Dual-Phase Stannous Oral Care Composition Stability
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Solution Overview
Problem
Stannous salts like stannous fluoride in oral care compositions are unstable, tend to stain teeth, and are not compatible with sodium tripolyphosphate, leading to undesirable intermediates and unpleasant taste, which limits their long-term stability and efficacy in combating plaque and tooth discoloration.
Innovation Solution
A dual-phase oral care composition with stannous salt and sodium tripolyphosphate physically separated in two aqueous mixtures, blended just before use to minimize stannous tripolyphosphate ionic intermediate formation, incorporating a methylvinyl ether-maleic anhydride copolymer to maintain stability and reduce staining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stannous salt and sodium tripolyphosphate are combined in the same phase, then the composition provides both anti-plaque and anti-tartar benefits, but the combination leads to formation of stannous tripolyphosphate intermediates and reduces long-term stability
Solution Approach 1:
The composition is divided into two distinct phases: a first phase containing stannous salt and a second phase containing sodium tripolyphosphate. This segmentation prevents direct contact between the two incompatible ingredients during storage, eliminating the formation of stannous tripolyphosphate intermediates while maintaining both anti-plaque and anti-tartar functionalities. The phases are kept separate until application when they are mixed together.
2Reliability
If stannous salt is used in oral care composition, then plaque prevention is improved, but the composition becomes unstable and produces unpleasant taste and astringency
Solution Approach 1:
The stannous salt is isolated in a separate first phase from other composition components, including flavoring agents and sweeteners in the second phase. This physical separation prevents stannous salt from interacting with taste-sensitive components, reducing astringency and unpleasant taste while preserving its anti-plaque efficacy. The phases are combined only during application.
3Reliability
If stannous salt and sodium tripolyphosphate are kept in separate phases, then long-term stability is improved and intermediate formation is reduced, but the device complexity increases
Solution Approach 1:
Two separately formulated phases are combined into a single oral care composition product. The first phase contains stannous salt in a first vehicle, and the second phase contains sodium tripolyphosphate in a second vehicle with different pH and composition characteristics. This merging allows both phases to coexist in one product while maintaining their individual stability profiles, achieving long-term stability without requiring completely separate products.
Data Source
AI summary
Oral care compositions containing a stannous salt and sodium tripolyphosphate are provided where stannous tripolyphosphate ionic intermediates comprise less than about 1% of the compositions. Tetrasodium pyrophosphate, a methylvinyl ether-maleic anhydride copolymer and/or a silica oral polishing agent may be added for further efficacy. In a single phase blend, the oral care composition may be effectively limited to comprise less than about 10% water. In a dual-phase blend, a mixture having the stannous salt in a first phase and the sodium tripolyphosphate in a second phase may be generated from a dual chamber storage tube (with each phase provided from a separate chamber) immediately prior to dental care usage.