Glass Ionomer Cement Kit Segmentation for Mixability
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Solution Overview
Problem
Glass ionomer cements used in dental applications face challenges such as brittleness, low physical-mechanical properties, and difficulties in mixing due to high viscosity, which affect their flexural and compressive strength, and storage stability.
Innovation Solution
A kit of parts comprising a Powder Part with an acid-reactive inorganic filler and a Liquid Part containing water, polyacid, and non-aggregated nano-sized particles, optimized to achieve a low viscosity paste with high filler content, allowing for easier mixing and improved mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the amount of polycarboxylic acid is increased to improve flexural strength, then the flexural strength is improved, but the liquid part becomes too viscous making it nearly impossible to adequately mix the powder and liquid component
Solution Approach 1:
The patent divides the polycarboxylic acid into two separate components: a liquid part containing the polycarboxylic acid and a powder part containing the acid-reactive filler. This segmentation allows the liquid part to have sufficient polyacid content for strength while maintaining manageable viscosity for mixing, as the polyacid concentration can be optimized independently in the liquid phase.
Solution Approach 2:
The patent optimizes the concentration of polycarboxylic acid in the liquid part to a specific range (5-20 wt%) and controls the molecular weight and composition parameters to achieve the desired balance between flexural strength and viscosity. By adjusting these parameters, the liquid part remains mixable while providing sufficient acid for strong bonding.
2Strength
If the amount of filler is increased to achieve certain physical mechanical properties, then the flexural and compressive strength are improved, but the composition becomes more viscous resulting in difficulties during mixing
Solution Approach 1:
The patent separates the filler into a dedicated powder part, distinct from the liquid part containing the polyacid. This allows the filler content in the powder part to be increased to achieve high strength properties without directly increasing the viscosity of the liquid part, maintaining good mixability while achieving the desired mechanical properties in the final composite.
Solution Approach 2:
The patent creates a composite system where acid-reactive filler particles are combined with polycarboxylic acid matrix. The filler provides mechanical strength while the polyacid matrix provides binding and adhesion. This composite structure allows high filler loading for strength while the liquid polyacid ensures proper workability and mixing characteristics.
3Ease of operation
If polycarboxylic acid is placed in dry form into the powder component to improve mixability, then the mixability is improved, but the storage stability is negatively affected as humidity may migrate into the powder component causing premature glass ionomer reaction
Solution Approach 1:
The patent maintains the segmentation of keeping polycarboxylic acid in the liquid part and acid-reactive filler in the powder part, preventing premature contact between reactive components during storage. This separation ensures storage stability by avoiding humidity-induced premature reactions in the powder, while still achieving good mixability when the components are combined during use.
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 solution enables a glass ionomer cement with enhanced handling properties, improved mechanical strengths, and storage stability, facilitating easier mixing and application in dental procedures.
Implementation Method 1
Glass ionomer cements are reacted by mixing a powder part with a liquid part. The powder component typically comprises as essential or important component an acid-reactive filler (e.g. a fluoro alumino silicate glass). The liquid component typically comprises as essential components water, polycarboxylic acid
Implementation Method 2
The liquid component typically comprises as essential components water, polycarboxylic acid and a complexing or chelating agent (e.g. tartaric acid) for adjusting the setting properties
Implementation Method 3
A kit of parts comprising a Powder Part with an acid-reactive inorganic filler and a Liquid Part containing water, polyacid, and non-aggregated nano-sized particles, optimized to achieve a low viscosity paste with high filler content
Data Source
AI summary
The invention relates to a kit of parts for preparing a glass ionomer composition for dental use, the kit of parts comprising a Powder Part P and a Liquid Part L, Powder Part P comprising: acid-reactive inorganic filler, Liquid Part L comprising: water, complexing agent, polyacid, either the Powder Part P or the Liquid Part L or the Powder Part P and the Liquid Part L comprising non-aggregated nano-sized particles based on silica or alumina, the composition obtained by combining the components of Powder Part P and Liquid Part L before hardening comprising the components in the following amounts: non-aggregated nano-sized particles: from 0.1 to 15 wt.-%, acid-reactive filler in an amount from 50 to 75 wt.-%, polyacid: 7 to 20 wt.-%, complexing agent: 0.5 to 3 wt.-%, water: 5 to 18 wt.-%, wt.-% with respect to the weight of the whole composition.