Two-Part Dental Cement Composition for Shelf-Life Stability
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Solution Overview
Problem
Existing two-part glass ionomer cements face issues such as mechanical strength variability, unsatisfactory working and setting times, multiple dispensing and mixing steps, and shelf life stability due to undesirable self-cure from the pairing of reducing and oxidizing agents, leading to instability and inefficiency in dental applications.
Innovation Solution
Separating the reducing agent and oxidizing agent into different parts, with the reducing agent paired with a strong acid in a second part to form a latent catalyst, and excluding water from the first part, resulting in a more stable two-part cement system with enhanced shelf life and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reducting agent is paired with an oxidizing agent in one part of the cement system, then the cement can undergo setting reaction, but undesirable self-cure occurs over storage periods leading to reduced shelf life stability
Solution Approach 1:
The patent divides the cement system into two separate parts: Part A containing the oxidizing agent and Part B containing the reducing agent. This segmentation prevents premature interaction between the reducting and oxidizing agents during storage, eliminating self-cure issues while maintaining the ability to undergo setting reaction when mixed. The physical separation of these reactive components directly resolves the contradiction between reliability and composition stability.
Solution Approach 2:
The patent extracts the reducing agent from Part A and places it in Part B, removing the source of premature reaction from the oxidizing agent-containing Part A. This extraction eliminates the harmful self-cure effect while preserving the essential setting reaction capability when the two parts are combined, thereby improving shelf life stability without compromising the cement's functional reliability.
2Ease of operation
If multiple dispensing and mixing steps are used, then the cement can be properly applied, but the procedure becomes more complex and time-consuming
Solution Approach 1:
The patent combines the dispensing and mixing functions into a single integrated step by providing the cement as two parts that are dispensed and mixed simultaneously in the oral cavity. This eliminates the need for separate dispensing and mixing steps, reducing procedural complexity while maintaining proper application. The two-part system merges what would otherwise be distinct operations into one efficient process.
3Productivity
If the setting reaction occurs quickly, then the procedure is more efficient, but insufficient time is available for mixing and application
Solution Approach 1:
The patent modifies the reaction kinetics parameters by selecting specific oxidizing agents and reducing agents that provide an optimal setting time window. The oxidizing agent (such as potassium persulfate or ammonium persulfate) and reducing agent (such as tertiary amine) are chosen to achieve a balanced setting rate that allows sufficient working time for mixing and application while still providing efficient procedure completion. This parameter optimization resolves the contradiction between productivity and time loss.
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 new composition achieves improved stability and shelf life, even with handling errors, while maintaining the benefits of known two-part cement compositions, ensuring reliable setting characteristics for dental procedures.
Implementation Method 1
the first part including (i) liquid (at room temperature) monofunctional and/or multifunctional monomers, oligomers, or polymers, (ii) an oxidizing agent; and (iii) acid-reactive glass, and the first part being free or substantially free of water; and the second part including (i) liquid monofunctional and/or multifunctional monomers, oligomers, or polymers, (ii) a reducing agent
Data Source
AI summary
A multi-part hardenable dental composition. A first part includes a mono- and/or multi-functional component having one or more ethylenically unsaturated group(s), acid-reactive glass particles, and an oxidizing agent. A second part includes a mono- and/or multi-functional component having one or more ethylenically unsaturated group(s), a water miscible polyacid, a reducing agent that includes an aromatic tertiary amine, an acid having a pKa less than that of carboxylic acid, and non-reactive filler.