APPLICATION OF GERSHON

• Decision Date: 16 February 1967
• Docket Number: Patent Appeal No. 7722.
• Citation: 372 F.2d 535,152 USPQ 602
• Parties: Application of Sol D. GERSHON, Melvin A. Goldberg and Oscar W. Neiditch.
• Court: U.S. Court of Customs and Patent Appeals (CCPA)

152 USPQ 602, 372 F.2d 535 (1967)

Application of Sol D. GERSHON, Melvin A. Goldberg and Oscar W. Neiditch.

Patent Appeal No. 7722.

United States Court of Customs and Patent Appeals.

February 16, 1967.

Eben M. Graves, Allen G. Weise, New York City, for appellants.

Joseph Schimmel, Washington, D. C. (Jack E. Armore, Washington, D. C., of counsel), for Commissioner of Patents.

Before WORLEY, Chief Judge, RICH, SMITH, and ALMOND, Judges, and Judge WILLIAM H. KIRKPATRICK.^*

ALMOND, Judge.

This is an appeal from the decision of the Patent Office Board of Appeals affirming final rejection of claims 1 to 14 of application serial No. 209,279, filed July 12, 1962, entitled "Fluoride Dentifrice."

The invention relates to a buffered fluoride dentifrice, in the form of either tooth paste or tooth power, comprising at least one fluoride-compatible polishing agent; a water-soluble, ionizable, anti-caries fluoride; a buffering agent in an amount sufficient to maintain a pH from 5 to 6 for the dentifrice in saliva; and optionally, a germicide.

Claim 1 is illustrative of the invention and reads as follows:

1. A dentifrice comprising from about 7% to about 80% by weight of at least one fluoride-compatible polishing agent; from about 0.01% to about 2% by weight of a water-soluble, ionizable, anti-caries fluoride, calculated as fluoride ion; and from about 0.02% to about 10% by weight of a buffering agent, said buffering agent being present in an amount within the said range sufficient to impart a pH from 5 to 6 to the dentifrice in saliva.

The references relied on are:

                  Gershon et al
                    (Gershon)                  2,723,217                 November 8, 1955
                  Gershon
                    (Australia)                  207,489                   April 17, 1957
                  Jordan et al., Journal of the American Dental Association, Vol. 54, No
                      5, pp. 589-594, May 1957
                  Gershon et al., Drug and Cosmetic Industry, Vol. 82, No. 2, pp. 160, 161
                      and 251-257, February 1958
                  Chemical Abstracts, Vol. 53, entry 3367e, 1959.
                

The Gershon American patent is relied on as a secondary reference disclosing the use of a bactericide, tyrothricin, in a dentifrice. The reference is also of interest in that it discloses the desirability of buffering "to keep the pH of the dentifrice within the desired range, approximating the neutral point, and preferably within the range from 6 to 7." Thus the patent also teaches buffering to maintain the dentifrice pH within the slightly acidic range.

Chemical Abstracts discloses the known bactericidal activity of hexachlorophene, the preferred bactericide or germicide used in appellants' dentifrices. The Patent Office position is that the substitution of hexachlorophene for the bactericide tyrothricin in a dentifrice would be obvious, in view of the aforesaid secondary references. In the absence of any evidence or substantial argument to the contrary, we agree with this position. We also note that appellants' brief contains the following statement:

Prior to appellants\' invention it was known that dentifrices containing a water-soluble, ionizable, anti-caries fluoride and a fluoride-compatible polishing agent decrease the solubility of dental enamel. This makes the enamel more resistant to the acid attack which occurs in the mouth and thereby reduces the incidence of dental caries. * * *

Thus the issue in this case is whether, in a dentifrice comprising agent, a fluoride and a germicide, it would have been obvious under 35 USC 103 to incorporate a buffering agent in an amount sufficient to maintain the pH for the claimed composition in the range from 5 to 6 in saliva.

On this issue the Gershon Australian patent, which is primarily directed to a dentifrice composition comprising a water-soluble fluoride and a mixture of polishing agents, is inconclusive. The reference discloses buffering "the compositions to within the desired pH range, which is from about pH 5.7 to about pH 7.5." The Patent Office tribunals take the position that a buffered dentifrice having a pH of 5.7 as conventionally measured in water would have only a slightly higher pH, still within the claimed weakly acidic range of 5 to 6, in the presence of weakly alkaline saliva in the mouth. If the Patent Office may rely on the pH of 5.7 at one extreme of the desired range, we think it is equally fair for appellants to rely on the pH of 7.5 at the other extreme of the range. From a realistic point of view, one of ordinary skill in the art would attach no more special significance to the acidic pH of 5.7 than to the slightly alkaline pH of 7.5. Consequently, we consider this reference to be equally as persuasive of the unobviousness of buffering to maintain the claimed slightly acidic pH range of 5 to 6, and we accord no weight to this inconclusive reference.

The Jordan article contains the pertinent disclosure that, in an abrasive-compatible stannous fluoride dentifrice, "Laboratory evidence indicated that a pH of around 5.0 was most likely to be suitable from the standpoints of stability and effectiveness of stannous fluoride but that this degree of acidity in a control dentifrice (without stannous fluoride) could introduce a real danger to dental enamel under usage conditions." Thus the references considered so far, especially the Jordan publication and the Gershon American patent, indicate the desirability in a dentifrice of a weakly acidic pH ranging from 5 or 6 up to the neutral point (7) and the possibly dangerous effect on dental enamel of a strongly acidic...