Dental Adhesive Composition Storage Stability
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Solution Overview
Problem
Dental adhesive compositions containing polyvalent metal ions and acidic group-containing polymerizable monomers, such as those with hydrogenphosphoric diester groups, face issues with storage stability due to excessive ionic bonding, leading to gelation and cloudiness, which affects adhering strength and appearance.
Innovation Solution
Incorporating fluoride ions with polyvalent metal ions in a specific valence number ratio, along with a polymerizable monomer having a hydrogenphosphoric diester group, to prevent gelation and cloudiness, ensuring the adhesive remains stable and effective during storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the adhesive composition contains a high concentration of acidic group-containing polymerizable monomer and polyvalent metal ions to increase adhering strength, then the adhering strength to the tooth is improved, but the composition undergoes excessive ionic bonding during storage leading to gelation and cloudiness
Solution Approach 1:
The patent introduces a specific ratio of monovalent metal ions as an intermediary component to modulate the ionic bonding between polyvalent metal ions and acidic groups. The monovalent metal ions compete for binding sites and reduce excessive crosslinking, preventing gelation while maintaining adequate adhering strength. This intermediary approach allows the system to achieve both high adhesion and storage stability.
Solution Approach 2:
The patent precisely controls the concentration ratios of different metal ions (polyvalent to monovalent ratio) and acidic group contents to optimize the balance between adhesion and stability. By adjusting these parameters, the composition achieves sufficient ionic bonding for strong adhesion while preventing excessive crosslinking that would cause gelation during storage.
2Strength
If the adhesive composition contains high concentration of polyvalent metal ions and acidic group-containing monomer, then the adhering strength is improved, but the liquid composition becomes cloudy and nozzle clogging occurs
Solution Approach 1:
Monovalent metal ions serve as a moderating intermediary that prevents excessive interaction between polyvalent metal ions and acidic groups. This reduces the formation of large aggregated structures that cause cloudiness and nozzle clogging, while still maintaining sufficient adhesion through controlled ionic bonding.
Solution Approach 2:
The patent optimizes the concentration parameters of metal ions and acidic groups to achieve a balance where adhesion is sufficient but excessive crosslinking is prevented. This parameter control ensures the composition remains liquid and applicable while providing strong bonding performance.
3Adaptability or versatility
If the adhesive composition contains high concentration of acidic group-containing polymerizable monomer, then the affinity to tooth (hydroxyapatite or collagen) is improved, but excessive ionic bonding occurs during storage causing gelation
Solution Approach 1:
The monovalent metal ions act as a buffer intermediary that moderates the interaction between acidic groups and polyvalent metal ions. This prevents excessive crosslinking that would cause gelation, while allowing sufficient affinity to tooth structures through controlled ionic bonding.
Solution Approach 2:
The patent carefully adjusts the concentration of acidic groups and metal ions to optimize the balance between tooth affinity and storage stability. By controlling these parameters, the composition maintains high affinity to hydroxyapatite and collagen without undergoing excessive ionic bonding during storage.
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 dental adhesive composition maintains high adhering strength to the tooth, prevents gelation and cloudiness, and ensures stable storage, preventing nozzle clogging and maintaining commercial value.
Implementation Method 1
the polymerizable monomer contained in the primer is polymerized and cured by the action of radicals formed by the adhesive at the time when the adhesive applied onto the primer undergoes the photo-curing reaction
Implementation Method 2
the polyvalent metal ions ionically bond to the acidic groups of the acidic group-containing polymerizable monomer to form a reinforced structure
Data Source
AI summary
[Problems] To provide a liquid dental adhesive composition which contains a phosphoric acid-type compound having a hydrogenphosphoric diester group as an acidic group-containing polymerizable monomer and, further, contains polyvalent metal ions, effectively preventing not only the gelation but also the formation of precipitates (cloudiness) during the storage. [Means for Solution] A dental adhesive composition which is acidic and contains an acidic group-containing polymerizable monomer (A), polyvalent metal ions (B), water (C), a water-soluble organic solvent (D) and fluoride ions (E), wherein at least 35% by mole of the acidic group-containing polymerizable monomer (A) is a phosphoric acid-type compound having a hydrogenphosphoric diester group, and the contents of the fluoride ions (E) and the polyvalent metal ions (B) are so set that a valence number ratio (RF) defined by the following formula (1): RF=VF/TVP wherein VF is a valence number of the fluoride ions (E) contained in the composition , and TVP is a total valence number of the polyvalent metal ions (B) contained in the composition, satisfies a range of 0.2 to 2.0.