Stannous Pyrophosphate Stabilization in Oral Care
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Solution Overview
Problem
Stannous ion sources, particularly stannous pyrophosphate, face stability issues in aqueous oral care compositions due to hydrolysis and oxidation, leading to reduced efficacy in caries prevention and malodor reduction, and the formation of potentially toxic species when combined with nitrate ions, making it challenging to formulate effective high-water oral care products.
Innovation Solution
Combining stannous pyrophosphate with nitric acid or soluble nitrate salts and alkali metal polyphosphates in high-water compositions, such as those containing potassium nitrate and tetrasodium pyrophosphate, stabilizes stannous ions, maintaining their solubility and therapeutic effectiveness while preventing the formation of toxic species.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stannous pyrophosphate is used in high-water oral care compositions, then therapeutic effectiveness for caries prevention and malodor reduction is improved, but stability is worsened due to hydrolysis and oxidation
Solution Approach 1:
The patent introduces alkaline earth metal ions (such as calcium or magnesium ions) as intermediary substances that complex with stannous ions to form stable complexes. This intermediary complexation prevents direct hydrolysis and oxidation of stannous ions while maintaining their therapeutic availability, thereby resolving the contradiction between stability and effectiveness in high-water compositions
Solution Approach 2:
The patent creates a composite ionic system where stannous pyrophosphate coexists with alkaline earth metal salts in aqueous solution. This composite formulation allows the stannous ions to be stabilized through interaction with the alkaline earth metal ions, enabling both stability and therapeutic effectiveness to be achieved simultaneously in high-water compositions
2Reliability
If stannous ions and nitrate ions are combined in aqueous compositions, then malodor reduction capability is improved, but harmful factors are worsened due to formation of toxic species
Solution Approach 1:
The patent uses alkaline earth metal ions as intermediary substances that complex with stannous ions, thereby reducing the direct reducing power of free stannous ions. This intermediary complexation allows nitrate ions to be present without being reduced to toxic nitrite or nitrosamines, while the complexed stannous ions retain their ability to bind volatile sulfur compounds for malodor reduction
Solution Approach 2:
The patent converts the potentially harmful interaction between stannous ions and nitrate ions into a beneficial system by using alkaline earth metal ions to modulate the reactivity. The controlled complexation allows the formulation to include both stannous pyrophosphate and nitrate salts, achieving enhanced malodor reduction through multiple mechanisms while preventing toxic species formation
3Ease of operation
If water content is increased in oral care compositions, then ease of operation and patient comfort are improved, but stability is worsened due to accelerated hydrolysis
Solution Approach 1:
The patent introduces alkaline earth metal ions as protective intermediaries that form stable complexes with stannous ions. This complexation protects stannous ions from water-mediated hydrolysis and oxidation, enabling the formulation to maintain high water content for patient comfort while preventing stability issues through the intermediary protective effect
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This combination achieves stable and soluble stannous ion concentrations, enhancing their availability for reducing volatile sulfur compounds and improving the aesthetic clarity of toothpaste and gel compositions, while maintaining therapeutic benefits and safety.
Implementation Method 1
Stannous salts readily hydrolyze at a pH above 4, resulting in precipitation from solution
Implementation Method 2
stannous pyrophosphate...is at high risk for oxidation to the Sn (IV) oxidation state
Implementation Method 3
Metal ions such as Sn and Zn are typically used to treat oral malodor owing to their affinity for sulfur in VSCs
Implementation Method 4
Metal ions such as Sn and Zn are typically used to treat oral malodor owing to their affinity for sulfur in VSCs
Data Source
AI summary
This application relates to novel aqueous oral care compositions useful for combining and delivering incompatible stannous pyrophosphate and potassium salts in a high-water composition, for example, to provide effective caries prevention, protection against dental erosion, relief from dental hypersensitivity, and to treat or reduce malodor. The compositions comprise stannous pyrophosphate, nitric acid or a water-soluble nitrate salt, a water-soluble alkali metal polyphosphate and more than 10% water, by weight of the composition.