Low-Surface-Area Silica Particles for Stannous-Compatible Dentifrice
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Solution Overview
Problem
Existing dentifrice compositions containing stannous fluoride face reduced effectiveness due to interactions with silica materials, particularly precipitated silica, which can diminish the availability and therapeutic efficacy of stannous ions.
Innovation Solution
Development of surface area reduced silica particles with specific characteristics, including BET surface area of 0.1 to 7 m²/g, pack density of 35 to 55 lb/ft³, and total mercury intrusion pore volume of 0.4 to 1.2 cc/g, ensuring high stannous compatibility and maintaining appropriate abrasive safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If precipitated silica is used in dentifrice formulations, then abrasive function is provided, but stannous ion availability and therapeutic efficacy are diminished
Solution Approach 1:
The patent applies parameter changes by modifying the surface area of silica particles from conventional high surface area (typically 50-500 m²/g) to reduced surface area (0.1 to 10 m²/g, preferably 0.5 to 5 m²/g). This parameter change reduces the surface area available for stannous ion interaction while maintaining abrasive function, thereby improving stannous ion availability and therapeutic efficacy.
Solution Approach 2:
The patent utilizes porous silica materials with controlled pore structures. By creating silica particles with specific pore characteristics (low surface area but controlled porosity), the invention reduces harmful surface interactions with stannous ions while maintaining the necessary abrasive properties for dental applications.
2Reliability
If silica surface area is reduced to improve stannous compatibility, then stannous ion availability increases, but abrasive safety may be compromised
Solution Approach 1:
The patent simultaneously optimizes multiple parameters: surface area (reduced to 0.1-10 m²/g), pore volume (controlled at 0.4-1.2 cc/g), and pack density (35-55 lb/ft³). This multi-parameter optimization ensures that stannous ion availability is improved while abrasive safety is maintained through controlled pore structure and particle density.
Solution Approach 2:
The patent creates a composite structure within the silica particles by controlling the pore volume and surface area relationship. The resulting material has a composite character combining low surface area (for stannous compatibility) with controlled internal porosity (for maintaining abrasive function and safety).
Data Source
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AI summary
A dentifrice composition containing an abrasive and a stannous ion source. The abrasive can contain precipitated silica particles where the extractable stannous ions after 30 days at 40C is greater than about 75% of the initial extractable stannous ion concentration.