Paste/Paste Glass Ionomer Cement Kit
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Solution Overview
Problem
Conventional glass ionomer cements are challenging to mix manually due to their powder/liquid system, often resulting in incorrect ratios and reduced mechanical properties, which can affect long-term performance and lead to product complaints.
Innovation Solution
A paste/paste system is developed, comprising Paste A with water and acid-reactive inorganic filler, and Paste B with polyacid and non-acid reactive filler, using phyllo silicates to facilitate easy mixing and storage stability, allowing for the use of a static mixing device and improved mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a powder/liquid system is used for glass ionomer cement, then the cement can be provided in a traditional format, but manual mixing becomes challenging and requires exhausting protocols to obtain a homogeneous mixture free of powder agglomerates and air inclusions
Solution Approach 1:
The patent transforms the traditional powder/liquid system into a paste/paste system by changing the physical state parameters of both components. Paste A converts glass powder to a paste by adding water and a thickening agent, while Paste B converts the liquid polyacid to a paste by adding filler and thickening agent. This parameter change fundamentally improves mixing ease and eliminates the problems associated with manual powder/liquid mixing.
Solution Approach 2:
The invention creates composite paste materials by combining multiple components in each paste. Paste A is a composite of glass powder, water, and thickening agent, while Paste B is a composite of polyacid, filler, and thickening agent. These composite structures provide the rheological properties necessary for easy mixing while maintaining the chemical reactivity required for cement formation.
2Ease of operation
If hand mixing of powder and liquid is performed, then the practitioner can mix the components, but the mixture viscosity increases and requires excess liquid to make mixing convenient, resulting in lower mechanical properties
Solution Approach 1:
The patent changes the viscosity parameter of both components before mixing by incorporating thickening agents in each paste. This pre-adjustment of rheological parameters allows the mixed cement to achieve optimal consistency without requiring excess liquid, thereby maintaining the recommended powder/liquid ratio and preserving mechanical properties.
Solution Approach 2:
The thickening agents are added to each paste separately before mixing, performing the viscosity adjustment action in advance. This preliminary action ensures that when the pastes are mixed, the resulting cement has the desired consistency without requiring additional liquid, thus maintaining strength properties.
3Ease of operation
If water is added to glass powder to transform it into a paste, then the cement becomes easier to mix, but the paste becomes rheopectic which is unfavorable for mixing purposes
Solution Approach 1:
The patent introduces a thickening agent as an intermediary substance between water and glass powder. This thickening agent mediates the interaction by providing controlled thickening without inducing rheopectic behavior, allowing the paste to remain mixable while achieving the desired consistency.
Solution Approach 2:
The thickening agent changes the rheological parameters of the glass powder paste, specifically adjusting the viscosity and flow characteristics. This parameter change allows the paste to maintain stability and remain favorable for mixing while still providing the desired paste formability.
4Ease of operation
If non-reactive filler is added to the liquid part, then the paste consistency is improved, but some fillers slowly react with polyacids resulting in insufficient shelf-life due to increased viscosity over time
Solution Approach 1:
The patent uses a thickening agent in Paste B that provides the necessary paste consistency but is designed to be chemically inert toward polyacids. This allows the filler to serve its thickening function without compromising shelf-life through unwanted chemical reactions that would increase viscosity over time.
Solution Approach 2:
The thickening agent changes the viscosity parameter of Paste B without initiating chemical reactions with the polyacid. This parameter change improves paste consistency while maintaining chemical stability and adequate shelf-life by selecting a thickening mechanism that does not involve acid-reactive processes.
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 paste/paste system enables easy mixing at high shear rates, maintains adequate mechanical properties after hardening, and is storage stable, with superior compressive strength compared to traditional systems.
Implementation Method 1
using phyllo silicates to facilitate easy mixing and storage stability
Implementation Method 2
After mixing, the polyacid acid is neutralized by the alkaline glass powder. In the process of neutralization, ions such as Ca2+ are released
Data Source
AI summary
The invention relates to a kit of parts for preparing a glass ionomer composition for dental use, the kit comprising a Paste A and a Paste B, Paste A comprising water, acid-reactive inorganic filler A, phyllo silicate(s), Paste B comprising water, polyacid, non acid-reactive filler B, optionally chelating agent. The invention also relates to a hardenable composition obtainable by combining the pastes of the kit or parts and to the use of such a composition as or for preparing a dental cement, dental filling material, dental core build up material or dental root channel filling material.