pH-Sensitive Inorganic Microcapsules for Dental Redox Initiation
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Solution Overview
Problem
Existing dental microcapsules containing redox-initiator systems are not sufficiently stable to withstand high shear forces during kneading processes, which is necessary for preparing paste/paste compositions, and are not effectively released in these systems, leading to delayed curing reactions.
Innovation Solution
Development of microcapsules with a non-water-soluble redox-initiator system core encapsulated in a pH-sensitive inorganic shell, which is mechanically stable and releases the initiator upon contact with an acidic environment, facilitating fast and efficient curing of dental compositions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If microcapsules are made with polymeric material to store redox-initiator components, then they provide storage stability, but they are not sufficiently stable to withstand high shear forces during kneading processes for paste/paste compositions
Solution Approach 1:
The patent employs a composite shell structure combining inorganic material (such as silica or glass) with organic polymer material. This composite construction provides both the mechanical strength needed to withstand kneading shear forces and the chemical stability required for long-term storage of redox-initiator components. The inorganic component reinforces the shell while the polymer matrix provides flexibility and stability.
Solution Approach 2:
The patent modifies the shell wall composition by incorporating crosslinking agents that increase the crosslink density of the polymer network. This parameter change enhances the mechanical strength and shear resistance of the microcapsules without compromising their ability to protect and store the redox-initiator components effectively.
2Strength
If microcapsules are made more robust to withstand kneading forces, then they survive processing, but the mixing forces are not sufficiently strong to break them for releasing active reagents
Solution Approach 1:
The patent creates a shell structure with non-uniform properties - the shell wall has a differentiated structure with a dense outer layer for mechanical strength and a more porous or weaker inner region that facilitates controlled breakdown. This local quality variation allows the microcapsule to withstand processing forces while still enabling effective release of active reagents when subjected to mixing forces.
Solution Approach 2:
The patent employs a shell material composition that exhibits dynamic response to mechanical stress - remaining intact under low stress conditions during storage and processing, but undergoing controlled breakdown when exposed to the shear forces generated during mixing. This dynamic behavior enables both protection during storage and release during application.
3Ease of manufacture
If polymeric material is used for microcapsule shell, then encapsulation is achieved, but the microcapsules cannot be used for producing storage-stable pasty compositions
Solution Approach 1:
The patent uses a composite shell structure combining inorganic and organic materials that together provide both encapsulation functionality and storage stability in pasty compositions. The inorganic component (silica or glass) provides chemical inertness and stability, while the polymer component provides flexibility and encapsulation, enabling the microcapsules to maintain integrity in pasty formulations during storage.
4Ease of manufacture
If microcapsules are designed for powder compositions, then they are easy to prepare and stabilize, but they cannot be used for paste/paste compositions requiring kneading processes
Solution Approach 1:
The patent employs a composite shell structure that provides enhanced mechanical strength to withstand the shear forces of kneading processes required for paste/paste compositions, while maintaining the ease of preparation advantages. The reinforced shell allows the microcapsules to be incorporated into pasty formulations without requiring special handling or preparation procedures.
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 microcapsules ensure stable processing and rapid release of the redox-initiator, enabling efficient curing of dental compositions without affecting the setting behavior, allowing for higher loading capacity and improved shelf-life stability of the redox-initiator components.
Implementation Method 1
the shell being composed of a pH-sensitive material... the pH-sensitive inorganic component, the microcapsules not comprising a polymeric material... wherein the pH-sensitive inorganic component is dissolved
Implementation Method 2
microcapsules comprising a non water-soluble first component of a redox-initiator system... containing a component of a redox-initiator system
Data Source
AI summary
The invention relates to a dental composition comprising a polymerizable component not comprising an acidic moiety, and microcapsules comprising a first component of a non water-soluble redox-initiator system, and a pH-sensitive inorganic component, the microcapsules not comprising a polymeric material. The invention also relates to the use of certain microcapsules for preparing a curable dental composition and to a process of curing a dental composition, as well as a device for storing the dental composition.