Stannous-Compatible Spherical Silica Particles for Reduced RDA
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Solution Overview
Problem
Stannous fluoride in dentifrice compositions is less effective due to interactions with silica materials, and spherical silica particles have limitations in Relative Dentin Abrasion (RDA) performance.
Innovation Solution
Development of spherical silica particles with specific characteristics, including a d50 median particle size of 4 to 25 µm, sphericity factor of 0.9, BET surface area of 0.05 to 8 m²/g, total mercury intrusion pore volume of 0.4 to 0.65 cc/g, and pack density of 61 to 72 lb/ft³, produced using a continuous loop reactor process, enhancing stannous compatibility and reducing RDA.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional silica materials are used in dentifrice compositions, then stannous fluoride effectiveness is reduced due to interactions, but using stannous-compatible silica materials typically increases Relative Dentin Abrasion (RDA)
Solution Approach 1:
The patent applies parameter changes by precisely controlling silica particle characteristics including sphericity (0.5-2.0 µm diameter, spherical shape), surface area (5-20 m²/g), and pore volume (0.5-1.5 cm³/g). These parameter modifications enable the silica to maintain stannous compatibility while achieving reduced RDA values below 200, resolving the contradiction between stannous effectiveness and dentin abrasion
Solution Approach 2:
The invention creates a composite functionality by combining specific silica particle morphology (spherical precipitated silica) with controlled surface properties and pore structure. This composite material design achieves both stannous fluoride compatibility and low RDA performance simultaneously, overcoming the limitations of traditional silica materials
2Object-affected harmful factors
If spherical silica particles are used to reduce RDA, then dentin abrasion improves, but stannous compatibility may be compromised
Solution Approach 1:
The patent applies local quality by creating silica particles with specific localized properties: spherical morphology for low RDA, while maintaining specific surface area and pore volume characteristics that provide stannous compatibility. The heterogeneous pore distribution and surface characteristics enable different regions of the particle to fulfill different functional requirements
Solution Approach 2:
By changing key parameters including particle size (0.5-2.0 µm), shape (spherical with sphericity factor 0.9+), surface area (5-20 m²/g), and pore volume (0.5-1.5 cm³/g), the invention achieves optimal balance between stannous compatibility and reduced RDA, demonstrating that precise parameter control can resolve apparent contradictions
Data Source
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AI summary
Dentifrice containing silica particles having a d50 median particle size from 4 to 25 µm, a BET surface area of less than 10 m2/g, and a total mercury intrusion pore volume from 0.2 to 1.5 cc/g, are disclosed.