Stannous Ion Stabilization in Aqueous Oral Care via Polyphosphate Complexation
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Solution Overview
Problem
Stannous ion sources in oral care compositions are unstable in aqueous solutions due to hydrolysis, limiting their therapeutic benefits, and existing solutions either restrict water content or use costly dual-phase systems, which are difficult to formulate and package effectively.
Innovation Solution
Combining stannous pyrophosphate, nitric acid or soluble nitrate salts with polyphosphate sources having three or more phosphate moieties, such as hexametaphosphate or phytic acid, in high-water compositions to stabilize stannous ions, allowing for effective caries prevention, dental erosion protection, and relief from hypersensitivity and malodor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stannous ion sources are used in aqueous oral care compositions, then therapeutic benefits (caries prevention, gingivitis reduction) are improved, but stability of the composition deteriorates due to hydrolysis and precipitation
Solution Approach 1:
The patent introduces nitrate ions and polyphosphate ions as intermediary substances that mediate between stannous ions and water. These intermediaries form soluble complexes with stannous ions, preventing direct hydrolysis and precipitation. The nitrate and polyphosphate act as protective mediators that maintain stannous ion stability in aqueous environments without compromising therapeutic efficacy.
Solution Approach 2:
The invention creates a composite ionic system where stannous ions are combined with nitrate ions and polyphosphate ions in specific ratios. This composite approach forms a stable multi-ionic complex that maintains the therapeutic properties of stannous ions while gaining the stability benefits of the nitrate-polyphosphate system. The composite material strategy allows simultaneous achievement of both stability and therapeutic benefit.
2Stability of the object's composition
If water content is limited to maintain stannous ion stability, then stability is improved, but ease of manufacture and rheological properties deteriorate
Solution Approach 1:
The patent fundamentally changes the chemical parameters of the system by introducing nitrate and polyphosphate ions. This parameter change allows the composition to maintain stannous ion stability at high water contents (above 10% w/w), eliminating the need to restrict water content. The parameter change transforms the stability-waterness trade-off into a win-win situation where both stability and ease of manufacture are improved.
3Stability of the object's composition
If dual-phase systems are used to stabilize stannous ions, then stability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The invention merges multiple stabilizing functions into a single-phase aqueous system. Instead of using separate phases as in traditional dual-phase systems, the patent combines stannous ions, nitrate ions, and polyphosphate ions into one homogeneous phase. This merging eliminates the complexity of phase separation, packaging, and manufacturing while maintaining stannous ion stability through the synergistic interaction of the ionic components.
4Stability of the object's composition
If polyphosphate sources with three or more phosphate moieties are combined with stannous ions, then solubility and stability are improved, but formulation complexity increases
Solution Approach 1:
The patent specifies optimal concentration ranges for polyphosphate sources (0.1-5% w/w) and defines the structural parameter of having three or more phosphate moieties. By establishing these clear parameter guidelines, the invention reduces formulation complexity while achieving the desired solubility and stability improvements. The parameter specifications provide a straightforward framework for formulation development.
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
The combination achieves stable and soluble stannous ions in high-water oral care compositions, maintaining therapeutic efficacy while providing clear and translucent toothpaste aesthetics, and is more cost-effective and easier to formulate than dual-phase systems.
Implementation Method 1
a combination of stannous pyrophosphate, nitric acid or a soluble nitrate salt, and one or more polyphosphate sources, wherein the polyphosphate source comprises three or more phosphate moieties or units... results in stability of stannous, fluoride and nitrate in solution
Implementation Method 2
stannous salts readily hydrolyze at a pH above 4, resulting in precipitation from solution... the combination... results in stability of stannous, fluoride and nitrate in solution
Data Source
AI summary
This application relates to novel aqueous oral care compositions useful for combining and delivering incompatible stannous fluoride, and/or stannous chloride, and/or stannous pyrophosphate and potassium salts, with a polyphosphate source, wherein the polyphosphate source comprises three or more phosphate moieties or units, 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.