Writing in its international patent, Colgate-Palmolive said it had developed the “novel black translucent oral care composition” by combining stannous fluoride or stannous chloride with potassium salts – two traditionally incompatible ingredients – into a single charcoal composition. The blend, it said, offered stable and effective protection against caries and dental erosion as well as relief from dental hypersensitivity. The formulation could be made into toothpaste or tooth gel formats.
“Oral care compositions which contain stannous ion sources exhibit excellent clinical benefits, particularly in the reduction of gingivitis,” the company wrote in its patent filing. But whilst stannous fluoride and stannous chloride had long been used in clinical dentistry, both were unstable in water – typically overcome with lower water content or dual-phase systems.
However, both strategies had “drawbacks”, Colgate-Palmolive, because low water oral care compositions were difficult to formulate with desired rheological properties and dual-phase options were more expensive to manufacture. “Thus, it is preferable to formulate a high-water composition which uses an alternative means to maintain stable, efficacious stannous ion concentrations,” it said.
The activated charcoal toothpaste trend
Colgate-Palmolive said activated charcoal had been a recent trend that had become increasingly popular amongst consumers in the toothpaste category, offering numerous benefits such as the absorption of sources of malodour and prevention of bacterial growth and plaque formation. Activated charcoal, it said, had also been used in formulations to offer stain-fighting, anti-caries and whitening benefits.
However, alongside interest in charcoal-based pastes, consumers were also increasingly attracted to transparent toothpastes – already common on the market in colours such as red, green and blue. By contrast, charcoal pastes thus far had remained “black or very dark brown in colour and completely opaque” because they were difficult to formulate into a translucent colour.
“It would be highly desirable to provide a translucent black dentifrice, especially one that provides stable stannous, fluoride and potassium together,” Colgate-Palmolive wrote.
Stable and efficacious blend
The company said it had made the “surprising discovery” that a combination of stannous fluoride or stannous chloride, nitric acid or a soluble nitrate salt, and an alkali metal polyphosphate salt remained stable in high-water oral care compositions.
Water was included at more than 10% by weight of the composition, it said, and activated charcoal at 0.001-0.025%, ideally below 0.008%.
In addition, Colgate-Palmolive said: “Without being bound by theory, it is believed that there could be a synergistic interaction between then charcoal and the stannous salts, especially stannous pyrophosphate, that would provide improved odour control compared to existing oral care compositions.”
WIPO International Patent No. WO/2023/028081
Published on: March 2, 2023. Filed on: August 23, 2022.
Title: “Oral care compositions and methods”
Inventor: Colgate-Palmolive – C. Myers and G. Govindaraju