of silver ions levels when stored, and since Craig teaches the solution to this problem is to purge dissolved oxygen from the AgF solution and to optimize the concentration of nitric acid to provide additional silver ion solubility due to the nitrate ions in solution because silver nitrate is one of the most soluble silver salts, Applicant’s result regarding precipitation is the result expected from optimizing the nitric acid concentration so that silver ion levels do not decrease in the solution by more than 5% over a period of at least 9 months at approximately 25°C as reported in Craig. Applicant’s observation of silver oxidation products is also the result expected when dissolved oxygen is not removed from the solutions as directed by Craig. The result of reduced silver precipitation is the same problem Craig had identified and addressed by removing dissolved oxygen and optimizing the nitric acid concentration in the solution. In other words, Craig teaches that removing oxygen and optimizing the concentration of nitric acid will achieve the result of stabilizing the silver fluoride in solution such that the silver ion levels do not decrease by more than 5% over a period of at least 9 months by reducing the precipitation of silver in the composition.
Consequently, the pH range claimed by Applicant represents the optimal concentration of added nitric acid which provides an effective nitrate ion concentration to achieve the expected result of reducing silver precipitation as reported in Craig when the solution contains dissolved oxygen. Generally, differences in concentration or temperature will not support the patentability of subject matter encompassed by the prior art unless there is evidence indicating such concentration or temperature is critical. MPEP 2145.05 II.
The data presented by Applicant appears represent the most effective concentration of nitric acid to provide a stabilizing amount of nitrate ion for a particular silver fluoride composition containing dissolved oxygen (to which the claim is not limited) when the composition has a pH of 4.75 or 5.1. However, this evidence is not sufficient to establish criticality for the claimed pH range over the full scope of the claimed invention at least because the evidence is not commensurate in scope with the pH range of the claimed invention and because the results do not appear to be unexpected.
The declaration states any acid may be used provided it does not form a precipitate with silver ions and that the present invention resides in the acid stabilization of AgF through a critical pH range (Declaration, e.g., 0024). However, this is not found persuasive. There is no evidence of record that other acids would predictably produce the same reduction in silver precipitation as was shown for nitric acid. In this regard, Craig clearly notes silver fluoride and silver nitrate are the most soluble silver salts known (Craig, e.g., ¶ 29). It is not clear from Applicant’s evidence of record that the pH alone is critical. In order to show criticality of the pH alone, evidence showing a number of compositions which have the same pH but structurally distinct acids with a representative number of structurally diverse conjugate bases would be needed to show the same reduction in silver precipitation proffered in the same way as nitric acid irrespective of the nature of the acid. The proffered data is insufficient to establish a clear nexus between the pH of the silver fluoride solution and the reduced silver precipitation observed at least because the result is only shown for the same nitric acid clearly taught by Craig.
The declaration states that a person skilled in the art would read Craig, ¶ 80, to mean that the amount of nitric acid is only to bring the solution down to pH 5.5-6 which is the required/intended pH range of Craig (Declaration, e.g., 29). This statement is directly refuted by the teachings of Craig. It is not found where Craig teaches the amount of acid is only effective to modify the pH in the range between 5.5-6.0. Rather, as enumerated, supra, Craig clearly and unequivocally states the concentration of nitric acid in the solution is effective for improved stability because silver fluoride and silver nitrate are the most soluble silver salts known. Further, Craig does not “require” a pH between 5.5 and 6 at least because the pH range in Craig is “approximate” and because Craig makes no claim that the pH range of 5.5-6 is critical.
Even if, arguendo, the skilled artisan optimized according to pH, the evidentiary reference was cited to show that the concentration of 3-5% explicitly taught by Craig has a pH minimum of less than 1. Therefore, taking the pH range expressly stated and the minimum pH of less than 1 due to the expressly recited concentration of nitric acid, the skilled artisan would clearly and unambiguously understand Craig’s teachings regarding pH are not limited to the range between 5.5 and 6 and instead extend to the range of from less than one to six.
Applicant’s data in Exhibit PF-1 does not reveal the composition of the tested silver fluoride solutions, i.e., ML 160418C and ML160412A and ML160711 and ML160418A. The comparative compositions in the specification are limited to a single concentration of silver fluoride and no composition having a pH within the range suggested by Craig is tested for residual silver content. Therefore, it is not possible to determine which claims, if any, may be commensurate in scope with the results proffered even if they were found to be both statistically and practically significant (MPEP 716.02(b)).
Applicant has argued (Dec., 27): in a salt solution, the pH of the solution will depend on a number of factors including the interaction between the various ions present in a solution, e.g., highly basic fluoride ions have a strong affinity for protons and tend to exist in solution in the form of HF2, therefore tying up protons and affecting the pH of the solution.
This argument is unpersuasive.
The declaration states a freshly made aqueous solution of 38% silver fluoride typically has a pH of 6.2-6.4 (Dec., e.g., 11). Assuming this solution has no other pH modifier, it appears fluoride is not ‘highly basic’ based on Applicant’s own evidence of record because the prepared AgF solution has an acidic pH even when present in an amount of 38 w/v%. This appears to be a contradiction in the declaration which requires further clarification. If the fluoride ion were a highly basic, a high concentration of silver fluoride would be expected to have a neutral or basic pH not an acidic one.
It is acknowledged that ions present in the solution may have an effect on the pH. However, fluoride ions are not highly basic because fluoride is understood to be a weak base by those skilled in the art. See, e.g., Veggini, Journal of Electroanalytical Chemistry, 378, 1994, entire document, e.g., pg. 130, c1.
While HF2 may be present in saturated hydrofluoric acid solutions (Giguere, JACS, 102, 1980, entire document, e.g., pg. 5473, c2 experimental), HF2 concentration remains low because of stoichiometry even in concentrated hydrofluoric acid solutions (Giguere, JACS, 102, 1980, entire document, e.g., pg. 5476, c1). Applicant provides no evidence or rationale supporting the conclusion that HF2 would be present in an amount effective to significantly modify the pH of Craig’s solutions. See In re Robertson, 169 F.3d 743, 745, 49 USPQ2d 1949, 1950-51 (Fed. Cir. 1999) (“To establish inherency, the extrinsic evidence ‘must make clear that the missing descriptive matter is necessarily present in the thing described in the reference, and that it would be so recognized by persons of ordinary skill. Inherency, however, may not be established by probabilities or possibilities. The mere fact that a certain thing may result from a given set of circumstances is not sufficient.”)
Moreover, Craig teaches adding powdered silver fluoride to argon purged water and then adding 3.02-5.03 mL concentrated nitric acid (Craig, e.g., 81) to the solution with additional nitrogen purged water for a total volume of 100mL (Craig, e.g., 85). Craig does not expressly characterize the pH of these solutions but Applicant has not either.
Applicant has argued (Dec., 28): the solution would contain silver ions, fluoride ions, nitrate ions, hydronium ions as well as a reducing agent (which may also have an affinity for protons). Applicant argues the solution pH will depend on the interaction of these ions. Applicant argues that even if nitric acid is added at a concentration of at 5% w/v, the solution pH is unlikely to be and simply cannot be pH 1, since the solution of Craig is also a dental solution, which cannot have a pH that would cause chemical burns to oral tissues.
This argument is unpersuasive.
Initially, it is noted that the statement that the solution will contain a reducing agent is an inaccurate characterization of the express teachings in Craig. The reducing agent in Craig is clearly a separate composition (Craig, e.g., 5). The silver fluoride solution and reducing solution are not stored together. Therefore, the composition of the reducing agent in Craig has no bearing on the pH and stability of the separately stored silver fluoride solution.
The rejection did not assert Craig teaches the composition has a pH of 1, rather, the rejection notes the skilled artisan would have understood that a 5wt% nitric acid solution has a pH of less than 1. The rejection notes that the pH of <1 is a lower limit for a silver fluoride solution containing a 3-5w% concentration of nitric acid. That represents the lowest possible pH Craig’s prepared solutions may have based on the concentration of 5% nitric acid. This establishes the general conditions reported by Craig within which the skilled artisan understood the pH may be modified. This understanding in combination with the 5.5-6.0 pH range in Craig provided the skilled artisan with concentration of nitric acid which has a lower limit of about 1 for the pH. The skilled artisan would have optimized the concentration of nitric acid because the quantity of nitric acid in the silver fluoride composition is an explicitly named result effective parameter useful for stabilizing silver ions in the solution by inhibiting silver precipitation as reported by Craig.
While Applicant has opined that the pH of Craig’s solution simply cannot be pH 1, it is noted that Craig clearly teaches a silver fluoride composition obtained by adding 3.02 mL of a 3% solution of nitric acid to 100 mL of water-based silver fluoride (Craig, e.g., 81). Applicant has provided no data illuminating the pH of this embodiment or a similar 5% nitric acid solution of silver fluoride (Craig, e.g., 82) which would support the contention that Craig’s silver fluoride solutions simply cannot be 1.
Applicant argues that based on the inventors' findings (as seen in the enclosed Declaration and Exhibit), Craig actually teaches a non-functioning pH range, or at least a pH range ineffective for stabilizing AgF in solution over possible storage periods/conditions, and hence cannot provide the product stability required/desired (Dec., e.g., 31).
This argument is unpersuasive.
It is not clear how the skilled artisan would conclude Craig actually teaches a non-functioning pH range based on the current record. The Exhibit PF-1 clearly states compositions having a pH >5 show worse stability when the aqueous solution contains oxygen. This still recognizes they show some stability meaning that while not optimal, this is a functional pH range for some degree of stability.
Craig teaches the silver fluoride solutions are purged with nitrogen to remove dissolved oxygen for the express purpose of preventing oxidation of silver ions in the solution. Since Applicant presents data showing the oxidation of silver ions in solution, e.g., AgOH, it appears that the data in PF-1 is not representative of the compositions found in the teachings of Craig.
Since the skilled artisan would understand that Craig actually teaches an effective pH range of from about 1 to about 6 when dissolved oxygen is removed from the silver fluoride solution, the skilled artisan would have understood that Craig teaches a functioning pH range for stabilizing silver ion in AgF solutions which have no dissolved oxygen so long as the concentration of nitrate ions in the composition is sufficient to reduce precipitation of silver.
Since Applicant’s data appears to be obtained using solutions with dissolved oxygen, the proffered evidence is not a comparison with Craig’s teachings.
Applicant argues that from attempting this non-functioning or ineffective pH range taught by Craig, a person skilled in the art will likely observe precipitation of silver over time and be led to think that acid stabilization of AgF does not work (or does not work effectively), thereby being turned away from the acid stabilization approach.
This argument is unpersuasive.
Craig does not teach a pH dependent stabilization of AgF solutions. Rather, Craig teaches the stabilization of AgF solutions by optimizing the concentration of nitric acid in the composition and removing dissolved oxygen. The improved stability results because there is less oxygen to oxidize the silver ions and because of the solubility benefit offered by the combination of fluoride and nitrate counter ions for silver. The pH of the composition is related to the fact that nitric acid is acidic, but underlying stability is a result of the additional nitrate ion concentration generated by the addition of nitric acid and removal of oxygen to prevent oxidation of silver ions as reported in Craig.
Applicant argues there is no actual experimental data provided in Craig to demonstrate the stability of the water-based silver fluoride solution. Applicant argues it is only in para. [34] and claim 4 of Craig that mere statements, are made asserting that the nitric acid is added in sufficient quantity to substantially stabilize 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. Applicant argues that Craig does not actually provide an enabling disclosure of its claimed invention in terms of comprising "nitric acid to stabilize the water-based silver fluoride solution", let alone an actual AgF solution with measured parameters before and after storage, to confirm that an AgF solution having a specific pH value within Craig's claimed range of pH 5.5-6.0 has the required ion concentrations over a reasonable storage period. Applicant has argued the lack of an actual example of an AgF solution with specific measured stability and pH values also does not provide guidance/motivation for a skilled person to modify the conditions of Craig to arrive at the claimed invention, as the person cannot have confidence from Craig that acid stabilization of AgF would actually work. There is also no teaching or suggestion in Craig to motivate a skilled person to modify the disclosed pH range of 5.5-6.0.
This argument is unpersuasive.
As enumerated previously, Craig clearly teaches the nitric acid concentration may be optimized for improved silver ion stability (Craig, e.g., claims). Craig also teaches silver ions may be stabilized by purging with nitrogen to remove dissolved oxygen (Craig, e.g., claim 9 and 84). Although Applicant has argued Craig does not provide an enabling disclosure of its claimed invention including an actual AgF solution with measured parameters before and after storage to confirm that an AgF solution having a specific pH value within Craig's claimed range of pH 5.5-6.0 has the required ion concentrations over a reasonable storage period, it is noted that Applicant provides no evidence to dispute the enablement of Craig’s disclosure. It is also reiterated that Craig does not teach the pH range of 5.5-6 is critical for silver ion stability and therefore requires no evidence to confirm the pH range of 5.5-6.0 is effective for stability over a reasonable storage period. Absence of evidence in Craig is not, by itself, evidence that Craig lacks enablement. When the reference relied on expressly anticipates or makes obvious all of the elements of the claimed invention, the reference is presumed to be operable. Once such a reference is found, the burden is on applicant to rebut the presumption of operability. See MPEP 2121, I.
Applicant has not shown that silver precipitation would be seen in the pH range of from 5.5-6 even when oxygen is removed from the solution by purging with nitrogen as is clearly taught by Craig.
It is additionally noted that Craig’s disclosure has been granted a patent in the US which presents claims commensurate in scope with the disclosure of Craig WO 2018058199. See US 10610468 B2.
Applicant argues secondary considerations, as noted in the enclosed Inventor Declaration, that the commercial product covered by the presently claimed invention has now been well tested and well received in Australia and overseas markets, including being widely commercialized in the US, the key market for the Applicant entity. Applicant argues the commercial success also confirms that acid stabilization of AgF through the critical pH range claimed in this application is a new, non-obvious, advantageous and reliable technical solution. These secondary considerations separately form a basis for allowing the claims in view of Craig.
This argument is unpersuasive. An applicant who is asserting commercial success to support its contention of nonobviousness bears the burden of proof in establishing commercial success. See MPEP 716.03. There does not appear to be any objective evidence commercial success which is commensurate in scope with the invention as presently claimed. See MPEP 716.03(a).
Claim Rejections - 35 USC § 101
35 U.S.C. 101 reads as follows:
Whoever invents or discovers any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof, may obtain a patent therefor, subject to the conditions and requirements of this title.
Section 33(a) of the America Invents Act reads as follows:
Notwithstanding any other provision of law, no patent may issue on a claim directed to or encompassing a human organism.
Claim 10 is rejected under 35 U.S.C. 101 and section 33(a) of the America Invents Act as being directed to or encompassing a human organism. See also Animals - Patentability, 1077 Off. Gaz. Pat. Office 24 (April 21, 1987) (indicating that human organisms are excluded from the scope of patentable subject matter under 35 U.S.C. 101).
Claim 10 contains the limitation of a composition comprising an aqueous Silver Fluoride solution as defined in Claim 9, the composition further comprising an iodide-salt-containing solution to reduce staining of the carious affected tooth or dentinal tissues after treatment with the aqueous Silver Fluoride solution.
The limitations of the claim encompass the composition of claim 9 applied to the tooth or dentinal tissues. The broadest reasonable interpretation of the limitations in claim 10 encompasses a tooth or dentinal tissues present in a human being to which the composition of claim 9 is applied. Consequently, the scope of claim 10 encompasses a human organism.
Claim Rejections - 35 USC § 112
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claim 10 is rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
It is not clear what conditions must be present to meet the limitations of claim 10. The subject matter may be interpreted such that the composition of claim 9 further comprises an iodide salt. However, claim 10 may also be interpreted such that the composition of claim 9 conditionally requires an iodide salt only after the composition of claim 9 is applied to a carious affected tooth or dentinal tissue.
There is also a lack of antecedent basis for the dentinal tissue in claim 10.
Clarification is required.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102 of this title, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claims 1-3, 6-9, and 11 are rejected under 35 U.S.C. 103 as being unpatentable over Craig, WO 2018058199 A1 as evidenced by Ricca Chemical, 5% (v/v) Nitric Acid, 2024.
Craig teaches silver fluoride solutions for dental caries treatment comprising nitric acid to stabilize the water-based silver fluoride solution (Craig, e.g., Abstract).
Craig teaches the concentration of silver fluoride may be 40% (Craig, e.g., ¶ 9 and 14). This meets the limitation of wherein the quantity of silver fluoride in the solution is no more than 50%.
Craig teaches the composition comprising a sufficient amount of nitric acid so as to stabilize the silver fluoride solution such that the silver ion levels do not decrease by more than 5% over a period of up to 24 months at approximately 25oC (Craig, e.g., ¶ 35).
Craig teaches the composition comprising a sufficient amount of nitric acid to bring the pH of the silver fluoride solution down to approximately 5.5 – 6.0 (Craig, e.g., ¶ 37).
Craig teaches the concentration of silver fluoride ranges from 2% to 75% (Craig, e.g., claim 2).
Craig teaches a composition comprising silver fluoride, water, and 3-5% nitric acid (Craig, e.g., ¶ 80, 81, 82, 85, and claim 5). A 5% nitric acid solution has a pH of less than 1 as evident from Ricca Chemical, 5% (v/v) Nitric Acid, 2024.
Thus, Craig suggests the pH of the silver fluoride solution may range from less than 1 to approximately 6 to stabilize silver ions in the solution.
Craig teaches the addition of acid to the silver fluoride solution unexpectedly increased the longevity of the silver ions and therefore the acid is a stabilizer for silver fluoride solutions (Craig, e.g., 24).
Craig does not expressly teach the pH range of 4.0-5.3.
However, the claimed range is close to the range of 5.5-6.0 stated in Craig.
In addition, Craig expressly teaches the amount of acid makes the silver fluoride solution shelf stable and expressly teaches the acid stabilizes the silver ion.
A prima facie case of obviousness exists where the claimed ranges and prior art ranges do not overlap but are close enough that one skilled in the art would have expected them to have the same properties. Titanium Metals Corp. of America v. Banner, 778 F.2d 775, 227 USPQ 773 (Fed. Cir. 1985). MPEP 2144.05. Here the claimed range of from 4.0-5.3 is very close to the prior art range of from approximately 5.5-6.0 taught by Craig. In addition, Craig teaches the acid stabilizes the silver ions in the silver fluoride solution rendering the solution storage stable to the same extent demonstrated by the presently claimed invention. Thus, even if the pH range explicitly stated in Craig does not expressly overlap with the claimed range, the ranges are close and have the same properties expected from the prior art composition. Any difference in pH does not appear to be critical to achieve the stability properties expected from Craig’s teachings.
Further, Craig’s teachings with respect to amount of acid and pH is not limited to the explicit range identified above. In light of Craig teaching that the nitric acid concentration may be 5%, and the fact that a 5% nitric acid solution is expected to have a pH of less than 1, the skilled artisan would have understood the teachings of Craig as suggesting a silver fluoride solution having a pH of from less than 1 to 6 for improved stability. The claimed range is entirely within the range suggested by Craig as evidenced by Ricca Chemical, 5% (v/v) Nitric Acid, 2024.
In the case where the claimed ranges “overlap or lie inside ranges disclosed by the prior art” a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990). MPEP 2144.05. Here the claimed range is entirely within the full range suggested by Craig and the composition as claimed appears to have the same stability properties expected from the teachings of Craig.
It would have been obvious before the effective filing date of t