Dental Curable Composition Segmentation for Adhesion Stability
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Solution Overview
Problem
Conventional dental adhesives with chemical polymerization initiators experience a significant decrease in adhesion strength over time, especially in severe oral cavity environments, due to excessive ionic crosslinking during storage, leading to poor durability and peeling of composite resin or prosthetic materials.
Innovation Solution
A dental curable composition is developed with a chemical polymerization initiator, containing an acidic group-containing polymerizable monomer, water, and polyvalent metal ions, where the components are stored in separate packages to control ionic crosslinking, ensuring the polyvalent metal ions and acidic monomer are present together only at the time of use, enhancing curing and adhesion strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polyvalent metal ions and acidic monomer are stored together to enable ionic crosslinking, then adhesion strength to teeth is improved, but excessive crosslinking occurs during storage leading to gel formation and reduced durability
Solution Approach 1:
The curable composition is divided into multiple separate packages: one package contains the acidic group-containing polymerizable monomer, another package contains the polyvalent metal ion-eluting filler, and a third package contains the chemical polymerization initiator. This segmentation prevents premature contact between components that would cause excessive ionic crosslinking during storage, while enabling all components to be present together at the application site for optimal adhesion strength and durability.
Solution Approach 2:
The acidic group-containing polymerizable monomer is prepared in advance with the capability to form ionic crosslinking structures, but the actual crosslinking is controlled to occur only when needed. The monomer is stored separately from the polyvalent metal ion source, allowing the system to be pre-prepared for high adhesion strength without actually forming the crosslinked structure until the moment of application, thus preventing storage instability.
2Adaptability or versatility
If chemical polymerization initiator is used to enable curing without light, then adhesion to non-light-transmitting materials is improved, but polymerization control becomes less precise
Solution Approach 1:
The chemical polymerization initiator is stored in a separate package from the monomer and filler components. This allows the initiator to be introduced locally at the application site only when needed, enabling precise control of the polymerization timing and location. The spatial separation maintains the advantage of chemical polymerization (curing without light) while improving control by preventing premature or uncontrolled polymerization during storage and handling.
3Strength
If ionic crosslinking is formed during storage to enhance adhesion, then initial bond strength is improved, but durability decreases due to peeling over time
Solution Approach 1:
The system segments the ionic crosslinking formation process into two distinct phases: storage phase (where components are separated and no crosslinking occurs) and application phase (where all components are present together and controlled crosslinking occurs). This segmentation ensures that ionic crosslinking structures are formed under controlled conditions at the application site, producing durable bonds that resist peeling over time, rather than forming uncontrolled crosslinked networks during storage that compromise long-term reliability.
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 composition achieves improved curing and adhesion strength, maintaining high adhesion to teeth and prosthetic materials for extended periods, even in harsh oral conditions, by optimizing the packaging and formulation to delay excessive crosslinking.
Implementation Method 1
a chemical polymerization initiator component (C) comprising a radical-generating species and a reactive species that generates radicals upon reacting with the radical-generating species
Implementation Method 2
generates radicals which serve as polymerization-initiating species upon contacting these two components together
Implementation Method 3
polyvalent metal ions eluted out from the polyvalent metal ion-eluting filler at the time of curing ionically bond to the acidic groups of the acidic group-containing polymerizable monomer to form ionic crosslinking
Implementation Method 4
acidic groups such as phosphoric acid group and carboxylic acid group have a high affinity to the teeth (hydroxyapatite or collagen)
Implementation Method 5
the adhesive containing the acidic group-containing polymerizable monomer exhibits both the demineralizing function (etching capability) and the penetrating function to the teeth owing to the action of the acidic group
Data Source
AI summary
[Problems] To provide a chemical polymerization type curable composition which can achieve a very large strength of adhesion even without irradiated with light, and is used in the field of dental therapy. [Means for Solution] A dental curable composition comprising (A) a polymerizable monomer component containing an acidic group-containing polymerizable monomer, (B) water, and (C) a chemical polymerization initiator component comprising a radical-generating species and a reactive species that generates radicals upon reacting with the radical-generating species; wherein, the dental curable composition is stored being divided into a plurality of packages, and is polymerized and cured by mixing together the components contained in the packages; and wherein one package (I) among the packages contains the component (A) and the component (B), and, further, contains polyvalent metal ions in an amount of 0.3 to 10 meq per gram of the polymerizable monomer component (A) contained in the package; and the chemical polymerization initiator (C) is stored being divided into at least two packages so that the radical-generating species and the reactive species do not come in contact with each other.